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      1 /*
      2  * Copyright (C) 2012 Victor Carbune (victor (at) rosedu.org)
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions
      6  * are met:
      7  * 1. Redistributions of source code must retain the above copyright
      8  *    notice, this list of conditions and the following disclaimer.
      9  * 2. Redistributions in binary form must reproduce the above copyright
     10  *    notice, this list of conditions and the following disclaimer in the
     11  *    documentation and/or other materials provided with the distribution.
     12  *
     13  * THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
     14  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     15  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     16  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE COMPUTER, INC. OR
     17  * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
     18  * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
     19  * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
     20  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
     21  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     22  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     23  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     24  */
     25 
     26 #include "config.h"
     27 #include "core/rendering/RenderVTTCue.h"
     28 
     29 #include "core/html/track/vtt/VTTCue.h"
     30 #include "core/rendering/LayoutRectRecorder.h"
     31 #include "core/rendering/RenderView.h"
     32 
     33 namespace WebCore {
     34 
     35 RenderVTTCue::RenderVTTCue(VTTCueBox* element)
     36     : RenderBlockFlow(element)
     37     , m_cue(element->getCue())
     38 {
     39 }
     40 
     41 void RenderVTTCue::layout()
     42 {
     43     LayoutRectRecorder recorder(*this);
     44     RenderBlockFlow::layout();
     45 
     46     // If WebVTT Regions are used, the regular WebVTT layout algorithm is no
     47     // longer necessary, since cues having the region parameter set do not have
     48     // any positioning parameters. Also, in this case, the regions themselves
     49     // have positioning information.
     50     if (!m_cue->regionId().isEmpty())
     51         return;
     52 
     53     LayoutStateMaintainer statePusher(view(), this, locationOffset(), hasTransform() || hasReflection() || style()->isFlippedBlocksWritingMode());
     54 
     55     if (m_cue->snapToLines())
     56         repositionCueSnapToLinesSet();
     57     else
     58         repositionCueSnapToLinesNotSet();
     59 
     60     statePusher.pop();
     61 }
     62 
     63 bool RenderVTTCue::findFirstLineBox(InlineFlowBox*& firstLineBox)
     64 {
     65     if (firstChild()->isRenderInline())
     66         firstLineBox = toRenderInline(firstChild())->firstLineBox();
     67     else
     68         return false;
     69 
     70     return true;
     71 }
     72 
     73 bool RenderVTTCue::initializeLayoutParameters(InlineFlowBox* firstLineBox, LayoutUnit& step, LayoutUnit& position)
     74 {
     75     ASSERT(firstChild());
     76 
     77     RenderBlock* parentBlock = containingBlock();
     78 
     79     // 1. Horizontal: Let step be the height of the first line box in boxes.
     80     //    Vertical: Let step be the width of the first line box in boxes.
     81     step = m_cue->getWritingDirection() == VTTCue::Horizontal ? firstLineBox->height() : firstLineBox->width();
     82 
     83     // 2. If step is zero, then jump to the step labeled done positioning below.
     84     if (!step)
     85         return false;
     86 
     87     // 3. Let line position be the text track cue computed line position.
     88     int linePosition = m_cue->calculateComputedLinePosition();
     89 
     90     // 4. Vertical Growing Left: Add one to line position then negate it.
     91     if (m_cue->getWritingDirection() == VTTCue::VerticalGrowingLeft)
     92         linePosition = -(linePosition + 1);
     93 
     94     // 5. Let position be the result of multiplying step and line position.
     95     position = step * linePosition;
     96 
     97     // 6. Vertical Growing Left: Decrease position by the width of the
     98     // bounding box of the boxes in boxes, then increase position by step.
     99     if (m_cue->getWritingDirection() == VTTCue::VerticalGrowingLeft) {
    100         position -= width();
    101         position += step;
    102     }
    103 
    104     // 7. If line position is less than zero...
    105     if (linePosition < 0) {
    106         // Horizontal / Vertical: ... then increase position by the
    107         // height / width of the video's rendering area ...
    108         position += m_cue->getWritingDirection() == VTTCue::Horizontal ? parentBlock->height() : parentBlock->width();
    109 
    110         // ... and negate step.
    111         step = -step;
    112     }
    113 
    114     return true;
    115 }
    116 
    117 void RenderVTTCue::placeBoxInDefaultPosition(LayoutUnit position, bool& switched)
    118 {
    119     // 8. Move all boxes in boxes ...
    120     if (m_cue->getWritingDirection() == VTTCue::Horizontal) {
    121         // Horizontal: ... down by the distance given by position
    122         setY(y() + position);
    123     } else {
    124         // Vertical: ... right by the distance given by position
    125         setX(x() + position);
    126     }
    127 
    128     // 9. Default: Remember the position of all the boxes in boxes as their
    129     // default position.
    130     m_fallbackPosition = FloatPoint(x(), y());
    131 
    132     // 10. Let switched be false.
    133     switched = false;
    134 }
    135 
    136 bool RenderVTTCue::isOutside() const
    137 {
    138     return !containingBlock()->absoluteBoundingBoxRect().contains(absoluteContentBox());
    139 }
    140 
    141 bool RenderVTTCue::isOverlapping() const
    142 {
    143     for (RenderObject* box = previousSibling(); box; box = box->previousSibling()) {
    144         IntRect boxRect = box->absoluteBoundingBoxRect();
    145 
    146         if (absoluteBoundingBoxRect().intersects(boxRect))
    147             return true;
    148     }
    149 
    150     return false;
    151 }
    152 
    153 bool RenderVTTCue::shouldSwitchDirection(InlineFlowBox* firstLineBox, LayoutUnit step) const
    154 {
    155     LayoutUnit top = y();
    156     LayoutUnit left = x();
    157     LayoutUnit bottom = top + firstLineBox->height();
    158     LayoutUnit right = left + firstLineBox->width();
    159 
    160     // 12. Horizontal: If step is negative and the top of the first line
    161     // box in boxes is now above the top of the video's rendering area,
    162     // or if step is positive and the bottom of the first line box in
    163     // boxes is now below the bottom of the video's rendering area, jump
    164     // to the step labeled switch direction.
    165     LayoutUnit parentHeight = containingBlock()->height();
    166     if (m_cue->getWritingDirection() == VTTCue::Horizontal && ((step < 0 && top < 0) || (step > 0 && bottom > parentHeight)))
    167         return true;
    168 
    169     // 12. Vertical: If step is negative and the left edge of the first line
    170     // box in boxes is now to the left of the left edge of the video's
    171     // rendering area, or if step is positive and the right edge of the
    172     // first line box in boxes is now to the right of the right edge of
    173     // the video's rendering area, jump to the step labeled switch direction.
    174     LayoutUnit parentWidth = containingBlock()->width();
    175     if (m_cue->getWritingDirection() != VTTCue::Horizontal && ((step < 0 && left < 0) || (step > 0 && right > parentWidth)))
    176         return true;
    177 
    178     return false;
    179 }
    180 
    181 void RenderVTTCue::moveBoxesByStep(LayoutUnit step)
    182 {
    183     // 13. Horizontal: Move all the boxes in boxes down by the distance
    184     // given by step. (If step is negative, then this will actually
    185     // result in an upwards movement of the boxes in absolute terms.)
    186     if (m_cue->getWritingDirection() == VTTCue::Horizontal)
    187         setY(y() + step);
    188 
    189     // 13. Vertical: Move all the boxes in boxes right by the distance
    190     // given by step. (If step is negative, then this will actually
    191     // result in a leftwards movement of the boxes in absolute terms.)
    192     else
    193         setX(x() + step);
    194 }
    195 
    196 bool RenderVTTCue::switchDirection(bool& switched, LayoutUnit& step)
    197 {
    198     // 15. Switch direction: Move all the boxes in boxes back to their
    199     // default position as determined in the step above labeled default.
    200     setX(m_fallbackPosition.x());
    201     setY(m_fallbackPosition.y());
    202 
    203     // 16. If switched is true, jump to the step labeled done
    204     // positioning below.
    205     if (switched)
    206         return false;
    207 
    208     // 17. Negate step.
    209     step = -step;
    210 
    211     // 18. Set switched to true.
    212     switched = true;
    213     return true;
    214 }
    215 
    216 void RenderVTTCue::repositionCueSnapToLinesSet()
    217 {
    218     InlineFlowBox* firstLineBox;
    219     LayoutUnit step;
    220     LayoutUnit position;
    221 
    222     if (!findFirstLineBox(firstLineBox))
    223         return;
    224 
    225     if (!initializeLayoutParameters(firstLineBox, step, position))
    226         return;
    227 
    228     bool switched;
    229     placeBoxInDefaultPosition(position, switched);
    230 
    231     // 11. Step loop: If none of the boxes in boxes would overlap any of the boxes
    232     // in output and all the boxes in output are within the video's rendering area
    233     // then jump to the step labeled done positioning.
    234     while (isOutside() || isOverlapping()) {
    235         if (!shouldSwitchDirection(firstLineBox, step)) {
    236             // 13. Move all the boxes in boxes ...
    237             // 14. Jump back to the step labeled step loop.
    238             moveBoxesByStep(step);
    239         } else if (!switchDirection(switched, step)) {
    240             break;
    241         }
    242 
    243         // 19. Jump back to the step labeled step loop.
    244     }
    245 
    246     // Acommodate extra top and bottom padding, border or margin.
    247     // Note: this is supported only for internal UA styling, not through the cue selector.
    248     if (hasInlineDirectionBordersPaddingOrMargin()) {
    249         IntRect containerRect = containingBlock()->absoluteBoundingBoxRect();
    250         IntRect cueRect = absoluteBoundingBoxRect();
    251 
    252         int topOverflow = cueRect.y() - containerRect.y();
    253         int bottomOverflow = containerRect.y() + containerRect.height() - cueRect.y() - cueRect.height();
    254 
    255         int adjustment = 0;
    256         if (topOverflow < 0)
    257             adjustment = -topOverflow;
    258         else if (bottomOverflow < 0)
    259             adjustment = bottomOverflow;
    260 
    261         if (adjustment)
    262             setY(y() + adjustment);
    263     }
    264 }
    265 
    266 void RenderVTTCue::repositionCueSnapToLinesNotSet()
    267 {
    268     // FIXME: Implement overlapping detection when snap-to-lines is not set. http://wkb.ug/84296
    269 }
    270 
    271 } // namespace WebCore
    272 
    273