third_party/WebKit/Source/core/layout/LayoutMultiColumnSpannerPlaceholder.cpp

   1 // Copyright 2014 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "config.h"
   6 #include "core/layout/LayoutMultiColumnSpannerPlaceholder.h"
   7
   8 namespace blink {
   9
  10 static void copyMarginProperties(ComputedStyle& placeholderStyle, const ComputedStyle& spannerStyle)
  11 {
  12     // We really only need the block direction margins, but there are no setters for that in
  13     // ComputedStyle. Just copy all margin sides. The inline ones don't matter anyway.
  14     placeholderStyle.setMarginLeft(spannerStyle.marginLeft());
  15     placeholderStyle.setMarginRight(spannerStyle.marginRight());
  16     placeholderStyle.setMarginTop(spannerStyle.marginTop());
  17     placeholderStyle.setMarginBottom(spannerStyle.marginBottom());
  18 }
  19
  20 LayoutMultiColumnSpannerPlaceholder* LayoutMultiColumnSpannerPlaceholder::createAnonymous(const ComputedStyle& parentStyle, LayoutBox& layoutObjectInFlowThread)
  21 {
  22     LayoutMultiColumnSpannerPlaceholder* newSpanner = new LayoutMultiColumnSpannerPlaceholder(&layoutObjectInFlowThread);
  23     Document& document = layoutObjectInFlowThread.document();
  24     newSpanner->setDocumentForAnonymous(&document);
  25     RefPtr<ComputedStyle> newStyle = ComputedStyle::createAnonymousStyleWithDisplay(parentStyle, BLOCK);
  26     copyMarginProperties(*newStyle, layoutObjectInFlowThread.styleRef());
  27     newSpanner->setStyle(newStyle);
  28     return newSpanner;
  29 }
  30
  31 LayoutMultiColumnSpannerPlaceholder::LayoutMultiColumnSpannerPlaceholder(LayoutBox* layoutObjectInFlowThread)
  32     : LayoutBox(nullptr)
  33     , m_layoutObjectInFlowThread(layoutObjectInFlowThread)
  34 {
  35 }
  36
  37 void LayoutMultiColumnSpannerPlaceholder::layoutObjectInFlowThreadStyleDidChange(const ComputedStyle* oldStyle)
  38 {
  39     LayoutBox* objectInFlowThread = m_layoutObjectInFlowThread;
  40     if (flowThread()->removeSpannerPlaceholderIfNoLongerValid(objectInFlowThread)) {
  41         // No longer a valid spanner, due to style changes. |this| is now dead.
  42         if (objectInFlowThread->style()->hasOutOfFlowPosition() && !oldStyle->hasOutOfFlowPosition()) {
  43             // We went from being a spanner to being out-of-flow positioned. When an object becomes
  44             // out-of-flow positioned, we need to lay out its parent, since that's where the
  45             // now-out-of-flow object gets added to the right containing block for out-of-flow
  46             // positioned objects. Since neither a spanner nor an out-of-flow object is guaranteed
  47             // to have this parent in its containing block chain, we need to mark it here, or we
  48             // risk that the object isn't laid out.
  49             objectInFlowThread->parent()->setNeedsLayout(LayoutInvalidationReason::ColumnsChanged);
  50         }
  51         return;
  52     }
  53     updateMarginProperties();
  54 }
  55
  56 void LayoutMultiColumnSpannerPlaceholder::updateMarginProperties()
  57 {
  58     RefPtr<ComputedStyle> newStyle = ComputedStyle::clone(styleRef());
  59     copyMarginProperties(*newStyle, m_layoutObjectInFlowThread->styleRef());
  60     setStyle(newStyle);
  61 }
  62
  63 void LayoutMultiColumnSpannerPlaceholder::willBeRemovedFromTree()
  64 {
  65     if (m_layoutObjectInFlowThread) {
  66         LayoutBox* exSpanner = m_layoutObjectInFlowThread;
  67         m_layoutObjectInFlowThread->clearSpannerPlaceholder();
  68         // Even if the placeholder is going away, the object in the flow thread might live on. Since
  69         // it's not a spanner anymore, it needs to be relaid out.
  70         exSpanner->setNeedsLayoutAndPrefWidthsRecalc(LayoutInvalidationReason::ColumnsChanged);
  71     }
  72     LayoutBox::willBeRemovedFromTree();
  73 }
  74
  75 bool LayoutMultiColumnSpannerPlaceholder::needsPreferredWidthsRecalculation() const
  76 {
  77     return m_layoutObjectInFlowThread->needsPreferredWidthsRecalculation();
  78 }
  79
  80 LayoutUnit LayoutMultiColumnSpannerPlaceholder::minPreferredLogicalWidth() const
  81 {
  82     return m_layoutObjectInFlowThread->minPreferredLogicalWidth();
  83 }
  84
  85 LayoutUnit LayoutMultiColumnSpannerPlaceholder::maxPreferredLogicalWidth() const
  86 {
  87     return m_layoutObjectInFlowThread->maxPreferredLogicalWidth();
  88 }
  89
  90 void LayoutMultiColumnSpannerPlaceholder::layout()
  91 {
  92     ASSERT(needsLayout());
  93
  94     // Lay out the actual column-span:all element.
  95     m_layoutObjectInFlowThread->layoutIfNeeded();
  96
  97     // The spanner has now been laid out, so its height is known. Time to update the placeholder's
  98     // height as well, so that we take up the correct amount of space in the multicol container.
  99     updateLogicalHeight();
 100
 101     // Take the overflow from the spanner, so that it gets
 102     // propagated to the multicol container and beyond.
 103     m_overflow.clear();
 104     addVisualOverflow(m_layoutObjectInFlowThread->visualOverflowRect());
 105     addLayoutOverflow(m_layoutObjectInFlowThread->layoutOverflowRect());
 106
 107     clearNeedsLayout();
 108 }
 109
 110 void LayoutMultiColumnSpannerPlaceholder::computeLogicalHeight(LayoutUnit, LayoutUnit logicalTop, LogicalExtentComputedValues& computedValues) const
 111 {
 112     computedValues.m_extent = m_layoutObjectInFlowThread->logicalHeight();
 113     computedValues.m_position = logicalTop;
 114     computedValues.m_margins.m_before = marginBefore();
 115     computedValues.m_margins.m_after = marginAfter();
 116 }
 117
 118 void LayoutMultiColumnSpannerPlaceholder::invalidateTreeIfNeeded(PaintInvalidationState& paintInvalidationState)
 119 {
 120     PaintInvalidationState newPaintInvalidationState(paintInvalidationState, *this, paintInvalidationState.paintInvalidationContainer());
 121     m_layoutObjectInFlowThread->invalidateTreeIfNeeded(newPaintInvalidationState);
 122     LayoutBox::invalidateTreeIfNeeded(paintInvalidationState);
 123 }
 124
 125 void LayoutMultiColumnSpannerPlaceholder::paint(const PaintInfo& paintInfo, const LayoutPoint& paintOffset)
 126 {
 127     if (!m_layoutObjectInFlowThread->hasSelfPaintingLayer())
 128         m_layoutObjectInFlowThread->paint(paintInfo, paintOffset);
 129 }
 130
 131 bool LayoutMultiColumnSpannerPlaceholder::nodeAtPoint(HitTestResult& result, const HitTestLocation& locationInContainer, const LayoutPoint& accumulatedOffset, HitTestAction action)
 132 {
 133     return !m_layoutObjectInFlowThread->hasSelfPaintingLayer() && m_layoutObjectInFlowThread->nodeAtPoint(result, locationInContainer, accumulatedOffset, action);
 134 }
 135
 136 }