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      1 /*
      2  * Copyright (C) 2009, 2010 Apple Inc. All rights reserved.
      3  * Copyright (C) Research In Motion Limited 2010. All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  * 1. Redistributions of source code must retain the above copyright
      9  *    notice, this list of conditions and the following disclaimer.
     10  * 2. Redistributions in binary form must reproduce the above copyright
     11  *    notice, this list of conditions and the following disclaimer in the
     12  *    documentation and/or other materials provided with the distribution.
     13  *
     14  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     15  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     17  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     18  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     19  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     20  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     21  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     22  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     23  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     24  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     25  */
     26 
     27 #include "config.h"
     28 #include "core/rendering/RenderObjectChildList.h"
     29 
     30 #include "core/accessibility/AXObjectCache.h"
     31 #include "core/rendering/RenderCounter.h"
     32 #include "core/rendering/RenderObject.h"
     33 #include "core/rendering/RenderView.h"
     34 #include "core/rendering/style/RenderStyle.h"
     35 
     36 namespace WebCore {
     37 
     38 void RenderObjectChildList::destroyLeftoverChildren()
     39 {
     40     while (firstChild()) {
     41         if (firstChild()->isListMarker() || (firstChild()->style()->styleType() == FIRST_LETTER && !firstChild()->isText()))
     42             firstChild()->remove();  // List markers are owned by their enclosing list and so don't get destroyed by this container. Similarly, first letters are destroyed by their remaining text fragment.
     43         else if (firstChild()->isRunIn() && firstChild()->node()) {
     44             firstChild()->node()->setRenderer(0);
     45             firstChild()->node()->setNeedsStyleRecalc();
     46             firstChild()->destroy();
     47         } else {
     48             // Destroy any anonymous children remaining in the render tree, as well as implicit (shadow) DOM elements like those used in the engine-based text fields.
     49             if (firstChild()->node())
     50                 firstChild()->node()->setRenderer(0);
     51             firstChild()->destroy();
     52         }
     53     }
     54 }
     55 
     56 RenderObject* RenderObjectChildList::removeChildNode(RenderObject* owner, RenderObject* oldChild, bool notifyRenderer)
     57 {
     58     ASSERT(oldChild->parent() == owner);
     59 
     60     if (oldChild->isFloatingOrOutOfFlowPositioned())
     61         toRenderBox(oldChild)->removeFloatingOrPositionedChildFromBlockLists();
     62 
     63     // So that we'll get the appropriate dirty bit set (either that a normal flow child got yanked or
     64     // that a positioned child got yanked). We also repaint, so that the area exposed when the child
     65     // disappears gets repainted properly.
     66     if (!owner->documentBeingDestroyed() && notifyRenderer && oldChild->everHadLayout()) {
     67         oldChild->setNeedsLayoutAndPrefWidthsRecalc();
     68         // We only repaint |oldChild| if we have a RenderLayer as its visual overflow may not be tracked by its parent.
     69         if (oldChild->isBody())
     70             owner->view()->repaint();
     71         else
     72             oldChild->repaint();
     73     }
     74 
     75     // If we have a line box wrapper, delete it.
     76     if (oldChild->isBox())
     77         toRenderBox(oldChild)->deleteLineBoxWrapper();
     78 
     79     // If oldChild is the start or end of the selection, then clear the selection to
     80     // avoid problems of invalid pointers.
     81     // FIXME: The FrameSelection should be responsible for this when it
     82     // is notified of DOM mutations.
     83     if (!owner->documentBeingDestroyed() && oldChild->isSelectionBorder())
     84         owner->view()->clearSelection();
     85 
     86     if (!owner->documentBeingDestroyed() && notifyRenderer)
     87         oldChild->willBeRemovedFromTree();
     88 
     89     // WARNING: There should be no code running between willBeRemovedFromTree and the actual removal below.
     90     // This is needed to avoid race conditions where willBeRemovedFromTree would dirty the tree's structure
     91     // and the code running here would force an untimely rebuilding, leaving |oldChild| dangling.
     92 
     93     if (oldChild->previousSibling())
     94         oldChild->previousSibling()->setNextSibling(oldChild->nextSibling());
     95     if (oldChild->nextSibling())
     96         oldChild->nextSibling()->setPreviousSibling(oldChild->previousSibling());
     97 
     98     if (firstChild() == oldChild)
     99         setFirstChild(oldChild->nextSibling());
    100     if (lastChild() == oldChild)
    101         setLastChild(oldChild->previousSibling());
    102 
    103     oldChild->setPreviousSibling(0);
    104     oldChild->setNextSibling(0);
    105     oldChild->setParent(0);
    106 
    107     // rendererRemovedFromTree walks the whole subtree. We can improve performance
    108     // by skipping this step when destroying the entire tree.
    109     if (!owner->documentBeingDestroyed())
    110         RenderCounter::rendererRemovedFromTree(oldChild);
    111 
    112     if (AXObjectCache* cache = owner->document()->existingAXObjectCache())
    113         cache->childrenChanged(owner);
    114 
    115     return oldChild;
    116 }
    117 
    118 void RenderObjectChildList::insertChildNode(RenderObject* owner, RenderObject* newChild, RenderObject* beforeChild, bool notifyRenderer)
    119 {
    120     ASSERT(!newChild->parent());
    121     ASSERT(!owner->isBlockFlow() || (!newChild->isTableSection() && !newChild->isTableRow() && !newChild->isTableCell()));
    122 
    123     while (beforeChild && beforeChild->parent() && beforeChild->parent() != owner)
    124         beforeChild = beforeChild->parent();
    125 
    126     // This should never happen, but if it does prevent render tree corruption
    127     // where child->parent() ends up being owner but child->nextSibling()->parent()
    128     // is not owner.
    129     if (beforeChild && beforeChild->parent() != owner) {
    130         ASSERT_NOT_REACHED();
    131         return;
    132     }
    133 
    134     newChild->setParent(owner);
    135 
    136     if (firstChild() == beforeChild)
    137         setFirstChild(newChild);
    138 
    139     if (beforeChild) {
    140         RenderObject* previousSibling = beforeChild->previousSibling();
    141         if (previousSibling)
    142             previousSibling->setNextSibling(newChild);
    143         newChild->setPreviousSibling(previousSibling);
    144         newChild->setNextSibling(beforeChild);
    145         beforeChild->setPreviousSibling(newChild);
    146     } else {
    147         if (lastChild())
    148             lastChild()->setNextSibling(newChild);
    149         newChild->setPreviousSibling(lastChild());
    150         setLastChild(newChild);
    151     }
    152 
    153     if (!owner->documentBeingDestroyed() && notifyRenderer)
    154         newChild->insertedIntoTree();
    155 
    156     if (!owner->documentBeingDestroyed()) {
    157         RenderCounter::rendererSubtreeAttached(newChild);
    158     }
    159 
    160     newChild->setNeedsLayoutAndPrefWidthsRecalc();
    161     if (!owner->normalChildNeedsLayout())
    162         owner->setChildNeedsLayout(); // We may supply the static position for an absolute positioned child.
    163 
    164     if (AXObjectCache* cache = owner->document()->axObjectCache())
    165         cache->childrenChanged(owner);
    166 }
    167 
    168 } // namespace WebCore
    169