Add grid/flex layout support for <fieldset>

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

Index: third_party/WebKit/Source/core/layout/LayoutFieldset.cpp
diff --git a/third_party/WebKit/Source/core/layout/LayoutFieldset.cpp b/third_party/WebKit/Source/core/layout/LayoutFieldset.cpp
index 93b43a8cf4a1d18ce98c3a02bc47b474edc5acb4..be509a6a4acaa6ca698f72c54cc557230490500c 100644
--- a/third_party/WebKit/Source/core/layout/LayoutFieldset.cpp
+++ b/third_party/WebKit/Source/core/layout/LayoutFieldset.cpp
@@ -25,6 +25,7 @@
 
 #include "core/CSSPropertyNames.h"
 #include "core/HTMLNames.h"
+#include "core/dom/AXObjectCache.h"
 #include "core/html/HTMLLegendElement.h"
 #include "core/paint/FieldsetPainter.h"
 
@@ -34,27 +35,83 @@ namespace blink {
 
 using namespace HTMLNames;
 
+namespace {
+
+void setInnerBlockPadding(bool isHorizontalWritingMode, const LayoutObject* innerBlock, const LayoutUnit& padding)
+{
+    if (isHorizontalWritingMode)
+        innerBlock->mutableStyleRef().setPaddingTop(Length(padding, Fixed));
+    else
+        innerBlock->mutableStyleRef().setPaddingLeft(Length(padding, Fixed));
+}
+
+void resetInnerBlockPadding(bool isHorizontalWritingMode, const LayoutObject* innerBlock)
+{
+    if (isHorizontalWritingMode)
+        innerBlock->mutableStyleRef().setPaddingTop(Length(0, Fixed));
+    else
+        innerBlock->mutableStyleRef().setPaddingLeft(Length(0, Fixed));
+}
+
+} // namespace
+
 LayoutFieldset::LayoutFieldset(Element* element)
-    : LayoutBlockFlow(element)
+    : LayoutFlexibleBox(element)
+    , m_innerBlock(nullptr)
+{
+}
+
+int LayoutFieldset::baselinePosition(FontBaseline baseline, bool firstLine, LineDirectionMode direction, LinePositionMode position) const
 {
+    return LayoutBlock::baselinePosition(baseline, firstLine, direction, position);
 }
 
-void LayoutFieldset::computePreferredLogicalWidths()
+void LayoutFieldset::computeIntrinsicLogicalWidths(LayoutUnit& minLogicalWidth, LayoutUnit& maxLogicalWidth) const
 {
-    LayoutBlockFlow::computePreferredLogicalWidths();
-    if (LayoutBox* legend = findInFlowLegend()) {
-        int legendMinWidth = legend->minPreferredLogicalWidth().toInt();
+    for (LayoutBox* child = firstChildBox(); child; child = child->nextSiblingBox()) {
+        if (child->isOutOfFlowPositioned())
+            continue;
+
+        LayoutUnit margin = marginIntrinsicLogicalWidthForChild(*child);
+
+        LayoutUnit minPreferredLogicalWidth;
+        LayoutUnit maxPreferredLogicalWidth;
+        computeChildPreferredLogicalWidths(*child, minPreferredLogicalWidth, maxPreferredLogicalWidth);
+        DCHECK_GE(minPreferredLogicalWidth, LayoutUnit());
+        DCHECK_GE(maxPreferredLogicalWidth, LayoutUnit());
+        minPreferredLogicalWidth += margin;
+        maxPreferredLogicalWidth += margin;
+        minLogicalWidth = std::max(minPreferredLogicalWidth, minLogicalWidth);
+        maxLogicalWidth = std::max(maxPreferredLogicalWidth, maxLogicalWidth);
+    }
 
-        Length legendMarginLeft = legend->style()->marginLeft();
-        Length legendMarginRight = legend->style()->marginRight();
+    maxLogicalWidth = std::max(minLogicalWidth, maxLogicalWidth);
 
-        if (legendMarginLeft.isFixed())
-            legendMinWidth += legendMarginLeft.value();
+    // Due to negative margins, it is possible that we calculated a negative intrinsic width. Make sure that we
+    // never return a negative width.
+    minLogicalWidth = std::max(LayoutUnit(), minLogicalWidth);
+    maxLogicalWidth = std::max(LayoutUnit(), maxLogicalWidth);
 
-        if (legendMarginRight.isFixed())
-            legendMinWidth += legendMarginRight.value();
+    LayoutUnit scrollbarWidth(scrollbarLogicalWidth());
+    maxLogicalWidth += scrollbarWidth;
+    minLogicalWidth += scrollbarWidth;
+}
+
+void LayoutFieldset::setLogicalLeftForChild(LayoutBox& child, LayoutUnit logicalLeft)
+{
+    if (isHorizontalWritingMode()) {
+        child.setX(logicalLeft);
+    } else {
+        child.setY(logicalLeft);
+    }
+}
 
-        m_minPreferredLogicalWidth = max(m_minPreferredLogicalWidth, legendMinWidth + borderAndPaddingWidth());
+void LayoutFieldset::setLogicalTopForChild(LayoutBox& child, LayoutUnit logicalTop)
+{
+    if (isHorizontalWritingMode()) {
+        child.setY(logicalTop);
+    } else {
+        child.setX(logicalTop);
     }
 }
 
@@ -106,6 +163,7 @@ LayoutObject* LayoutFieldset::layoutSpecialExcludedChild(bool relayoutChildren,
 
         LayoutUnit legendLogicalTop;
         LayoutUnit collapsedLegendExtent;
+        LayoutUnit innerBlockPadding;
         // FIXME: We need to account for the legend's margin before too.
         if (fieldsetBorderBefore > legendLogicalHeight) {
             // The <legend> is smaller than the associated fieldset before border
@@ -114,16 +172,22 @@ LayoutObject* LayoutFieldset::layoutSpecialExcludedChild(bool relayoutChildren,
             // Firefox completely ignores the margins in this case which seems wrong.
             legendLogicalTop = (fieldsetBorderBefore - legendLogicalHeight) / 2;
             collapsedLegendExtent = max<LayoutUnit>(fieldsetBorderBefore, legendLogicalTop + legendLogicalHeight + marginAfterForChild(*legend));
+            innerBlockPadding = marginAfterForChild(*legend) ? marginAfterForChild(*legend) - legendLogicalTop : LayoutUnit();
         } else {
             collapsedLegendExtent = legendLogicalHeight + marginAfterForChild(*legend);
+            innerBlockPadding = legendLogicalHeight - borderAfter() + marginAfterForChild(*legend);
         }
 
+        if (m_innerBlock)
+            setInnerBlockPadding(isHorizontalWritingMode(), m_innerBlock, innerBlockPadding);
         setLogicalTopForChild(*legend, legendLogicalTop);
         setLogicalHeight(paddingBefore() + collapsedLegendExtent);
 
         if (legend->frameRect() != oldLegendFrameRect) {
             // We need to invalidate the fieldset border if the legend's frame changed.
             setShouldDoFullPaintInvalidation();
+            if (m_innerBlock)
+                m_innerBlock->setNeedsLayout(LayoutInvalidationReason::FieldsetChanged, MarkOnlyThis);
         }
     }
     return legend;
@@ -153,4 +217,68 @@ void LayoutFieldset::paintMask(const PaintInfo& paintInfo, const LayoutPoint& pa
     FieldsetPainter(*this).paintMask(paintInfo, paintOffset);
 }
 
+void LayoutFieldset::updateAnonymousChildStyle(const LayoutObject& child, ComputedStyle& childStyle) const
+{
+    childStyle.setFlexShrink(1.0f);
+    childStyle.setFlexGrow(1.0f);
+    // min-width: 0; is needed for correct shrinking.
+    childStyle.setMinWidth(Length(0, Fixed));
+    childStyle.setFlexDirection(style()->flexDirection());
+    childStyle.setJustifyContent(style()->justifyContent());
+    childStyle.setFlexWrap(style()->flexWrap());
+    childStyle.setAlignItems(style()->alignItems());
+    childStyle.setAlignContent(style()->alignContent());
+    // Let anonymous block to be the 1st for correct layout positioning.
+    childStyle.setOrder(1);
+}
+
+void LayoutFieldset::addChild(LayoutObject* newChild, LayoutObject* beforeChild)
+{
+    if (!m_innerBlock)
+        createInnerBlock();
+
+    if (isHTMLLegendElement(newChild->node())) {
+        // Let legend block to be the 2nd for correct layout positioning.
+        newChild->mutableStyle()->setOrder(2);
+        LayoutFlexibleBox::addChild(newChild, m_innerBlock);
+    } else {
+        if (beforeChild && isHTMLLegendElement(beforeChild->node())) {
+            m_innerBlock->addChild(newChild);
+        } else {
+            m_innerBlock->addChild(newChild, beforeChild);
+        }
+        if (AXObjectCache* cache = document().existingAXObjectCache())
+            cache->childrenChanged(this);
+    }
+}
+
+void LayoutFieldset::createInnerBlock()
+{
+    if (m_innerBlock) {
+        DCHECK(firstChild() == m_innerBlock);
+        return;
+    }
+    m_innerBlock = createAnonymousBlock(style()->display());
+    LayoutFlexibleBox::addChild(m_innerBlock);
+}
+
+void LayoutFieldset::removeChild(LayoutObject* oldChild)
+{
+    if (isHTMLLegendElement(oldChild->node())) {
+        LayoutFlexibleBox::removeChild(oldChild);
+        if (m_innerBlock) {
+            resetInnerBlockPadding(isHorizontalWritingMode(), m_innerBlock);
+            m_innerBlock->setNeedsLayout(LayoutInvalidationReason::FieldsetChanged, MarkOnlyThis);
+        }
+        setShouldDoFullPaintInvalidation();
+    } else if (oldChild == m_innerBlock) {
+        LayoutFlexibleBox::removeChild(oldChild);
+        m_innerBlock = nullptr;
+    } else if (oldChild->parent() == this) {
+        LayoutFlexibleBox::removeChild(oldChild);
+    } else if (m_innerBlock) {
+        m_innerBlock->removeChild(oldChild);
+    }
+}
+
 } // namespace blink