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      1 /*
      2  * Copyright (C) 1999 Lars Knoll (knoll (at) kde.org)
      3  *           (C) 1999 Antti Koivisto (koivisto (at) kde.org)
      4  *           (C) 2005 Allan Sandfeld Jensen (kde (at) carewolf.com)
      5  *           (C) 2005, 2006 Samuel Weinig (sam.weinig (at) gmail.com)
      6  * Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010 Apple Inc. All rights reserved.
      7  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
      8  *
      9  * This library is free software; you can redistribute it and/or
     10  * modify it under the terms of the GNU Library General Public
     11  * License as published by the Free Software Foundation; either
     12  * version 2 of the License, or (at your option) any later version.
     13  *
     14  * This library is distributed in the hope that it will be useful,
     15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
     16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     17  * Library General Public License for more details.
     18  *
     19  * You should have received a copy of the GNU Library General Public License
     20  * along with this library; see the file COPYING.LIB.  If not, write to
     21  * the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     22  * Boston, MA 02110-1301, USA.
     23  *
     24  */
     25 
     26 #include "config.h"
     27 #include "core/rendering/RenderBox.h"
     28 
     29 #include "core/HTMLNames.h"
     30 #include "core/dom/Document.h"
     31 #include "core/editing/htmlediting.h"
     32 #include "core/frame/FrameHost.h"
     33 #include "core/frame/FrameView.h"
     34 #include "core/frame/LocalFrame.h"
     35 #include "core/frame/PinchViewport.h"
     36 #include "core/frame/Settings.h"
     37 #include "core/html/HTMLElement.h"
     38 #include "core/html/HTMLFrameElementBase.h"
     39 #include "core/html/HTMLFrameOwnerElement.h"
     40 #include "core/page/AutoscrollController.h"
     41 #include "core/page/EventHandler.h"
     42 #include "core/page/Page.h"
     43 #include "core/paint/BackgroundImageGeometry.h"
     44 #include "core/paint/BoxPainter.h"
     45 #include "core/rendering/HitTestResult.h"
     46 #include "core/rendering/PaintInfo.h"
     47 #include "core/rendering/RenderDeprecatedFlexibleBox.h"
     48 #include "core/rendering/RenderFlexibleBox.h"
     49 #include "core/rendering/RenderGeometryMap.h"
     50 #include "core/rendering/RenderGrid.h"
     51 #include "core/rendering/RenderInline.h"
     52 #include "core/rendering/RenderLayer.h"
     53 #include "core/rendering/RenderListBox.h"
     54 #include "core/rendering/RenderListMarker.h"
     55 #include "core/rendering/RenderTableCell.h"
     56 #include "core/rendering/RenderView.h"
     57 #include "core/rendering/compositing/RenderLayerCompositor.h"
     58 #include "platform/LengthFunctions.h"
     59 #include "platform/geometry/FloatQuad.h"
     60 #include "platform/geometry/TransformState.h"
     61 #include <algorithm>
     62 #include <math.h>
     63 
     64 namespace blink {
     65 
     66 using namespace HTMLNames;
     67 
     68 // Used by flexible boxes when flexing this element and by table cells.
     69 typedef WTF::HashMap<const RenderBox*, LayoutUnit> OverrideSizeMap;
     70 
     71 // Used by grid elements to properly size their grid items.
     72 // FIXME: Move these into RenderBoxRareData.
     73 static OverrideSizeMap* gOverrideContainingBlockLogicalHeightMap = 0;
     74 static OverrideSizeMap* gOverrideContainingBlockLogicalWidthMap = 0;
     75 
     76 
     77 // Size of border belt for autoscroll. When mouse pointer in border belt,
     78 // autoscroll is started.
     79 static const int autoscrollBeltSize = 20;
     80 static const unsigned backgroundObscurationTestMaxDepth = 4;
     81 
     82 static bool skipBodyBackground(const RenderBox* bodyElementRenderer)
     83 {
     84     ASSERT(bodyElementRenderer->isBody());
     85     // The <body> only paints its background if the root element has defined a background independent of the body,
     86     // or if the <body>'s parent is not the document element's renderer (e.g. inside SVG foreignObject).
     87     RenderObject* documentElementRenderer = bodyElementRenderer->document().documentElement()->renderer();
     88     return documentElementRenderer
     89         && !documentElementRenderer->hasBackground()
     90         && (documentElementRenderer == bodyElementRenderer->parent());
     91 }
     92 
     93 RenderBox::RenderBox(ContainerNode* node)
     94     : RenderBoxModelObject(node)
     95     , m_intrinsicContentLogicalHeight(-1)
     96     , m_minPreferredLogicalWidth(-1)
     97     , m_maxPreferredLogicalWidth(-1)
     98 {
     99     setIsBox();
    100 }
    101 
    102 void RenderBox::willBeDestroyed()
    103 {
    104     clearOverrideSize();
    105     clearContainingBlockOverrideSize();
    106 
    107     RenderBlock::removePercentHeightDescendantIfNeeded(this);
    108 
    109     ShapeOutsideInfo::removeInfo(*this);
    110 
    111     RenderBoxModelObject::willBeDestroyed();
    112 }
    113 
    114 void RenderBox::removeFloatingOrPositionedChildFromBlockLists()
    115 {
    116     ASSERT(isFloatingOrOutOfFlowPositioned());
    117 
    118     if (documentBeingDestroyed())
    119         return;
    120 
    121     if (isFloating()) {
    122         RenderBlockFlow* parentBlockFlow = 0;
    123         for (RenderObject* curr = parent(); curr && !curr->isRenderView(); curr = curr->parent()) {
    124             if (curr->isRenderBlockFlow()) {
    125                 RenderBlockFlow* currBlockFlow = toRenderBlockFlow(curr);
    126                 if (!parentBlockFlow || currBlockFlow->containsFloat(this))
    127                     parentBlockFlow = currBlockFlow;
    128             }
    129         }
    130 
    131         if (parentBlockFlow) {
    132             parentBlockFlow->markSiblingsWithFloatsForLayout(this);
    133             parentBlockFlow->markAllDescendantsWithFloatsForLayout(this, false);
    134         }
    135     }
    136 
    137     if (isOutOfFlowPositioned())
    138         RenderBlock::removePositionedObject(this);
    139 }
    140 
    141 void RenderBox::styleWillChange(StyleDifference diff, const RenderStyle& newStyle)
    142 {
    143     RenderStyle* oldStyle = style();
    144     if (oldStyle) {
    145         // The background of the root element or the body element could propagate up to
    146         // the canvas. Just dirty the entire canvas when our style changes substantially.
    147         if ((diff.needsPaintInvalidation() || diff.needsLayout()) && node()
    148             && (isHTMLHtmlElement(*node()) || isHTMLBodyElement(*node()))) {
    149             view()->setShouldDoFullPaintInvalidation(true);
    150 
    151             if (oldStyle->hasEntirelyFixedBackground() != newStyle.hasEntirelyFixedBackground())
    152                 view()->compositor()->setNeedsUpdateFixedBackground();
    153         }
    154 
    155         // When a layout hint happens and an object's position style changes, we have to do a layout
    156         // to dirty the render tree using the old position value now.
    157         if (diff.needsFullLayout() && parent() && oldStyle->position() != newStyle.position()) {
    158             markContainingBlocksForLayout();
    159             if (oldStyle->position() == StaticPosition)
    160                 setShouldDoFullPaintInvalidation(true);
    161             else if (newStyle.hasOutOfFlowPosition())
    162                 parent()->setChildNeedsLayout();
    163             if (isFloating() && !isOutOfFlowPositioned() && newStyle.hasOutOfFlowPosition())
    164                 removeFloatingOrPositionedChildFromBlockLists();
    165         }
    166     // FIXME: This branch runs when !oldStyle, which means that layout was never called
    167     // so what's the point in invalidating the whole view that we never painted?
    168     } else if (isBody()) {
    169         view()->setShouldDoFullPaintInvalidation(true);
    170     }
    171 
    172     RenderBoxModelObject::styleWillChange(diff, newStyle);
    173 }
    174 
    175 void RenderBox::styleDidChange(StyleDifference diff, const RenderStyle* oldStyle)
    176 {
    177     // Horizontal writing mode definition is updated in RenderBoxModelObject::updateFromStyle,
    178     // (as part of the RenderBoxModelObject::styleDidChange call below). So, we can safely cache the horizontal
    179     // writing mode value before style change here.
    180     bool oldHorizontalWritingMode = isHorizontalWritingMode();
    181 
    182     RenderBoxModelObject::styleDidChange(diff, oldStyle);
    183 
    184     RenderStyle* newStyle = style();
    185     if (needsLayout() && oldStyle)
    186         RenderBlock::removePercentHeightDescendantIfNeeded(this);
    187 
    188     if (RenderBlock::hasPercentHeightContainerMap() && slowFirstChild()
    189         && oldHorizontalWritingMode != isHorizontalWritingMode())
    190         RenderBlock::clearPercentHeightDescendantsFrom(this);
    191 
    192     // If our zoom factor changes and we have a defined scrollLeft/Top, we need to adjust that value into the
    193     // new zoomed coordinate space.
    194     if (hasOverflowClip() && oldStyle && newStyle && oldStyle->effectiveZoom() != newStyle->effectiveZoom() && layer()) {
    195         if (int left = layer()->scrollableArea()->scrollXOffset()) {
    196             left = (left / oldStyle->effectiveZoom()) * newStyle->effectiveZoom();
    197             layer()->scrollableArea()->scrollToXOffset(left);
    198         }
    199         if (int top = layer()->scrollableArea()->scrollYOffset()) {
    200             top = (top / oldStyle->effectiveZoom()) * newStyle->effectiveZoom();
    201             layer()->scrollableArea()->scrollToYOffset(top);
    202         }
    203     }
    204 
    205     // Our opaqueness might have changed without triggering layout.
    206     if (diff.needsPaintInvalidation()) {
    207         RenderObject* parentToInvalidate = parent();
    208         for (unsigned i = 0; i < backgroundObscurationTestMaxDepth && parentToInvalidate; ++i) {
    209             parentToInvalidate->invalidateBackgroundObscurationStatus();
    210             parentToInvalidate = parentToInvalidate->parent();
    211         }
    212     }
    213 
    214     if (isDocumentElement() || isBody())
    215         document().view()->recalculateScrollbarOverlayStyle();
    216 
    217     updateShapeOutsideInfoAfterStyleChange(*style(), oldStyle);
    218     updateGridPositionAfterStyleChange(oldStyle);
    219 }
    220 
    221 void RenderBox::updateShapeOutsideInfoAfterStyleChange(const RenderStyle& style, const RenderStyle* oldStyle)
    222 {
    223     const ShapeValue* shapeOutside = style.shapeOutside();
    224     const ShapeValue* oldShapeOutside = oldStyle ? oldStyle->shapeOutside() : RenderStyle::initialShapeOutside();
    225 
    226     Length shapeMargin = style.shapeMargin();
    227     Length oldShapeMargin = oldStyle ? oldStyle->shapeMargin() : RenderStyle::initialShapeMargin();
    228 
    229     float shapeImageThreshold = style.shapeImageThreshold();
    230     float oldShapeImageThreshold = oldStyle ? oldStyle->shapeImageThreshold() : RenderStyle::initialShapeImageThreshold();
    231 
    232     // FIXME: A future optimization would do a deep comparison for equality. (bug 100811)
    233     if (shapeOutside == oldShapeOutside && shapeMargin == oldShapeMargin && shapeImageThreshold == oldShapeImageThreshold)
    234         return;
    235 
    236     if (!shapeOutside)
    237         ShapeOutsideInfo::removeInfo(*this);
    238     else
    239         ShapeOutsideInfo::ensureInfo(*this).markShapeAsDirty();
    240 
    241     if (shapeOutside || shapeOutside != oldShapeOutside)
    242         markShapeOutsideDependentsForLayout();
    243 }
    244 
    245 void RenderBox::updateGridPositionAfterStyleChange(const RenderStyle* oldStyle)
    246 {
    247     if (!oldStyle || !parent() || !parent()->isRenderGrid())
    248         return;
    249 
    250     if (oldStyle->gridColumnStart() == style()->gridColumnStart()
    251         && oldStyle->gridColumnEnd() == style()->gridColumnEnd()
    252         && oldStyle->gridRowStart() == style()->gridRowStart()
    253         && oldStyle->gridRowEnd() == style()->gridRowEnd()
    254         && oldStyle->order() == style()->order()
    255         && oldStyle->hasOutOfFlowPosition() == style()->hasOutOfFlowPosition())
    256         return;
    257 
    258     // It should be possible to not dirty the grid in some cases (like moving an explicitly placed grid item).
    259     // For now, it's more simple to just always recompute the grid.
    260     toRenderGrid(parent())->dirtyGrid();
    261 }
    262 
    263 void RenderBox::updateFromStyle()
    264 {
    265     RenderBoxModelObject::updateFromStyle();
    266 
    267     RenderStyle* styleToUse = style();
    268     bool isRootObject = isDocumentElement();
    269     bool isViewObject = isRenderView();
    270 
    271     // The root and the RenderView always paint their backgrounds/borders.
    272     if (isRootObject || isViewObject)
    273         setHasBoxDecorationBackground(true);
    274 
    275     setFloating(!isOutOfFlowPositioned() && styleToUse->isFloating());
    276 
    277     bool boxHasOverflowClip = false;
    278     if (!styleToUse->isOverflowVisible() && isRenderBlock() && !isViewObject) {
    279         // If overflow has been propagated to the viewport, it has no effect here.
    280         if (node() != document().viewportDefiningElement())
    281             boxHasOverflowClip = true;
    282     }
    283 
    284     if (boxHasOverflowClip != hasOverflowClip()) {
    285         // FIXME: This shouldn't be required if we tracked the visual overflow
    286         // generated by positioned children or self painting layers. crbug.com/345403
    287         for (RenderObject* child = slowFirstChild(); child; child = child->nextSibling())
    288             child->setShouldDoFullPaintInvalidationIfSelfPaintingLayer(true);
    289     }
    290 
    291     setHasOverflowClip(boxHasOverflowClip);
    292 
    293     setHasTransform(styleToUse->hasTransformRelatedProperty());
    294     setHasReflection(styleToUse->boxReflect());
    295 }
    296 
    297 void RenderBox::layout()
    298 {
    299     ASSERT(needsLayout());
    300 
    301     RenderObject* child = slowFirstChild();
    302     if (!child) {
    303         clearNeedsLayout();
    304         return;
    305     }
    306 
    307     LayoutState state(*this, locationOffset());
    308     while (child) {
    309         child->layoutIfNeeded();
    310         ASSERT(!child->needsLayout());
    311         child = child->nextSibling();
    312     }
    313     invalidateBackgroundObscurationStatus();
    314     clearNeedsLayout();
    315 }
    316 
    317 // More IE extensions.  clientWidth and clientHeight represent the interior of an object
    318 // excluding border and scrollbar.
    319 LayoutUnit RenderBox::clientWidth() const
    320 {
    321     return width() - borderLeft() - borderRight() - verticalScrollbarWidth();
    322 }
    323 
    324 LayoutUnit RenderBox::clientHeight() const
    325 {
    326     return height() - borderTop() - borderBottom() - horizontalScrollbarHeight();
    327 }
    328 
    329 int RenderBox::pixelSnappedClientWidth() const
    330 {
    331     return snapSizeToPixel(clientWidth(), x() + clientLeft());
    332 }
    333 
    334 int RenderBox::pixelSnappedClientHeight() const
    335 {
    336     return snapSizeToPixel(clientHeight(), y() + clientTop());
    337 }
    338 
    339 int RenderBox::pixelSnappedOffsetWidth() const
    340 {
    341     return snapSizeToPixel(offsetWidth(), x() + clientLeft());
    342 }
    343 
    344 int RenderBox::pixelSnappedOffsetHeight() const
    345 {
    346     return snapSizeToPixel(offsetHeight(), y() + clientTop());
    347 }
    348 
    349 LayoutUnit RenderBox::scrollWidth() const
    350 {
    351     if (hasOverflowClip())
    352         return layer()->scrollableArea()->scrollWidth();
    353     // For objects with visible overflow, this matches IE.
    354     // FIXME: Need to work right with writing modes.
    355     if (style()->isLeftToRightDirection())
    356         return std::max(clientWidth(), layoutOverflowRect().maxX() - borderLeft());
    357     return clientWidth() - std::min<LayoutUnit>(0, layoutOverflowRect().x() - borderLeft());
    358 }
    359 
    360 LayoutUnit RenderBox::scrollHeight() const
    361 {
    362     if (hasOverflowClip())
    363         return layer()->scrollableArea()->scrollHeight();
    364     // For objects with visible overflow, this matches IE.
    365     // FIXME: Need to work right with writing modes.
    366     return std::max(clientHeight(), layoutOverflowRect().maxY() - borderTop());
    367 }
    368 
    369 LayoutUnit RenderBox::scrollLeft() const
    370 {
    371     return hasOverflowClip() ? layer()->scrollableArea()->scrollXOffset() : 0;
    372 }
    373 
    374 LayoutUnit RenderBox::scrollTop() const
    375 {
    376     return hasOverflowClip() ? layer()->scrollableArea()->scrollYOffset() : 0;
    377 }
    378 
    379 int RenderBox::pixelSnappedScrollWidth() const
    380 {
    381     return snapSizeToPixel(scrollWidth(), x() + clientLeft());
    382 }
    383 
    384 int RenderBox::pixelSnappedScrollHeight() const
    385 {
    386     if (hasOverflowClip())
    387         return layer()->scrollableArea()->scrollHeight();
    388     // For objects with visible overflow, this matches IE.
    389     // FIXME: Need to work right with writing modes.
    390     return snapSizeToPixel(scrollHeight(), y() + clientTop());
    391 }
    392 
    393 void RenderBox::setScrollLeft(LayoutUnit newLeft)
    394 {
    395     // This doesn't hit in any tests, but since the equivalent code in setScrollTop
    396     // does, presumably this code does as well.
    397     DisableCompositingQueryAsserts disabler;
    398 
    399     if (hasOverflowClip())
    400         layer()->scrollableArea()->scrollToXOffset(newLeft, ScrollOffsetClamped);
    401 }
    402 
    403 void RenderBox::setScrollTop(LayoutUnit newTop)
    404 {
    405     // Hits in compositing/overflow/do-not-assert-on-invisible-composited-layers.html
    406     DisableCompositingQueryAsserts disabler;
    407 
    408     if (hasOverflowClip())
    409         layer()->scrollableArea()->scrollToYOffset(newTop, ScrollOffsetClamped);
    410 }
    411 
    412 void RenderBox::scrollToOffset(const IntSize& offset)
    413 {
    414     ASSERT(hasOverflowClip());
    415 
    416     // This doesn't hit in any tests, but since the equivalent code in setScrollTop
    417     // does, presumably this code does as well.
    418     DisableCompositingQueryAsserts disabler;
    419     layer()->scrollableArea()->scrollToOffset(offset, ScrollOffsetClamped);
    420 }
    421 
    422 static inline bool frameElementAndViewPermitScroll(HTMLFrameElementBase* frameElementBase, FrameView* frameView)
    423 {
    424     // If scrollbars aren't explicitly forbidden, permit scrolling.
    425     if (frameElementBase && frameElementBase->scrollingMode() != ScrollbarAlwaysOff)
    426         return true;
    427 
    428     // If scrollbars are forbidden, user initiated scrolls should obviously be ignored.
    429     if (frameView->wasScrolledByUser())
    430         return false;
    431 
    432     // Forbid autoscrolls when scrollbars are off, but permits other programmatic scrolls,
    433     // like navigation to an anchor.
    434     Page* page = frameView->frame().page();
    435     if (!page)
    436         return false;
    437     return !page->autoscrollController().autoscrollInProgress();
    438 }
    439 
    440 void RenderBox::scrollRectToVisible(const LayoutRect& rect, const ScrollAlignment& alignX, const ScrollAlignment& alignY)
    441 {
    442     // Presumably the same issue as in setScrollTop. See crbug.com/343132.
    443     DisableCompositingQueryAsserts disabler;
    444 
    445     RenderBox* parentBox = 0;
    446     LayoutRect newRect = rect;
    447 
    448     bool restrictedByLineClamp = false;
    449     if (parent()) {
    450         parentBox = parent()->enclosingBox();
    451         restrictedByLineClamp = !parent()->style()->lineClamp().isNone();
    452     }
    453 
    454     if (hasOverflowClip() && !restrictedByLineClamp) {
    455         // Don't scroll to reveal an overflow layer that is restricted by the -webkit-line-clamp property.
    456         // This will prevent us from revealing text hidden by the slider in Safari RSS.
    457         newRect = layer()->scrollableArea()->exposeRect(rect, alignX, alignY);
    458     } else if (!parentBox && canBeProgramaticallyScrolled()) {
    459         if (FrameView* frameView = this->frameView()) {
    460             HTMLFrameOwnerElement* ownerElement = document().ownerElement();
    461 
    462             if (ownerElement && ownerElement->renderer()) {
    463                 HTMLFrameElementBase* frameElementBase = isHTMLFrameElementBase(*ownerElement) ? toHTMLFrameElementBase(ownerElement) : 0;
    464                 if (frameElementAndViewPermitScroll(frameElementBase, frameView)) {
    465                     LayoutRect viewRect = frameView->visibleContentRect();
    466                     LayoutRect exposeRect = ScrollAlignment::getRectToExpose(viewRect, rect, alignX, alignY);
    467 
    468                     int xOffset = roundToInt(exposeRect.x());
    469                     int yOffset = roundToInt(exposeRect.y());
    470                     // Adjust offsets if they're outside of the allowable range.
    471                     xOffset = std::max(0, std::min(frameView->contentsWidth(), xOffset));
    472                     yOffset = std::max(0, std::min(frameView->contentsHeight(), yOffset));
    473 
    474                     frameView->setScrollPosition(IntPoint(xOffset, yOffset));
    475                     if (frameView->safeToPropagateScrollToParent()) {
    476                         parentBox = ownerElement->renderer()->enclosingBox();
    477                         // FIXME: This doesn't correctly convert the rect to
    478                         // absolute coordinates in the parent.
    479                         newRect.setX(rect.x() - frameView->scrollX() + frameView->x());
    480                         newRect.setY(rect.y() - frameView->scrollY() + frameView->y());
    481                     } else {
    482                         parentBox = 0;
    483                     }
    484                 }
    485             } else {
    486                 if (frame()->settings()->pinchVirtualViewportEnabled()) {
    487                     PinchViewport& pinchViewport = frame()->page()->frameHost().pinchViewport();
    488                     LayoutRect r = ScrollAlignment::getRectToExpose(LayoutRect(pinchViewport.visibleRectInDocument()), rect, alignX, alignY);
    489                     pinchViewport.scrollIntoView(r);
    490                 } else {
    491                     LayoutRect viewRect = frameView->visibleContentRect();
    492                     LayoutRect r = ScrollAlignment::getRectToExpose(viewRect, rect, alignX, alignY);
    493                     frameView->setScrollPosition(roundedIntPoint(r.location()));
    494                 }
    495             }
    496         }
    497     }
    498 
    499     if (frame()->page()->autoscrollController().autoscrollInProgress())
    500         parentBox = enclosingScrollableBox();
    501 
    502     if (parentBox)
    503         parentBox->scrollRectToVisible(newRect, alignX, alignY);
    504 }
    505 
    506 void RenderBox::absoluteRects(Vector<IntRect>& rects, const LayoutPoint& accumulatedOffset) const
    507 {
    508     rects.append(pixelSnappedIntRect(accumulatedOffset, size()));
    509 }
    510 
    511 void RenderBox::absoluteQuads(Vector<FloatQuad>& quads, bool* wasFixed) const
    512 {
    513     quads.append(localToAbsoluteQuad(FloatRect(0, 0, width().toFloat(), height().toFloat()), 0 /* mode */, wasFixed));
    514 }
    515 
    516 void RenderBox::updateLayerTransformAfterLayout()
    517 {
    518     // Transform-origin depends on box size, so we need to update the layer transform after layout.
    519     if (hasLayer())
    520         layer()->updateTransformationMatrix();
    521 }
    522 
    523 LayoutUnit RenderBox::constrainLogicalWidthByMinMax(LayoutUnit logicalWidth, LayoutUnit availableWidth, RenderBlock* cb) const
    524 {
    525     RenderStyle* styleToUse = style();
    526     if (!styleToUse->logicalMaxWidth().isMaxSizeNone())
    527         logicalWidth = std::min(logicalWidth, computeLogicalWidthUsing(MaxSize, styleToUse->logicalMaxWidth(), availableWidth, cb));
    528     return std::max(logicalWidth, computeLogicalWidthUsing(MinSize, styleToUse->logicalMinWidth(), availableWidth, cb));
    529 }
    530 
    531 LayoutUnit RenderBox::constrainLogicalHeightByMinMax(LayoutUnit logicalHeight, LayoutUnit intrinsicContentHeight) const
    532 {
    533     RenderStyle* styleToUse = style();
    534     if (!styleToUse->logicalMaxHeight().isMaxSizeNone()) {
    535         LayoutUnit maxH = computeLogicalHeightUsing(styleToUse->logicalMaxHeight(), intrinsicContentHeight);
    536         if (maxH != -1)
    537             logicalHeight = std::min(logicalHeight, maxH);
    538     }
    539     return std::max(logicalHeight, computeLogicalHeightUsing(styleToUse->logicalMinHeight(), intrinsicContentHeight));
    540 }
    541 
    542 LayoutUnit RenderBox::constrainContentBoxLogicalHeightByMinMax(LayoutUnit logicalHeight, LayoutUnit intrinsicContentHeight) const
    543 {
    544     RenderStyle* styleToUse = style();
    545     if (!styleToUse->logicalMaxHeight().isMaxSizeNone()) {
    546         LayoutUnit maxH = computeContentLogicalHeight(styleToUse->logicalMaxHeight(), intrinsicContentHeight);
    547         if (maxH != -1)
    548             logicalHeight = std::min(logicalHeight, maxH);
    549     }
    550     return std::max(logicalHeight, computeContentLogicalHeight(styleToUse->logicalMinHeight(), intrinsicContentHeight));
    551 }
    552 
    553 IntRect RenderBox::absoluteContentBox() const
    554 {
    555     // This is wrong with transforms and flipped writing modes.
    556     IntRect rect = pixelSnappedIntRect(contentBoxRect());
    557     FloatPoint absPos = localToAbsolute();
    558     rect.move(absPos.x(), absPos.y());
    559     return rect;
    560 }
    561 
    562 FloatQuad RenderBox::absoluteContentQuad() const
    563 {
    564     LayoutRect rect = contentBoxRect();
    565     return localToAbsoluteQuad(FloatRect(rect));
    566 }
    567 
    568 void RenderBox::addFocusRingRects(Vector<LayoutRect>& rects, const LayoutPoint& additionalOffset, const RenderLayerModelObject*) const
    569 {
    570     if (!size().isEmpty())
    571         rects.append(LayoutRect(additionalOffset, size()));
    572 }
    573 
    574 bool RenderBox::canResize() const
    575 {
    576     // We need a special case for <iframe> because they never have
    577     // hasOverflowClip(). However, they do "implicitly" clip their contents, so
    578     // we want to allow resizing them also.
    579     return (hasOverflowClip() || isRenderIFrame()) && style()->resize() != RESIZE_NONE;
    580 }
    581 
    582 void RenderBox::addLayerHitTestRects(LayerHitTestRects& layerRects, const RenderLayer* currentLayer, const LayoutPoint& layerOffset, const LayoutRect& containerRect) const
    583 {
    584     LayoutPoint adjustedLayerOffset = layerOffset + locationOffset();
    585     RenderBoxModelObject::addLayerHitTestRects(layerRects, currentLayer, adjustedLayerOffset, containerRect);
    586 }
    587 
    588 void RenderBox::computeSelfHitTestRects(Vector<LayoutRect>& rects, const LayoutPoint& layerOffset) const
    589 {
    590     if (!size().isEmpty())
    591         rects.append(LayoutRect(layerOffset, size()));
    592 }
    593 
    594 int RenderBox::reflectionOffset() const
    595 {
    596     if (!style()->boxReflect())
    597         return 0;
    598     if (style()->boxReflect()->direction() == ReflectionLeft || style()->boxReflect()->direction() == ReflectionRight)
    599         return valueForLength(style()->boxReflect()->offset(), borderBoxRect().width());
    600     return valueForLength(style()->boxReflect()->offset(), borderBoxRect().height());
    601 }
    602 
    603 LayoutRect RenderBox::reflectedRect(const LayoutRect& r) const
    604 {
    605     if (!style()->boxReflect())
    606         return LayoutRect();
    607 
    608     LayoutRect box = borderBoxRect();
    609     LayoutRect result = r;
    610     switch (style()->boxReflect()->direction()) {
    611         case ReflectionBelow:
    612             result.setY(box.maxY() + reflectionOffset() + (box.maxY() - r.maxY()));
    613             break;
    614         case ReflectionAbove:
    615             result.setY(box.y() - reflectionOffset() - box.height() + (box.maxY() - r.maxY()));
    616             break;
    617         case ReflectionLeft:
    618             result.setX(box.x() - reflectionOffset() - box.width() + (box.maxX() - r.maxX()));
    619             break;
    620         case ReflectionRight:
    621             result.setX(box.maxX() + reflectionOffset() + (box.maxX() - r.maxX()));
    622             break;
    623     }
    624     return result;
    625 }
    626 
    627 int RenderBox::verticalScrollbarWidth() const
    628 {
    629     if (!hasOverflowClip() || style()->overflowY() == OOVERLAY)
    630         return 0;
    631 
    632     return layer()->scrollableArea()->verticalScrollbarWidth();
    633 }
    634 
    635 int RenderBox::horizontalScrollbarHeight() const
    636 {
    637     if (!hasOverflowClip() || style()->overflowX() == OOVERLAY)
    638         return 0;
    639 
    640     return layer()->scrollableArea()->horizontalScrollbarHeight();
    641 }
    642 
    643 int RenderBox::instrinsicScrollbarLogicalWidth() const
    644 {
    645     if (!hasOverflowClip())
    646         return 0;
    647 
    648     if (isHorizontalWritingMode() && style()->overflowY() == OSCROLL) {
    649         ASSERT(layer()->scrollableArea() && layer()->scrollableArea()->hasVerticalScrollbar());
    650         return verticalScrollbarWidth();
    651     }
    652 
    653     if (!isHorizontalWritingMode() && style()->overflowX() == OSCROLL) {
    654         ASSERT(layer()->scrollableArea() && layer()->scrollableArea()->hasHorizontalScrollbar());
    655         return horizontalScrollbarHeight();
    656     }
    657 
    658     return 0;
    659 }
    660 
    661 bool RenderBox::scroll(ScrollDirection direction, ScrollGranularity granularity, float delta)
    662 {
    663     // Presumably the same issue as in setScrollTop. See crbug.com/343132.
    664     DisableCompositingQueryAsserts disabler;
    665 
    666     // Logical scroll is a higher level concept, all directions by here must be physical
    667     ASSERT(!isLogical(direction));
    668 
    669     if (!layer() || !layer()->scrollableArea())
    670         return false;
    671 
    672     return layer()->scrollableArea()->scroll(direction, granularity, delta);
    673 }
    674 
    675 bool RenderBox::canBeScrolledAndHasScrollableArea() const
    676 {
    677     return canBeProgramaticallyScrolled() && (pixelSnappedScrollHeight() != pixelSnappedClientHeight() || pixelSnappedScrollWidth() != pixelSnappedClientWidth());
    678 }
    679 
    680 bool RenderBox::canBeProgramaticallyScrolled() const
    681 {
    682     Node* node = this->node();
    683     if (node && node->isDocumentNode())
    684         return true;
    685 
    686     if (!hasOverflowClip())
    687         return false;
    688 
    689     bool hasScrollableOverflow = hasScrollableOverflowX() || hasScrollableOverflowY();
    690     if (scrollsOverflow() && hasScrollableOverflow)
    691         return true;
    692 
    693     return node && node->hasEditableStyle();
    694 }
    695 
    696 bool RenderBox::usesCompositedScrolling() const
    697 {
    698     return hasOverflowClip() && hasLayer() && layer()->scrollableArea()->usesCompositedScrolling();
    699 }
    700 
    701 void RenderBox::autoscroll(const IntPoint& position)
    702 {
    703     LocalFrame* frame = this->frame();
    704     if (!frame)
    705         return;
    706 
    707     FrameView* frameView = frame->view();
    708     if (!frameView)
    709         return;
    710 
    711     IntPoint currentDocumentPosition = frameView->windowToContents(position);
    712     scrollRectToVisible(LayoutRect(currentDocumentPosition, LayoutSize(1, 1)), ScrollAlignment::alignToEdgeIfNeeded, ScrollAlignment::alignToEdgeIfNeeded);
    713 }
    714 
    715 bool RenderBox::autoscrollInProgress() const
    716 {
    717     return frame() && frame()->page() && frame()->page()->autoscrollController().autoscrollInProgress(this);
    718 }
    719 
    720 // There are two kinds of renderer that can autoscroll.
    721 bool RenderBox::canAutoscroll() const
    722 {
    723     if (node() && node()->isDocumentNode())
    724         return view()->frameView()->isScrollable();
    725 
    726     // Check for a box that can be scrolled in its own right.
    727     return canBeScrolledAndHasScrollableArea();
    728 }
    729 
    730 // If specified point is in border belt, returned offset denotes direction of
    731 // scrolling.
    732 IntSize RenderBox::calculateAutoscrollDirection(const IntPoint& windowPoint) const
    733 {
    734     if (!frame())
    735         return IntSize();
    736 
    737     FrameView* frameView = frame()->view();
    738     if (!frameView)
    739         return IntSize();
    740 
    741     IntRect box(absoluteBoundingBoxRect());
    742     box.move(view()->frameView()->scrollOffset());
    743     IntRect windowBox = view()->frameView()->contentsToWindow(box);
    744 
    745     IntPoint windowAutoscrollPoint = windowPoint;
    746 
    747     if (windowAutoscrollPoint.x() < windowBox.x() + autoscrollBeltSize)
    748         windowAutoscrollPoint.move(-autoscrollBeltSize, 0);
    749     else if (windowAutoscrollPoint.x() > windowBox.maxX() - autoscrollBeltSize)
    750         windowAutoscrollPoint.move(autoscrollBeltSize, 0);
    751 
    752     if (windowAutoscrollPoint.y() < windowBox.y() + autoscrollBeltSize)
    753         windowAutoscrollPoint.move(0, -autoscrollBeltSize);
    754     else if (windowAutoscrollPoint.y() > windowBox.maxY() - autoscrollBeltSize)
    755         windowAutoscrollPoint.move(0, autoscrollBeltSize);
    756 
    757     return windowAutoscrollPoint - windowPoint;
    758 }
    759 
    760 RenderBox* RenderBox::findAutoscrollable(RenderObject* renderer)
    761 {
    762     while (renderer && !(renderer->isBox() && toRenderBox(renderer)->canAutoscroll())) {
    763         if (!renderer->parent() && renderer->node() == renderer->document() && renderer->document().ownerElement())
    764             renderer = renderer->document().ownerElement()->renderer();
    765         else
    766             renderer = renderer->parent();
    767     }
    768 
    769     return renderer && renderer->isBox() ? toRenderBox(renderer) : 0;
    770 }
    771 
    772 static inline int adjustedScrollDelta(int beginningDelta)
    773 {
    774     // This implemention matches Firefox's.
    775     // http://mxr.mozilla.org/firefox/source/toolkit/content/widgets/browser.xml#856.
    776     const int speedReducer = 12;
    777 
    778     int adjustedDelta = beginningDelta / speedReducer;
    779     if (adjustedDelta > 1)
    780         adjustedDelta = static_cast<int>(adjustedDelta * sqrt(static_cast<double>(adjustedDelta))) - 1;
    781     else if (adjustedDelta < -1)
    782         adjustedDelta = static_cast<int>(adjustedDelta * sqrt(static_cast<double>(-adjustedDelta))) + 1;
    783 
    784     return adjustedDelta;
    785 }
    786 
    787 static inline IntSize adjustedScrollDelta(const IntSize& delta)
    788 {
    789     return IntSize(adjustedScrollDelta(delta.width()), adjustedScrollDelta(delta.height()));
    790 }
    791 
    792 void RenderBox::panScroll(const IntPoint& sourcePoint)
    793 {
    794     LocalFrame* frame = this->frame();
    795     if (!frame)
    796         return;
    797 
    798     IntPoint lastKnownMousePosition = frame->eventHandler().lastKnownMousePosition();
    799 
    800     // We need to check if the last known mouse position is out of the window. When the mouse is out of the window, the position is incoherent
    801     static IntPoint previousMousePosition;
    802     if (lastKnownMousePosition.x() < 0 || lastKnownMousePosition.y() < 0)
    803         lastKnownMousePosition = previousMousePosition;
    804     else
    805         previousMousePosition = lastKnownMousePosition;
    806 
    807     IntSize delta = lastKnownMousePosition - sourcePoint;
    808 
    809     if (abs(delta.width()) <= ScrollView::noPanScrollRadius) // at the center we let the space for the icon
    810         delta.setWidth(0);
    811     if (abs(delta.height()) <= ScrollView::noPanScrollRadius)
    812         delta.setHeight(0);
    813 
    814     scrollByRecursively(adjustedScrollDelta(delta), ScrollOffsetClamped);
    815 }
    816 
    817 void RenderBox::scrollByRecursively(const IntSize& delta, ScrollOffsetClamping clamp)
    818 {
    819     if (delta.isZero())
    820         return;
    821 
    822     bool restrictedByLineClamp = false;
    823     if (parent())
    824         restrictedByLineClamp = !parent()->style()->lineClamp().isNone();
    825 
    826     if (hasOverflowClip() && !restrictedByLineClamp) {
    827         IntSize newScrollOffset = layer()->scrollableArea()->adjustedScrollOffset() + delta;
    828         layer()->scrollableArea()->scrollToOffset(newScrollOffset, clamp);
    829 
    830         // If this layer can't do the scroll we ask the next layer up that can scroll to try
    831         IntSize remainingScrollOffset = newScrollOffset - layer()->scrollableArea()->adjustedScrollOffset();
    832         if (!remainingScrollOffset.isZero() && parent()) {
    833             if (RenderBox* scrollableBox = enclosingScrollableBox())
    834                 scrollableBox->scrollByRecursively(remainingScrollOffset, clamp);
    835 
    836             LocalFrame* frame = this->frame();
    837             if (frame && frame->page())
    838                 frame->page()->autoscrollController().updateAutoscrollRenderer();
    839         }
    840     } else if (view()->frameView()) {
    841         // If we are here, we were called on a renderer that can be programmatically scrolled, but doesn't
    842         // have an overflow clip. Which means that it is a document node that can be scrolled.
    843         view()->frameView()->scrollBy(delta);
    844 
    845         // FIXME: If we didn't scroll the whole way, do we want to try looking at the frames ownerElement?
    846         // https://bugs.webkit.org/show_bug.cgi?id=28237
    847     }
    848 }
    849 
    850 bool RenderBox::needsPreferredWidthsRecalculation() const
    851 {
    852     return style()->paddingStart().isPercent() || style()->paddingEnd().isPercent();
    853 }
    854 
    855 IntSize RenderBox::scrolledContentOffset() const
    856 {
    857     ASSERT(hasOverflowClip());
    858     ASSERT(hasLayer());
    859     return layer()->scrollableArea()->scrollOffset();
    860 }
    861 
    862 void RenderBox::applyCachedClipAndScrollOffsetForPaintInvalidation(LayoutRect& paintRect) const
    863 {
    864     ASSERT(hasLayer());
    865     ASSERT(hasOverflowClip());
    866 
    867     flipForWritingMode(paintRect);
    868     paintRect.move(-scrolledContentOffset()); // For overflow:auto/scroll/hidden.
    869 
    870     // Do not clip scroll layer contents because the compositor expects the whole layer
    871     // to be always invalidated in-time.
    872     if (usesCompositedScrolling()) {
    873         flipForWritingMode(paintRect);
    874         return;
    875     }
    876 
    877     // height() is inaccurate if we're in the middle of a layout of this RenderBox, so use the
    878     // layer's size instead. Even if the layer's size is wrong, the layer itself will issue paint invalidations
    879     // anyway if its size does change.
    880     LayoutRect clipRect(LayoutPoint(), layer()->size());
    881     paintRect = intersection(paintRect, clipRect);
    882     flipForWritingMode(paintRect);
    883 }
    884 
    885 void RenderBox::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
    886 {
    887     minLogicalWidth = minPreferredLogicalWidth() - borderAndPaddingLogicalWidth();
    888     maxLogicalWidth = maxPreferredLogicalWidth() - borderAndPaddingLogicalWidth();
    889 }
    890 
    891 LayoutUnit RenderBox::minPreferredLogicalWidth() const
    892 {
    893     if (preferredLogicalWidthsDirty()) {
    894 #if ENABLE(ASSERT)
    895         SetLayoutNeededForbiddenScope layoutForbiddenScope(const_cast<RenderBox&>(*this));
    896 #endif
    897         const_cast<RenderBox*>(this)->computePreferredLogicalWidths();
    898     }
    899 
    900     return m_minPreferredLogicalWidth;
    901 }
    902 
    903 LayoutUnit RenderBox::maxPreferredLogicalWidth() const
    904 {
    905     if (preferredLogicalWidthsDirty()) {
    906 #if ENABLE(ASSERT)
    907         SetLayoutNeededForbiddenScope layoutForbiddenScope(const_cast<RenderBox&>(*this));
    908 #endif
    909         const_cast<RenderBox*>(this)->computePreferredLogicalWidths();
    910     }
    911 
    912     return m_maxPreferredLogicalWidth;
    913 }
    914 
    915 bool RenderBox::hasOverrideHeight() const
    916 {
    917     return m_rareData && m_rareData->m_overrideLogicalContentHeight != -1;
    918 }
    919 
    920 bool RenderBox::hasOverrideWidth() const
    921 {
    922     return m_rareData && m_rareData->m_overrideLogicalContentWidth != -1;
    923 }
    924 
    925 void RenderBox::setOverrideLogicalContentHeight(LayoutUnit height)
    926 {
    927     ASSERT(height >= 0);
    928     ensureRareData().m_overrideLogicalContentHeight = height;
    929 }
    930 
    931 void RenderBox::setOverrideLogicalContentWidth(LayoutUnit width)
    932 {
    933     ASSERT(width >= 0);
    934     ensureRareData().m_overrideLogicalContentWidth = width;
    935 }
    936 
    937 void RenderBox::clearOverrideLogicalContentHeight()
    938 {
    939     if (m_rareData)
    940         m_rareData->m_overrideLogicalContentHeight = -1;
    941 }
    942 
    943 void RenderBox::clearOverrideLogicalContentWidth()
    944 {
    945     if (m_rareData)
    946         m_rareData->m_overrideLogicalContentWidth = -1;
    947 }
    948 
    949 void RenderBox::clearOverrideSize()
    950 {
    951     clearOverrideLogicalContentHeight();
    952     clearOverrideLogicalContentWidth();
    953 }
    954 
    955 LayoutUnit RenderBox::overrideLogicalContentWidth() const
    956 {
    957     ASSERT(hasOverrideWidth());
    958     return m_rareData->m_overrideLogicalContentWidth;
    959 }
    960 
    961 LayoutUnit RenderBox::overrideLogicalContentHeight() const
    962 {
    963     ASSERT(hasOverrideHeight());
    964     return m_rareData->m_overrideLogicalContentHeight;
    965 }
    966 
    967 LayoutUnit RenderBox::overrideContainingBlockContentLogicalWidth() const
    968 {
    969     ASSERT(hasOverrideContainingBlockLogicalWidth());
    970     return gOverrideContainingBlockLogicalWidthMap->get(this);
    971 }
    972 
    973 LayoutUnit RenderBox::overrideContainingBlockContentLogicalHeight() const
    974 {
    975     ASSERT(hasOverrideContainingBlockLogicalHeight());
    976     return gOverrideContainingBlockLogicalHeightMap->get(this);
    977 }
    978 
    979 bool RenderBox::hasOverrideContainingBlockLogicalWidth() const
    980 {
    981     return gOverrideContainingBlockLogicalWidthMap && gOverrideContainingBlockLogicalWidthMap->contains(this);
    982 }
    983 
    984 bool RenderBox::hasOverrideContainingBlockLogicalHeight() const
    985 {
    986     return gOverrideContainingBlockLogicalHeightMap && gOverrideContainingBlockLogicalHeightMap->contains(this);
    987 }
    988 
    989 void RenderBox::setOverrideContainingBlockContentLogicalWidth(LayoutUnit logicalWidth)
    990 {
    991     if (!gOverrideContainingBlockLogicalWidthMap)
    992         gOverrideContainingBlockLogicalWidthMap = new OverrideSizeMap;
    993     gOverrideContainingBlockLogicalWidthMap->set(this, logicalWidth);
    994 }
    995 
    996 void RenderBox::setOverrideContainingBlockContentLogicalHeight(LayoutUnit logicalHeight)
    997 {
    998     if (!gOverrideContainingBlockLogicalHeightMap)
    999         gOverrideContainingBlockLogicalHeightMap = new OverrideSizeMap;
   1000     gOverrideContainingBlockLogicalHeightMap->set(this, logicalHeight);
   1001 }
   1002 
   1003 void RenderBox::clearContainingBlockOverrideSize()
   1004 {
   1005     if (gOverrideContainingBlockLogicalWidthMap)
   1006         gOverrideContainingBlockLogicalWidthMap->remove(this);
   1007     clearOverrideContainingBlockContentLogicalHeight();
   1008 }
   1009 
   1010 void RenderBox::clearOverrideContainingBlockContentLogicalHeight()
   1011 {
   1012     if (gOverrideContainingBlockLogicalHeightMap)
   1013         gOverrideContainingBlockLogicalHeightMap->remove(this);
   1014 }
   1015 
   1016 LayoutUnit RenderBox::adjustBorderBoxLogicalWidthForBoxSizing(LayoutUnit width) const
   1017 {
   1018     LayoutUnit bordersPlusPadding = borderAndPaddingLogicalWidth();
   1019     if (style()->boxSizing() == CONTENT_BOX)
   1020         return width + bordersPlusPadding;
   1021     return std::max(width, bordersPlusPadding);
   1022 }
   1023 
   1024 LayoutUnit RenderBox::adjustBorderBoxLogicalHeightForBoxSizing(LayoutUnit height) const
   1025 {
   1026     LayoutUnit bordersPlusPadding = borderAndPaddingLogicalHeight();
   1027     if (style()->boxSizing() == CONTENT_BOX)
   1028         return height + bordersPlusPadding;
   1029     return std::max(height, bordersPlusPadding);
   1030 }
   1031 
   1032 LayoutUnit RenderBox::adjustContentBoxLogicalWidthForBoxSizing(LayoutUnit width) const
   1033 {
   1034     if (style()->boxSizing() == BORDER_BOX)
   1035         width -= borderAndPaddingLogicalWidth();
   1036     return std::max<LayoutUnit>(0, width);
   1037 }
   1038 
   1039 LayoutUnit RenderBox::adjustContentBoxLogicalHeightForBoxSizing(LayoutUnit height) const
   1040 {
   1041     if (style()->boxSizing() == BORDER_BOX)
   1042         height -= borderAndPaddingLogicalHeight();
   1043     return std::max<LayoutUnit>(0, height);
   1044 }
   1045 
   1046 // Hit Testing
   1047 bool RenderBox::nodeAtPoint(const HitTestRequest& request, HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction action)
   1048 {
   1049     LayoutPoint adjustedLocation = accumulatedOffset + location();
   1050 
   1051     // Check kids first.
   1052     for (RenderObject* child = slowLastChild(); child; child = child->previousSibling()) {
   1053         if ((!child->hasLayer() || !toRenderLayerModelObject(child)->layer()->isSelfPaintingLayer()) && child->nodeAtPoint(request, result, locationInContainer, adjustedLocation, action)) {
   1054             updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
   1055             return true;
   1056         }
   1057     }
   1058 
   1059     // Check our bounds next. For this purpose always assume that we can only be hit in the
   1060     // foreground phase (which is true for replaced elements like images).
   1061     LayoutRect boundsRect = borderBoxRect();
   1062     boundsRect.moveBy(adjustedLocation);
   1063     if (visibleToHitTestRequest(request) && action == HitTestForeground && locationInContainer.intersects(boundsRect)) {
   1064         updateHitTestResult(result, locationInContainer.point() - toLayoutSize(adjustedLocation));
   1065         if (!result.addNodeToRectBasedTestResult(node(), request, locationInContainer, boundsRect))
   1066             return true;
   1067     }
   1068 
   1069     return false;
   1070 }
   1071 
   1072 void RenderBox::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
   1073 {
   1074     BoxPainter(*this).paint(paintInfo, paintOffset);
   1075 }
   1076 
   1077 
   1078 void RenderBox::paintBoxDecorationBackground(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
   1079 {
   1080     BoxPainter(*this).paintBoxDecorationBackground(paintInfo, paintOffset);
   1081 }
   1082 
   1083 
   1084 bool RenderBox::getBackgroundPaintedExtent(LayoutRect& paintedExtent)
   1085 {
   1086     ASSERT(hasBackground());
   1087     LayoutRect backgroundRect = pixelSnappedIntRect(borderBoxRect());
   1088 
   1089     Color backgroundColor = resolveColor(CSSPropertyBackgroundColor);
   1090     if (backgroundColor.alpha()) {
   1091         paintedExtent = backgroundRect;
   1092         return true;
   1093     }
   1094 
   1095     if (!style()->backgroundLayers().image() || style()->backgroundLayers().next()) {
   1096         paintedExtent =  backgroundRect;
   1097         return true;
   1098     }
   1099 
   1100     BackgroundImageGeometry geometry;
   1101     BoxPainter::calculateBackgroundImageGeometry(*this, 0, style()->backgroundLayers(), backgroundRect, geometry);
   1102     if (geometry.hasNonLocalGeometry())
   1103         return false;
   1104     paintedExtent = geometry.destRect();
   1105     return true;
   1106 }
   1107 
   1108 bool RenderBox::backgroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect) const
   1109 {
   1110     if (isBody() && skipBodyBackground(this))
   1111         return false;
   1112 
   1113     Color backgroundColor = resolveColor(CSSPropertyBackgroundColor);
   1114     if (backgroundColor.hasAlpha())
   1115         return false;
   1116 
   1117     // If the element has appearance, it might be painted by theme.
   1118     // We cannot be sure if theme paints the background opaque.
   1119     // In this case it is safe to not assume opaqueness.
   1120     // FIXME: May be ask theme if it paints opaque.
   1121     if (style()->hasAppearance())
   1122         return false;
   1123     // FIXME: Check the opaqueness of background images.
   1124 
   1125     // FIXME: Use rounded rect if border radius is present.
   1126     if (style()->hasBorderRadius())
   1127         return false;
   1128     // FIXME: The background color clip is defined by the last layer.
   1129     if (style()->backgroundLayers().next())
   1130         return false;
   1131     LayoutRect backgroundRect;
   1132     switch (style()->backgroundClip()) {
   1133     case BorderFillBox:
   1134         backgroundRect = borderBoxRect();
   1135         break;
   1136     case PaddingFillBox:
   1137         backgroundRect = paddingBoxRect();
   1138         break;
   1139     case ContentFillBox:
   1140         backgroundRect = contentBoxRect();
   1141         break;
   1142     default:
   1143         break;
   1144     }
   1145     return backgroundRect.contains(localRect);
   1146 }
   1147 
   1148 static bool isCandidateForOpaquenessTest(RenderBox* childBox)
   1149 {
   1150     RenderStyle* childStyle = childBox->style();
   1151     if (childStyle->position() != StaticPosition && childBox->containingBlock() != childBox->parent())
   1152         return false;
   1153     if (childStyle->visibility() != VISIBLE || childStyle->shapeOutside())
   1154         return false;
   1155     if (!childBox->width() || !childBox->height())
   1156         return false;
   1157     if (RenderLayer* childLayer = childBox->layer()) {
   1158         // FIXME: perhaps this could be less conservative?
   1159         if (childLayer->compositingState() != NotComposited)
   1160             return false;
   1161         // FIXME: Deal with z-index.
   1162         if (!childStyle->hasAutoZIndex())
   1163             return false;
   1164         if (childLayer->hasTransform() || childLayer->isTransparent() || childLayer->hasFilter())
   1165             return false;
   1166         if (childBox->hasOverflowClip() && childStyle->hasBorderRadius())
   1167             return false;
   1168     }
   1169     return true;
   1170 }
   1171 
   1172 bool RenderBox::foregroundIsKnownToBeOpaqueInRect(const LayoutRect& localRect, unsigned maxDepthToTest) const
   1173 {
   1174     if (!maxDepthToTest)
   1175         return false;
   1176     for (RenderObject* child = slowFirstChild(); child; child = child->nextSibling()) {
   1177         if (!child->isBox())
   1178             continue;
   1179         RenderBox* childBox = toRenderBox(child);
   1180         if (!isCandidateForOpaquenessTest(childBox))
   1181             continue;
   1182         LayoutPoint childLocation = childBox->location();
   1183         if (childBox->isRelPositioned())
   1184             childLocation.move(childBox->relativePositionOffset());
   1185         LayoutRect childLocalRect = localRect;
   1186         childLocalRect.moveBy(-childLocation);
   1187         if (childLocalRect.y() < 0 || childLocalRect.x() < 0) {
   1188             // If there is unobscured area above/left of a static positioned box then the rect is probably not covered.
   1189             if (childBox->style()->position() == StaticPosition)
   1190                 return false;
   1191             continue;
   1192         }
   1193         if (childLocalRect.maxY() > childBox->height() || childLocalRect.maxX() > childBox->width())
   1194             continue;
   1195         if (childBox->backgroundIsKnownToBeOpaqueInRect(childLocalRect))
   1196             return true;
   1197         if (childBox->foregroundIsKnownToBeOpaqueInRect(childLocalRect, maxDepthToTest - 1))
   1198             return true;
   1199     }
   1200     return false;
   1201 }
   1202 
   1203 bool RenderBox::computeBackgroundIsKnownToBeObscured()
   1204 {
   1205     // Test to see if the children trivially obscure the background.
   1206     // FIXME: This test can be much more comprehensive.
   1207     if (!hasBackground())
   1208         return false;
   1209     // Table and root background painting is special.
   1210     if (isTable() || isDocumentElement())
   1211         return false;
   1212     // FIXME: box-shadow is painted while background painting.
   1213     if (style()->boxShadow())
   1214         return false;
   1215     LayoutRect backgroundRect;
   1216     if (!getBackgroundPaintedExtent(backgroundRect))
   1217         return false;
   1218     return foregroundIsKnownToBeOpaqueInRect(backgroundRect, backgroundObscurationTestMaxDepth);
   1219 }
   1220 
   1221 bool RenderBox::backgroundHasOpaqueTopLayer() const
   1222 {
   1223     const FillLayer& fillLayer = style()->backgroundLayers();
   1224     if (fillLayer.clip() != BorderFillBox)
   1225         return false;
   1226 
   1227     // Clipped with local scrolling
   1228     if (hasOverflowClip() && fillLayer.attachment() == LocalBackgroundAttachment)
   1229         return false;
   1230 
   1231     if (fillLayer.hasOpaqueImage(this) && fillLayer.hasRepeatXY() && fillLayer.image()->canRender(*this, style()->effectiveZoom()))
   1232         return true;
   1233 
   1234     // If there is only one layer and no image, check whether the background color is opaque
   1235     if (!fillLayer.next() && !fillLayer.hasImage()) {
   1236         Color bgColor = resolveColor(CSSPropertyBackgroundColor);
   1237         if (bgColor.alpha() == 255)
   1238             return true;
   1239     }
   1240 
   1241     return false;
   1242 }
   1243 
   1244 void RenderBox::paintMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
   1245 {
   1246     BoxPainter(*this).paintMask(paintInfo, paintOffset);
   1247 }
   1248 
   1249 void RenderBox::paintClippingMask(PaintInfo& paintInfo, const LayoutPoint& paintOffset)
   1250 {
   1251     BoxPainter(*this).paintClippingMask(paintInfo, paintOffset);
   1252 }
   1253 
   1254 void RenderBox::imageChanged(WrappedImagePtr image, const IntRect*)
   1255 {
   1256     if (!parent())
   1257         return;
   1258 
   1259     AllowPaintInvalidationScope scoper(frameView());
   1260 
   1261     if ((style()->borderImage().image() && style()->borderImage().image()->data() == image) ||
   1262         (style()->maskBoxImage().image() && style()->maskBoxImage().image()->data() == image)) {
   1263         setShouldDoFullPaintInvalidation(true);
   1264         return;
   1265     }
   1266 
   1267     ShapeValue* shapeOutsideValue = style()->shapeOutside();
   1268     if (!frameView()->isInPerformLayout() && isFloating() && shapeOutsideValue && shapeOutsideValue->image() && shapeOutsideValue->image()->data() == image) {
   1269         ShapeOutsideInfo& info = ShapeOutsideInfo::ensureInfo(*this);
   1270         if (!info.isComputingShape()) {
   1271             info.markShapeAsDirty();
   1272             markShapeOutsideDependentsForLayout();
   1273         }
   1274     }
   1275 
   1276     if (!paintInvalidationLayerRectsForImage(image, style()->backgroundLayers(), true))
   1277         paintInvalidationLayerRectsForImage(image, style()->maskLayers(), false);
   1278 }
   1279 
   1280 bool RenderBox::paintInvalidationLayerRectsForImage(WrappedImagePtr image, const FillLayer& layers, bool drawingBackground)
   1281 {
   1282     Vector<RenderObject*> layerRenderers;
   1283 
   1284     // A background of the body or document must extend to the total visible size of the document. This means the union of the
   1285     // view and document bounds, since it can be the case that the view is larger than the document and vice-versa.
   1286     // http://dev.w3.org/csswg/css-backgrounds/#the-background
   1287     if (drawingBackground && (isDocumentElement() || (isBody() && !document().documentElement()->renderer()->hasBackground()))) {
   1288         layerRenderers.append(document().documentElement()->renderer());
   1289         layerRenderers.append(view());
   1290         if (view()->frameView())
   1291             view()->frameView()->setNeedsFullPaintInvalidation();
   1292     } else {
   1293         layerRenderers.append(this);
   1294     }
   1295     for (const FillLayer* curLayer = &layers; curLayer; curLayer = curLayer->next()) {
   1296         if (curLayer->image() && image == curLayer->image()->data() && curLayer->image()->canRender(*this, style()->effectiveZoom())) {
   1297                 for (Vector<RenderObject*>::const_iterator it = layerRenderers.begin(); it != layerRenderers.end(); ++it) {
   1298 			(*it)->setShouldDoFullPaintInvalidation(true);
   1299    	         }
   1300 		return true;
   1301         }
   1302     }
   1303     return false;
   1304 }
   1305 
   1306 InvalidationReason RenderBox::invalidatePaintIfNeeded(const PaintInvalidationState& paintInvalidationState, const RenderLayerModelObject& newPaintInvalidationContainer)
   1307 {
   1308     // If we are set to do a full paint invalidation that means the RenderView will be
   1309     // issue paint invalidations. We can then skip issuing of paint invalidations for the child
   1310     // renderers as they'll be covered by the RenderView.
   1311     if (!view()->doingFullPaintInvalidation()) {
   1312         if ((onlyNeededPositionedMovementLayout() && compositingState() != PaintsIntoOwnBacking)
   1313             || (shouldDoFullPaintInvalidationIfSelfPaintingLayer()
   1314                 && hasLayer()
   1315                 && layer()->isSelfPaintingLayer())) {
   1316             setShouldDoFullPaintInvalidation(true, MarkOnlyThis);
   1317         }
   1318     }
   1319 
   1320     InvalidationReason reason = RenderBoxModelObject::invalidatePaintIfNeeded(paintInvalidationState, newPaintInvalidationContainer);
   1321 
   1322     if (!view()->doingFullPaintInvalidation()) {
   1323         if (reason == InvalidationNone || reason == InvalidationIncremental)
   1324             invalidatePaintForOverflowIfNeeded();
   1325 
   1326         // Issue paint invalidations for any scrollbars if there is a scrollable area for this renderer.
   1327         if (ScrollableArea* area = scrollableArea()) {
   1328             if (area->hasVerticalBarDamage())
   1329                 invalidatePaintRectangle(area->verticalBarDamage());
   1330             if (area->hasHorizontalBarDamage())
   1331                 invalidatePaintRectangle(area->horizontalBarDamage());
   1332         }
   1333     }
   1334 
   1335     // This is for the next invalidatePaintIfNeeded so must be at the end.
   1336     savePreviousBorderBoxSizeIfNeeded();
   1337     return reason;
   1338 }
   1339 
   1340 void RenderBox::clearPaintInvalidationState(const PaintInvalidationState& paintInvalidationState)
   1341 {
   1342     RenderBoxModelObject::clearPaintInvalidationState(paintInvalidationState);
   1343 
   1344     if (ScrollableArea* area = scrollableArea())
   1345         area->resetScrollbarDamage();
   1346 }
   1347 
   1348 #if ENABLE(ASSERT)
   1349 bool RenderBox::paintInvalidationStateIsDirty() const
   1350 {
   1351     if (ScrollableArea* area = scrollableArea()) {
   1352         if (area->hasVerticalBarDamage() || area->hasHorizontalBarDamage())
   1353             return true;
   1354     }
   1355     return RenderBoxModelObject::paintInvalidationStateIsDirty();
   1356 }
   1357 #endif
   1358 
   1359 bool RenderBox::pushContentsClip(PaintInfo& paintInfo, const LayoutPoint& accumulatedOffset, ContentsClipBehavior contentsClipBehavior)
   1360 {
   1361     if (paintInfo.phase == PaintPhaseBlockBackground || paintInfo.phase == PaintPhaseSelfOutline || paintInfo.phase == PaintPhaseMask)
   1362         return false;
   1363 
   1364     bool isControlClip = hasControlClip();
   1365     bool isOverflowClip = hasOverflowClip() && !layer()->isSelfPaintingLayer();
   1366 
   1367     if (!isControlClip && !isOverflowClip)
   1368         return false;
   1369 
   1370     LayoutRect clipRect = isControlClip ? controlClipRect(accumulatedOffset) : overflowClipRect(accumulatedOffset);
   1371     RoundedRect clipRoundedRect(0, 0, 0, 0);
   1372     bool hasBorderRadius = style()->hasBorderRadius();
   1373     if (hasBorderRadius)
   1374         clipRoundedRect = style()->getRoundedInnerBorderFor(LayoutRect(accumulatedOffset, size()));
   1375 
   1376     if (contentsClipBehavior == SkipContentsClipIfPossible) {
   1377         LayoutRect contentsVisualOverflow = contentsVisualOverflowRect();
   1378         if (contentsVisualOverflow.isEmpty())
   1379             return false;
   1380 
   1381         LayoutRect conservativeClipRect = clipRect;
   1382         if (hasBorderRadius)
   1383             conservativeClipRect.intersect(clipRoundedRect.radiusCenterRect());
   1384         conservativeClipRect.moveBy(-accumulatedOffset);
   1385         if (hasLayer())
   1386             conservativeClipRect.move(scrolledContentOffset());
   1387         if (conservativeClipRect.contains(contentsVisualOverflow))
   1388             return false;
   1389     }
   1390 
   1391     if (paintInfo.phase == PaintPhaseOutline)
   1392         paintInfo.phase = PaintPhaseChildOutlines;
   1393     else if (paintInfo.phase == PaintPhaseChildBlockBackground) {
   1394         paintInfo.phase = PaintPhaseBlockBackground;
   1395         paintObject(paintInfo, accumulatedOffset);
   1396         paintInfo.phase = PaintPhaseChildBlockBackgrounds;
   1397     }
   1398     paintInfo.context->save();
   1399     if (hasBorderRadius)
   1400         paintInfo.context->clipRoundedRect(clipRoundedRect);
   1401     paintInfo.context->clip(pixelSnappedIntRect(clipRect));
   1402     return true;
   1403 }
   1404 
   1405 void RenderBox::popContentsClip(PaintInfo& paintInfo, PaintPhase originalPhase, const LayoutPoint& accumulatedOffset)
   1406 {
   1407     ASSERT(hasControlClip() || (hasOverflowClip() && !layer()->isSelfPaintingLayer()));
   1408 
   1409     paintInfo.context->restore();
   1410     if (originalPhase == PaintPhaseOutline) {
   1411         paintInfo.phase = PaintPhaseSelfOutline;
   1412         paintObject(paintInfo, accumulatedOffset);
   1413         paintInfo.phase = originalPhase;
   1414     } else if (originalPhase == PaintPhaseChildBlockBackground)
   1415         paintInfo.phase = originalPhase;
   1416 }
   1417 
   1418 LayoutRect RenderBox::overflowClipRect(const LayoutPoint& location, OverlayScrollbarSizeRelevancy relevancy)
   1419 {
   1420     // FIXME: When overflow-clip (CSS3) is implemented, we'll obtain the property
   1421     // here.
   1422     LayoutRect clipRect = borderBoxRect();
   1423     clipRect.setLocation(location + clipRect.location() + LayoutSize(borderLeft(), borderTop()));
   1424     clipRect.setSize(clipRect.size() - LayoutSize(borderLeft() + borderRight(), borderTop() + borderBottom()));
   1425 
   1426     if (!hasOverflowClip())
   1427         return clipRect;
   1428 
   1429     // Subtract out scrollbars if we have them.
   1430     if (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
   1431         clipRect.move(layer()->scrollableArea()->verticalScrollbarWidth(relevancy), 0);
   1432     clipRect.contract(layer()->scrollableArea()->verticalScrollbarWidth(relevancy), layer()->scrollableArea()->horizontalScrollbarHeight(relevancy));
   1433 
   1434     return clipRect;
   1435 }
   1436 
   1437 LayoutRect RenderBox::clipRect(const LayoutPoint& location)
   1438 {
   1439     LayoutRect borderBoxRect = this->borderBoxRect();
   1440     LayoutRect clipRect = LayoutRect(borderBoxRect.location() + location, borderBoxRect.size());
   1441 
   1442     if (!style()->clipLeft().isAuto()) {
   1443         LayoutUnit c = valueForLength(style()->clipLeft(), borderBoxRect.width());
   1444         clipRect.move(c, 0);
   1445         clipRect.contract(c, 0);
   1446     }
   1447 
   1448     if (!style()->clipRight().isAuto())
   1449         clipRect.contract(width() - valueForLength(style()->clipRight(), width()), 0);
   1450 
   1451     if (!style()->clipTop().isAuto()) {
   1452         LayoutUnit c = valueForLength(style()->clipTop(), borderBoxRect.height());
   1453         clipRect.move(0, c);
   1454         clipRect.contract(0, c);
   1455     }
   1456 
   1457     if (!style()->clipBottom().isAuto())
   1458         clipRect.contract(0, height() - valueForLength(style()->clipBottom(), height()));
   1459 
   1460     return clipRect;
   1461 }
   1462 
   1463 static LayoutUnit portionOfMarginNotConsumedByFloat(LayoutUnit childMargin, LayoutUnit contentSide, LayoutUnit offset)
   1464 {
   1465     if (childMargin <= 0)
   1466         return 0;
   1467     LayoutUnit contentSideWithMargin = contentSide + childMargin;
   1468     if (offset > contentSideWithMargin)
   1469         return childMargin;
   1470     return offset - contentSide;
   1471 }
   1472 
   1473 LayoutUnit RenderBox::shrinkLogicalWidthToAvoidFloats(LayoutUnit childMarginStart, LayoutUnit childMarginEnd, const RenderBlockFlow* cb) const
   1474 {
   1475     LayoutUnit logicalTopPosition = logicalTop();
   1476     LayoutUnit startOffsetForContent = cb->startOffsetForContent();
   1477     LayoutUnit endOffsetForContent = cb->endOffsetForContent();
   1478     LayoutUnit startOffsetForLine = cb->startOffsetForLine(logicalTopPosition, false);
   1479     LayoutUnit endOffsetForLine = cb->endOffsetForLine(logicalTopPosition, false);
   1480 
   1481     // If there aren't any floats constraining us then allow the margins to shrink/expand the width as much as they want.
   1482     if (startOffsetForContent == startOffsetForLine && endOffsetForContent == endOffsetForLine)
   1483         return cb->availableLogicalWidthForLine(logicalTopPosition, false) - childMarginStart - childMarginEnd;
   1484 
   1485     LayoutUnit width = cb->availableLogicalWidthForLine(logicalTopPosition, false) - std::max<LayoutUnit>(0, childMarginStart) - std::max<LayoutUnit>(0, childMarginEnd);
   1486     // We need to see if margins on either the start side or the end side can contain the floats in question. If they can,
   1487     // then just using the line width is inaccurate. In the case where a float completely fits, we don't need to use the line
   1488     // offset at all, but can instead push all the way to the content edge of the containing block. In the case where the float
   1489     // doesn't fit, we can use the line offset, but we need to grow it by the margin to reflect the fact that the margin was
   1490     // "consumed" by the float. Negative margins aren't consumed by the float, and so we ignore them.
   1491     width += portionOfMarginNotConsumedByFloat(childMarginStart, startOffsetForContent, startOffsetForLine);
   1492     width += portionOfMarginNotConsumedByFloat(childMarginEnd, endOffsetForContent, endOffsetForLine);
   1493     return width;
   1494 }
   1495 
   1496 LayoutUnit RenderBox::containingBlockLogicalWidthForContent() const
   1497 {
   1498     if (hasOverrideContainingBlockLogicalWidth())
   1499         return overrideContainingBlockContentLogicalWidth();
   1500 
   1501     RenderBlock* cb = containingBlock();
   1502     return cb->availableLogicalWidth();
   1503 }
   1504 
   1505 LayoutUnit RenderBox::containingBlockLogicalHeightForContent(AvailableLogicalHeightType heightType) const
   1506 {
   1507     if (hasOverrideContainingBlockLogicalHeight())
   1508         return overrideContainingBlockContentLogicalHeight();
   1509 
   1510     RenderBlock* cb = containingBlock();
   1511     return cb->availableLogicalHeight(heightType);
   1512 }
   1513 
   1514 LayoutUnit RenderBox::containingBlockAvailableLineWidth() const
   1515 {
   1516     RenderBlock* cb = containingBlock();
   1517     if (cb->isRenderBlockFlow())
   1518         return toRenderBlockFlow(cb)->availableLogicalWidthForLine(logicalTop(), false, availableLogicalHeight(IncludeMarginBorderPadding));
   1519     return 0;
   1520 }
   1521 
   1522 LayoutUnit RenderBox::perpendicularContainingBlockLogicalHeight() const
   1523 {
   1524     if (hasOverrideContainingBlockLogicalHeight())
   1525         return overrideContainingBlockContentLogicalHeight();
   1526 
   1527     RenderBlock* cb = containingBlock();
   1528     if (cb->hasOverrideHeight())
   1529         return cb->overrideLogicalContentHeight();
   1530 
   1531     RenderStyle* containingBlockStyle = cb->style();
   1532     Length logicalHeightLength = containingBlockStyle->logicalHeight();
   1533 
   1534     // FIXME: For now just support fixed heights.  Eventually should support percentage heights as well.
   1535     if (!logicalHeightLength.isFixed()) {
   1536         LayoutUnit fillFallbackExtent = containingBlockStyle->isHorizontalWritingMode()
   1537             ? view()->frameView()->unscaledVisibleContentSize().height()
   1538             : view()->frameView()->unscaledVisibleContentSize().width();
   1539         LayoutUnit fillAvailableExtent = containingBlock()->availableLogicalHeight(ExcludeMarginBorderPadding);
   1540         return std::min(fillAvailableExtent, fillFallbackExtent);
   1541     }
   1542 
   1543     // Use the content box logical height as specified by the style.
   1544     return cb->adjustContentBoxLogicalHeightForBoxSizing(logicalHeightLength.value());
   1545 }
   1546 
   1547 void RenderBox::mapLocalToContainer(const RenderLayerModelObject* paintInvalidationContainer, TransformState& transformState, MapCoordinatesFlags mode, bool* wasFixed, const PaintInvalidationState* paintInvalidationState) const
   1548 {
   1549     if (paintInvalidationContainer == this)
   1550         return;
   1551 
   1552     if (paintInvalidationState && paintInvalidationState->canMapToContainer(paintInvalidationContainer)) {
   1553         LayoutSize offset = paintInvalidationState->paintOffset() + locationOffset();
   1554         if (style()->hasInFlowPosition() && layer())
   1555             offset += layer()->offsetForInFlowPosition();
   1556         transformState.move(offset);
   1557         return;
   1558     }
   1559 
   1560     bool containerSkipped;
   1561     RenderObject* o = container(paintInvalidationContainer, &containerSkipped);
   1562     if (!o)
   1563         return;
   1564 
   1565     bool isFixedPos = style()->position() == FixedPosition;
   1566     bool hasTransform = hasLayer() && layer()->transform();
   1567     // If this box has a transform, it acts as a fixed position container for fixed descendants,
   1568     // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
   1569     if (hasTransform && !isFixedPos)
   1570         mode &= ~IsFixed;
   1571     else if (isFixedPos)
   1572         mode |= IsFixed;
   1573 
   1574     if (wasFixed)
   1575         *wasFixed = mode & IsFixed;
   1576 
   1577     LayoutSize containerOffset = offsetFromContainer(o, roundedLayoutPoint(transformState.mappedPoint()));
   1578 
   1579     bool preserve3D = mode & UseTransforms && (o->style()->preserves3D() || style()->preserves3D());
   1580     if (mode & UseTransforms && shouldUseTransformFromContainer(o)) {
   1581         TransformationMatrix t;
   1582         getTransformFromContainer(o, containerOffset, t);
   1583         transformState.applyTransform(t, preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
   1584     } else
   1585         transformState.move(containerOffset.width(), containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
   1586 
   1587     if (containerSkipped) {
   1588         // There can't be a transform between paintInvalidationContainer and o, because transforms create containers, so it should be safe
   1589         // to just subtract the delta between the paintInvalidationContainer and o.
   1590         LayoutSize containerOffset = paintInvalidationContainer->offsetFromAncestorContainer(o);
   1591         transformState.move(-containerOffset.width(), -containerOffset.height(), preserve3D ? TransformState::AccumulateTransform : TransformState::FlattenTransform);
   1592         return;
   1593     }
   1594 
   1595     mode &= ~ApplyContainerFlip;
   1596 
   1597     o->mapLocalToContainer(paintInvalidationContainer, transformState, mode, wasFixed);
   1598 }
   1599 
   1600 void RenderBox::mapAbsoluteToLocalPoint(MapCoordinatesFlags mode, TransformState& transformState) const
   1601 {
   1602     bool isFixedPos = style()->position() == FixedPosition;
   1603     bool hasTransform = hasLayer() && layer()->transform();
   1604     if (hasTransform && !isFixedPos) {
   1605         // If this box has a transform, it acts as a fixed position container for fixed descendants,
   1606         // and may itself also be fixed position. So propagate 'fixed' up only if this box is fixed position.
   1607         mode &= ~IsFixed;
   1608     } else if (isFixedPos)
   1609         mode |= IsFixed;
   1610 
   1611     RenderBoxModelObject::mapAbsoluteToLocalPoint(mode, transformState);
   1612 }
   1613 
   1614 LayoutSize RenderBox::offsetFromContainer(const RenderObject* o, const LayoutPoint& point, bool* offsetDependsOnPoint) const
   1615 {
   1616     ASSERT(o == container());
   1617 
   1618     LayoutSize offset;
   1619     if (isRelPositioned())
   1620         offset += offsetForInFlowPosition();
   1621 
   1622     if (!isInline() || isReplaced()) {
   1623         if (!style()->hasOutOfFlowPosition() && o->hasColumns()) {
   1624             const RenderBlock* block = toRenderBlock(o);
   1625             LayoutRect columnRect(frameRect());
   1626             block->adjustStartEdgeForWritingModeIncludingColumns(columnRect);
   1627             offset += toSize(columnRect.location());
   1628             LayoutPoint columnPoint = block->flipForWritingModeIncludingColumns(point + offset);
   1629             offset = toLayoutSize(block->flipForWritingModeIncludingColumns(toLayoutPoint(offset)));
   1630             offset += o->columnOffset(columnPoint);
   1631             offset = block->flipForWritingMode(offset);
   1632 
   1633             if (offsetDependsOnPoint)
   1634                 *offsetDependsOnPoint = true;
   1635         } else {
   1636             offset += topLeftLocationOffset();
   1637             if (o->isRenderFlowThread()) {
   1638                 // So far the point has been in flow thread coordinates (i.e. as if everything in
   1639                 // the fragmentation context lived in one tall single column). Convert it to a
   1640                 // visual point now.
   1641                 LayoutPoint pointInContainer = point + offset;
   1642                 offset += o->columnOffset(pointInContainer);
   1643                 if (offsetDependsOnPoint)
   1644                     *offsetDependsOnPoint = true;
   1645             }
   1646         }
   1647     }
   1648 
   1649     if (o->hasOverflowClip())
   1650         offset -= toRenderBox(o)->scrolledContentOffset();
   1651 
   1652     if (style()->position() == AbsolutePosition && o->isRelPositioned() && o->isRenderInline())
   1653         offset += toRenderInline(o)->offsetForInFlowPositionedInline(*this);
   1654 
   1655     return offset;
   1656 }
   1657 
   1658 InlineBox* RenderBox::createInlineBox()
   1659 {
   1660     return new InlineBox(*this);
   1661 }
   1662 
   1663 void RenderBox::dirtyLineBoxes(bool fullLayout)
   1664 {
   1665     if (inlineBoxWrapper()) {
   1666         if (fullLayout) {
   1667             inlineBoxWrapper()->destroy();
   1668             ASSERT(m_rareData);
   1669             m_rareData->m_inlineBoxWrapper = 0;
   1670         } else {
   1671             inlineBoxWrapper()->dirtyLineBoxes();
   1672         }
   1673     }
   1674 }
   1675 
   1676 void RenderBox::positionLineBox(InlineBox* box)
   1677 {
   1678     if (isOutOfFlowPositioned()) {
   1679         // Cache the x position only if we were an INLINE type originally.
   1680         bool wasInline = style()->isOriginalDisplayInlineType();
   1681         if (wasInline) {
   1682             // The value is cached in the xPos of the box.  We only need this value if
   1683             // our object was inline originally, since otherwise it would have ended up underneath
   1684             // the inlines.
   1685             RootInlineBox& root = box->root();
   1686             root.block().setStaticInlinePositionForChild(this, LayoutUnit::fromFloatRound(box->logicalLeft()));
   1687             if (style()->hasStaticInlinePosition(box->isHorizontal()))
   1688                 setChildNeedsLayout(MarkOnlyThis); // Just go ahead and mark the positioned object as needing layout, so it will update its position properly.
   1689         } else {
   1690             // Our object was a block originally, so we make our normal flow position be
   1691             // just below the line box (as though all the inlines that came before us got
   1692             // wrapped in an anonymous block, which is what would have happened had we been
   1693             // in flow).  This value was cached in the y() of the box.
   1694             layer()->setStaticBlockPosition(box->logicalTop());
   1695             if (style()->hasStaticBlockPosition(box->isHorizontal()))
   1696                 setChildNeedsLayout(MarkOnlyThis); // Just go ahead and mark the positioned object as needing layout, so it will update its position properly.
   1697         }
   1698 
   1699         if (container()->isRenderInline())
   1700             moveWithEdgeOfInlineContainerIfNecessary(box->isHorizontal());
   1701 
   1702         // Nuke the box.
   1703         box->remove(DontMarkLineBoxes);
   1704         box->destroy();
   1705     } else if (isReplaced()) {
   1706         setLocation(roundedLayoutPoint(box->topLeft()));
   1707         setInlineBoxWrapper(box);
   1708     }
   1709 }
   1710 
   1711 void RenderBox::moveWithEdgeOfInlineContainerIfNecessary(bool isHorizontal)
   1712 {
   1713     ASSERT(isOutOfFlowPositioned() && container()->isRenderInline() && container()->isRelPositioned());
   1714     // If this object is inside a relative positioned inline and its inline position is an explicit offset from the edge of its container
   1715     // then it will need to move if its inline container has changed width. We do not track if the width has changed
   1716     // but if we are here then we are laying out lines inside it, so it probably has - mark our object for layout so that it can
   1717     // move to the new offset created by the new width.
   1718     if (!normalChildNeedsLayout() && !style()->hasStaticInlinePosition(isHorizontal))
   1719         setChildNeedsLayout(MarkOnlyThis);
   1720 }
   1721 
   1722 void RenderBox::deleteLineBoxWrapper()
   1723 {
   1724     if (inlineBoxWrapper()) {
   1725         if (!documentBeingDestroyed())
   1726             inlineBoxWrapper()->remove();
   1727         inlineBoxWrapper()->destroy();
   1728         ASSERT(m_rareData);
   1729         m_rareData->m_inlineBoxWrapper = 0;
   1730     }
   1731 }
   1732 
   1733 LayoutRect RenderBox::clippedOverflowRectForPaintInvalidation(const RenderLayerModelObject* paintInvalidationContainer, const PaintInvalidationState* paintInvalidationState) const
   1734 {
   1735     if (style()->visibility() != VISIBLE) {
   1736         RenderLayer* layer = enclosingLayer();
   1737         layer->updateDescendantDependentFlags();
   1738         if (layer->subtreeIsInvisible())
   1739             return LayoutRect();
   1740     }
   1741 
   1742     LayoutRect r = visualOverflowRect();
   1743     mapRectToPaintInvalidationBacking(paintInvalidationContainer, r, paintInvalidationState);
   1744     return r;
   1745 }
   1746 
   1747 void RenderBox::mapRectToPaintInvalidationBacking(const RenderLayerModelObject* paintInvalidationContainer, LayoutRect& rect, const PaintInvalidationState* paintInvalidationState) const
   1748 {
   1749     // The rect we compute at each step is shifted by our x/y offset in the parent container's coordinate space.
   1750     // Only when we cross a writing mode boundary will we have to possibly flipForWritingMode (to convert into a more appropriate
   1751     // offset corner for the enclosing container). This allows for a fully RL or BT document to issue paint invalidations
   1752     // properly even during layout, since the rect remains flipped all the way until the end.
   1753     //
   1754     // RenderView::computeRectForPaintInvalidation then converts the rect to physical coordinates. We also convert to
   1755     // physical when we hit a paintInvalidationContainer boundary. Therefore the final rect returned is always in the
   1756     // physical coordinate space of the paintInvalidationContainer.
   1757     RenderStyle* styleToUse = style();
   1758 
   1759     EPosition position = styleToUse->position();
   1760 
   1761     // We need to inflate the paint invalidation rect before we use paintInvalidationState,
   1762     // else we would forget to inflate it for the current renderer. FIXME: If these were
   1763     // included into the visual overflow for repaint, we wouldn't have this issue.
   1764     inflatePaintInvalidationRectForReflectionAndFilter(rect);
   1765 
   1766     if (paintInvalidationState && paintInvalidationState->canMapToContainer(paintInvalidationContainer) && position != FixedPosition) {
   1767         if (layer() && layer()->transform())
   1768             rect = layer()->transform()->mapRect(pixelSnappedIntRect(rect));
   1769 
   1770         // We can't trust the bits on RenderObject, because this might be called while re-resolving style.
   1771         if (styleToUse->hasInFlowPosition() && layer())
   1772             rect.move(layer()->offsetForInFlowPosition());
   1773 
   1774         rect.moveBy(location());
   1775         rect.move(paintInvalidationState->paintOffset());
   1776         if (paintInvalidationState->isClipped())
   1777             rect.intersect(paintInvalidationState->clipRect());
   1778         return;
   1779     }
   1780 
   1781     if (paintInvalidationContainer == this) {
   1782         if (paintInvalidationContainer->style()->isFlippedBlocksWritingMode())
   1783             flipForWritingMode(rect);
   1784         return;
   1785     }
   1786 
   1787     bool containerSkipped;
   1788     RenderObject* o = container(paintInvalidationContainer, &containerSkipped);
   1789     if (!o)
   1790         return;
   1791 
   1792     if (isWritingModeRoot())
   1793         flipForWritingMode(rect);
   1794 
   1795     LayoutPoint topLeft = rect.location();
   1796     topLeft.move(locationOffset());
   1797 
   1798     // We are now in our parent container's coordinate space.  Apply our transform to obtain a bounding box
   1799     // in the parent's coordinate space that encloses us.
   1800     if (hasLayer() && layer()->transform()) {
   1801         rect = layer()->transform()->mapRect(pixelSnappedIntRect(rect));
   1802         topLeft = rect.location();
   1803         topLeft.move(locationOffset());
   1804     }
   1805 
   1806     if (position == AbsolutePosition && o->isRelPositioned() && o->isRenderInline()) {
   1807         topLeft += toRenderInline(o)->offsetForInFlowPositionedInline(*this);
   1808     } else if (styleToUse->hasInFlowPosition() && layer()) {
   1809         // Apply the relative position offset when invalidating a rectangle.  The layer
   1810         // is translated, but the render box isn't, so we need to do this to get the
   1811         // right dirty rect.  Since this is called from RenderObject::setStyle, the relative position
   1812         // flag on the RenderObject has been cleared, so use the one on the style().
   1813         topLeft += layer()->offsetForInFlowPosition();
   1814     }
   1815 
   1816     if (position != AbsolutePosition && position != FixedPosition && o->hasColumns() && o->isRenderBlockFlow()) {
   1817         LayoutRect paintInvalidationRect(topLeft, rect.size());
   1818         toRenderBlock(o)->adjustRectForColumns(paintInvalidationRect);
   1819         topLeft = paintInvalidationRect.location();
   1820         rect = paintInvalidationRect;
   1821     }
   1822 
   1823     // FIXME: We ignore the lightweight clipping rect that controls use, since if |o| is in mid-layout,
   1824     // its controlClipRect will be wrong. For overflow clip we use the values cached by the layer.
   1825     rect.setLocation(topLeft);
   1826     if (o->hasOverflowClip()) {
   1827         RenderBox* containerBox = toRenderBox(o);
   1828         containerBox->applyCachedClipAndScrollOffsetForPaintInvalidation(rect);
   1829         if (rect.isEmpty())
   1830             return;
   1831     }
   1832 
   1833     if (containerSkipped) {
   1834         // If the paintInvalidationContainer is below o, then we need to map the rect into paintInvalidationContainer's coordinates.
   1835         LayoutSize containerOffset = paintInvalidationContainer->offsetFromAncestorContainer(o);
   1836         rect.move(-containerOffset);
   1837         return;
   1838     }
   1839 
   1840     if (o->isRenderView())
   1841         toRenderView(o)->mapRectToPaintInvalidationBacking(paintInvalidationContainer, rect, position == FixedPosition ? RenderView::IsFixedPosition : RenderView::IsNotFixedPosition, paintInvalidationState);
   1842     else
   1843         o->mapRectToPaintInvalidationBacking(paintInvalidationContainer, rect, paintInvalidationState);
   1844 }
   1845 
   1846 void RenderBox::inflatePaintInvalidationRectForReflectionAndFilter(LayoutRect& paintInvalidationRect) const
   1847 {
   1848     if (hasReflection())
   1849         paintInvalidationRect.unite(reflectedRect(paintInvalidationRect));
   1850 
   1851     if (style()->hasFilter())
   1852         style()->filterOutsets().expandRect(paintInvalidationRect);
   1853 }
   1854 
   1855 void RenderBox::invalidatePaintForOverhangingFloats(bool)
   1856 {
   1857 }
   1858 
   1859 void RenderBox::updateLogicalWidth()
   1860 {
   1861     LogicalExtentComputedValues computedValues;
   1862     computeLogicalWidth(computedValues);
   1863 
   1864     setLogicalWidth(computedValues.m_extent);
   1865     setLogicalLeft(computedValues.m_position);
   1866     setMarginStart(computedValues.m_margins.m_start);
   1867     setMarginEnd(computedValues.m_margins.m_end);
   1868 }
   1869 
   1870 static float getMaxWidthListMarker(const RenderBox* renderer)
   1871 {
   1872 #if ENABLE(ASSERT)
   1873     ASSERT(renderer);
   1874     Node* parentNode = renderer->generatingNode();
   1875     ASSERT(parentNode);
   1876     ASSERT(isHTMLOListElement(parentNode) || isHTMLUListElement(parentNode));
   1877     ASSERT(renderer->style()->textAutosizingMultiplier() != 1);
   1878 #endif
   1879     float maxWidth = 0;
   1880     for (RenderObject* child = renderer->slowFirstChild(); child; child = child->nextSibling()) {
   1881         if (!child->isListItem())
   1882             continue;
   1883 
   1884         RenderBox* listItem = toRenderBox(child);
   1885         for (RenderObject* itemChild = listItem->slowFirstChild(); itemChild; itemChild = itemChild->nextSibling()) {
   1886             if (!itemChild->isListMarker())
   1887                 continue;
   1888             RenderBox* itemMarker = toRenderBox(itemChild);
   1889             // Make sure to compute the autosized width.
   1890             if (itemMarker->needsLayout())
   1891                 itemMarker->layout();
   1892             maxWidth = std::max<float>(maxWidth, toRenderListMarker(itemMarker)->logicalWidth().toFloat());
   1893             break;
   1894         }
   1895     }
   1896     return maxWidth;
   1897 }
   1898 
   1899 void RenderBox::computeLogicalWidth(LogicalExtentComputedValues& computedValues) const
   1900 {
   1901     computedValues.m_extent = logicalWidth();
   1902     computedValues.m_position = logicalLeft();
   1903     computedValues.m_margins.m_start = marginStart();
   1904     computedValues.m_margins.m_end = marginEnd();
   1905 
   1906     if (isOutOfFlowPositioned()) {
   1907         // FIXME: This calculation is not patched for block-flow yet.
   1908         // https://bugs.webkit.org/show_bug.cgi?id=46500
   1909         computePositionedLogicalWidth(computedValues);
   1910         return;
   1911     }
   1912 
   1913     // If layout is limited to a subtree, the subtree root's logical width does not change.
   1914     if (node() && view()->frameView() && view()->frameView()->layoutRoot(true) == this)
   1915         return;
   1916 
   1917     // The parent box is flexing us, so it has increased or decreased our
   1918     // width.  Use the width from the style context.
   1919     // FIXME: Account for block-flow in flexible boxes.
   1920     // https://bugs.webkit.org/show_bug.cgi?id=46418
   1921     if (hasOverrideWidth() && (style()->borderFit() == BorderFitLines || parent()->isFlexibleBoxIncludingDeprecated())) {
   1922         computedValues.m_extent = overrideLogicalContentWidth() + borderAndPaddingLogicalWidth();
   1923         return;
   1924     }
   1925 
   1926     // FIXME: Account for block-flow in flexible boxes.
   1927     // https://bugs.webkit.org/show_bug.cgi?id=46418
   1928     bool inVerticalBox = parent()->isDeprecatedFlexibleBox() && (parent()->style()->boxOrient() == VERTICAL);
   1929     bool stretching = (parent()->style()->boxAlign() == BSTRETCH);
   1930     bool treatAsReplaced = shouldComputeSizeAsReplaced() && (!inVerticalBox || !stretching);
   1931 
   1932     RenderStyle* styleToUse = style();
   1933     Length logicalWidthLength = treatAsReplaced ? Length(computeReplacedLogicalWidth(), Fixed) : styleToUse->logicalWidth();
   1934 
   1935     RenderBlock* cb = containingBlock();
   1936     LayoutUnit containerLogicalWidth = std::max<LayoutUnit>(0, containingBlockLogicalWidthForContent());
   1937     bool hasPerpendicularContainingBlock = cb->isHorizontalWritingMode() != isHorizontalWritingMode();
   1938 
   1939     if (isInline() && !isInlineBlockOrInlineTable()) {
   1940         // just calculate margins
   1941         computedValues.m_margins.m_start = minimumValueForLength(styleToUse->marginStart(), containerLogicalWidth);
   1942         computedValues.m_margins.m_end = minimumValueForLength(styleToUse->marginEnd(), containerLogicalWidth);
   1943         if (treatAsReplaced)
   1944             computedValues.m_extent = std::max<LayoutUnit>(floatValueForLength(logicalWidthLength, 0) + borderAndPaddingLogicalWidth(), minPreferredLogicalWidth());
   1945         return;
   1946     }
   1947 
   1948     // Width calculations
   1949     if (treatAsReplaced)
   1950         computedValues.m_extent = logicalWidthLength.value() + borderAndPaddingLogicalWidth();
   1951     else {
   1952         LayoutUnit containerWidthInInlineDirection = containerLogicalWidth;
   1953         if (hasPerpendicularContainingBlock)
   1954             containerWidthInInlineDirection = perpendicularContainingBlockLogicalHeight();
   1955         LayoutUnit preferredWidth = computeLogicalWidthUsing(MainOrPreferredSize, styleToUse->logicalWidth(), containerWidthInInlineDirection, cb);
   1956         computedValues.m_extent = constrainLogicalWidthByMinMax(preferredWidth, containerWidthInInlineDirection, cb);
   1957     }
   1958 
   1959     // Margin calculations.
   1960     computeMarginsForDirection(InlineDirection, cb, containerLogicalWidth, computedValues.m_extent, computedValues.m_margins.m_start,
   1961         computedValues.m_margins.m_end, style()->marginStart(), style()->marginEnd());
   1962 
   1963     if (!hasPerpendicularContainingBlock && containerLogicalWidth && containerLogicalWidth != (computedValues.m_extent + computedValues.m_margins.m_start + computedValues.m_margins.m_end)
   1964         && !isFloating() && !isInline() && !cb->isFlexibleBoxIncludingDeprecated() && !cb->isRenderGrid()) {
   1965         LayoutUnit newMargin = containerLogicalWidth - computedValues.m_extent - cb->marginStartForChild(this);
   1966         bool hasInvertedDirection = cb->style()->isLeftToRightDirection() != style()->isLeftToRightDirection();
   1967         if (hasInvertedDirection)
   1968             computedValues.m_margins.m_start = newMargin;
   1969         else
   1970             computedValues.m_margins.m_end = newMargin;
   1971     }
   1972 
   1973     if (styleToUse->textAutosizingMultiplier() != 1 && styleToUse->marginStart().type() == Fixed) {
   1974         Node* parentNode = generatingNode();
   1975         if (parentNode && (isHTMLOListElement(*parentNode) || isHTMLUListElement(*parentNode))) {
   1976             // Make sure the markers in a list are properly positioned (i.e. not chopped off) when autosized.
   1977             const float adjustedMargin = (1 - 1.0 / styleToUse->textAutosizingMultiplier()) * getMaxWidthListMarker(this);
   1978             bool hasInvertedDirection = cb->style()->isLeftToRightDirection() != style()->isLeftToRightDirection();
   1979             if (hasInvertedDirection)
   1980                 computedValues.m_margins.m_end += adjustedMargin;
   1981             else
   1982                 computedValues.m_margins.m_start += adjustedMargin;
   1983         }
   1984     }
   1985 }
   1986 
   1987 LayoutUnit RenderBox::fillAvailableMeasure(LayoutUnit availableLogicalWidth) const
   1988 {
   1989     LayoutUnit marginStart = 0;
   1990     LayoutUnit marginEnd = 0;
   1991     return fillAvailableMeasure(availableLogicalWidth, marginStart, marginEnd);
   1992 }
   1993 
   1994 LayoutUnit RenderBox::fillAvailableMeasure(LayoutUnit availableLogicalWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd) const
   1995 {
   1996     marginStart = minimumValueForLength(style()->marginStart(), availableLogicalWidth);
   1997     marginEnd = minimumValueForLength(style()->marginEnd(), availableLogicalWidth);
   1998     return availableLogicalWidth - marginStart - marginEnd;
   1999 }
   2000 
   2001 LayoutUnit RenderBox::computeIntrinsicLogicalWidthUsing(const Length& logicalWidthLength, LayoutUnit availableLogicalWidth, LayoutUnit borderAndPadding) const
   2002 {
   2003     if (logicalWidthLength.type() == FillAvailable)
   2004         return fillAvailableMeasure(availableLogicalWidth);
   2005 
   2006     LayoutUnit minLogicalWidth = 0;
   2007     LayoutUnit maxLogicalWidth = 0;
   2008     computeIntrinsicLogicalWidths(minLogicalWidth, maxLogicalWidth);
   2009 
   2010     if (logicalWidthLength.type() == MinContent)
   2011         return minLogicalWidth + borderAndPadding;
   2012 
   2013     if (logicalWidthLength.type() == MaxContent)
   2014         return maxLogicalWidth + borderAndPadding;
   2015 
   2016     if (logicalWidthLength.type() == FitContent) {
   2017         minLogicalWidth += borderAndPadding;
   2018         maxLogicalWidth += borderAndPadding;
   2019         return std::max(minLogicalWidth, std::min(maxLogicalWidth, fillAvailableMeasure(availableLogicalWidth)));
   2020     }
   2021 
   2022     ASSERT_NOT_REACHED();
   2023     return 0;
   2024 }
   2025 
   2026 LayoutUnit RenderBox::computeLogicalWidthUsing(SizeType widthType, const Length& logicalWidth, LayoutUnit availableLogicalWidth, const RenderBlock* cb) const
   2027 {
   2028     if (!logicalWidth.isIntrinsicOrAuto()) {
   2029         // FIXME: If the containing block flow is perpendicular to our direction we need to use the available logical height instead.
   2030         return adjustBorderBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, availableLogicalWidth));
   2031     }
   2032 
   2033     if (logicalWidth.isIntrinsic())
   2034         return computeIntrinsicLogicalWidthUsing(logicalWidth, availableLogicalWidth, borderAndPaddingLogicalWidth());
   2035 
   2036     LayoutUnit marginStart = 0;
   2037     LayoutUnit marginEnd = 0;
   2038     LayoutUnit logicalWidthResult = fillAvailableMeasure(availableLogicalWidth, marginStart, marginEnd);
   2039 
   2040     if (shrinkToAvoidFloats() && cb->isRenderBlockFlow() && toRenderBlockFlow(cb)->containsFloats())
   2041         logicalWidthResult = std::min(logicalWidthResult, shrinkLogicalWidthToAvoidFloats(marginStart, marginEnd, toRenderBlockFlow(cb)));
   2042 
   2043     if (widthType == MainOrPreferredSize && sizesLogicalWidthToFitContent(logicalWidth))
   2044         return std::max(minPreferredLogicalWidth(), std::min(maxPreferredLogicalWidth(), logicalWidthResult));
   2045     return logicalWidthResult;
   2046 }
   2047 
   2048 static bool columnFlexItemHasStretchAlignment(const RenderObject* flexitem)
   2049 {
   2050     RenderObject* parent = flexitem->parent();
   2051     // auto margins mean we don't stretch. Note that this function will only be used for
   2052     // widths, so we don't have to check marginBefore/marginAfter.
   2053     ASSERT(parent->style()->isColumnFlexDirection());
   2054     if (flexitem->style()->marginStart().isAuto() || flexitem->style()->marginEnd().isAuto())
   2055         return false;
   2056     return flexitem->style()->alignSelf() == ItemPositionStretch || (flexitem->style()->alignSelf() == ItemPositionAuto && parent->style()->alignItems() == ItemPositionStretch);
   2057 }
   2058 
   2059 static bool isStretchingColumnFlexItem(const RenderObject* flexitem)
   2060 {
   2061     RenderObject* parent = flexitem->parent();
   2062     if (parent->isDeprecatedFlexibleBox() && parent->style()->boxOrient() == VERTICAL && parent->style()->boxAlign() == BSTRETCH)
   2063         return true;
   2064 
   2065     // We don't stretch multiline flexboxes because they need to apply line spacing (align-content) first.
   2066     if (parent->isFlexibleBox() && parent->style()->flexWrap() == FlexNoWrap && parent->style()->isColumnFlexDirection() && columnFlexItemHasStretchAlignment(flexitem))
   2067         return true;
   2068     return false;
   2069 }
   2070 
   2071 bool RenderBox::sizesLogicalWidthToFitContent(const Length& logicalWidth) const
   2072 {
   2073     // Marquees in WinIE are like a mixture of blocks and inline-blocks.  They size as though they're blocks,
   2074     // but they allow text to sit on the same line as the marquee.
   2075     if (isFloating() || (isInlineBlockOrInlineTable() && !isMarquee()))
   2076         return true;
   2077 
   2078     if (logicalWidth.type() == Intrinsic)
   2079         return true;
   2080 
   2081     // Children of a horizontal marquee do not fill the container by default.
   2082     // FIXME: Need to deal with MAUTO value properly.  It could be vertical.
   2083     // FIXME: Think about block-flow here.  Need to find out how marquee direction relates to
   2084     // block-flow (as well as how marquee overflow should relate to block flow).
   2085     // https://bugs.webkit.org/show_bug.cgi?id=46472
   2086     if (parent()->isMarquee()) {
   2087         EMarqueeDirection dir = parent()->style()->marqueeDirection();
   2088         if (dir == MAUTO || dir == MFORWARD || dir == MBACKWARD || dir == MLEFT || dir == MRIGHT)
   2089             return true;
   2090     }
   2091 
   2092     // Flexible box items should shrink wrap, so we lay them out at their intrinsic widths.
   2093     // In the case of columns that have a stretch alignment, we go ahead and layout at the
   2094     // stretched size to avoid an extra layout when applying alignment.
   2095     if (parent()->isFlexibleBox()) {
   2096         // For multiline columns, we need to apply align-content first, so we can't stretch now.
   2097         if (!parent()->style()->isColumnFlexDirection() || parent()->style()->flexWrap() != FlexNoWrap)
   2098             return true;
   2099         if (!columnFlexItemHasStretchAlignment(this))
   2100             return true;
   2101     }
   2102 
   2103     // Flexible horizontal boxes lay out children at their intrinsic widths.  Also vertical boxes
   2104     // that don't stretch their kids lay out their children at their intrinsic widths.
   2105     // FIXME: Think about block-flow here.
   2106     // https://bugs.webkit.org/show_bug.cgi?id=46473
   2107     if (parent()->isDeprecatedFlexibleBox() && (parent()->style()->boxOrient() == HORIZONTAL || parent()->style()->boxAlign() != BSTRETCH))
   2108         return true;
   2109 
   2110     // Button, input, select, textarea, and legend treat width value of 'auto' as 'intrinsic' unless it's in a
   2111     // stretching column flexbox.
   2112     // FIXME: Think about block-flow here.
   2113     // https://bugs.webkit.org/show_bug.cgi?id=46473
   2114     if (logicalWidth.isAuto() && !isStretchingColumnFlexItem(this) && autoWidthShouldFitContent())
   2115         return true;
   2116 
   2117     if (isHorizontalWritingMode() != containingBlock()->isHorizontalWritingMode())
   2118         return true;
   2119 
   2120     return false;
   2121 }
   2122 
   2123 bool RenderBox::autoWidthShouldFitContent() const
   2124 {
   2125     return node() && (isHTMLInputElement(*node()) || isHTMLSelectElement(*node()) || isHTMLButtonElement(*node())
   2126         || isHTMLTextAreaElement(*node()) || (isHTMLLegendElement(*node()) && !style()->hasOutOfFlowPosition()));
   2127 }
   2128 
   2129 void RenderBox::computeMarginsForDirection(MarginDirection flowDirection, const RenderBlock* containingBlock, LayoutUnit containerWidth, LayoutUnit childWidth, LayoutUnit& marginStart, LayoutUnit& marginEnd, Length marginStartLength, Length marginEndLength) const
   2130 {
   2131     if (flowDirection == BlockDirection || isFloating() || isInline()) {
   2132         if (isTableCell() && flowDirection == BlockDirection) {
   2133             // FIXME: Not right if we allow cells to have different directionality than the table. If we do allow this, though,
   2134             // we may just do it with an extra anonymous block inside the cell.
   2135             marginStart = 0;
   2136             marginEnd = 0;
   2137             return;
   2138         }
   2139 
   2140         // Margins are calculated with respect to the logical width of
   2141         // the containing block (8.3)
   2142         // Inline blocks/tables and floats don't have their margins increased.
   2143         marginStart = minimumValueForLength(marginStartLength, containerWidth);
   2144         marginEnd = minimumValueForLength(marginEndLength, containerWidth);
   2145         return;
   2146     }
   2147 
   2148     if (containingBlock->isFlexibleBox()) {
   2149         // We need to let flexbox handle the margin adjustment - otherwise, flexbox
   2150         // will think we're wider than we actually are and calculate line sizes wrong.
   2151         // See also http://dev.w3.org/csswg/css-flexbox/#auto-margins
   2152         if (marginStartLength.isAuto())
   2153             marginStartLength.setValue(0);
   2154         if (marginEndLength.isAuto())
   2155             marginEndLength.setValue(0);
   2156     }
   2157 
   2158     LayoutUnit marginStartWidth = minimumValueForLength(marginStartLength, containerWidth);
   2159     LayoutUnit marginEndWidth = minimumValueForLength(marginEndLength, containerWidth);
   2160 
   2161     LayoutUnit availableWidth = containerWidth;
   2162     if (avoidsFloats() && containingBlock->isRenderBlockFlow() && toRenderBlockFlow(containingBlock)->containsFloats()) {
   2163         availableWidth = containingBlockAvailableLineWidth();
   2164         if (shrinkToAvoidFloats() && availableWidth < containerWidth) {
   2165             marginStart = std::max<LayoutUnit>(0, marginStartWidth);
   2166             marginEnd = std::max<LayoutUnit>(0, marginEndWidth);
   2167         }
   2168     }
   2169 
   2170     // CSS 2.1 (10.3.3): "If 'width' is not 'auto' and 'border-left-width' + 'padding-left' + 'width' + 'padding-right' + 'border-right-width'
   2171     // (plus any of 'margin-left' or 'margin-right' that are not 'auto') is larger than the width of the containing block, then any 'auto'
   2172     // values for 'margin-left' or 'margin-right' are, for the following rules, treated as zero.
   2173     LayoutUnit marginBoxWidth = childWidth + (!style()->width().isAuto() ? marginStartWidth + marginEndWidth : LayoutUnit());
   2174 
   2175     // CSS 2.1: "If both 'margin-left' and 'margin-right' are 'auto', their used values are equal. This horizontally centers the element
   2176     // with respect to the edges of the containing block."
   2177     const RenderStyle* containingBlockStyle = containingBlock->style();
   2178     if ((marginStartLength.isAuto() && marginEndLength.isAuto() && marginBoxWidth < availableWidth)
   2179         || (!marginStartLength.isAuto() && !marginEndLength.isAuto() && containingBlockStyle->textAlign() == WEBKIT_CENTER)) {
   2180         // Other browsers center the margin box for align=center elements so we match them here.
   2181         LayoutUnit centeredMarginBoxStart = std::max<LayoutUnit>(0, (availableWidth - childWidth - marginStartWidth - marginEndWidth) / 2);
   2182         marginStart = centeredMarginBoxStart + marginStartWidth;
   2183         marginEnd = availableWidth - childWidth - marginStart + marginEndWidth;
   2184         return;
   2185     }
   2186 
   2187     // CSS 2.1: "If there is exactly one value specified as 'auto', its used value follows from the equality."
   2188     if (marginEndLength.isAuto() && marginBoxWidth < availableWidth) {
   2189         marginStart = marginStartWidth;
   2190         marginEnd = availableWidth - childWidth - marginStart;
   2191         return;
   2192     }
   2193 
   2194     bool pushToEndFromTextAlign = !marginEndLength.isAuto() && ((!containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_LEFT)
   2195         || (containingBlockStyle->isLeftToRightDirection() && containingBlockStyle->textAlign() == WEBKIT_RIGHT));
   2196     if ((marginStartLength.isAuto() && marginBoxWidth < availableWidth) || pushToEndFromTextAlign) {
   2197         marginEnd = marginEndWidth;
   2198         marginStart = availableWidth - childWidth - marginEnd;
   2199         return;
   2200     }
   2201 
   2202     // Either no auto margins, or our margin box width is >= the container width, auto margins will just turn into 0.
   2203     marginStart = marginStartWidth;
   2204     marginEnd = marginEndWidth;
   2205 }
   2206 
   2207 void RenderBox::updateLogicalHeight()
   2208 {
   2209     m_intrinsicContentLogicalHeight = contentLogicalHeight();
   2210 
   2211     LogicalExtentComputedValues computedValues;
   2212     computeLogicalHeight(logicalHeight(), logicalTop(), computedValues);
   2213 
   2214     setLogicalHeight(computedValues.m_extent);
   2215     setLogicalTop(computedValues.m_position);
   2216     setMarginBefore(computedValues.m_margins.m_before);
   2217     setMarginAfter(computedValues.m_margins.m_after);
   2218 }
   2219 
   2220 void RenderBox::computeLogicalHeight(LayoutUnit logicalHeight, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
   2221 {
   2222     computedValues.m_extent = logicalHeight;
   2223     computedValues.m_position = logicalTop;
   2224 
   2225     // Cell height is managed by the table and inline non-replaced elements do not support a height property.
   2226     if (isTableCell() || (isInline() && !isReplaced()))
   2227         return;
   2228 
   2229     Length h;
   2230     if (isOutOfFlowPositioned())
   2231         computePositionedLogicalHeight(computedValues);
   2232     else {
   2233         RenderBlock* cb = containingBlock();
   2234 
   2235         // If we are perpendicular to our containing block then we need to resolve our block-start and block-end margins so that if they
   2236         // are 'auto' we are centred or aligned within the inline flow containing block: this is done by computing the margins as though they are inline.
   2237         // Note that as this is the 'sizing phase' we are using our own writing mode rather than the containing block's. We use the containing block's
   2238         // writing mode when figuring out the block-direction margins for positioning in |computeAndSetBlockDirectionMargins| (i.e. margin collapsing etc.).
   2239         // See http://www.w3.org/TR/2014/CR-css-writing-modes-3-20140320/#orthogonal-flows
   2240         MarginDirection flowDirection = isHorizontalWritingMode() != cb->isHorizontalWritingMode() ? InlineDirection : BlockDirection;
   2241 
   2242         // For tables, calculate margins only.
   2243         if (isTable()) {
   2244             computeMarginsForDirection(flowDirection, cb, containingBlockLogicalWidthForContent(), computedValues.m_extent, computedValues.m_margins.m_before,
   2245                 computedValues.m_margins.m_after, style()->marginBefore(), style()->marginAfter());
   2246             return;
   2247         }
   2248 
   2249         // FIXME: Account for block-flow in flexible boxes.
   2250         // https://bugs.webkit.org/show_bug.cgi?id=46418
   2251         bool inHorizontalBox = parent()->isDeprecatedFlexibleBox() && parent()->style()->boxOrient() == HORIZONTAL;
   2252         bool stretching = parent()->style()->boxAlign() == BSTRETCH;
   2253         bool treatAsReplaced = shouldComputeSizeAsReplaced() && (!inHorizontalBox || !stretching);
   2254         bool checkMinMaxHeight = false;
   2255 
   2256         // The parent box is flexing us, so it has increased or decreased our height.  We have to
   2257         // grab our cached flexible height.
   2258         // FIXME: Account for block-flow in flexible boxes.
   2259         // https://bugs.webkit.org/show_bug.cgi?id=46418
   2260         if (hasOverrideHeight() && parent()->isFlexibleBoxIncludingDeprecated())
   2261             h = Length(overrideLogicalContentHeight(), Fixed);
   2262         else if (treatAsReplaced)
   2263             h = Length(computeReplacedLogicalHeight(), Fixed);
   2264         else {
   2265             h = style()->logicalHeight();
   2266             checkMinMaxHeight = true;
   2267         }
   2268 
   2269         // Block children of horizontal flexible boxes fill the height of the box.
   2270         // FIXME: Account for block-flow in flexible boxes.
   2271         // https://bugs.webkit.org/show_bug.cgi?id=46418
   2272         if (h.isAuto() && inHorizontalBox && toRenderDeprecatedFlexibleBox(parent())->isStretchingChildren()) {
   2273             h = Length(parentBox()->contentLogicalHeight() - marginBefore() - marginAfter() - borderAndPaddingLogicalHeight(), Fixed);
   2274             checkMinMaxHeight = false;
   2275         }
   2276 
   2277         LayoutUnit heightResult;
   2278         if (checkMinMaxHeight) {
   2279             heightResult = computeLogicalHeightUsing(style()->logicalHeight(), computedValues.m_extent - borderAndPaddingLogicalHeight());
   2280             if (heightResult == -1)
   2281                 heightResult = computedValues.m_extent;
   2282             heightResult = constrainLogicalHeightByMinMax(heightResult, computedValues.m_extent - borderAndPaddingLogicalHeight());
   2283         } else {
   2284             // The only times we don't check min/max height are when a fixed length has
   2285             // been given as an override.  Just use that.  The value has already been adjusted
   2286             // for box-sizing.
   2287             ASSERT(h.isFixed());
   2288             heightResult = h.value() + borderAndPaddingLogicalHeight();
   2289         }
   2290 
   2291         computedValues.m_extent = heightResult;
   2292         computeMarginsForDirection(flowDirection, cb, containingBlockLogicalWidthForContent(), computedValues.m_extent, computedValues.m_margins.m_before,
   2293             computedValues.m_margins.m_after, style()->marginBefore(), style()->marginAfter());
   2294     }
   2295 
   2296     // WinIE quirk: The <html> block always fills the entire canvas in quirks mode.  The <body> always fills the
   2297     // <html> block in quirks mode.  Only apply this quirk if the block is normal flow and no height
   2298     // is specified. When we're printing, we also need this quirk if the body or root has a percentage
   2299     // height since we don't set a height in RenderView when we're printing. So without this quirk, the
   2300     // height has nothing to be a percentage of, and it ends up being 0. That is bad.
   2301     bool paginatedContentNeedsBaseHeight = document().printing() && h.isPercent()
   2302         && (isDocumentElement() || (isBody() && document().documentElement()->renderer()->style()->logicalHeight().isPercent())) && !isInline();
   2303     if (stretchesToViewport() || paginatedContentNeedsBaseHeight) {
   2304         LayoutUnit margins = collapsedMarginBefore() + collapsedMarginAfter();
   2305         LayoutUnit visibleHeight = view()->viewLogicalHeightForPercentages();
   2306         if (isDocumentElement())
   2307             computedValues.m_extent = std::max(computedValues.m_extent, visibleHeight - margins);
   2308         else {
   2309             LayoutUnit marginsBordersPadding = margins + parentBox()->marginBefore() + parentBox()->marginAfter() + parentBox()->borderAndPaddingLogicalHeight();
   2310             computedValues.m_extent = std::max(computedValues.m_extent, visibleHeight - marginsBordersPadding);
   2311         }
   2312     }
   2313 }
   2314 
   2315 LayoutUnit RenderBox::computeLogicalHeightUsing(const Length& height, LayoutUnit intrinsicContentHeight) const
   2316 {
   2317     LayoutUnit logicalHeight = computeContentAndScrollbarLogicalHeightUsing(height, intrinsicContentHeight);
   2318     if (logicalHeight != -1)
   2319         logicalHeight = adjustBorderBoxLogicalHeightForBoxSizing(logicalHeight);
   2320     return logicalHeight;
   2321 }
   2322 
   2323 LayoutUnit RenderBox::computeContentLogicalHeight(const Length& height, LayoutUnit intrinsicContentHeight) const
   2324 {
   2325     LayoutUnit heightIncludingScrollbar = computeContentAndScrollbarLogicalHeightUsing(height, intrinsicContentHeight);
   2326     if (heightIncludingScrollbar == -1)
   2327         return -1;
   2328     return std::max<LayoutUnit>(0, adjustContentBoxLogicalHeightForBoxSizing(heightIncludingScrollbar) - scrollbarLogicalHeight());
   2329 }
   2330 
   2331 LayoutUnit RenderBox::computeIntrinsicLogicalContentHeightUsing(const Length& logicalHeightLength, LayoutUnit intrinsicContentHeight, LayoutUnit borderAndPadding) const
   2332 {
   2333     // FIXME(cbiesinger): The css-sizing spec is considering changing what min-content/max-content should resolve to.
   2334     // If that happens, this code will have to change.
   2335     if (logicalHeightLength.isMinContent() || logicalHeightLength.isMaxContent() || logicalHeightLength.isFitContent()) {
   2336         if (isReplaced())
   2337             return intrinsicSize().height();
   2338         if (m_intrinsicContentLogicalHeight != -1)
   2339             return m_intrinsicContentLogicalHeight;
   2340         return intrinsicContentHeight;
   2341     }
   2342     if (logicalHeightLength.isFillAvailable())
   2343         return containingBlock()->availableLogicalHeight(ExcludeMarginBorderPadding) - borderAndPadding;
   2344     ASSERT_NOT_REACHED();
   2345     return 0;
   2346 }
   2347 
   2348 LayoutUnit RenderBox::computeContentAndScrollbarLogicalHeightUsing(const Length& height, LayoutUnit intrinsicContentHeight) const
   2349 {
   2350     // FIXME(cbiesinger): The css-sizing spec is considering changing what min-content/max-content should resolve to.
   2351     // If that happens, this code will have to change.
   2352     if (height.isIntrinsic()) {
   2353         if (intrinsicContentHeight == -1)
   2354             return -1; // Intrinsic height isn't available.
   2355         return computeIntrinsicLogicalContentHeightUsing(height, intrinsicContentHeight, borderAndPaddingLogicalHeight());
   2356     }
   2357     if (height.isFixed())
   2358         return height.value();
   2359     if (height.isPercent())
   2360         return computePercentageLogicalHeight(height);
   2361     return -1;
   2362 }
   2363 
   2364 bool RenderBox::skipContainingBlockForPercentHeightCalculation(const RenderBox* containingBlock) const
   2365 {
   2366     // Flow threads for multicol or paged overflow should be skipped. They are invisible to the DOM,
   2367     // and percent heights of children should be resolved against the multicol or paged container.
   2368     if (containingBlock->isRenderFlowThread())
   2369         return true;
   2370 
   2371     // For quirks mode and anonymous blocks, we skip auto-height containingBlocks when computing percentages.
   2372     // For standards mode, we treat the percentage as auto if it has an auto-height containing block.
   2373     if (!document().inQuirksMode() && !containingBlock->isAnonymousBlock())
   2374         return false;
   2375     return !containingBlock->isTableCell() && !containingBlock->isOutOfFlowPositioned() && containingBlock->style()->logicalHeight().isAuto() && isHorizontalWritingMode() == containingBlock->isHorizontalWritingMode();
   2376 }
   2377 
   2378 LayoutUnit RenderBox::computePercentageLogicalHeight(const Length& height) const
   2379 {
   2380     LayoutUnit availableHeight = -1;
   2381 
   2382     bool skippedAutoHeightContainingBlock = false;
   2383     RenderBlock* cb = containingBlock();
   2384     const RenderBox* containingBlockChild = this;
   2385     LayoutUnit rootMarginBorderPaddingHeight = 0;
   2386     while (!cb->isRenderView() && skipContainingBlockForPercentHeightCalculation(cb)) {
   2387         if (cb->isBody() || cb->isDocumentElement())
   2388             rootMarginBorderPaddingHeight += cb->marginBefore() + cb->marginAfter() + cb->borderAndPaddingLogicalHeight();
   2389         skippedAutoHeightContainingBlock = true;
   2390         containingBlockChild = cb;
   2391         cb = cb->containingBlock();
   2392     }
   2393     cb->addPercentHeightDescendant(const_cast<RenderBox*>(this));
   2394 
   2395     RenderStyle* cbstyle = cb->style();
   2396 
   2397     // A positioned element that specified both top/bottom or that specifies height should be treated as though it has a height
   2398     // explicitly specified that can be used for any percentage computations.
   2399     bool isOutOfFlowPositionedWithSpecifiedHeight = cb->isOutOfFlowPositioned() && (!cbstyle->logicalHeight().isAuto() || (!cbstyle->logicalTop().isAuto() && !cbstyle->logicalBottom().isAuto()));
   2400 
   2401     bool includeBorderPadding = isTable();
   2402 
   2403     if (isHorizontalWritingMode() != cb->isHorizontalWritingMode())
   2404         availableHeight = containingBlockChild->containingBlockLogicalWidthForContent();
   2405     else if (hasOverrideContainingBlockLogicalHeight())
   2406         availableHeight = overrideContainingBlockContentLogicalHeight();
   2407     else if (cb->isTableCell()) {
   2408         if (!skippedAutoHeightContainingBlock) {
   2409             // Table cells violate what the CSS spec says to do with heights. Basically we
   2410             // don't care if the cell specified a height or not. We just always make ourselves
   2411             // be a percentage of the cell's current content height.
   2412             if (!cb->hasOverrideHeight()) {
   2413                 // Normally we would let the cell size intrinsically, but scrolling overflow has to be
   2414                 // treated differently, since WinIE lets scrolled overflow regions shrink as needed.
   2415                 // While we can't get all cases right, we can at least detect when the cell has a specified
   2416                 // height or when the table has a specified height. In these cases we want to initially have
   2417                 // no size and allow the flexing of the table or the cell to its specified height to cause us
   2418                 // to grow to fill the space. This could end up being wrong in some cases, but it is
   2419                 // preferable to the alternative (sizing intrinsically and making the row end up too big).
   2420                 RenderTableCell* cell = toRenderTableCell(cb);
   2421                 if (scrollsOverflowY() && (!cell->style()->logicalHeight().isAuto() || !cell->table()->style()->logicalHeight().isAuto()))
   2422                     return 0;
   2423                 return -1;
   2424             }
   2425             availableHeight = cb->overrideLogicalContentHeight();
   2426             includeBorderPadding = true;
   2427         }
   2428     } else if (cbstyle->logicalHeight().isFixed()) {
   2429         LayoutUnit contentBoxHeight = cb->adjustContentBoxLogicalHeightForBoxSizing(cbstyle->logicalHeight().value());
   2430         availableHeight = std::max<LayoutUnit>(0, cb->constrainContentBoxLogicalHeightByMinMax(contentBoxHeight - cb->scrollbarLogicalHeight(), -1));
   2431     } else if (cbstyle->logicalHeight().isPercent() && !isOutOfFlowPositionedWithSpecifiedHeight) {
   2432         // We need to recur and compute the percentage height for our containing block.
   2433         LayoutUnit heightWithScrollbar = cb->computePercentageLogicalHeight(cbstyle->logicalHeight());
   2434         if (heightWithScrollbar != -1) {
   2435             LayoutUnit contentBoxHeightWithScrollbar = cb->adjustContentBoxLogicalHeightForBoxSizing(heightWithScrollbar);
   2436             // We need to adjust for min/max height because this method does not
   2437             // handle the min/max of the current block, its caller does. So the
   2438             // return value from the recursive call will not have been adjusted
   2439             // yet.
   2440             LayoutUnit contentBoxHeight = cb->constrainContentBoxLogicalHeightByMinMax(contentBoxHeightWithScrollbar - cb->scrollbarLogicalHeight(), -1);
   2441             availableHeight = std::max<LayoutUnit>(0, contentBoxHeight);
   2442         }
   2443     } else if (isOutOfFlowPositionedWithSpecifiedHeight) {
   2444         // Don't allow this to affect the block' height() member variable, since this
   2445         // can get called while the block is still laying out its kids.
   2446         LogicalExtentComputedValues computedValues;
   2447         cb->computeLogicalHeight(cb->logicalHeight(), 0, computedValues);
   2448         availableHeight = computedValues.m_extent - cb->borderAndPaddingLogicalHeight() - cb->scrollbarLogicalHeight();
   2449     } else if (cb->isRenderView())
   2450         availableHeight = view()->viewLogicalHeightForPercentages();
   2451 
   2452     if (availableHeight == -1)
   2453         return availableHeight;
   2454 
   2455     availableHeight -= rootMarginBorderPaddingHeight;
   2456 
   2457     if (isTable() && isOutOfFlowPositioned())
   2458         availableHeight += cb->paddingLogicalHeight();
   2459 
   2460     LayoutUnit result = valueForLength(height, availableHeight);
   2461     if (includeBorderPadding) {
   2462         // FIXME: Table cells should default to box-sizing: border-box so we can avoid this hack.
   2463         // It is necessary to use the border-box to match WinIE's broken
   2464         // box model. This is essential for sizing inside
   2465         // table cells using percentage heights.
   2466         result -= borderAndPaddingLogicalHeight();
   2467         return std::max<LayoutUnit>(0, result);
   2468     }
   2469     return result;
   2470 }
   2471 
   2472 LayoutUnit RenderBox::computeReplacedLogicalWidth(ShouldComputePreferred shouldComputePreferred) const
   2473 {
   2474     return computeReplacedLogicalWidthRespectingMinMaxWidth(computeReplacedLogicalWidthUsing(style()->logicalWidth()), shouldComputePreferred);
   2475 }
   2476 
   2477 LayoutUnit RenderBox::computeReplacedLogicalWidthRespectingMinMaxWidth(LayoutUnit logicalWidth, ShouldComputePreferred shouldComputePreferred) const
   2478 {
   2479     LayoutUnit minLogicalWidth = (shouldComputePreferred == ComputePreferred && style()->logicalMinWidth().isPercent()) || style()->logicalMinWidth().isMaxSizeNone() ? logicalWidth : computeReplacedLogicalWidthUsing(style()->logicalMinWidth());
   2480     LayoutUnit maxLogicalWidth = (shouldComputePreferred == ComputePreferred && style()->logicalMaxWidth().isPercent()) || style()->logicalMaxWidth().isMaxSizeNone() ? logicalWidth : computeReplacedLogicalWidthUsing(style()->logicalMaxWidth());
   2481     return std::max(minLogicalWidth, std::min(logicalWidth, maxLogicalWidth));
   2482 }
   2483 
   2484 LayoutUnit RenderBox::computeReplacedLogicalWidthUsing(const Length& logicalWidth) const
   2485 {
   2486     switch (logicalWidth.type()) {
   2487         case Fixed:
   2488             return adjustContentBoxLogicalWidthForBoxSizing(logicalWidth.value());
   2489         case MinContent:
   2490         case MaxContent: {
   2491             // MinContent/MaxContent don't need the availableLogicalWidth argument.
   2492             LayoutUnit availableLogicalWidth = 0;
   2493             return computeIntrinsicLogicalWidthUsing(logicalWidth, availableLogicalWidth, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
   2494         }
   2495         case FitContent:
   2496         case FillAvailable:
   2497         case Percent:
   2498         case Calculated: {
   2499             // FIXME: containingBlockLogicalWidthForContent() is wrong if the replaced element's block-flow is perpendicular to the
   2500             // containing block's block-flow.
   2501             // https://bugs.webkit.org/show_bug.cgi?id=46496
   2502             const LayoutUnit cw = isOutOfFlowPositioned() ? containingBlockLogicalWidthForPositioned(toRenderBoxModelObject(container())) : containingBlockLogicalWidthForContent();
   2503             Length containerLogicalWidth = containingBlock()->style()->logicalWidth();
   2504             // FIXME: Handle cases when containing block width is calculated or viewport percent.
   2505             // https://bugs.webkit.org/show_bug.cgi?id=91071
   2506             if (logicalWidth.isIntrinsic())
   2507                 return computeIntrinsicLogicalWidthUsing(logicalWidth, cw, borderAndPaddingLogicalWidth()) - borderAndPaddingLogicalWidth();
   2508             if (cw > 0 || (!cw && (containerLogicalWidth.isFixed() || containerLogicalWidth.isPercent())))
   2509                 return adjustContentBoxLogicalWidthForBoxSizing(minimumValueForLength(logicalWidth, cw));
   2510             return 0;
   2511         }
   2512         case Intrinsic:
   2513         case MinIntrinsic:
   2514         case Auto:
   2515         case MaxSizeNone:
   2516             return intrinsicLogicalWidth();
   2517         case ExtendToZoom:
   2518         case DeviceWidth:
   2519         case DeviceHeight:
   2520             break;
   2521     }
   2522 
   2523     ASSERT_NOT_REACHED();
   2524     return 0;
   2525 }
   2526 
   2527 LayoutUnit RenderBox::computeReplacedLogicalHeight() const
   2528 {
   2529     return computeReplacedLogicalHeightRespectingMinMaxHeight(computeReplacedLogicalHeightUsing(style()->logicalHeight()));
   2530 }
   2531 
   2532 bool RenderBox::logicalHeightComputesAsNone(SizeType sizeType) const
   2533 {
   2534     ASSERT(sizeType == MinSize || sizeType == MaxSize);
   2535     Length logicalHeight = sizeType == MinSize ? style()->logicalMinHeight() : style()->logicalMaxHeight();
   2536     Length initialLogicalHeight = sizeType == MinSize ? RenderStyle::initialMinSize() : RenderStyle::initialMaxSize();
   2537 
   2538     if (logicalHeight == initialLogicalHeight)
   2539         return true;
   2540 
   2541     if (!logicalHeight.isPercent() || isOutOfFlowPositioned())
   2542         return false;
   2543 
   2544     // Anonymous block boxes are ignored when resolving percentage values that would refer to it:
   2545     // the closest non-anonymous ancestor box is used instead.
   2546     RenderBlock* containingBlock = this->containingBlock();
   2547     while (containingBlock->isAnonymous())
   2548         containingBlock = containingBlock->containingBlock();
   2549 
   2550     return containingBlock->hasAutoHeightOrContainingBlockWithAutoHeight();
   2551 }
   2552 
   2553 LayoutUnit RenderBox::computeReplacedLogicalHeightRespectingMinMaxHeight(LayoutUnit logicalHeight) const
   2554 {
   2555     // If the height of the containing block is not specified explicitly (i.e., it depends on content height), and this element is not absolutely positioned,
   2556     // the percentage value is treated as '0' (for 'min-height') or 'none' (for 'max-height').
   2557     LayoutUnit minLogicalHeight;
   2558     if (!logicalHeightComputesAsNone(MinSize))
   2559         minLogicalHeight = computeReplacedLogicalHeightUsing(style()->logicalMinHeight());
   2560     LayoutUnit maxLogicalHeight = logicalHeight;
   2561     if (!logicalHeightComputesAsNone(MaxSize))
   2562         maxLogicalHeight =  computeReplacedLogicalHeightUsing(style()->logicalMaxHeight());
   2563     return std::max(minLogicalHeight, std::min(logicalHeight, maxLogicalHeight));
   2564 }
   2565 
   2566 LayoutUnit RenderBox::computeReplacedLogicalHeightUsing(const Length& logicalHeight) const
   2567 {
   2568     switch (logicalHeight.type()) {
   2569         case Fixed:
   2570             return adjustContentBoxLogicalHeightForBoxSizing(logicalHeight.value());
   2571         case Percent:
   2572         case Calculated:
   2573         {
   2574             RenderObject* cb = isOutOfFlowPositioned() ? container() : containingBlock();
   2575             while (cb->isAnonymous())
   2576                 cb = cb->containingBlock();
   2577             if (cb->isRenderBlock())
   2578                 toRenderBlock(cb)->addPercentHeightDescendant(const_cast<RenderBox*>(this));
   2579 
   2580             // FIXME: This calculation is not patched for block-flow yet.
   2581             // https://bugs.webkit.org/show_bug.cgi?id=46500
   2582             if (cb->isOutOfFlowPositioned() && cb->style()->height().isAuto() && !(cb->style()->top().isAuto() || cb->style()->bottom().isAuto())) {
   2583                 ASSERT_WITH_SECURITY_IMPLICATION(cb->isRenderBlock());
   2584                 RenderBlock* block = toRenderBlock(cb);
   2585                 LogicalExtentComputedValues computedValues;
   2586                 block->computeLogicalHeight(block->logicalHeight(), 0, computedValues);
   2587                 LayoutUnit newContentHeight = computedValues.m_extent - block->borderAndPaddingLogicalHeight() - block->scrollbarLogicalHeight();
   2588                 LayoutUnit newHeight = block->adjustContentBoxLogicalHeightForBoxSizing(newContentHeight);
   2589                 return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeight, newHeight));
   2590             }
   2591 
   2592             // FIXME: availableLogicalHeight() is wrong if the replaced element's block-flow is perpendicular to the
   2593             // containing block's block-flow.
   2594             // https://bugs.webkit.org/show_bug.cgi?id=46496
   2595             LayoutUnit availableHeight;
   2596             if (isOutOfFlowPositioned())
   2597                 availableHeight = containingBlockLogicalHeightForPositioned(toRenderBoxModelObject(cb));
   2598             else {
   2599                 availableHeight = containingBlockLogicalHeightForContent(IncludeMarginBorderPadding);
   2600                 // It is necessary to use the border-box to match WinIE's broken
   2601                 // box model.  This is essential for sizing inside
   2602                 // table cells using percentage heights.
   2603                 // FIXME: This needs to be made block-flow-aware.  If the cell and image are perpendicular block-flows, this isn't right.
   2604                 // https://bugs.webkit.org/show_bug.cgi?id=46997
   2605                 while (cb && !cb->isRenderView() && (cb->style()->logicalHeight().isAuto() || cb->style()->logicalHeight().isPercent())) {
   2606                     if (cb->isTableCell()) {
   2607                         // Don't let table cells squeeze percent-height replaced elements
   2608                         // <http://bugs.webkit.org/show_bug.cgi?id=15359>
   2609                         availableHeight = std::max(availableHeight, intrinsicLogicalHeight());
   2610                         return valueForLength(logicalHeight, availableHeight - borderAndPaddingLogicalHeight());
   2611                     }
   2612                     toRenderBlock(cb)->addPercentHeightDescendant(const_cast<RenderBox*>(this));
   2613                     cb = cb->containingBlock();
   2614                 }
   2615             }
   2616             return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeight, availableHeight));
   2617         }
   2618         case MinContent:
   2619         case MaxContent:
   2620         case FitContent:
   2621         case FillAvailable:
   2622             return adjustContentBoxLogicalHeightForBoxSizing(computeIntrinsicLogicalContentHeightUsing(logicalHeight, intrinsicLogicalHeight(), borderAndPaddingHeight()));
   2623         default:
   2624             return intrinsicLogicalHeight();
   2625     }
   2626 }
   2627 
   2628 LayoutUnit RenderBox::availableLogicalHeight(AvailableLogicalHeightType heightType) const
   2629 {
   2630     // http://www.w3.org/TR/CSS2/visudet.html#propdef-height - We are interested in the content height.
   2631     return constrainContentBoxLogicalHeightByMinMax(availableLogicalHeightUsing(style()->logicalHeight(), heightType), -1);
   2632 }
   2633 
   2634 LayoutUnit RenderBox::availableLogicalHeightUsing(const Length& h, AvailableLogicalHeightType heightType) const
   2635 {
   2636     if (isRenderView())
   2637         return isHorizontalWritingMode() ? toRenderView(this)->frameView()->unscaledVisibleContentSize().height() : toRenderView(this)->frameView()->unscaledVisibleContentSize().width();
   2638 
   2639     // We need to stop here, since we don't want to increase the height of the table
   2640     // artificially.  We're going to rely on this cell getting expanded to some new
   2641     // height, and then when we lay out again we'll use the calculation below.
   2642     if (isTableCell() && (h.isAuto() || h.isPercent())) {
   2643         if (hasOverrideHeight())
   2644             return overrideLogicalContentHeight();
   2645         return logicalHeight() - borderAndPaddingLogicalHeight();
   2646     }
   2647 
   2648     if (h.isPercent() && isOutOfFlowPositioned() && !isRenderFlowThread()) {
   2649         // FIXME: This is wrong if the containingBlock has a perpendicular writing mode.
   2650         LayoutUnit availableHeight = containingBlockLogicalHeightForPositioned(containingBlock());
   2651         return adjustContentBoxLogicalHeightForBoxSizing(valueForLength(h, availableHeight));
   2652     }
   2653 
   2654     LayoutUnit heightIncludingScrollbar = computeContentAndScrollbarLogicalHeightUsing(h, -1);
   2655     if (heightIncludingScrollbar != -1)
   2656         return std::max<LayoutUnit>(0, adjustContentBoxLogicalHeightForBoxSizing(heightIncludingScrollbar) - scrollbarLogicalHeight());
   2657 
   2658     // FIXME: Check logicalTop/logicalBottom here to correctly handle vertical writing-mode.
   2659     // https://bugs.webkit.org/show_bug.cgi?id=46500
   2660     if (isRenderBlock() && isOutOfFlowPositioned() && style()->height().isAuto() && !(style()->top().isAuto() || style()->bottom().isAuto())) {
   2661         RenderBlock* block = const_cast<RenderBlock*>(toRenderBlock(this));
   2662         LogicalExtentComputedValues computedValues;
   2663         block->computeLogicalHeight(block->logicalHeight(), 0, computedValues);
   2664         LayoutUnit newContentHeight = computedValues.m_extent - block->borderAndPaddingLogicalHeight() - block->scrollbarLogicalHeight();
   2665         return adjustContentBoxLogicalHeightForBoxSizing(newContentHeight);
   2666     }
   2667 
   2668     // FIXME: This is wrong if the containingBlock has a perpendicular writing mode.
   2669     LayoutUnit availableHeight = containingBlockLogicalHeightForContent(heightType);
   2670     if (heightType == ExcludeMarginBorderPadding) {
   2671         // FIXME: Margin collapsing hasn't happened yet, so this incorrectly removes collapsed margins.
   2672         availableHeight -= marginBefore() + marginAfter() + borderAndPaddingLogicalHeight();
   2673     }
   2674     return availableHeight;
   2675 }
   2676 
   2677 void RenderBox::computeAndSetBlockDirectionMargins(const RenderBlock* containingBlock)
   2678 {
   2679     LayoutUnit marginBefore;
   2680     LayoutUnit marginAfter;
   2681     computeMarginsForDirection(BlockDirection, containingBlock, containingBlockLogicalWidthForContent(), logicalHeight(), marginBefore, marginAfter,
   2682         style()->marginBeforeUsing(containingBlock->style()),
   2683         style()->marginAfterUsing(containingBlock->style()));
   2684     // Note that in this 'positioning phase' of the layout we are using the containing block's writing mode rather than our own when calculating margins.
   2685     // See http://www.w3.org/TR/2014/CR-css-writing-modes-3-20140320/#orthogonal-flows
   2686     containingBlock->setMarginBeforeForChild(this, marginBefore);
   2687     containingBlock->setMarginAfterForChild(this, marginAfter);
   2688 }
   2689 
   2690 LayoutUnit RenderBox::containingBlockLogicalWidthForPositioned(const RenderBoxModelObject* containingBlock, bool checkForPerpendicularWritingMode) const
   2691 {
   2692     if (checkForPerpendicularWritingMode && containingBlock->isHorizontalWritingMode() != isHorizontalWritingMode())
   2693         return containingBlockLogicalHeightForPositioned(containingBlock, false);
   2694 
   2695     // Use viewport as container for top-level fixed-position elements.
   2696     if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
   2697         const RenderView* view = toRenderView(containingBlock);
   2698         if (FrameView* frameView = view->frameView()) {
   2699             LayoutRect viewportRect = frameView->viewportConstrainedVisibleContentRect();
   2700             return containingBlock->isHorizontalWritingMode() ? viewportRect.width() : viewportRect.height();
   2701         }
   2702     }
   2703 
   2704     if (containingBlock->isBox())
   2705         return toRenderBox(containingBlock)->clientLogicalWidth();
   2706 
   2707     ASSERT(containingBlock->isRenderInline() && containingBlock->isRelPositioned());
   2708 
   2709     const RenderInline* flow = toRenderInline(containingBlock);
   2710     InlineFlowBox* first = flow->firstLineBox();
   2711     InlineFlowBox* last = flow->lastLineBox();
   2712 
   2713     // If the containing block is empty, return a width of 0.
   2714     if (!first || !last)
   2715         return 0;
   2716 
   2717     LayoutUnit fromLeft;
   2718     LayoutUnit fromRight;
   2719     if (containingBlock->style()->isLeftToRightDirection()) {
   2720         fromLeft = first->logicalLeft() + first->borderLogicalLeft();
   2721         fromRight = last->logicalLeft() + last->logicalWidth() - last->borderLogicalRight();
   2722     } else {
   2723         fromRight = first->logicalLeft() + first->logicalWidth() - first->borderLogicalRight();
   2724         fromLeft = last->logicalLeft() + last->borderLogicalLeft();
   2725     }
   2726 
   2727     return std::max<LayoutUnit>(0, fromRight - fromLeft);
   2728 }
   2729 
   2730 LayoutUnit RenderBox::containingBlockLogicalHeightForPositioned(const RenderBoxModelObject* containingBlock, bool checkForPerpendicularWritingMode) const
   2731 {
   2732     if (checkForPerpendicularWritingMode && containingBlock->isHorizontalWritingMode() != isHorizontalWritingMode())
   2733         return containingBlockLogicalWidthForPositioned(containingBlock, false);
   2734 
   2735     // Use viewport as container for top-level fixed-position elements.
   2736     if (style()->position() == FixedPosition && containingBlock->isRenderView()) {
   2737         const RenderView* view = toRenderView(containingBlock);
   2738         if (FrameView* frameView = view->frameView()) {
   2739             LayoutRect viewportRect = frameView->viewportConstrainedVisibleContentRect();
   2740             return containingBlock->isHorizontalWritingMode() ? viewportRect.height() : viewportRect.width();
   2741         }
   2742     }
   2743 
   2744     if (containingBlock->isBox()) {
   2745         const RenderBlock* cb = containingBlock->isRenderBlock() ?
   2746             toRenderBlock(containingBlock) : containingBlock->containingBlock();
   2747         return cb->clientLogicalHeight();
   2748     }
   2749 
   2750     ASSERT(containingBlock->isRenderInline() && containingBlock->isRelPositioned());
   2751 
   2752     const RenderInline* flow = toRenderInline(containingBlock);
   2753     InlineFlowBox* first = flow->firstLineBox();
   2754     InlineFlowBox* last = flow->lastLineBox();
   2755 
   2756     // If the containing block is empty, return a height of 0.
   2757     if (!first || !last)
   2758         return 0;
   2759 
   2760     LayoutUnit heightResult;
   2761     LayoutRect boundingBox = flow->linesBoundingBox();
   2762     if (containingBlock->isHorizontalWritingMode())
   2763         heightResult = boundingBox.height();
   2764     else
   2765         heightResult = boundingBox.width();
   2766     heightResult -= (containingBlock->borderBefore() + containingBlock->borderAfter());
   2767     return heightResult;
   2768 }
   2769 
   2770 static void computeInlineStaticDistance(Length& logicalLeft, Length& logicalRight, const RenderBox* child, const RenderBoxModelObject* containerBlock, LayoutUnit containerLogicalWidth)
   2771 {
   2772     if (!logicalLeft.isAuto() || !logicalRight.isAuto())
   2773         return;
   2774 
   2775     // FIXME: The static distance computation has not been patched for mixed writing modes yet.
   2776     if (child->parent()->style()->direction() == LTR) {
   2777         LayoutUnit staticPosition = child->layer()->staticInlinePosition() - containerBlock->borderLogicalLeft();
   2778         for (RenderObject* curr = child->parent(); curr && curr != containerBlock; curr = curr->container()) {
   2779             if (curr->isBox()) {
   2780                 staticPosition += toRenderBox(curr)->logicalLeft();
   2781                 if (toRenderBox(curr)->isRelPositioned())
   2782                     staticPosition += toRenderBox(curr)->relativePositionOffset().width();
   2783             } else if (curr->isInline()) {
   2784                 if (curr->isRelPositioned()) {
   2785                     if (!curr->style()->logicalLeft().isAuto())
   2786                         staticPosition += curr->style()->logicalLeft().value();
   2787                     else
   2788                         staticPosition -= curr->style()->logicalRight().value();
   2789                 }
   2790             }
   2791         }
   2792         logicalLeft.setValue(Fixed, staticPosition);
   2793     } else {
   2794         RenderBox* enclosingBox = child->parent()->enclosingBox();
   2795         LayoutUnit staticPosition = child->layer()->staticInlinePosition() + containerLogicalWidth + containerBlock->borderLogicalLeft();
   2796         for (RenderObject* curr = child->parent(); curr; curr = curr->container()) {
   2797             if (curr->isBox()) {
   2798                 if (curr != containerBlock) {
   2799                     staticPosition -= toRenderBox(curr)->logicalLeft();
   2800                     if (toRenderBox(curr)->isRelPositioned())
   2801                         staticPosition -= toRenderBox(curr)->relativePositionOffset().width();
   2802                 }
   2803                 if (curr == enclosingBox)
   2804                     staticPosition -= enclosingBox->logicalWidth();
   2805             } else if (curr->isInline()) {
   2806                 if (curr->isRelPositioned()) {
   2807                     if (!curr->style()->logicalLeft().isAuto())
   2808                         staticPosition -= curr->style()->logicalLeft().value();
   2809                     else
   2810                         staticPosition += curr->style()->logicalRight().value();
   2811                 }
   2812             }
   2813             if (curr == containerBlock)
   2814                 break;
   2815         }
   2816         logicalRight.setValue(Fixed, staticPosition);
   2817     }
   2818 }
   2819 
   2820 void RenderBox::computePositionedLogicalWidth(LogicalExtentComputedValues& computedValues) const
   2821 {
   2822     if (isReplaced()) {
   2823         computePositionedLogicalWidthReplaced(computedValues);
   2824         return;
   2825     }
   2826 
   2827     // QUESTIONS
   2828     // FIXME 1: Should we still deal with these the cases of 'left' or 'right' having
   2829     // the type 'static' in determining whether to calculate the static distance?
   2830     // NOTE: 'static' is not a legal value for 'left' or 'right' as of CSS 2.1.
   2831 
   2832     // FIXME 2: Can perhaps optimize out cases when max-width/min-width are greater
   2833     // than or less than the computed width().  Be careful of box-sizing and
   2834     // percentage issues.
   2835 
   2836     // The following is based off of the W3C Working Draft from April 11, 2006 of
   2837     // CSS 2.1: Section 10.3.7 "Absolutely positioned, non-replaced elements"
   2838     // <http://www.w3.org/TR/CSS21/visudet.html#abs-non-replaced-width>
   2839     // (block-style-comments in this function and in computePositionedLogicalWidthUsing()
   2840     // correspond to text from the spec)
   2841 
   2842 
   2843     // We don't use containingBlock(), since we may be positioned by an enclosing
   2844     // relative positioned inline.
   2845     const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());
   2846 
   2847     const LayoutUnit containerLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock);
   2848 
   2849     // Use the container block's direction except when calculating the static distance
   2850     // This conforms with the reference results for abspos-replaced-width-margin-000.htm
   2851     // of the CSS 2.1 test suite
   2852     TextDirection containerDirection = containerBlock->style()->direction();
   2853 
   2854     bool isHorizontal = isHorizontalWritingMode();
   2855     const LayoutUnit bordersPlusPadding = borderAndPaddingLogicalWidth();
   2856     const Length marginLogicalLeft = isHorizontal ? style()->marginLeft() : style()->marginTop();
   2857     const Length marginLogicalRight = isHorizontal ? style()->marginRight() : style()->marginBottom();
   2858 
   2859     Length logicalLeftLength = style()->logicalLeft();
   2860     Length logicalRightLength = style()->logicalRight();
   2861 
   2862     /*---------------------------------------------------------------------------*\
   2863      * For the purposes of this section and the next, the term "static position"
   2864      * (of an element) refers, roughly, to the position an element would have had
   2865      * in the normal flow. More precisely:
   2866      *
   2867      * * The static position for 'left' is the distance from the left edge of the
   2868      *   containing block to the left margin edge of a hypothetical box that would
   2869      *   have been the first box of the element if its 'position' property had
   2870      *   been 'static' and 'float' had been 'none'. The value is negative if the
   2871      *   hypothetical box is to the left of the containing block.
   2872      * * The static position for 'right' is the distance from the right edge of the
   2873      *   containing block to the right margin edge of the same hypothetical box as
   2874      *   above. The value is positive if the hypothetical box is to the left of the
   2875      *   containing block's edge.
   2876      *
   2877      * But rather than actually calculating the dimensions of that hypothetical box,
   2878      * user agents are free to make a guess at its probable position.
   2879      *
   2880      * For the purposes of calculating the static position, the containing block of
   2881      * fixed positioned elements is the initial containing block instead of the
   2882      * viewport, and all scrollable boxes should be assumed to be scrolled to their
   2883      * origin.
   2884     \*---------------------------------------------------------------------------*/
   2885 
   2886     // see FIXME 1
   2887     // Calculate the static distance if needed.
   2888     computeInlineStaticDistance(logicalLeftLength, logicalRightLength, this, containerBlock, containerLogicalWidth);
   2889 
   2890     // Calculate constraint equation values for 'width' case.
   2891     computePositionedLogicalWidthUsing(style()->logicalWidth(), containerBlock, containerDirection,
   2892                                        containerLogicalWidth, bordersPlusPadding,
   2893                                        logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
   2894                                        computedValues);
   2895 
   2896     // Calculate constraint equation values for 'max-width' case.
   2897     if (!style()->logicalMaxWidth().isMaxSizeNone()) {
   2898         LogicalExtentComputedValues maxValues;
   2899 
   2900         computePositionedLogicalWidthUsing(style()->logicalMaxWidth(), containerBlock, containerDirection,
   2901                                            containerLogicalWidth, bordersPlusPadding,
   2902                                            logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
   2903                                            maxValues);
   2904 
   2905         if (computedValues.m_extent > maxValues.m_extent) {
   2906             computedValues.m_extent = maxValues.m_extent;
   2907             computedValues.m_position = maxValues.m_position;
   2908             computedValues.m_margins.m_start = maxValues.m_margins.m_start;
   2909             computedValues.m_margins.m_end = maxValues.m_margins.m_end;
   2910         }
   2911     }
   2912 
   2913     // Calculate constraint equation values for 'min-width' case.
   2914     if (!style()->logicalMinWidth().isZero() || style()->logicalMinWidth().isIntrinsic()) {
   2915         LogicalExtentComputedValues minValues;
   2916 
   2917         computePositionedLogicalWidthUsing(style()->logicalMinWidth(), containerBlock, containerDirection,
   2918                                            containerLogicalWidth, bordersPlusPadding,
   2919                                            logicalLeftLength, logicalRightLength, marginLogicalLeft, marginLogicalRight,
   2920                                            minValues);
   2921 
   2922         if (computedValues.m_extent < minValues.m_extent) {
   2923             computedValues.m_extent = minValues.m_extent;
   2924             computedValues.m_position = minValues.m_position;
   2925             computedValues.m_margins.m_start = minValues.m_margins.m_start;
   2926             computedValues.m_margins.m_end = minValues.m_margins.m_end;
   2927         }
   2928     }
   2929 
   2930     computedValues.m_extent += bordersPlusPadding;
   2931 }
   2932 
   2933 static void computeLogicalLeftPositionedOffset(LayoutUnit& logicalLeftPos, const RenderBox* child, LayoutUnit logicalWidthValue, const RenderBoxModelObject* containerBlock, LayoutUnit containerLogicalWidth)
   2934 {
   2935     // Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space. If the containing block is flipped
   2936     // along this axis, then we need to flip the coordinate.  This can only happen if the containing block is both a flipped mode and perpendicular to us.
   2937     if (containerBlock->isHorizontalWritingMode() != child->isHorizontalWritingMode() && containerBlock->style()->isFlippedBlocksWritingMode()) {
   2938         logicalLeftPos = containerLogicalWidth - logicalWidthValue - logicalLeftPos;
   2939         logicalLeftPos += (child->isHorizontalWritingMode() ? containerBlock->borderRight() : containerBlock->borderBottom());
   2940     } else {
   2941         logicalLeftPos += (child->isHorizontalWritingMode() ? containerBlock->borderLeft() : containerBlock->borderTop());
   2942     }
   2943 }
   2944 
   2945 void RenderBox::shrinkToFitWidth(const LayoutUnit availableSpace, const LayoutUnit logicalLeftValue, const LayoutUnit bordersPlusPadding, LogicalExtentComputedValues& computedValues) const
   2946 {
   2947     // FIXME: would it be better to have shrink-to-fit in one step?
   2948     LayoutUnit preferredWidth = maxPreferredLogicalWidth() - bordersPlusPadding;
   2949     LayoutUnit preferredMinWidth = minPreferredLogicalWidth() - bordersPlusPadding;
   2950     LayoutUnit availableWidth = availableSpace - logicalLeftValue;
   2951     computedValues.m_extent = std::min(std::max(preferredMinWidth, availableWidth), preferredWidth);
   2952 }
   2953 
   2954 void RenderBox::computePositionedLogicalWidthUsing(Length logicalWidth, const RenderBoxModelObject* containerBlock, TextDirection containerDirection,
   2955                                                    LayoutUnit containerLogicalWidth, LayoutUnit bordersPlusPadding,
   2956                                                    const Length& logicalLeft, const Length& logicalRight, const Length& marginLogicalLeft,
   2957                                                    const Length& marginLogicalRight, LogicalExtentComputedValues& computedValues) const
   2958 {
   2959     if (logicalWidth.isIntrinsic())
   2960         logicalWidth = Length(computeIntrinsicLogicalWidthUsing(logicalWidth, containerLogicalWidth, bordersPlusPadding) - bordersPlusPadding, Fixed);
   2961 
   2962     // 'left' and 'right' cannot both be 'auto' because one would of been
   2963     // converted to the static position already
   2964     ASSERT(!(logicalLeft.isAuto() && logicalRight.isAuto()));
   2965 
   2966     LayoutUnit logicalLeftValue = 0;
   2967 
   2968     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);
   2969 
   2970     bool logicalWidthIsAuto = logicalWidth.isIntrinsicOrAuto();
   2971     bool logicalLeftIsAuto = logicalLeft.isAuto();
   2972     bool logicalRightIsAuto = logicalRight.isAuto();
   2973     LayoutUnit& marginLogicalLeftValue = style()->isLeftToRightDirection() ? computedValues.m_margins.m_start : computedValues.m_margins.m_end;
   2974     LayoutUnit& marginLogicalRightValue = style()->isLeftToRightDirection() ? computedValues.m_margins.m_end : computedValues.m_margins.m_start;
   2975     if (!logicalLeftIsAuto && !logicalWidthIsAuto && !logicalRightIsAuto) {
   2976         /*-----------------------------------------------------------------------*\
   2977          * If none of the three is 'auto': If both 'margin-left' and 'margin-
   2978          * right' are 'auto', solve the equation under the extra constraint that
   2979          * the two margins get equal values, unless this would make them negative,
   2980          * in which case when direction of the containing block is 'ltr' ('rtl'),
   2981          * set 'margin-left' ('margin-right') to zero and solve for 'margin-right'
   2982          * ('margin-left'). If one of 'margin-left' or 'margin-right' is 'auto',
   2983          * solve the equation for that value. If the values are over-constrained,
   2984          * ignore the value for 'left' (in case the 'direction' property of the
   2985          * containing block is 'rtl') or 'right' (in case 'direction' is 'ltr')
   2986          * and solve for that value.
   2987         \*-----------------------------------------------------------------------*/
   2988         // NOTE:  It is not necessary to solve for 'right' in the over constrained
   2989         // case because the value is not used for any further calculations.
   2990 
   2991         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   2992         computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
   2993 
   2994         const LayoutUnit availableSpace = containerLogicalWidth - (logicalLeftValue + computedValues.m_extent + valueForLength(logicalRight, containerLogicalWidth) + bordersPlusPadding);
   2995 
   2996         // Margins are now the only unknown
   2997         if (marginLogicalLeft.isAuto() && marginLogicalRight.isAuto()) {
   2998             // Both margins auto, solve for equality
   2999             if (availableSpace >= 0) {
   3000                 marginLogicalLeftValue = availableSpace / 2; // split the difference
   3001                 marginLogicalRightValue = availableSpace - marginLogicalLeftValue; // account for odd valued differences
   3002             } else {
   3003                 // Use the containing block's direction rather than the parent block's
   3004                 // per CSS 2.1 reference test abspos-non-replaced-width-margin-000.
   3005                 if (containerDirection == LTR) {
   3006                     marginLogicalLeftValue = 0;
   3007                     marginLogicalRightValue = availableSpace; // will be negative
   3008                 } else {
   3009                     marginLogicalLeftValue = availableSpace; // will be negative
   3010                     marginLogicalRightValue = 0;
   3011                 }
   3012             }
   3013         } else if (marginLogicalLeft.isAuto()) {
   3014             // Solve for left margin
   3015             marginLogicalRightValue = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
   3016             marginLogicalLeftValue = availableSpace - marginLogicalRightValue;
   3017         } else if (marginLogicalRight.isAuto()) {
   3018             // Solve for right margin
   3019             marginLogicalLeftValue = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
   3020             marginLogicalRightValue = availableSpace - marginLogicalLeftValue;
   3021         } else {
   3022             // Over-constrained, solve for left if direction is RTL
   3023             marginLogicalLeftValue = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
   3024             marginLogicalRightValue = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
   3025 
   3026             // Use the containing block's direction rather than the parent block's
   3027             // per CSS 2.1 reference test abspos-non-replaced-width-margin-000.
   3028             if (containerDirection == RTL)
   3029                 logicalLeftValue = (availableSpace + logicalLeftValue) - marginLogicalLeftValue - marginLogicalRightValue;
   3030         }
   3031     } else {
   3032         /*--------------------------------------------------------------------*\
   3033          * Otherwise, set 'auto' values for 'margin-left' and 'margin-right'
   3034          * to 0, and pick the one of the following six rules that applies.
   3035          *
   3036          * 1. 'left' and 'width' are 'auto' and 'right' is not 'auto', then the
   3037          *    width is shrink-to-fit. Then solve for 'left'
   3038          *
   3039          *              OMIT RULE 2 AS IT SHOULD NEVER BE HIT
   3040          * ------------------------------------------------------------------
   3041          * 2. 'left' and 'right' are 'auto' and 'width' is not 'auto', then if
   3042          *    the 'direction' property of the containing block is 'ltr' set
   3043          *    'left' to the static position, otherwise set 'right' to the
   3044          *    static position. Then solve for 'left' (if 'direction is 'rtl')
   3045          *    or 'right' (if 'direction' is 'ltr').
   3046          * ------------------------------------------------------------------
   3047          *
   3048          * 3. 'width' and 'right' are 'auto' and 'left' is not 'auto', then the
   3049          *    width is shrink-to-fit . Then solve for 'right'
   3050          * 4. 'left' is 'auto', 'width' and 'right' are not 'auto', then solve
   3051          *    for 'left'
   3052          * 5. 'width' is 'auto', 'left' and 'right' are not 'auto', then solve
   3053          *    for 'width'
   3054          * 6. 'right' is 'auto', 'left' and 'width' are not 'auto', then solve
   3055          *    for 'right'
   3056          *
   3057          * Calculation of the shrink-to-fit width is similar to calculating the
   3058          * width of a table cell using the automatic table layout algorithm.
   3059          * Roughly: calculate the preferred width by formatting the content
   3060          * without breaking lines other than where explicit line breaks occur,
   3061          * and also calculate the preferred minimum width, e.g., by trying all
   3062          * possible line breaks. CSS 2.1 does not define the exact algorithm.
   3063          * Thirdly, calculate the available width: this is found by solving
   3064          * for 'width' after setting 'left' (in case 1) or 'right' (in case 3)
   3065          * to 0.
   3066          *
   3067          * Then the shrink-to-fit width is:
   3068          * min(max(preferred minimum width, available width), preferred width).
   3069         \*--------------------------------------------------------------------*/
   3070         // NOTE: For rules 3 and 6 it is not necessary to solve for 'right'
   3071         // because the value is not used for any further calculations.
   3072 
   3073         // Calculate margins, 'auto' margins are ignored.
   3074         marginLogicalLeftValue = minimumValueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
   3075         marginLogicalRightValue = minimumValueForLength(marginLogicalRight, containerRelativeLogicalWidth);
   3076 
   3077         const LayoutUnit availableSpace = containerLogicalWidth - (marginLogicalLeftValue + marginLogicalRightValue + bordersPlusPadding);
   3078 
   3079         // FIXME: Is there a faster way to find the correct case?
   3080         // Use rule/case that applies.
   3081         if (logicalLeftIsAuto && logicalWidthIsAuto && !logicalRightIsAuto) {
   3082             // RULE 1: (use shrink-to-fit for width, and solve of left)
   3083             LayoutUnit logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
   3084 
   3085             // FIXME: would it be better to have shrink-to-fit in one step?
   3086             LayoutUnit preferredWidth = maxPreferredLogicalWidth() - bordersPlusPadding;
   3087             LayoutUnit preferredMinWidth = minPreferredLogicalWidth() - bordersPlusPadding;
   3088             LayoutUnit availableWidth = availableSpace - logicalRightValue;
   3089             computedValues.m_extent = std::min(std::max(preferredMinWidth, availableWidth), preferredWidth);
   3090             logicalLeftValue = availableSpace - (computedValues.m_extent + logicalRightValue);
   3091         } else if (!logicalLeftIsAuto && logicalWidthIsAuto && logicalRightIsAuto) {
   3092             // RULE 3: (use shrink-to-fit for width, and no need solve of right)
   3093             logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3094 
   3095             shrinkToFitWidth(availableSpace, logicalLeftValue, bordersPlusPadding, computedValues);
   3096         } else if (logicalLeftIsAuto && !logicalWidthIsAuto && !logicalRightIsAuto) {
   3097             // RULE 4: (solve for left)
   3098             computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
   3099             logicalLeftValue = availableSpace - (computedValues.m_extent + valueForLength(logicalRight, containerLogicalWidth));
   3100         } else if (!logicalLeftIsAuto && logicalWidthIsAuto && !logicalRightIsAuto) {
   3101             // RULE 5: (solve for width)
   3102             logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3103             if (autoWidthShouldFitContent())
   3104                 shrinkToFitWidth(availableSpace, logicalLeftValue, bordersPlusPadding, computedValues);
   3105             else
   3106                 computedValues.m_extent = std::max<LayoutUnit>(0, availableSpace - (logicalLeftValue + valueForLength(logicalRight, containerLogicalWidth)));
   3107         } else if (!logicalLeftIsAuto && !logicalWidthIsAuto && logicalRightIsAuto) {
   3108             // RULE 6: (no need solve for right)
   3109             logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3110             computedValues.m_extent = adjustContentBoxLogicalWidthForBoxSizing(valueForLength(logicalWidth, containerLogicalWidth));
   3111         }
   3112     }
   3113 
   3114     // Use computed values to calculate the horizontal position.
   3115 
   3116     // FIXME: This hack is needed to calculate the  logical left position for a 'rtl' relatively
   3117     // positioned, inline because right now, it is using the logical left position
   3118     // of the first line box when really it should use the last line box.  When
   3119     // this is fixed elsewhere, this block should be removed.
   3120     if (containerBlock->isRenderInline() && !containerBlock->style()->isLeftToRightDirection()) {
   3121         const RenderInline* flow = toRenderInline(containerBlock);
   3122         InlineFlowBox* firstLine = flow->firstLineBox();
   3123         InlineFlowBox* lastLine = flow->lastLineBox();
   3124         if (firstLine && lastLine && firstLine != lastLine) {
   3125             computedValues.m_position = logicalLeftValue + marginLogicalLeftValue + lastLine->borderLogicalLeft() + (lastLine->logicalLeft() - firstLine->logicalLeft());
   3126             return;
   3127         }
   3128     }
   3129 
   3130     if (containerBlock->isBox() && toRenderBox(containerBlock)->scrollsOverflowY() && containerBlock->style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft()) {
   3131         logicalLeftValue = logicalLeftValue + toRenderBox(containerBlock)->verticalScrollbarWidth();
   3132     }
   3133 
   3134     computedValues.m_position = logicalLeftValue + marginLogicalLeftValue;
   3135     computeLogicalLeftPositionedOffset(computedValues.m_position, this, computedValues.m_extent, containerBlock, containerLogicalWidth);
   3136 }
   3137 
   3138 static void computeBlockStaticDistance(Length& logicalTop, Length& logicalBottom, const RenderBox* child, const RenderBoxModelObject* containerBlock)
   3139 {
   3140     if (!logicalTop.isAuto() || !logicalBottom.isAuto())
   3141         return;
   3142 
   3143     // FIXME: The static distance computation has not been patched for mixed writing modes.
   3144     LayoutUnit staticLogicalTop = child->layer()->staticBlockPosition() - containerBlock->borderBefore();
   3145     for (RenderObject* curr = child->parent(); curr && curr != containerBlock; curr = curr->container()) {
   3146         if (curr->isBox() && !curr->isTableRow())
   3147             staticLogicalTop += toRenderBox(curr)->logicalTop();
   3148     }
   3149     logicalTop.setValue(Fixed, staticLogicalTop);
   3150 }
   3151 
   3152 void RenderBox::computePositionedLogicalHeight(LogicalExtentComputedValues& computedValues) const
   3153 {
   3154     if (isReplaced()) {
   3155         computePositionedLogicalHeightReplaced(computedValues);
   3156         return;
   3157     }
   3158 
   3159     // The following is based off of the W3C Working Draft from April 11, 2006 of
   3160     // CSS 2.1: Section 10.6.4 "Absolutely positioned, non-replaced elements"
   3161     // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-non-replaced-height>
   3162     // (block-style-comments in this function and in computePositionedLogicalHeightUsing()
   3163     // correspond to text from the spec)
   3164 
   3165 
   3166     // We don't use containingBlock(), since we may be positioned by an enclosing relpositioned inline.
   3167     const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());
   3168 
   3169     const LayoutUnit containerLogicalHeight = containingBlockLogicalHeightForPositioned(containerBlock);
   3170 
   3171     RenderStyle* styleToUse = style();
   3172     const LayoutUnit bordersPlusPadding = borderAndPaddingLogicalHeight();
   3173     const Length marginBefore = styleToUse->marginBefore();
   3174     const Length marginAfter = styleToUse->marginAfter();
   3175     Length logicalTopLength = styleToUse->logicalTop();
   3176     Length logicalBottomLength = styleToUse->logicalBottom();
   3177 
   3178     /*---------------------------------------------------------------------------*\
   3179      * For the purposes of this section and the next, the term "static position"
   3180      * (of an element) refers, roughly, to the position an element would have had
   3181      * in the normal flow. More precisely, the static position for 'top' is the
   3182      * distance from the top edge of the containing block to the top margin edge
   3183      * of a hypothetical box that would have been the first box of the element if
   3184      * its 'position' property had been 'static' and 'float' had been 'none'. The
   3185      * value is negative if the hypothetical box is above the containing block.
   3186      *
   3187      * But rather than actually calculating the dimensions of that hypothetical
   3188      * box, user agents are free to make a guess at its probable position.
   3189      *
   3190      * For the purposes of calculating the static position, the containing block
   3191      * of fixed positioned elements is the initial containing block instead of
   3192      * the viewport.
   3193     \*---------------------------------------------------------------------------*/
   3194 
   3195     // see FIXME 1
   3196     // Calculate the static distance if needed.
   3197     computeBlockStaticDistance(logicalTopLength, logicalBottomLength, this, containerBlock);
   3198 
   3199     // Calculate constraint equation values for 'height' case.
   3200     LayoutUnit logicalHeight = computedValues.m_extent;
   3201     computePositionedLogicalHeightUsing(styleToUse->logicalHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
   3202                                         logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
   3203                                         computedValues);
   3204 
   3205     // Avoid doing any work in the common case (where the values of min-height and max-height are their defaults).
   3206     // see FIXME 2
   3207 
   3208     // Calculate constraint equation values for 'max-height' case.
   3209     if (!styleToUse->logicalMaxHeight().isMaxSizeNone()) {
   3210         LogicalExtentComputedValues maxValues;
   3211 
   3212         computePositionedLogicalHeightUsing(styleToUse->logicalMaxHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
   3213                                             logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
   3214                                             maxValues);
   3215 
   3216         if (computedValues.m_extent > maxValues.m_extent) {
   3217             computedValues.m_extent = maxValues.m_extent;
   3218             computedValues.m_position = maxValues.m_position;
   3219             computedValues.m_margins.m_before = maxValues.m_margins.m_before;
   3220             computedValues.m_margins.m_after = maxValues.m_margins.m_after;
   3221         }
   3222     }
   3223 
   3224     // Calculate constraint equation values for 'min-height' case.
   3225     if (!styleToUse->logicalMinHeight().isZero() || styleToUse->logicalMinHeight().isIntrinsic()) {
   3226         LogicalExtentComputedValues minValues;
   3227 
   3228         computePositionedLogicalHeightUsing(styleToUse->logicalMinHeight(), containerBlock, containerLogicalHeight, bordersPlusPadding, logicalHeight,
   3229                                             logicalTopLength, logicalBottomLength, marginBefore, marginAfter,
   3230                                             minValues);
   3231 
   3232         if (computedValues.m_extent < minValues.m_extent) {
   3233             computedValues.m_extent = minValues.m_extent;
   3234             computedValues.m_position = minValues.m_position;
   3235             computedValues.m_margins.m_before = minValues.m_margins.m_before;
   3236             computedValues.m_margins.m_after = minValues.m_margins.m_after;
   3237         }
   3238     }
   3239 
   3240     // Set final height value.
   3241     computedValues.m_extent += bordersPlusPadding;
   3242 }
   3243 
   3244 static void computeLogicalTopPositionedOffset(LayoutUnit& logicalTopPos, const RenderBox* child, LayoutUnit logicalHeightValue, const RenderBoxModelObject* containerBlock, LayoutUnit containerLogicalHeight)
   3245 {
   3246     // Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space. If the containing block is flipped
   3247     // along this axis, then we need to flip the coordinate.  This can only happen if the containing block is both a flipped mode and perpendicular to us.
   3248     if ((child->style()->isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() != containerBlock->isHorizontalWritingMode())
   3249         || (child->style()->isFlippedBlocksWritingMode() != containerBlock->style()->isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() == containerBlock->isHorizontalWritingMode()))
   3250         logicalTopPos = containerLogicalHeight - logicalHeightValue - logicalTopPos;
   3251 
   3252     // Our offset is from the logical bottom edge in a flipped environment, e.g., right for vertical-rl and bottom for horizontal-bt.
   3253     if (containerBlock->style()->isFlippedBlocksWritingMode() && child->isHorizontalWritingMode() == containerBlock->isHorizontalWritingMode()) {
   3254         if (child->isHorizontalWritingMode())
   3255             logicalTopPos += containerBlock->borderBottom();
   3256         else
   3257             logicalTopPos += containerBlock->borderRight();
   3258     } else {
   3259         if (child->isHorizontalWritingMode())
   3260             logicalTopPos += containerBlock->borderTop();
   3261         else
   3262             logicalTopPos += containerBlock->borderLeft();
   3263     }
   3264 }
   3265 
   3266 void RenderBox::computePositionedLogicalHeightUsing(Length logicalHeightLength, const RenderBoxModelObject* containerBlock,
   3267                                                     LayoutUnit containerLogicalHeight, LayoutUnit bordersPlusPadding, LayoutUnit logicalHeight,
   3268                                                     const Length& logicalTop, const Length& logicalBottom, const Length& marginBefore,
   3269                                                     const Length& marginAfter, LogicalExtentComputedValues& computedValues) const
   3270 {
   3271     // 'top' and 'bottom' cannot both be 'auto' because 'top would of been
   3272     // converted to the static position in computePositionedLogicalHeight()
   3273     ASSERT(!(logicalTop.isAuto() && logicalBottom.isAuto()));
   3274 
   3275     LayoutUnit logicalHeightValue;
   3276     LayoutUnit contentLogicalHeight = logicalHeight - bordersPlusPadding;
   3277 
   3278     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);
   3279 
   3280     LayoutUnit logicalTopValue = 0;
   3281 
   3282     bool logicalHeightIsAuto = logicalHeightLength.isAuto();
   3283     bool logicalTopIsAuto = logicalTop.isAuto();
   3284     bool logicalBottomIsAuto = logicalBottom.isAuto();
   3285 
   3286     LayoutUnit resolvedLogicalHeight;
   3287     // Height is never unsolved for tables.
   3288     if (isTable()) {
   3289         resolvedLogicalHeight = contentLogicalHeight;
   3290         logicalHeightIsAuto = false;
   3291     } else {
   3292         if (logicalHeightLength.isIntrinsic())
   3293             resolvedLogicalHeight = computeIntrinsicLogicalContentHeightUsing(logicalHeightLength, contentLogicalHeight, bordersPlusPadding);
   3294         else
   3295             resolvedLogicalHeight = adjustContentBoxLogicalHeightForBoxSizing(valueForLength(logicalHeightLength, containerLogicalHeight));
   3296     }
   3297 
   3298     if (!logicalTopIsAuto && !logicalHeightIsAuto && !logicalBottomIsAuto) {
   3299         /*-----------------------------------------------------------------------*\
   3300          * If none of the three are 'auto': If both 'margin-top' and 'margin-
   3301          * bottom' are 'auto', solve the equation under the extra constraint that
   3302          * the two margins get equal values. If one of 'margin-top' or 'margin-
   3303          * bottom' is 'auto', solve the equation for that value. If the values
   3304          * are over-constrained, ignore the value for 'bottom' and solve for that
   3305          * value.
   3306         \*-----------------------------------------------------------------------*/
   3307         // NOTE:  It is not necessary to solve for 'bottom' in the over constrained
   3308         // case because the value is not used for any further calculations.
   3309 
   3310         logicalHeightValue = resolvedLogicalHeight;
   3311         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3312 
   3313         const LayoutUnit availableSpace = containerLogicalHeight - (logicalTopValue + logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight) + bordersPlusPadding);
   3314 
   3315         // Margins are now the only unknown
   3316         if (marginBefore.isAuto() && marginAfter.isAuto()) {
   3317             // Both margins auto, solve for equality
   3318             // NOTE: This may result in negative values.
   3319             computedValues.m_margins.m_before = availableSpace / 2; // split the difference
   3320             computedValues.m_margins.m_after = availableSpace - computedValues.m_margins.m_before; // account for odd valued differences
   3321         } else if (marginBefore.isAuto()) {
   3322             // Solve for top margin
   3323             computedValues.m_margins.m_after = valueForLength(marginAfter, containerRelativeLogicalWidth);
   3324             computedValues.m_margins.m_before = availableSpace - computedValues.m_margins.m_after;
   3325         } else if (marginAfter.isAuto()) {
   3326             // Solve for bottom margin
   3327             computedValues.m_margins.m_before = valueForLength(marginBefore, containerRelativeLogicalWidth);
   3328             computedValues.m_margins.m_after = availableSpace - computedValues.m_margins.m_before;
   3329         } else {
   3330             // Over-constrained, (no need solve for bottom)
   3331             computedValues.m_margins.m_before = valueForLength(marginBefore, containerRelativeLogicalWidth);
   3332             computedValues.m_margins.m_after = valueForLength(marginAfter, containerRelativeLogicalWidth);
   3333         }
   3334     } else {
   3335         /*--------------------------------------------------------------------*\
   3336          * Otherwise, set 'auto' values for 'margin-top' and 'margin-bottom'
   3337          * to 0, and pick the one of the following six rules that applies.
   3338          *
   3339          * 1. 'top' and 'height' are 'auto' and 'bottom' is not 'auto', then
   3340          *    the height is based on the content, and solve for 'top'.
   3341          *
   3342          *              OMIT RULE 2 AS IT SHOULD NEVER BE HIT
   3343          * ------------------------------------------------------------------
   3344          * 2. 'top' and 'bottom' are 'auto' and 'height' is not 'auto', then
   3345          *    set 'top' to the static position, and solve for 'bottom'.
   3346          * ------------------------------------------------------------------
   3347          *
   3348          * 3. 'height' and 'bottom' are 'auto' and 'top' is not 'auto', then
   3349          *    the height is based on the content, and solve for 'bottom'.
   3350          * 4. 'top' is 'auto', 'height' and 'bottom' are not 'auto', and
   3351          *    solve for 'top'.
   3352          * 5. 'height' is 'auto', 'top' and 'bottom' are not 'auto', and
   3353          *    solve for 'height'.
   3354          * 6. 'bottom' is 'auto', 'top' and 'height' are not 'auto', and
   3355          *    solve for 'bottom'.
   3356         \*--------------------------------------------------------------------*/
   3357         // NOTE: For rules 3 and 6 it is not necessary to solve for 'bottom'
   3358         // because the value is not used for any further calculations.
   3359 
   3360         // Calculate margins, 'auto' margins are ignored.
   3361         computedValues.m_margins.m_before = minimumValueForLength(marginBefore, containerRelativeLogicalWidth);
   3362         computedValues.m_margins.m_after = minimumValueForLength(marginAfter, containerRelativeLogicalWidth);
   3363 
   3364         const LayoutUnit availableSpace = containerLogicalHeight - (computedValues.m_margins.m_before + computedValues.m_margins.m_after + bordersPlusPadding);
   3365 
   3366         // Use rule/case that applies.
   3367         if (logicalTopIsAuto && logicalHeightIsAuto && !logicalBottomIsAuto) {
   3368             // RULE 1: (height is content based, solve of top)
   3369             logicalHeightValue = contentLogicalHeight;
   3370             logicalTopValue = availableSpace - (logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight));
   3371         } else if (!logicalTopIsAuto && logicalHeightIsAuto && logicalBottomIsAuto) {
   3372             // RULE 3: (height is content based, no need solve of bottom)
   3373             logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3374             logicalHeightValue = contentLogicalHeight;
   3375         } else if (logicalTopIsAuto && !logicalHeightIsAuto && !logicalBottomIsAuto) {
   3376             // RULE 4: (solve of top)
   3377             logicalHeightValue = resolvedLogicalHeight;
   3378             logicalTopValue = availableSpace - (logicalHeightValue + valueForLength(logicalBottom, containerLogicalHeight));
   3379         } else if (!logicalTopIsAuto && logicalHeightIsAuto && !logicalBottomIsAuto) {
   3380             // RULE 5: (solve of height)
   3381             logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3382             logicalHeightValue = std::max<LayoutUnit>(0, availableSpace - (logicalTopValue + valueForLength(logicalBottom, containerLogicalHeight)));
   3383         } else if (!logicalTopIsAuto && !logicalHeightIsAuto && logicalBottomIsAuto) {
   3384             // RULE 6: (no need solve of bottom)
   3385             logicalHeightValue = resolvedLogicalHeight;
   3386             logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3387         }
   3388     }
   3389     computedValues.m_extent = logicalHeightValue;
   3390 
   3391     // Use computed values to calculate the vertical position.
   3392     computedValues.m_position = logicalTopValue + computedValues.m_margins.m_before;
   3393     computeLogicalTopPositionedOffset(computedValues.m_position, this, logicalHeightValue, containerBlock, containerLogicalHeight);
   3394 }
   3395 
   3396 void RenderBox::computePositionedLogicalWidthReplaced(LogicalExtentComputedValues& computedValues) const
   3397 {
   3398     // The following is based off of the W3C Working Draft from April 11, 2006 of
   3399     // CSS 2.1: Section 10.3.8 "Absolutely positioned, replaced elements"
   3400     // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-replaced-width>
   3401     // (block-style-comments in this function correspond to text from the spec and
   3402     // the numbers correspond to numbers in spec)
   3403 
   3404     // We don't use containingBlock(), since we may be positioned by an enclosing
   3405     // relative positioned inline.
   3406     const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());
   3407 
   3408     const LayoutUnit containerLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock);
   3409     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);
   3410 
   3411     // To match WinIE, in quirks mode use the parent's 'direction' property
   3412     // instead of the the container block's.
   3413     TextDirection containerDirection = containerBlock->style()->direction();
   3414 
   3415     // Variables to solve.
   3416     bool isHorizontal = isHorizontalWritingMode();
   3417     Length logicalLeft = style()->logicalLeft();
   3418     Length logicalRight = style()->logicalRight();
   3419     Length marginLogicalLeft = isHorizontal ? style()->marginLeft() : style()->marginTop();
   3420     Length marginLogicalRight = isHorizontal ? style()->marginRight() : style()->marginBottom();
   3421     LayoutUnit& marginLogicalLeftAlias = style()->isLeftToRightDirection() ? computedValues.m_margins.m_start : computedValues.m_margins.m_end;
   3422     LayoutUnit& marginLogicalRightAlias = style()->isLeftToRightDirection() ? computedValues.m_margins.m_end : computedValues.m_margins.m_start;
   3423 
   3424     /*-----------------------------------------------------------------------*\
   3425      * 1. The used value of 'width' is determined as for inline replaced
   3426      *    elements.
   3427     \*-----------------------------------------------------------------------*/
   3428     // NOTE: This value of width is FINAL in that the min/max width calculations
   3429     // are dealt with in computeReplacedWidth().  This means that the steps to produce
   3430     // correct max/min in the non-replaced version, are not necessary.
   3431     computedValues.m_extent = computeReplacedLogicalWidth() + borderAndPaddingLogicalWidth();
   3432 
   3433     const LayoutUnit availableSpace = containerLogicalWidth - computedValues.m_extent;
   3434 
   3435     /*-----------------------------------------------------------------------*\
   3436      * 2. If both 'left' and 'right' have the value 'auto', then if 'direction'
   3437      *    of the containing block is 'ltr', set 'left' to the static position;
   3438      *    else if 'direction' is 'rtl', set 'right' to the static position.
   3439     \*-----------------------------------------------------------------------*/
   3440     // see FIXME 1
   3441     computeInlineStaticDistance(logicalLeft, logicalRight, this, containerBlock, containerLogicalWidth);
   3442 
   3443     /*-----------------------------------------------------------------------*\
   3444      * 3. If 'left' or 'right' are 'auto', replace any 'auto' on 'margin-left'
   3445      *    or 'margin-right' with '0'.
   3446     \*-----------------------------------------------------------------------*/
   3447     if (logicalLeft.isAuto() || logicalRight.isAuto()) {
   3448         if (marginLogicalLeft.isAuto())
   3449             marginLogicalLeft.setValue(Fixed, 0);
   3450         if (marginLogicalRight.isAuto())
   3451             marginLogicalRight.setValue(Fixed, 0);
   3452     }
   3453 
   3454     /*-----------------------------------------------------------------------*\
   3455      * 4. If at this point both 'margin-left' and 'margin-right' are still
   3456      *    'auto', solve the equation under the extra constraint that the two
   3457      *    margins must get equal values, unless this would make them negative,
   3458      *    in which case when the direction of the containing block is 'ltr'
   3459      *    ('rtl'), set 'margin-left' ('margin-right') to zero and solve for
   3460      *    'margin-right' ('margin-left').
   3461     \*-----------------------------------------------------------------------*/
   3462     LayoutUnit logicalLeftValue = 0;
   3463     LayoutUnit logicalRightValue = 0;
   3464 
   3465     if (marginLogicalLeft.isAuto() && marginLogicalRight.isAuto()) {
   3466         // 'left' and 'right' cannot be 'auto' due to step 3
   3467         ASSERT(!(logicalLeft.isAuto() && logicalRight.isAuto()));
   3468 
   3469         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3470         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
   3471 
   3472         LayoutUnit difference = availableSpace - (logicalLeftValue + logicalRightValue);
   3473         if (difference > 0) {
   3474             marginLogicalLeftAlias = difference / 2; // split the difference
   3475             marginLogicalRightAlias = difference - marginLogicalLeftAlias; // account for odd valued differences
   3476         } else {
   3477             // Use the containing block's direction rather than the parent block's
   3478             // per CSS 2.1 reference test abspos-replaced-width-margin-000.
   3479             if (containerDirection == LTR) {
   3480                 marginLogicalLeftAlias = 0;
   3481                 marginLogicalRightAlias = difference; // will be negative
   3482             } else {
   3483                 marginLogicalLeftAlias = difference; // will be negative
   3484                 marginLogicalRightAlias = 0;
   3485             }
   3486         }
   3487 
   3488     /*-----------------------------------------------------------------------*\
   3489      * 5. If at this point there is an 'auto' left, solve the equation for
   3490      *    that value.
   3491     \*-----------------------------------------------------------------------*/
   3492     } else if (logicalLeft.isAuto()) {
   3493         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
   3494         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
   3495         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
   3496 
   3497         // Solve for 'left'
   3498         logicalLeftValue = availableSpace - (logicalRightValue + marginLogicalLeftAlias + marginLogicalRightAlias);
   3499     } else if (logicalRight.isAuto()) {
   3500         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
   3501         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
   3502         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3503 
   3504         // Solve for 'right'
   3505         logicalRightValue = availableSpace - (logicalLeftValue + marginLogicalLeftAlias + marginLogicalRightAlias);
   3506     } else if (marginLogicalLeft.isAuto()) {
   3507         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
   3508         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3509         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
   3510 
   3511         // Solve for 'margin-left'
   3512         marginLogicalLeftAlias = availableSpace - (logicalLeftValue + logicalRightValue + marginLogicalRightAlias);
   3513     } else if (marginLogicalRight.isAuto()) {
   3514         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
   3515         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3516         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
   3517 
   3518         // Solve for 'margin-right'
   3519         marginLogicalRightAlias = availableSpace - (logicalLeftValue + logicalRightValue + marginLogicalLeftAlias);
   3520     } else {
   3521         // Nothing is 'auto', just calculate the values.
   3522         marginLogicalLeftAlias = valueForLength(marginLogicalLeft, containerRelativeLogicalWidth);
   3523         marginLogicalRightAlias = valueForLength(marginLogicalRight, containerRelativeLogicalWidth);
   3524         logicalRightValue = valueForLength(logicalRight, containerLogicalWidth);
   3525         logicalLeftValue = valueForLength(logicalLeft, containerLogicalWidth);
   3526         // If the containing block is right-to-left, then push the left position as far to the right as possible
   3527         if (containerDirection == RTL) {
   3528             int totalLogicalWidth = computedValues.m_extent + logicalLeftValue + logicalRightValue +  marginLogicalLeftAlias + marginLogicalRightAlias;
   3529             logicalLeftValue = containerLogicalWidth - (totalLogicalWidth - logicalLeftValue);
   3530         }
   3531     }
   3532 
   3533     /*-----------------------------------------------------------------------*\
   3534      * 6. If at this point the values are over-constrained, ignore the value
   3535      *    for either 'left' (in case the 'direction' property of the
   3536      *    containing block is 'rtl') or 'right' (in case 'direction' is
   3537      *    'ltr') and solve for that value.
   3538     \*-----------------------------------------------------------------------*/
   3539     // NOTE: Constraints imposed by the width of the containing block and its content have already been accounted for above.
   3540 
   3541     // FIXME: Deal with differing writing modes here.  Our offset needs to be in the containing block's coordinate space, so that
   3542     // can make the result here rather complicated to compute.
   3543 
   3544     // Use computed values to calculate the horizontal position.
   3545 
   3546     // FIXME: This hack is needed to calculate the logical left position for a 'rtl' relatively
   3547     // positioned, inline containing block because right now, it is using the logical left position
   3548     // of the first line box when really it should use the last line box.  When
   3549     // this is fixed elsewhere, this block should be removed.
   3550     if (containerBlock->isRenderInline() && !containerBlock->style()->isLeftToRightDirection()) {
   3551         const RenderInline* flow = toRenderInline(containerBlock);
   3552         InlineFlowBox* firstLine = flow->firstLineBox();
   3553         InlineFlowBox* lastLine = flow->lastLineBox();
   3554         if (firstLine && lastLine && firstLine != lastLine) {
   3555             computedValues.m_position = logicalLeftValue + marginLogicalLeftAlias + lastLine->borderLogicalLeft() + (lastLine->logicalLeft() - firstLine->logicalLeft());
   3556             return;
   3557         }
   3558     }
   3559 
   3560     LayoutUnit logicalLeftPos = logicalLeftValue + marginLogicalLeftAlias;
   3561     computeLogicalLeftPositionedOffset(logicalLeftPos, this, computedValues.m_extent, containerBlock, containerLogicalWidth);
   3562     computedValues.m_position = logicalLeftPos;
   3563 }
   3564 
   3565 void RenderBox::computePositionedLogicalHeightReplaced(LogicalExtentComputedValues& computedValues) const
   3566 {
   3567     // The following is based off of the W3C Working Draft from April 11, 2006 of
   3568     // CSS 2.1: Section 10.6.5 "Absolutely positioned, replaced elements"
   3569     // <http://www.w3.org/TR/2005/WD-CSS21-20050613/visudet.html#abs-replaced-height>
   3570     // (block-style-comments in this function correspond to text from the spec and
   3571     // the numbers correspond to numbers in spec)
   3572 
   3573     // We don't use containingBlock(), since we may be positioned by an enclosing relpositioned inline.
   3574     const RenderBoxModelObject* containerBlock = toRenderBoxModelObject(container());
   3575 
   3576     const LayoutUnit containerLogicalHeight = containingBlockLogicalHeightForPositioned(containerBlock);
   3577     const LayoutUnit containerRelativeLogicalWidth = containingBlockLogicalWidthForPositioned(containerBlock, false);
   3578 
   3579     // Variables to solve.
   3580     Length marginBefore = style()->marginBefore();
   3581     Length marginAfter = style()->marginAfter();
   3582     LayoutUnit& marginBeforeAlias = computedValues.m_margins.m_before;
   3583     LayoutUnit& marginAfterAlias = computedValues.m_margins.m_after;
   3584 
   3585     Length logicalTop = style()->logicalTop();
   3586     Length logicalBottom = style()->logicalBottom();
   3587 
   3588     /*-----------------------------------------------------------------------*\
   3589      * 1. The used value of 'height' is determined as for inline replaced
   3590      *    elements.
   3591     \*-----------------------------------------------------------------------*/
   3592     // NOTE: This value of height is FINAL in that the min/max height calculations
   3593     // are dealt with in computeReplacedHeight().  This means that the steps to produce
   3594     // correct max/min in the non-replaced version, are not necessary.
   3595     computedValues.m_extent = computeReplacedLogicalHeight() + borderAndPaddingLogicalHeight();
   3596     const LayoutUnit availableSpace = containerLogicalHeight - computedValues.m_extent;
   3597 
   3598     /*-----------------------------------------------------------------------*\
   3599      * 2. If both 'top' and 'bottom' have the value 'auto', replace 'top'
   3600      *    with the element's static position.
   3601     \*-----------------------------------------------------------------------*/
   3602     // see FIXME 1
   3603     computeBlockStaticDistance(logicalTop, logicalBottom, this, containerBlock);
   3604 
   3605     /*-----------------------------------------------------------------------*\
   3606      * 3. If 'bottom' is 'auto', replace any 'auto' on 'margin-top' or
   3607      *    'margin-bottom' with '0'.
   3608     \*-----------------------------------------------------------------------*/
   3609     // FIXME: The spec. says that this step should only be taken when bottom is
   3610     // auto, but if only top is auto, this makes step 4 impossible.
   3611     if (logicalTop.isAuto() || logicalBottom.isAuto()) {
   3612         if (marginBefore.isAuto())
   3613             marginBefore.setValue(Fixed, 0);
   3614         if (marginAfter.isAuto())
   3615             marginAfter.setValue(Fixed, 0);
   3616     }
   3617 
   3618     /*-----------------------------------------------------------------------*\
   3619      * 4. If at this point both 'margin-top' and 'margin-bottom' are still
   3620      *    'auto', solve the equation under the extra constraint that the two
   3621      *    margins must get equal values.
   3622     \*-----------------------------------------------------------------------*/
   3623     LayoutUnit logicalTopValue = 0;
   3624     LayoutUnit logicalBottomValue = 0;
   3625 
   3626     if (marginBefore.isAuto() && marginAfter.isAuto()) {
   3627         // 'top' and 'bottom' cannot be 'auto' due to step 2 and 3 combined.
   3628         ASSERT(!(logicalTop.isAuto() || logicalBottom.isAuto()));
   3629 
   3630         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3631         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);
   3632 
   3633         LayoutUnit difference = availableSpace - (logicalTopValue + logicalBottomValue);
   3634         // NOTE: This may result in negative values.
   3635         marginBeforeAlias =  difference / 2; // split the difference
   3636         marginAfterAlias = difference - marginBeforeAlias; // account for odd valued differences
   3637 
   3638     /*-----------------------------------------------------------------------*\
   3639      * 5. If at this point there is only one 'auto' left, solve the equation
   3640      *    for that value.
   3641     \*-----------------------------------------------------------------------*/
   3642     } else if (logicalTop.isAuto()) {
   3643         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
   3644         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
   3645         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);
   3646 
   3647         // Solve for 'top'
   3648         logicalTopValue = availableSpace - (logicalBottomValue + marginBeforeAlias + marginAfterAlias);
   3649     } else if (logicalBottom.isAuto()) {
   3650         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
   3651         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
   3652         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3653 
   3654         // Solve for 'bottom'
   3655         // NOTE: It is not necessary to solve for 'bottom' because we don't ever
   3656         // use the value.
   3657     } else if (marginBefore.isAuto()) {
   3658         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
   3659         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3660         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);
   3661 
   3662         // Solve for 'margin-top'
   3663         marginBeforeAlias = availableSpace - (logicalTopValue + logicalBottomValue + marginAfterAlias);
   3664     } else if (marginAfter.isAuto()) {
   3665         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
   3666         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3667         logicalBottomValue = valueForLength(logicalBottom, containerLogicalHeight);
   3668 
   3669         // Solve for 'margin-bottom'
   3670         marginAfterAlias = availableSpace - (logicalTopValue + logicalBottomValue + marginBeforeAlias);
   3671     } else {
   3672         // Nothing is 'auto', just calculate the values.
   3673         marginBeforeAlias = valueForLength(marginBefore, containerRelativeLogicalWidth);
   3674         marginAfterAlias = valueForLength(marginAfter, containerRelativeLogicalWidth);
   3675         logicalTopValue = valueForLength(logicalTop, containerLogicalHeight);
   3676         // NOTE: It is not necessary to solve for 'bottom' because we don't ever
   3677         // use the value.
   3678      }
   3679 
   3680     /*-----------------------------------------------------------------------*\
   3681      * 6. If at this point the values are over-constrained, ignore the value
   3682      *    for 'bottom' and solve for that value.
   3683     \*-----------------------------------------------------------------------*/
   3684     // NOTE: It is not necessary to do this step because we don't end up using
   3685     // the value of 'bottom' regardless of whether the values are over-constrained
   3686     // or not.
   3687 
   3688     // Use computed values to calculate the vertical position.
   3689     LayoutUnit logicalTopPos = logicalTopValue + marginBeforeAlias;
   3690     computeLogicalTopPositionedOffset(logicalTopPos, this, computedValues.m_extent, containerBlock, containerLogicalHeight);
   3691     computedValues.m_position = logicalTopPos;
   3692 }
   3693 
   3694 LayoutRect RenderBox::localCaretRect(InlineBox* box, int caretOffset, LayoutUnit* extraWidthToEndOfLine)
   3695 {
   3696     // VisiblePositions at offsets inside containers either a) refer to the positions before/after
   3697     // those containers (tables and select elements) or b) refer to the position inside an empty block.
   3698     // They never refer to children.
   3699     // FIXME: Paint the carets inside empty blocks differently than the carets before/after elements.
   3700 
   3701     LayoutRect rect(location(), LayoutSize(caretWidth, height()));
   3702     bool ltr = box ? box->isLeftToRightDirection() : style()->isLeftToRightDirection();
   3703 
   3704     if ((!caretOffset) ^ ltr)
   3705         rect.move(LayoutSize(width() - caretWidth, 0));
   3706 
   3707     if (box) {
   3708         RootInlineBox& rootBox = box->root();
   3709         LayoutUnit top = rootBox.lineTop();
   3710         rect.setY(top);
   3711         rect.setHeight(rootBox.lineBottom() - top);
   3712     }
   3713 
   3714     // If height of box is smaller than font height, use the latter one,
   3715     // otherwise the caret might become invisible.
   3716     //
   3717     // Also, if the box is not a replaced element, always use the font height.
   3718     // This prevents the "big caret" bug described in:
   3719     // <rdar://problem/3777804> Deleting all content in a document can result in giant tall-as-window insertion point
   3720     //
   3721     // FIXME: ignoring :first-line, missing good reason to take care of
   3722     LayoutUnit fontHeight = style()->fontMetrics().height();
   3723     if (fontHeight > rect.height() || (!isReplaced() && !isTable()))
   3724         rect.setHeight(fontHeight);
   3725 
   3726     if (extraWidthToEndOfLine)
   3727         *extraWidthToEndOfLine = x() + width() - rect.maxX();
   3728 
   3729     // Move to local coords
   3730     rect.moveBy(-location());
   3731 
   3732     // FIXME: Border/padding should be added for all elements but this workaround
   3733     // is needed because we use offsets inside an "atomic" element to represent
   3734     // positions before and after the element in deprecated editing offsets.
   3735     if (node() && !(editingIgnoresContent(node()) || isRenderedTableElement(node()))) {
   3736         rect.setX(rect.x() + borderLeft() + paddingLeft());
   3737         rect.setY(rect.y() + paddingTop() + borderTop());
   3738     }
   3739 
   3740     if (!isHorizontalWritingMode())
   3741         return rect.transposedRect();
   3742 
   3743     return rect;
   3744 }
   3745 
   3746 PositionWithAffinity RenderBox::positionForPoint(const LayoutPoint& point)
   3747 {
   3748     // no children...return this render object's element, if there is one, and offset 0
   3749     RenderObject* firstChild = slowFirstChild();
   3750     if (!firstChild)
   3751         return createPositionWithAffinity(nonPseudoNode() ? firstPositionInOrBeforeNode(nonPseudoNode()) : Position());
   3752 
   3753     if (isTable() && nonPseudoNode()) {
   3754         LayoutUnit right = contentWidth() + borderAndPaddingWidth();
   3755         LayoutUnit bottom = contentHeight() + borderAndPaddingHeight();
   3756 
   3757         if (point.x() < 0 || point.x() > right || point.y() < 0 || point.y() > bottom) {
   3758             if (point.x() <= right / 2)
   3759                 return createPositionWithAffinity(firstPositionInOrBeforeNode(nonPseudoNode()));
   3760             return createPositionWithAffinity(lastPositionInOrAfterNode(nonPseudoNode()));
   3761         }
   3762     }
   3763 
   3764     // Pass off to the closest child.
   3765     LayoutUnit minDist = LayoutUnit::max();
   3766     RenderBox* closestRenderer = 0;
   3767     LayoutPoint adjustedPoint = point;
   3768     if (isTableRow())
   3769         adjustedPoint.moveBy(location());
   3770 
   3771     for (RenderObject* renderObject = firstChild; renderObject; renderObject = renderObject->nextSibling()) {
   3772         if ((!renderObject->slowFirstChild() && !renderObject->isInline() && !renderObject->isRenderBlockFlow() )
   3773             || renderObject->style()->visibility() != VISIBLE)
   3774             continue;
   3775 
   3776         if (!renderObject->isBox())
   3777             continue;
   3778 
   3779         RenderBox* renderer = toRenderBox(renderObject);
   3780 
   3781         LayoutUnit top = renderer->borderTop() + renderer->paddingTop() + (isTableRow() ? LayoutUnit() : renderer->y());
   3782         LayoutUnit bottom = top + renderer->contentHeight();
   3783         LayoutUnit left = renderer->borderLeft() + renderer->paddingLeft() + (isTableRow() ? LayoutUnit() : renderer->x());
   3784         LayoutUnit right = left + renderer->contentWidth();
   3785 
   3786         if (point.x() <= right && point.x() >= left && point.y() <= top && point.y() >= bottom) {
   3787             if (renderer->isTableRow())
   3788                 return renderer->positionForPoint(point + adjustedPoint - renderer->locationOffset());
   3789             return renderer->positionForPoint(point - renderer->locationOffset());
   3790         }
   3791 
   3792         // Find the distance from (x, y) to the box.  Split the space around the box into 8 pieces
   3793         // and use a different compare depending on which piece (x, y) is in.
   3794         LayoutPoint cmp;
   3795         if (point.x() > right) {
   3796             if (point.y() < top)
   3797                 cmp = LayoutPoint(right, top);
   3798             else if (point.y() > bottom)
   3799                 cmp = LayoutPoint(right, bottom);
   3800             else
   3801                 cmp = LayoutPoint(right, point.y());
   3802         } else if (point.x() < left) {
   3803             if (point.y() < top)
   3804                 cmp = LayoutPoint(left, top);
   3805             else if (point.y() > bottom)
   3806                 cmp = LayoutPoint(left, bottom);
   3807             else
   3808                 cmp = LayoutPoint(left, point.y());
   3809         } else {
   3810             if (point.y() < top)
   3811                 cmp = LayoutPoint(point.x(), top);
   3812             else
   3813                 cmp = LayoutPoint(point.x(), bottom);
   3814         }
   3815 
   3816         LayoutSize difference = cmp - point;
   3817 
   3818         LayoutUnit dist = difference.width() * difference.width() + difference.height() * difference.height();
   3819         if (dist < minDist) {
   3820             closestRenderer = renderer;
   3821             minDist = dist;
   3822         }
   3823     }
   3824 
   3825     if (closestRenderer)
   3826         return closestRenderer->positionForPoint(adjustedPoint - closestRenderer->locationOffset());
   3827     return createPositionWithAffinity(firstPositionInOrBeforeNode(nonPseudoNode()));
   3828 }
   3829 
   3830 bool RenderBox::shrinkToAvoidFloats() const
   3831 {
   3832     // Floating objects don't shrink.  Objects that don't avoid floats don't shrink.  Marquees don't shrink.
   3833     if ((isInline() && !isMarquee()) || !avoidsFloats() || isFloating())
   3834         return false;
   3835 
   3836     // Only auto width objects can possibly shrink to avoid floats.
   3837     return style()->width().isAuto();
   3838 }
   3839 
   3840 static bool isReplacedElement(Node* node)
   3841 {
   3842     // Checkboxes and radioboxes are not isReplaced() nor do they have their own renderer in which to override avoidFloats().
   3843     return node && node->isElementNode() && toElement(node)->isFormControlElement();
   3844 }
   3845 
   3846 bool RenderBox::avoidsFloats() const
   3847 {
   3848     return isReplaced() || isReplacedElement(node()) || hasOverflowClip() || isHR() || isLegend() || isWritingModeRoot() || isFlexItemIncludingDeprecated();
   3849 }
   3850 
   3851 InvalidationReason RenderBox::getPaintInvalidationReason(const RenderLayerModelObject& paintInvalidationContainer,
   3852     const LayoutRect& oldBounds, const LayoutPoint& oldLocation, const LayoutRect& newBounds, const LayoutPoint& newLocation)
   3853 {
   3854     InvalidationReason invalidationReason = RenderBoxModelObject::getPaintInvalidationReason(paintInvalidationContainer, oldBounds, oldLocation, newBounds, newLocation);
   3855     if (invalidationReason != InvalidationNone && invalidationReason != InvalidationIncremental)
   3856         return invalidationReason;
   3857 
   3858     if (!style()->hasBackground() && !style()->hasBoxDecorations())
   3859         return invalidationReason;
   3860 
   3861     LayoutSize oldBorderBoxSize = computePreviousBorderBoxSize(oldBounds.size());
   3862     LayoutSize newBorderBoxSize = size();
   3863 
   3864     if (oldBorderBoxSize == newBorderBoxSize)
   3865         return invalidationReason;
   3866 
   3867     // FIXME: Implement correct incremental invalidation for visual overflowing effects.
   3868     if (style()->hasVisualOverflowingEffect() || style()->hasAppearance() || style()->hasFilter())
   3869         return InvalidationBorderBoxChange;
   3870 
   3871     if (style()->hasBorderRadius()) {
   3872         // If a border-radius exists and width/height is smaller than radius width/height,
   3873         // we need to fully invalidate to cover the changed radius.
   3874         RoundedRect oldRoundedRect = style()->getRoundedBorderFor(LayoutRect(LayoutPoint(0, 0), oldBorderBoxSize));
   3875         RoundedRect newRoundedRect = style()->getRoundedBorderFor(LayoutRect(LayoutPoint(0, 0), newBorderBoxSize));
   3876         if (oldRoundedRect.radii() != newRoundedRect.radii())
   3877             return InvalidationBorderBoxChange;
   3878     }
   3879 
   3880     if (oldBorderBoxSize.width() != newBorderBoxSize.width() && mustInvalidateBackgroundOrBorderPaintOnWidthChange())
   3881         return InvalidationBorderBoxChange;
   3882     if (oldBorderBoxSize.height() != newBorderBoxSize.height() && mustInvalidateBackgroundOrBorderPaintOnHeightChange())
   3883         return InvalidationBorderBoxChange;
   3884 
   3885     return InvalidationIncremental;
   3886 }
   3887 
   3888 void RenderBox::incrementallyInvalidatePaint(const RenderLayerModelObject& paintInvalidationContainer, const LayoutRect& oldBounds, const LayoutRect& newBounds, const LayoutPoint& positionFromPaintInvalidationBacking)
   3889 {
   3890     RenderObject::incrementallyInvalidatePaint(paintInvalidationContainer, oldBounds, newBounds, positionFromPaintInvalidationBacking);
   3891 
   3892     bool hasBoxDecorations = style()->hasBoxDecorations();
   3893     if (!style()->hasBackground() && !hasBoxDecorations)
   3894         return;
   3895 
   3896     LayoutSize oldBorderBoxSize = computePreviousBorderBoxSize(oldBounds.size());
   3897     LayoutSize newBorderBoxSize = size();
   3898 
   3899     // If border box size didn't change, RenderObject's incrementallyInvalidatePaint() is good.
   3900     if (oldBorderBoxSize == newBorderBoxSize)
   3901         return;
   3902 
   3903     // If size of the paint invalidation rect equals to size of border box, RenderObject::incrementallyInvalidatePaint()
   3904     // is good for boxes having background without box decorations.
   3905     ASSERT(oldBounds.location() == newBounds.location()); // Otherwise we won't do incremental invalidation.
   3906     if (!hasBoxDecorations
   3907         && positionFromPaintInvalidationBacking == newBounds.location()
   3908         && oldBorderBoxSize == oldBounds.size()
   3909         && newBorderBoxSize == newBounds.size())
   3910         return;
   3911 
   3912     // Invalidate the right delta part and the right border of the old or new box which has smaller width.
   3913     LayoutUnit deltaWidth = absoluteValue(oldBorderBoxSize.width() - newBorderBoxSize.width());
   3914     if (deltaWidth) {
   3915         LayoutUnit smallerWidth = std::min(oldBorderBoxSize.width(), newBorderBoxSize.width());
   3916         LayoutUnit borderTopRightRadiusWidth = valueForLength(style()->borderTopRightRadius().width(), smallerWidth);
   3917         LayoutUnit borderBottomRightRadiusWidth = valueForLength(style()->borderBottomRightRadius().width(), smallerWidth);
   3918         LayoutUnit borderWidth = std::max<LayoutUnit>(borderRight(), std::max(borderTopRightRadiusWidth, borderBottomRightRadiusWidth));
   3919         LayoutRect rightDeltaRect(positionFromPaintInvalidationBacking.x() + smallerWidth - borderWidth,
   3920             positionFromPaintInvalidationBacking.y(),
   3921             deltaWidth + borderWidth,
   3922             std::max(oldBorderBoxSize.height(), newBorderBoxSize.height()));
   3923         invalidatePaintRectClippedByOldAndNewBounds(paintInvalidationContainer, rightDeltaRect, oldBounds, newBounds);
   3924     }
   3925 
   3926     // Invalidate the bottom delta part and the bottom border of the old or new box which has smaller height.
   3927     LayoutUnit deltaHeight = absoluteValue(oldBorderBoxSize.height() - newBorderBoxSize.height());
   3928     if (deltaHeight) {
   3929         LayoutUnit smallerHeight = std::min(oldBorderBoxSize.height(), newBorderBoxSize.height());
   3930         LayoutUnit borderBottomLeftRadiusHeight = valueForLength(style()->borderBottomLeftRadius().height(), smallerHeight);
   3931         LayoutUnit borderBottomRightRadiusHeight = valueForLength(style()->borderBottomRightRadius().height(), smallerHeight);
   3932         LayoutUnit borderHeight = std::max<LayoutUnit>(borderBottom(), std::max(borderBottomLeftRadiusHeight, borderBottomRightRadiusHeight));
   3933         LayoutRect bottomDeltaRect(positionFromPaintInvalidationBacking.x(),
   3934             positionFromPaintInvalidationBacking.y() + smallerHeight - borderHeight,
   3935             std::max(oldBorderBoxSize.width(), newBorderBoxSize.width()),
   3936             deltaHeight + borderHeight);
   3937         invalidatePaintRectClippedByOldAndNewBounds(paintInvalidationContainer, bottomDeltaRect, oldBounds, newBounds);
   3938     }
   3939 }
   3940 
   3941 void RenderBox::invalidatePaintRectClippedByOldAndNewBounds(const RenderLayerModelObject& paintInvalidationContainer, const LayoutRect& rect, const LayoutRect& oldBounds, const LayoutRect& newBounds)
   3942 {
   3943     if (rect.isEmpty())
   3944         return;
   3945     LayoutRect rectClippedByOldBounds = intersection(rect, oldBounds);
   3946     LayoutRect rectClippedByNewBounds = intersection(rect, newBounds);
   3947     // Invalidate only once if the clipped rects equal.
   3948     if (rectClippedByOldBounds == rectClippedByNewBounds) {
   3949         invalidatePaintUsingContainer(&paintInvalidationContainer, rectClippedByOldBounds, InvalidationIncremental);
   3950         return;
   3951     }
   3952     // Invalidate the bigger one if one contains another. Otherwise invalidate both.
   3953     if (!rectClippedByNewBounds.contains(rectClippedByOldBounds))
   3954         invalidatePaintUsingContainer(&paintInvalidationContainer, rectClippedByOldBounds, InvalidationIncremental);
   3955     if (!rectClippedByOldBounds.contains(rectClippedByNewBounds))
   3956         invalidatePaintUsingContainer(&paintInvalidationContainer, rectClippedByNewBounds, InvalidationIncremental);
   3957 }
   3958 
   3959 void RenderBox::markForPaginationRelayoutIfNeeded(SubtreeLayoutScope& layoutScope)
   3960 {
   3961     ASSERT(!needsLayout());
   3962     // If fragmentation height has changed, we need to lay out. No need to enter the renderer if it
   3963     // is childless, though.
   3964     if (view()->layoutState()->pageLogicalHeightChanged() && slowFirstChild())
   3965         layoutScope.setChildNeedsLayout(this);
   3966 }
   3967 
   3968 void RenderBox::addVisualEffectOverflow()
   3969 {
   3970     if (!style()->hasVisualOverflowingEffect())
   3971         return;
   3972 
   3973     // Add in the final overflow with shadows, outsets and outline combined.
   3974     LayoutRect visualEffectOverflow = borderBoxRect();
   3975     visualEffectOverflow.expand(computeVisualEffectOverflowExtent());
   3976     addVisualOverflow(visualEffectOverflow);
   3977 }
   3978 
   3979 LayoutBoxExtent RenderBox::computeVisualEffectOverflowExtent() const
   3980 {
   3981     ASSERT(style()->hasVisualOverflowingEffect());
   3982 
   3983     LayoutUnit top;
   3984     LayoutUnit right;
   3985     LayoutUnit bottom;
   3986     LayoutUnit left;
   3987 
   3988     if (style()->boxShadow()) {
   3989         style()->getBoxShadowExtent(top, right, bottom, left);
   3990 
   3991         // Box shadow extent's top and left are negative when extend to left and top direction, respectively.
   3992         // Negate to make them positive.
   3993         top = -top;
   3994         left = -left;
   3995     }
   3996 
   3997     if (style()->hasBorderImageOutsets()) {
   3998         LayoutBoxExtent borderOutsets = style()->borderImageOutsets();
   3999         top = std::max(top, borderOutsets.top());
   4000         right = std::max(right, borderOutsets.right());
   4001         bottom = std::max(bottom, borderOutsets.bottom());
   4002         left = std::max(left, borderOutsets.left());
   4003     }
   4004 
   4005     if (style()->hasOutline()) {
   4006         if (style()->outlineStyleIsAuto()) {
   4007             // The result focus ring rects are in coordinates of this object's border box.
   4008             Vector<LayoutRect> focusRingRects;
   4009             addFocusRingRects(focusRingRects, LayoutPoint(), this);
   4010             LayoutRect rect = unionRect(focusRingRects);
   4011 
   4012             int outlineSize = GraphicsContext::focusRingOutsetExtent(style()->outlineOffset(), style()->outlineWidth());
   4013             top = std::max(top, -rect.y() + outlineSize);
   4014             right = std::max(right, rect.maxX() - width() + outlineSize);
   4015             bottom = std::max(bottom, rect.maxY() - height() + outlineSize);
   4016             left = std::max(left, -rect.x() + outlineSize);
   4017         } else {
   4018             LayoutUnit outlineSize = style()->outlineSize();
   4019             top = std::max(top, outlineSize);
   4020             right = std::max(right, outlineSize);
   4021             bottom = std::max(bottom, outlineSize);
   4022             left = std::max(left, outlineSize);
   4023         }
   4024     }
   4025 
   4026     return LayoutBoxExtent(top, right, bottom, left);
   4027 }
   4028 
   4029 void RenderBox::addOverflowFromChild(RenderBox* child, const LayoutSize& delta)
   4030 {
   4031     // Never allow flow threads to propagate overflow up to a parent.
   4032     if (child->isRenderFlowThread())
   4033         return;
   4034 
   4035     // Only propagate layout overflow from the child if the child isn't clipping its overflow.  If it is, then
   4036     // its overflow is internal to it, and we don't care about it.  layoutOverflowRectForPropagation takes care of this
   4037     // and just propagates the border box rect instead.
   4038     LayoutRect childLayoutOverflowRect = child->layoutOverflowRectForPropagation(style());
   4039     childLayoutOverflowRect.move(delta);
   4040     addLayoutOverflow(childLayoutOverflowRect);
   4041 
   4042     // Add in visual overflow from the child.  Even if the child clips its overflow, it may still
   4043     // have visual overflow of its own set from box shadows or reflections.  It is unnecessary to propagate this
   4044     // overflow if we are clipping our own overflow.
   4045     if (child->hasSelfPaintingLayer())
   4046         return;
   4047     LayoutRect childVisualOverflowRect = child->visualOverflowRectForPropagation(style());
   4048     childVisualOverflowRect.move(delta);
   4049     addContentsVisualOverflow(childVisualOverflowRect);
   4050 }
   4051 
   4052 void RenderBox::addLayoutOverflow(const LayoutRect& rect)
   4053 {
   4054     LayoutRect clientBox = noOverflowRect();
   4055     if (clientBox.contains(rect) || rect.isEmpty())
   4056         return;
   4057 
   4058     // For overflow clip objects, we don't want to propagate overflow into unreachable areas.
   4059     LayoutRect overflowRect(rect);
   4060     if (hasOverflowClip() || isRenderView()) {
   4061         // Overflow is in the block's coordinate space and thus is flipped for horizontal-bt and vertical-rl
   4062         // writing modes.  At this stage that is actually a simplification, since we can treat horizontal-tb/bt as the same
   4063         // and vertical-lr/rl as the same.
   4064         bool hasTopOverflow = !style()->isLeftToRightDirection() && !isHorizontalWritingMode();
   4065         bool hasLeftOverflow = !style()->isLeftToRightDirection() && isHorizontalWritingMode();
   4066         if (isFlexibleBox() && style()->isReverseFlexDirection()) {
   4067             RenderFlexibleBox* flexibleBox = toRenderFlexibleBox(this);
   4068             if (flexibleBox->isHorizontalFlow())
   4069                 hasLeftOverflow = true;
   4070             else
   4071                 hasTopOverflow = true;
   4072         }
   4073 
   4074         if (!hasTopOverflow)
   4075             overflowRect.shiftYEdgeTo(std::max(overflowRect.y(), clientBox.y()));
   4076         else
   4077             overflowRect.shiftMaxYEdgeTo(std::min(overflowRect.maxY(), clientBox.maxY()));
   4078         if (!hasLeftOverflow)
   4079             overflowRect.shiftXEdgeTo(std::max(overflowRect.x(), clientBox.x()));
   4080         else
   4081             overflowRect.shiftMaxXEdgeTo(std::min(overflowRect.maxX(), clientBox.maxX()));
   4082 
   4083         // Now re-test with the adjusted rectangle and see if it has become unreachable or fully
   4084         // contained.
   4085         if (clientBox.contains(overflowRect) || overflowRect.isEmpty())
   4086             return;
   4087     }
   4088 
   4089     if (!m_overflow)
   4090         m_overflow = adoptPtr(new RenderOverflow(clientBox, borderBoxRect()));
   4091 
   4092     m_overflow->addLayoutOverflow(overflowRect);
   4093 }
   4094 
   4095 void RenderBox::addVisualOverflow(const LayoutRect& rect)
   4096 {
   4097     LayoutRect borderBox = borderBoxRect();
   4098     if (borderBox.contains(rect) || rect.isEmpty())
   4099         return;
   4100 
   4101     if (!m_overflow)
   4102         m_overflow = adoptPtr(new RenderOverflow(noOverflowRect(), borderBox));
   4103 
   4104     m_overflow->addVisualOverflow(rect);
   4105 }
   4106 
   4107 void RenderBox::addContentsVisualOverflow(const LayoutRect& rect)
   4108 {
   4109     if (!hasOverflowClip()) {
   4110         addVisualOverflow(rect);
   4111         return;
   4112     }
   4113 
   4114     if (!m_overflow)
   4115         m_overflow = adoptPtr(new RenderOverflow(noOverflowRect(), borderBoxRect()));
   4116     m_overflow->addContentsVisualOverflow(rect);
   4117 }
   4118 
   4119 void RenderBox::clearLayoutOverflow()
   4120 {
   4121     if (!m_overflow)
   4122         return;
   4123 
   4124     if (!hasVisualOverflow() && contentsVisualOverflowRect().isEmpty()) {
   4125         clearAllOverflows();
   4126         return;
   4127     }
   4128 
   4129     m_overflow->setLayoutOverflow(noOverflowRect());
   4130 }
   4131 
   4132 inline static bool percentageLogicalHeightIsResolvable(const RenderBox* box)
   4133 {
   4134     return RenderBox::percentageLogicalHeightIsResolvableFromBlock(box->containingBlock(), box->isOutOfFlowPositioned());
   4135 }
   4136 
   4137 bool RenderBox::percentageLogicalHeightIsResolvableFromBlock(const RenderBlock* containingBlock, bool isOutOfFlowPositioned)
   4138 {
   4139     // In quirks mode, blocks with auto height are skipped, and we keep looking for an enclosing
   4140     // block that may have a specified height and then use it. In strict mode, this violates the
   4141     // specification, which states that percentage heights just revert to auto if the containing
   4142     // block has an auto height. We still skip anonymous containing blocks in both modes, though, and look
   4143     // only at explicit containers.
   4144     const RenderBlock* cb = containingBlock;
   4145     bool inQuirksMode = cb->document().inQuirksMode();
   4146     while (!cb->isRenderView() && !cb->isBody() && !cb->isTableCell() && !cb->isOutOfFlowPositioned() && cb->style()->logicalHeight().isAuto()) {
   4147         if (!inQuirksMode && !cb->isAnonymousBlock())
   4148             break;
   4149         cb = cb->containingBlock();
   4150     }
   4151 
   4152     // A positioned element that specified both top/bottom or that specifies height should be treated as though it has a height
   4153     // explicitly specified that can be used for any percentage computations.
   4154     // FIXME: We can't just check top/bottom here.
   4155     // https://bugs.webkit.org/show_bug.cgi?id=46500
   4156     bool isOutOfFlowPositionedWithSpecifiedHeight = cb->isOutOfFlowPositioned() && (!cb->style()->logicalHeight().isAuto() || (!cb->style()->top().isAuto() && !cb->style()->bottom().isAuto()));
   4157 
   4158     // Table cells violate what the CSS spec says to do with heights.  Basically we
   4159     // don't care if the cell specified a height or not.  We just always make ourselves
   4160     // be a percentage of the cell's current content height.
   4161     if (cb->isTableCell())
   4162         return true;
   4163 
   4164     // Otherwise we only use our percentage height if our containing block had a specified
   4165     // height.
   4166     if (cb->style()->logicalHeight().isFixed())
   4167         return true;
   4168     if (cb->style()->logicalHeight().isPercent() && !isOutOfFlowPositionedWithSpecifiedHeight)
   4169         return percentageLogicalHeightIsResolvableFromBlock(cb->containingBlock(), cb->isOutOfFlowPositioned());
   4170     if (cb->isRenderView() || inQuirksMode || isOutOfFlowPositionedWithSpecifiedHeight)
   4171         return true;
   4172     if (cb->isDocumentElement() && isOutOfFlowPositioned) {
   4173         // Match the positioned objects behavior, which is that positioned objects will fill their viewport
   4174         // always.  Note we could only hit this case by recurring into computePercentageLogicalHeight on a positioned containing block.
   4175         return true;
   4176     }
   4177 
   4178     return false;
   4179 }
   4180 
   4181 bool RenderBox::hasUnsplittableScrollingOverflow() const
   4182 {
   4183     // We will paginate as long as we don't scroll overflow in the pagination direction.
   4184     bool isHorizontal = isHorizontalWritingMode();
   4185     if ((isHorizontal && !scrollsOverflowY()) || (!isHorizontal && !scrollsOverflowX()))
   4186         return false;
   4187 
   4188     // We do have overflow. We'll still be willing to paginate as long as the block
   4189     // has auto logical height, auto or undefined max-logical-height and a zero or auto min-logical-height.
   4190     // Note this is just a heuristic, and it's still possible to have overflow under these
   4191     // conditions, but it should work out to be good enough for common cases. Paginating overflow
   4192     // with scrollbars present is not the end of the world and is what we used to do in the old model anyway.
   4193     return !style()->logicalHeight().isIntrinsicOrAuto()
   4194         || (!style()->logicalMaxHeight().isIntrinsicOrAuto() && !style()->logicalMaxHeight().isMaxSizeNone() && (!style()->logicalMaxHeight().isPercent() || percentageLogicalHeightIsResolvable(this)))
   4195         || (!style()->logicalMinHeight().isIntrinsicOrAuto() && style()->logicalMinHeight().isPositive() && (!style()->logicalMinHeight().isPercent() || percentageLogicalHeightIsResolvable(this)));
   4196 }
   4197 
   4198 bool RenderBox::isUnsplittableForPagination() const
   4199 {
   4200     return isReplaced() || hasUnsplittableScrollingOverflow() || (parent() && isWritingModeRoot());
   4201 }
   4202 
   4203 LayoutUnit RenderBox::lineHeight(bool /*firstLine*/, LineDirectionMode direction, LinePositionMode /*linePositionMode*/) const
   4204 {
   4205     if (isReplaced())
   4206         return direction == HorizontalLine ? m_marginBox.top() + height() + m_marginBox.bottom() : m_marginBox.right() + width() + m_marginBox.left();
   4207     return 0;
   4208 }
   4209 
   4210 int RenderBox::baselinePosition(FontBaseline baselineType, bool /*firstLine*/, LineDirectionMode direction, LinePositionMode linePositionMode) const
   4211 {
   4212     ASSERT(linePositionMode == PositionOnContainingLine);
   4213     if (isReplaced()) {
   4214         int result = direction == HorizontalLine ? m_marginBox.top() + height() + m_marginBox.bottom() : m_marginBox.right() + width() + m_marginBox.left();
   4215         if (baselineType == AlphabeticBaseline)
   4216             return result;
   4217         return result - result / 2;
   4218     }
   4219     return 0;
   4220 }
   4221 
   4222 
   4223 RenderLayer* RenderBox::enclosingFloatPaintingLayer() const
   4224 {
   4225     const RenderObject* curr = this;
   4226     while (curr) {
   4227         RenderLayer* layer = curr->hasLayer() && curr->isBox() ? toRenderBox(curr)->layer() : 0;
   4228         if (layer && layer->isSelfPaintingLayer())
   4229             return layer;
   4230         curr = curr->parent();
   4231     }
   4232     return 0;
   4233 }
   4234 
   4235 LayoutRect RenderBox::logicalVisualOverflowRectForPropagation(RenderStyle* parentStyle) const
   4236 {
   4237     LayoutRect rect = visualOverflowRectForPropagation(parentStyle);
   4238     if (!parentStyle->isHorizontalWritingMode())
   4239         return rect.transposedRect();
   4240     return rect;
   4241 }
   4242 
   4243 LayoutRect RenderBox::visualOverflowRectForPropagation(RenderStyle* parentStyle) const
   4244 {
   4245     // If the writing modes of the child and parent match, then we don't have to
   4246     // do anything fancy. Just return the result.
   4247     LayoutRect rect = visualOverflowRect();
   4248     if (parentStyle->writingMode() == style()->writingMode())
   4249         return rect;
   4250 
   4251     // We are putting ourselves into our parent's coordinate space.  If there is a flipped block mismatch
   4252     // in a particular axis, then we have to flip the rect along that axis.
   4253     if (style()->writingMode() == RightToLeftWritingMode || parentStyle->writingMode() == RightToLeftWritingMode)
   4254         rect.setX(width() - rect.maxX());
   4255     else if (style()->writingMode() == BottomToTopWritingMode || parentStyle->writingMode() == BottomToTopWritingMode)
   4256         rect.setY(height() - rect.maxY());
   4257 
   4258     return rect;
   4259 }
   4260 
   4261 LayoutRect RenderBox::logicalLayoutOverflowRectForPropagation(RenderStyle* parentStyle) const
   4262 {
   4263     LayoutRect rect = layoutOverflowRectForPropagation(parentStyle);
   4264     if (!parentStyle->isHorizontalWritingMode())
   4265         return rect.transposedRect();
   4266     return rect;
   4267 }
   4268 
   4269 LayoutRect RenderBox::layoutOverflowRectForPropagation(RenderStyle* parentStyle) const
   4270 {
   4271     // Only propagate interior layout overflow if we don't clip it.
   4272     LayoutRect rect = borderBoxRect();
   4273     // We want to include the margin, but only when it adds height. Quirky margins don't contribute height
   4274     // nor do the margins of self-collapsing blocks.
   4275     if (!style()->hasMarginAfterQuirk() && !isSelfCollapsingBlock())
   4276         rect.expand(isHorizontalWritingMode() ? LayoutSize(LayoutUnit(), marginAfter()) : LayoutSize(marginAfter(), LayoutUnit()));
   4277 
   4278     if (!hasOverflowClip())
   4279         rect.unite(layoutOverflowRect());
   4280 
   4281     bool hasTransform = hasLayer() && layer()->transform();
   4282     if (isRelPositioned() || hasTransform) {
   4283         // If we are relatively positioned or if we have a transform, then we have to convert
   4284         // this rectangle into physical coordinates, apply relative positioning and transforms
   4285         // to it, and then convert it back.
   4286         flipForWritingMode(rect);
   4287 
   4288         if (hasTransform)
   4289             rect = layer()->currentTransform().mapRect(rect);
   4290 
   4291         if (isRelPositioned())
   4292             rect.move(offsetForInFlowPosition());
   4293 
   4294         // Now we need to flip back.
   4295         flipForWritingMode(rect);
   4296     }
   4297 
   4298     // If the writing modes of the child and parent match, then we don't have to
   4299     // do anything fancy. Just return the result.
   4300     if (parentStyle->writingMode() == style()->writingMode())
   4301         return rect;
   4302 
   4303     // We are putting ourselves into our parent's coordinate space.  If there is a flipped block mismatch
   4304     // in a particular axis, then we have to flip the rect along that axis.
   4305     if (style()->writingMode() == RightToLeftWritingMode || parentStyle->writingMode() == RightToLeftWritingMode)
   4306         rect.setX(width() - rect.maxX());
   4307     else if (style()->writingMode() == BottomToTopWritingMode || parentStyle->writingMode() == BottomToTopWritingMode)
   4308         rect.setY(height() - rect.maxY());
   4309 
   4310     return rect;
   4311 }
   4312 
   4313 LayoutRect RenderBox::noOverflowRect() const
   4314 {
   4315     // Because of the special coordinate system used for overflow rectangles and many other
   4316     // rectangles (not quite logical, not quite physical), we need to flip the block progression
   4317     // coordinate in vertical-rl and horizontal-bt writing modes. In other words, the rectangle
   4318     // returned is physical, except for the block direction progression coordinate (y in horizontal
   4319     // writing modes, x in vertical writing modes), which is always "logical top". Apart from the
   4320     // flipping, this method does the same as clientBoxRect().
   4321 
   4322     const int scrollBarWidth = verticalScrollbarWidth();
   4323     const int scrollBarHeight = horizontalScrollbarHeight();
   4324     LayoutUnit left = borderLeft() + (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft() ? scrollBarWidth : 0);
   4325     LayoutUnit top = borderTop();
   4326     LayoutUnit right = borderRight();
   4327     LayoutUnit bottom = borderBottom();
   4328     LayoutRect rect(left, top, width() - left - right, height() - top - bottom);
   4329     flipForWritingMode(rect);
   4330     // Subtract space occupied by scrollbars. Order is important here: first flip, then subtract
   4331     // scrollbars. This may seem backwards and weird, since one would think that a horizontal
   4332     // scrollbar at the physical bottom in horizontal-bt ought to be at the logical top (physical
   4333     // bottom), between the logical top (physical bottom) border and the logical top (physical
   4334     // bottom) padding. But this is how the rest of the code expects us to behave. This is highly
   4335     // related to https://bugs.webkit.org/show_bug.cgi?id=76129
   4336     // FIXME: when the above mentioned bug is fixed, it should hopefully be possible to call
   4337     // clientBoxRect() or paddingBoxRect() in this method, rather than fiddling with the edges on
   4338     // our own.
   4339     if (style()->shouldPlaceBlockDirectionScrollbarOnLogicalLeft())
   4340         rect.contract(0, scrollBarHeight);
   4341     else
   4342         rect.contract(scrollBarWidth, scrollBarHeight);
   4343     return rect;
   4344 }
   4345 
   4346 LayoutUnit RenderBox::offsetLeft() const
   4347 {
   4348     return adjustedPositionRelativeToOffsetParent(topLeftLocation()).x();
   4349 }
   4350 
   4351 LayoutUnit RenderBox::offsetTop() const
   4352 {
   4353     return adjustedPositionRelativeToOffsetParent(topLeftLocation()).y();
   4354 }
   4355 
   4356 LayoutPoint RenderBox::flipForWritingModeForChild(const RenderBox* child, const LayoutPoint& point) const
   4357 {
   4358     if (!style()->isFlippedBlocksWritingMode())
   4359         return point;
   4360 
   4361     // The child is going to add in its x() and y(), so we have to make sure it ends up in
   4362     // the right place.
   4363     if (isHorizontalWritingMode())
   4364         return LayoutPoint(point.x(), point.y() + height() - child->height() - (2 * child->y()));
   4365     return LayoutPoint(point.x() + width() - child->width() - (2 * child->x()), point.y());
   4366 }
   4367 
   4368 void RenderBox::flipForWritingMode(LayoutRect& rect) const
   4369 {
   4370     if (!style()->isFlippedBlocksWritingMode())
   4371         return;
   4372 
   4373     if (isHorizontalWritingMode())
   4374         rect.setY(height() - rect.maxY());
   4375     else
   4376         rect.setX(width() - rect.maxX());
   4377 }
   4378 
   4379 LayoutUnit RenderBox::flipForWritingMode(LayoutUnit position) const
   4380 {
   4381     if (!style()->isFlippedBlocksWritingMode())
   4382         return position;
   4383     return logicalHeight() - position;
   4384 }
   4385 
   4386 LayoutPoint RenderBox::flipForWritingMode(const LayoutPoint& position) const
   4387 {
   4388     if (!style()->isFlippedBlocksWritingMode())
   4389         return position;
   4390     return isHorizontalWritingMode() ? LayoutPoint(position.x(), height() - position.y()) : LayoutPoint(width() - position.x(), position.y());
   4391 }
   4392 
   4393 LayoutPoint RenderBox::flipForWritingModeIncludingColumns(const LayoutPoint& point) const
   4394 {
   4395     if (!hasColumns() || !style()->isFlippedBlocksWritingMode())
   4396         return flipForWritingMode(point);
   4397     return toRenderBlock(this)->flipForWritingModeIncludingColumns(point);
   4398 }
   4399 
   4400 LayoutSize RenderBox::flipForWritingMode(const LayoutSize& offset) const
   4401 {
   4402     if (!style()->isFlippedBlocksWritingMode())
   4403         return offset;
   4404     return isHorizontalWritingMode() ? LayoutSize(offset.width(), height() - offset.height()) : LayoutSize(width() - offset.width(), offset.height());
   4405 }
   4406 
   4407 FloatPoint RenderBox::flipForWritingMode(const FloatPoint& position) const
   4408 {
   4409     if (!style()->isFlippedBlocksWritingMode())
   4410         return position;
   4411     return isHorizontalWritingMode() ? FloatPoint(position.x(), height() - position.y()) : FloatPoint(width() - position.x(), position.y());
   4412 }
   4413 
   4414 void RenderBox::flipForWritingMode(FloatRect& rect) const
   4415 {
   4416     if (!style()->isFlippedBlocksWritingMode())
   4417         return;
   4418 
   4419     if (isHorizontalWritingMode())
   4420         rect.setY(height() - rect.maxY());
   4421     else
   4422         rect.setX(width() - rect.maxX());
   4423 }
   4424 
   4425 LayoutPoint RenderBox::topLeftLocation() const
   4426 {
   4427     RenderBlock* containerBlock = containingBlock();
   4428     if (!containerBlock || containerBlock == this)
   4429         return location();
   4430     return containerBlock->flipForWritingModeForChild(this, location());
   4431 }
   4432 
   4433 LayoutSize RenderBox::topLeftLocationOffset() const
   4434 {
   4435     RenderBlock* containerBlock = containingBlock();
   4436     if (!containerBlock || containerBlock == this)
   4437         return locationOffset();
   4438 
   4439     LayoutRect rect(frameRect());
   4440     containerBlock->flipForWritingMode(rect); // FIXME: This is wrong if we are an absolutely positioned object enclosed by a relative-positioned inline.
   4441     return LayoutSize(rect.x(), rect.y());
   4442 }
   4443 
   4444 bool RenderBox::hasRelativeLogicalHeight() const
   4445 {
   4446     return style()->logicalHeight().isPercent()
   4447         || style()->logicalMinHeight().isPercent()
   4448         || style()->logicalMaxHeight().isPercent();
   4449 }
   4450 
   4451 static void markBoxForRelayoutAfterSplit(RenderBox* box)
   4452 {
   4453     // FIXME: The table code should handle that automatically. If not,
   4454     // we should fix it and remove the table part checks.
   4455     if (box->isTable()) {
   4456         // Because we may have added some sections with already computed column structures, we need to
   4457         // sync the table structure with them now. This avoids crashes when adding new cells to the table.
   4458         toRenderTable(box)->forceSectionsRecalc();
   4459     } else if (box->isTableSection())
   4460         toRenderTableSection(box)->setNeedsCellRecalc();
   4461 
   4462     box->setNeedsLayoutAndPrefWidthsRecalcAndFullPaintInvalidation();
   4463 }
   4464 
   4465 RenderObject* RenderBox::splitAnonymousBoxesAroundChild(RenderObject* beforeChild)
   4466 {
   4467     bool didSplitParentAnonymousBoxes = false;
   4468 
   4469     while (beforeChild->parent() != this) {
   4470         RenderBox* boxToSplit = toRenderBox(beforeChild->parent());
   4471         if (boxToSplit->slowFirstChild() != beforeChild && boxToSplit->isAnonymous()) {
   4472             didSplitParentAnonymousBoxes = true;
   4473 
   4474             // We have to split the parent box into two boxes and move children
   4475             // from |beforeChild| to end into the new post box.
   4476             RenderBox* postBox = boxToSplit->createAnonymousBoxWithSameTypeAs(this);
   4477             postBox->setChildrenInline(boxToSplit->childrenInline());
   4478             RenderBox* parentBox = toRenderBox(boxToSplit->parent());
   4479             // We need to invalidate the |parentBox| before inserting the new node
   4480             // so that the table paint invalidation logic knows the structure is dirty.
   4481             // See for example RenderTableCell:clippedOverflowRectForPaintInvalidation.
   4482             markBoxForRelayoutAfterSplit(parentBox);
   4483             parentBox->virtualChildren()->insertChildNode(parentBox, postBox, boxToSplit->nextSibling());
   4484             boxToSplit->moveChildrenTo(postBox, beforeChild, 0, true);
   4485 
   4486             markBoxForRelayoutAfterSplit(boxToSplit);
   4487             markBoxForRelayoutAfterSplit(postBox);
   4488 
   4489             beforeChild = postBox;
   4490         } else
   4491             beforeChild = boxToSplit;
   4492     }
   4493 
   4494     if (didSplitParentAnonymousBoxes)
   4495         markBoxForRelayoutAfterSplit(this);
   4496 
   4497     ASSERT(beforeChild->parent() == this);
   4498     return beforeChild;
   4499 }
   4500 
   4501 LayoutUnit RenderBox::offsetFromLogicalTopOfFirstPage() const
   4502 {
   4503     LayoutState* layoutState = view()->layoutState();
   4504     if (layoutState && !layoutState->isPaginated())
   4505         return 0;
   4506 
   4507     if (!layoutState && !flowThreadContainingBlock())
   4508         return 0;
   4509 
   4510     RenderBlock* containerBlock = containingBlock();
   4511     return containerBlock->offsetFromLogicalTopOfFirstPage() + logicalTop();
   4512 }
   4513 
   4514 void RenderBox::savePreviousBorderBoxSizeIfNeeded()
   4515 {
   4516     // If m_rareData is already created, always save.
   4517     if (!m_rareData) {
   4518         LayoutSize paintInvalidationSize = previousPaintInvalidationRect().size();
   4519 
   4520         // Don't save old border box size if the paint rect is empty because we'll
   4521         // full invalidate once the paint rect becomes non-empty.
   4522         if (paintInvalidationSize.isEmpty())
   4523             return;
   4524 
   4525         // Don't save old border box size if we can use size of the old paint rect
   4526         // as the old border box size in the next invalidation.
   4527         if (paintInvalidationSize == size())
   4528             return;
   4529 
   4530         // We need the old border box size only when the box has background or box decorations.
   4531         if (!style()->hasBackground() && !style()->hasBoxDecorations())
   4532             return;
   4533     }
   4534 
   4535     ensureRareData().m_previousBorderBoxSize = size();
   4536 }
   4537 
   4538 LayoutSize RenderBox::computePreviousBorderBoxSize(const LayoutSize& previousBoundsSize) const
   4539 {
   4540     // PreviousBorderBoxSize is only valid when there is background or box decorations.
   4541     ASSERT(style()->hasBackground() || style()->hasBoxDecorations());
   4542 
   4543     if (m_rareData && m_rareData->m_previousBorderBoxSize.width() != -1)
   4544         return m_rareData->m_previousBorderBoxSize;
   4545 
   4546     // We didn't save the old border box size because it was the same as the size of oldBounds.
   4547     return previousBoundsSize;
   4548 }
   4549 
   4550 } // namespace blink
   4551