Attachment 338898 Details for Bug 185036 – Patch

[patch] Patch

bug-185036-20180426113337.patch (text/plain), 11.92 KB, created by zalan on 2018-04-26 11:33:38 PDT

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Creator: zalan

Created: 2018-04-26 11:33:38 PDT

Size: 11.92 KB

patch

obsolete

>Subversion Revision: 231038
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index af46292fc656ab02433503336226c32a680599eb..e5d2df88adc783565b3e029d631653b34ebe45c6 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,28 @@
>+2018-04-26  Zalan Bujtas  <zalan@apple.com>
>+
>+        [LFC] Implement BlockMarginCollapse functions.
>+        https://bugs.webkit.org/show_bug.cgi?id=185036
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * layout/blockformatting/BlockMarginCollapse.cpp:
>+        (WebCore::Layout::marginValue):
>+        (WebCore::Layout::BlockMarginCollapse::BlockMarginCollapse):
>+        (WebCore::Layout::BlockMarginCollapse::marginTop const):
>+        (WebCore::Layout::BlockMarginCollapse::marginBottom const):
>+        (WebCore::Layout::BlockMarginCollapse::isMarginTopCollapsedWithSibling const):
>+        (WebCore::Layout::BlockMarginCollapse::isMarginBottomCollapsedWithSibling const):
>+        (WebCore::Layout::BlockMarginCollapse::isMarginTopCollapsedWithParent const):
>+        (WebCore::Layout::BlockMarginCollapse::isMarginBottomCollapsedWithParent const):
>+        (WebCore::Layout::BlockMarginCollapse::nonCollapsedMarginTop const):
>+        (WebCore::Layout::BlockMarginCollapse::nonCollapsedMarginBottom const):
>+        (WebCore::Layout::BlockMarginCollapse::collapsedMarginTopFromFirstChild const):
>+        (WebCore::Layout::BlockMarginCollapse::collapsedMarginBottomFromLastChild const):
>+        (WebCore::Layout::BlockMarginCollapse::hasAdjoiningMarginTopAndBottom const):
>+        * layout/blockformatting/BlockMarginCollapse.h:
>+        * layout/layouttree/LayoutBox.h:
>+        (WebCore::Layout::Box::style const):
>+
> 2018-04-25  Zalan Bujtas  <zalan@apple.com>
> 
>         [LFC] Add support for is<> and downcast<>
>diff --git a/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp b/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp
>index f9ab0fbc665166635e7e5915b41d8b5cd8285dcf..bd4046cdc773db4b75f17ce6fc9a52ed8caab39a 100644
>--- a/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp
>+++ b/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp
>@@ -25,3 +25,234 @@
> 
> #include "config.h"
> #include "BlockMarginCollapse.h"
>+
>+#if ENABLE(LAYOUT_FORMATTING_CONTEXT)
>+
>+#include "LayoutBox.h"
>+#include "LayoutContainer.h"
>+#include "LayoutUnit.h"
>+#include "RenderStyle.h"
>+#include <wtf/IsoMallocInlines.h>
>+
>+namespace WebCore {
>+namespace Layout {
>+
>+WTF_MAKE_ISO_ALLOCATED_IMPL(BlockMarginCollapse);
>+
>+static LayoutUnit marginValue(LayoutUnit currentMarginValue, LayoutUnit candidateMarginValue)
>+{
>+    if (!candidateMarginValue)
>+        return currentMarginValue;
>+    if (!currentMarginValue)
>+        return candidateMarginValue;
>+    // Both margins are positive.
>+    if (candidateMarginValue > 0 && currentMarginValue > 0)
>+        return std::max(candidateMarginValue, currentMarginValue);
>+    // Both margins are negative.
>+    if (candidateMarginValue < 0 && currentMarginValue < 0)
>+        return 0 - std::max(std::abs(candidateMarginValue.toFloat()), std::abs(currentMarginValue.toFloat()));
>+    // One of the margins is negative.
>+    return currentMarginValue + candidateMarginValue;
>+}
>+
>+BlockMarginCollapse::BlockMarginCollapse()
>+{
>+}
>+
>+LayoutUnit BlockMarginCollapse::marginTop(const Box& layoutBox) const
>+{
>+    if (layoutBox.isAnonymous())
>+        return 0;
>+    
>+    // TODO: take _hasAdjoiningMarginTopAndBottom() into account.
>+    if (isMarginTopCollapsedWithParent(layoutBox))
>+        return 0;
>+    
>+    // Floats and out of flow positioned boxes do not collapse their margins.
>+    if (!isMarginTopCollapsedWithSibling(layoutBox))
>+        return nonCollapsedMarginTop(layoutBox);
>+    
>+    // The bottom margin of an in-flow block-level element always collapses with the top margin of its next in-flow block-level sibling,
>+    // unless that sibling has clearance.
>+    auto* previousInFlowSibling = layoutBox.previousInFlowSibling();
>+    if (!previousInFlowSibling)
>+        return nonCollapsedMarginTop(layoutBox);
>+
>+    auto previousSiblingMarginBottom = nonCollapsedMarginBottom(*previousInFlowSibling);
>+    auto marginTop = nonCollapsedMarginTop(layoutBox);
>+    return marginValue(marginTop, previousSiblingMarginBottom);
>+}
>+
>+LayoutUnit BlockMarginCollapse::marginBottom(const Box& layoutBox) const
>+{
>+    if (layoutBox.isAnonymous())
>+        return 0;
>+
>+    // TODO: take _hasAdjoiningMarginTopAndBottom() into account.
>+    if (isMarginBottomCollapsedWithParent(layoutBox))
>+        return 0;
>+
>+    // Floats and out of flow positioned boxes do not collapse their margins.
>+    if (!isMarginBottomCollapsedWithSibling(layoutBox))
>+        return nonCollapsedMarginBottom(layoutBox);
>+    
>+    // The bottom margin of an in-flow block-level element always collapses with the top margin of its next in-flow block-level sibling,
>+    // unless that sibling has clearance.
>+    if (layoutBox.nextInFlowSibling())
>+        return 0;
>+    return nonCollapsedMarginBottom(layoutBox);
>+}
>+
>+bool BlockMarginCollapse::isMarginTopCollapsedWithSibling(const Box& layoutBox) const
>+{
>+    if (layoutBox.isFloatingPositioned())
>+        return false;
>+
>+    if (!layoutBox.isPositioned() || layoutBox.isInFlowPositioned())
>+        return true;
>+
>+    // Out of flow positioned.
>+    ASSERT(layoutBox.isOutOfFlowPositioned());
>+    return layoutBox.style().top().isAuto();
>+}
>+
>+bool BlockMarginCollapse::isMarginBottomCollapsedWithSibling(const Box& layoutBox) const
>+{
>+    if (layoutBox.isFloatingPositioned())
>+        return false;
>+
>+    if (!layoutBox.isPositioned() || layoutBox.isInFlowPositioned())
>+        return true;
>+
>+    // Out of flow positioned.
>+    ASSERT(layoutBox.isOutOfFlowPositioned());
>+    return layoutBox.style().bottom().isAuto();
>+}
>+
>+bool BlockMarginCollapse::isMarginTopCollapsedWithParent(const Box& layoutBox) const
>+{
>+    // The first inflow child could propagate its top margin to parent.
>+    // https://www.w3.org/TR/CSS21/box.html#collapsing-margins
>+    if (layoutBox.isAnonymous())
>+        return false;
>+
>+    if (layoutBox.isFloatingOrOutOfFlowPositioned())
>+        return false;
>+
>+    // We never margin collapse the initial containing block.
>+    ASSERT(layoutBox.parent());
>+    auto& parent = *layoutBox.parent();
>+    // Is this box the first inlflow child?
>+    if (parent.firstInFlowChild() != &layoutBox)
>+        return false;
>+
>+    if (parent.establishesBlockFormattingContext())
>+        return false;
>+
>+    // Margins of the root element's box do not collapse.
>+    if (parent.isInitialContainingBlock())
>+        return false;
>+
>+    if (!parent.style().borderTop().nonZero())
>+        return false;
>+
>+    if (!parent.style().paddingTop().isZero())
>+        return false;
>+
>+    return true;
>+}
>+
>+bool BlockMarginCollapse::isMarginBottomCollapsedWithParent(const Box& layoutBox) const
>+{
>+    // last inflow box to parent.
>+    // https://www.w3.org/TR/CSS21/box.html#collapsing-margins
>+    if (layoutBox.isAnonymous())
>+        return false;
>+
>+    if (layoutBox.isFloatingOrOutOfFlowPositioned())
>+        return false;
>+
>+    // We never margin collapse the initial containing block.
>+    ASSERT(layoutBox.parent());
>+    auto& parent = *layoutBox.parent();
>+    // Is this the last inlflow child?
>+    if (parent.lastInFlowChild() != &layoutBox)
>+        return false;
>+
>+    if (parent.establishesBlockFormattingContext())
>+        return false;
>+
>+    // Margins of the root element's box do not collapse.
>+    if (parent.isInitialContainingBlock())
>+        return false;
>+
>+    if (!parent.style().borderTop().nonZero())
>+        return false;
>+
>+    if (!parent.style().paddingTop().isZero())
>+        return false;
>+
>+    if (!parent.style().height().isAuto())
>+        return false;
>+
>+    return true;
>+}
>+
>+LayoutUnit BlockMarginCollapse::nonCollapsedMarginTop(const Box& layoutBox) const
>+{
>+    // Non collapsed margin top includes collapsed margin from inflow first child.
>+    return marginValue(layoutBox.style().marginTop().value(), collapsedMarginTopFromFirstChild(layoutBox));
>+}
>+
>+LayoutUnit BlockMarginCollapse::nonCollapsedMarginBottom(const Box& layoutBox) const
>+{
>+    // Non collapsed margin bottom includes collapsed margin from inflow last child.
>+    return marginValue(layoutBox.style().marginBottom().value(), collapsedMarginBottomFromLastChild(layoutBox));
>+}
>+
>+LayoutUnit BlockMarginCollapse::collapsedMarginTopFromFirstChild(const Box& layoutBox) const
>+{
>+    // Check if the first child collapses its margin top.
>+    if (!is<Container>(layoutBox) || !downcast<Container>(layoutBox).hasInFlowChild())
>+        return 0;
>+
>+    auto& firstInFlowChild = *downcast<Container>(layoutBox).firstInFlowChild();
>+    if (!isMarginTopCollapsedWithParent(firstInFlowChild))
>+        return 0;
>+
>+    // Collect collapsed margin top recursively.
>+    return marginValue(firstInFlowChild.style().marginTop().value(), collapsedMarginTopFromFirstChild(firstInFlowChild));
>+}
>+
>+LayoutUnit BlockMarginCollapse::collapsedMarginBottomFromLastChild(const Box& layoutBox) const
>+{
>+    // Check if the last child propagates its margin bottom.
>+    if (!is<Container>(layoutBox) || !downcast<Container>(layoutBox).hasInFlowChild())
>+        return 0;
>+
>+    auto& lastInFlowChild = *downcast<Container>(layoutBox).lastInFlowChild();
>+    if (!isMarginBottomCollapsedWithParent(lastInFlowChild))
>+        return 0;
>+
>+    // Collect collapsed margin bottom recursively.
>+    return marginValue(lastInFlowChild.style().marginBottom().value(), collapsedMarginBottomFromLastChild(lastInFlowChild));
>+}
>+
>+bool BlockMarginCollapse::hasAdjoiningMarginTopAndBottom(const Box&) const
>+{
>+    // Two margins are adjoining if and only if:
>+    // 1. both belong to in-flow block-level boxes that participate in the same block formatting context
>+    // 2. no line boxes, no clearance, no padding and no border separate them (Note that certain zero-height line boxes (see 9.4.2) are ignored for this purpose.)
>+    // 3. both belong to vertically-adjacent box edges, i.e. form one of the following pairs:
>+    //        top margin of a box and top margin of its first in-flow child
>+    //        bottom margin of box and top margin of its next in-flow following sibling
>+    //        bottom margin of a last in-flow child and bottom margin of its parent if the parent has 'auto' computed height
>+    //        top and bottom margins of a box that does not establish a new block formatting context and that has zero computed 'min-height',
>+    //        zero or 'auto' computed 'height', and no in-flow children
>+    // A collapsed margin is considered adjoining to another margin if any of its component margins is adjoining to that margin.
>+    return false;
>+}
>+
>+}
>+}
>+#endif
>diff --git a/Source/WebCore/layout/blockformatting/BlockMarginCollapse.h b/Source/WebCore/layout/blockformatting/BlockMarginCollapse.h
>index b20fab8198e0cc071c392e5277892672a99a547d..8dd229c91c9e0857f683e1a21a0407e484ba1e28 100644
>--- a/Source/WebCore/layout/blockformatting/BlockMarginCollapse.h
>+++ b/Source/WebCore/layout/blockformatting/BlockMarginCollapse.h
>@@ -55,7 +55,6 @@ private:
>     LayoutUnit nonCollapsedMarginBottom(const Box&) const;
>     LayoutUnit collapsedMarginTopFromFirstChild(const Box&) const;
>     LayoutUnit collapsedMarginBottomFromLastChild(const Box&) const;
>-    LayoutUnit marginValue(LayoutUnit currentMarginValue, LayoutUnit candidateMarginValue) const;
> 
>     bool hasAdjoiningMarginTopAndBottom(const Box&) const;
> };
>diff --git a/Source/WebCore/layout/layouttree/LayoutBox.h b/Source/WebCore/layout/layouttree/LayoutBox.h
>index d3124a5747e95db00390ed63adfd06151d9e3cb7..d8fdb76f216a0abb2d42e4b4c89af6d5ba9b1902 100644
>--- a/Source/WebCore/layout/layouttree/LayoutBox.h
>+++ b/Source/WebCore/layout/layouttree/LayoutBox.h
>@@ -87,6 +87,7 @@ public:
>     bool isInlineBox() const { return m_baseTypeFlags & InlineBoxFlag; }
>     bool isInlineContainer() const { return m_baseTypeFlags & InlineContainerFlag; }
> 
>+    const RenderStyle& style() const { return m_style; }
>     auto& weakPtrFactory() const { return m_weakFactory; }
> 
> protected:

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Attachments on bug 185036: 338898