Title: [239330] trunk/Source/WebCore
- Revision
- 239330
- Author
- [email protected]
- Date
- 2018-12-18 07:19:21 -0800 (Tue, 18 Dec 2018)
Log Message
[LFC][BFC][MarginCollapsing] Expand marginAfterCollapsesWithParentMarginAfter and marginBeforeCollapsesWithParentMarginBefore collapsing logic
https://bugs.webkit.org/show_bug.cgi?id=192787
Reviewed by Antti Koivisto.
* layout/blockformatting/BlockFormattingContext.h:
* layout/blockformatting/BlockMarginCollapse.cpp:
(WebCore::Layout::hasClearance):
(WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginBeforeCollapsesWithParentMarginBefore):
(WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithSiblingMarginBeforeWithClearance):
(WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithParentMarginBefore):
(WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithParentMarginAfter):
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (239329 => 239330)
--- trunk/Source/WebCore/ChangeLog 2018-12-18 13:00:36 UTC (rev 239329)
+++ trunk/Source/WebCore/ChangeLog 2018-12-18 15:19:21 UTC (rev 239330)
@@ -1,3 +1,18 @@
+2018-12-18 Zalan Bujtas <[email protected]>
+
+ [LFC][BFC][MarginCollapsing] Expand marginAfterCollapsesWithParentMarginAfter and marginBeforeCollapsesWithParentMarginBefore collapsing logic
+ https://bugs.webkit.org/show_bug.cgi?id=192787
+
+ Reviewed by Antti Koivisto.
+
+ * layout/blockformatting/BlockFormattingContext.h:
+ * layout/blockformatting/BlockMarginCollapse.cpp:
+ (WebCore::Layout::hasClearance):
+ (WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginBeforeCollapsesWithParentMarginBefore):
+ (WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithSiblingMarginBeforeWithClearance):
+ (WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithParentMarginBefore):
+ (WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithParentMarginAfter):
+
2018-12-17 Fujii Hironori <[email protected]>
[Win][Clang] Fix compilation warnings WebCore/platform/graphics directory
Modified: trunk/Source/WebCore/layout/blockformatting/BlockFormattingContext.h (239329 => 239330)
--- trunk/Source/WebCore/layout/blockformatting/BlockFormattingContext.h 2018-12-18 13:00:36 UTC (rev 239329)
+++ trunk/Source/WebCore/layout/blockformatting/BlockFormattingContext.h 2018-12-18 15:19:21 UTC (rev 239330)
@@ -105,6 +105,8 @@
static bool marginBeforeCollapsesWithParentMarginBefore(const LayoutState&, const Box&);
static bool marginBeforeCollapsesWithPreviousSibling(const Box&);
static bool marginAfterCollapsesWithNextSibling(const Box&);
+ static bool marginAfterCollapsesWithSiblingMarginBeforeWithClearance(const Box&);
+ static bool marginAfterCollapsesWithParentMarginBefore(const Box&);
static bool marginsCollapseThrough(const Box&);
};
Modified: trunk/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp (239329 => 239330)
--- trunk/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp 2018-12-18 13:00:36 UTC (rev 239329)
+++ trunk/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp 2018-12-18 15:19:21 UTC (rev 239330)
@@ -69,6 +69,14 @@
return hasPadding(layoutBox.style().paddingAfter());
}
+static bool hasClearance(const Box& layoutBox)
+{
+ if (!layoutBox.hasFloatClear())
+ return false;
+ // FIXME
+ return false;
+}
+
static bool establishesBlockFormattingContext(const Box& layoutBox)
{
// WebKit treats the document element renderer as a block formatting context root. It probably only impacts margin collapsing, so let's not do
@@ -179,9 +187,18 @@
ASSERT(layoutBox.isBlockLevelBox());
- if (layoutBox.isFloatingOrOutOfFlowPositioned())
+ // Margins between a floated box and any other box do not collapse.
+ if (layoutBox.isFloatingPositioned())
return false;
+ // Margins of absolutely positioned boxes do not collapse.
+ if (layoutBox.isOutOfFlowPositioned())
+ return false;
+
+ // Margins of inline-block boxes do not collapse.
+ if (layoutBox.isInlineBlockBox())
+ return false;
+
// Only the first inlflow child collapses with parent.
if (layoutBox.previousInFlowSibling())
return false;
@@ -197,6 +214,10 @@
if (hasPaddingBefore(parent))
return false;
+ // ...and the child has no clearance.
+ if (hasClearance(layoutBox))
+ return false;
+
if (BlockFormattingContext::Quirks::shouldIgnoreMarginBefore(layoutState, layoutBox))
return false;
@@ -203,39 +224,65 @@
return true;
}
+bool BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithSiblingMarginBeforeWithClearance(const Box&)
+{
+ return false;
+}
+
+bool BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithParentMarginBefore(const Box&)
+{
+ return false;
+}
+
bool BlockFormattingContext::Geometry::MarginCollapse::marginAfterCollapsesWithParentMarginAfter(const Box& layoutBox)
{
- // last inflow box to parent.
- // https://www.w3.org/TR/CSS21/box.html#collapsing-margins
if (layoutBox.isAnonymous())
return false;
ASSERT(layoutBox.isBlockLevelBox());
- if (layoutBox.isFloatingOrOutOfFlowPositioned())
+ // Margins between a floated box and any other box do not collapse.
+ if (layoutBox.isFloatingPositioned())
return false;
- if (marginsCollapseThrough(layoutBox))
+ // Margins of absolutely positioned boxes do not collapse.
+ if (layoutBox.isOutOfFlowPositioned())
return false;
+ // Margins of inline-block boxes do not collapse.
+ if (layoutBox.isInlineBlockBox())
+ return false;
+
// Only the last inlflow child collapses with parent.
if (layoutBox.nextInFlowSibling())
return false;
auto& parent = *layoutBox.parent();
- // Margins of elements that establish new block formatting contexts do not collapse with their in-flow children
+ // Margins of elements that establish new block formatting contexts do not collapse with their in-flow children.
if (establishesBlockFormattingContext(parent))
return false;
- if (hasBorderBefore(parent))
+ // The bottom margin of an in-flow block box with a 'height' of 'auto' collapses with its last in-flow block-level child's bottom margin, if:
+ if (!parent.style().height().isAuto())
return false;
+ // the box has no bottom padding, and
if (hasPaddingBefore(parent))
return false;
- if (!parent.style().height().isAuto())
+ // the box has no bottom border, and
+ if (hasBorderBefore(parent))
return false;
+ // the child's bottom margin neither collapses with a top margin that has clearance...
+ if (marginAfterCollapsesWithSiblingMarginBeforeWithClearance(layoutBox))
+ return false;
+
+ // nor (if the box's min-height is non-zero) with the box's top margin.
+ auto computedMinHeight = parent.style().logicalMinHeight();
+ if (!computedMinHeight.isAuto() && computedMinHeight.value() && marginAfterCollapsesWithParentMarginBefore(layoutBox))
+ return false;
+
return true;
}
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