Title: [238930] trunk/Source/WebCore
- Revision
- 238930
- Author
- [email protected]
- Date
- 2018-12-06 07:21:48 -0800 (Thu, 06 Dec 2018)
Log Message
[LFC][BFC][MarginCollapsing] Add MarginCollapse::establishesBlockFormattingContext
https://bugs.webkit.org/show_bug.cgi?id=192297
Reviewed by Antti Koivisto.
WebKit treats the document element renderer as a block formatting context root.
* layout/blockformatting/BlockMarginCollapse.cpp:
(WebCore::Layout::establishesBlockFormattingContext):
(WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::isMarginTopCollapsedWithParent):
(WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::isMarginBottomCollapsedWithParent):
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (238929 => 238930)
--- trunk/Source/WebCore/ChangeLog 2018-12-06 13:07:46 UTC (rev 238929)
+++ trunk/Source/WebCore/ChangeLog 2018-12-06 15:21:48 UTC (rev 238930)
@@ -1,3 +1,17 @@
+2018-12-06 Zalan Bujtas <[email protected]>
+
+ [LFC][BFC][MarginCollapsing] Add MarginCollapse::establishesBlockFormattingContext
+ https://bugs.webkit.org/show_bug.cgi?id=192297
+
+ Reviewed by Antti Koivisto.
+
+ WebKit treats the document element renderer as a block formatting context root.
+
+ * layout/blockformatting/BlockMarginCollapse.cpp:
+ (WebCore::Layout::establishesBlockFormattingContext):
+ (WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::isMarginTopCollapsedWithParent):
+ (WebCore::Layout::BlockFormattingContext::Geometry::MarginCollapse::isMarginBottomCollapsedWithParent):
+
2018-12-06 Carlos Eduardo Ramalho <[email protected]>
[GStreamer] -DENABLE_VIDEO=ON -DENABLE_OPENGL=OFF still tries to build GstreamerGL
Modified: trunk/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp (238929 => 238930)
--- trunk/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp 2018-12-06 13:07:46 UTC (rev 238929)
+++ trunk/Source/WebCore/layout/blockformatting/BlockMarginCollapse.cpp 2018-12-06 15:21:48 UTC (rev 238930)
@@ -69,6 +69,15 @@
return hasPadding(layoutBox.style().paddingAfter());
}
+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
+ // a layout wide quirk on this for now.
+ if (layoutBox.isDocumentBox())
+ return true;
+ return layoutBox.establishesBlockFormattingContext();
+}
+
static LayoutUnit marginValue(LayoutUnit currentMarginValue, LayoutUnit candidateMarginValue)
{
if (!candidateMarginValue)
@@ -131,16 +140,11 @@
if (layoutBox.previousInFlowSibling())
return false;
- // We never margin collapse the initial containing block.
- ASSERT(layoutBox.parent());
auto& parent = *layoutBox.parent();
- if (parent.establishesBlockFormattingContext())
+ // Margins of elements that establish new block formatting contexts do not collapse with their in-flow children
+ if (establishesBlockFormattingContext(parent))
return false;
- // Margins of the root element's box do not collapse.
- if (parent.isDocumentBox() || parent.isInitialContainingBlock())
- return false;
-
if (hasBorderBefore(parent))
return false;
@@ -308,20 +312,15 @@
if (isMarginBottomCollapsedThrough(layoutBox))
return false;
- // We never margin collapse the initial containing block.
- ASSERT(layoutBox.parent());
- auto& parent = *layoutBox.parent();
// Only the last inlflow child collapses with parent.
if (layoutBox.nextInFlowSibling())
return false;
- if (parent.establishesBlockFormattingContext())
+ auto& parent = *layoutBox.parent();
+ // Margins of elements that establish new block formatting contexts do not collapse with their in-flow children
+ if (establishesBlockFormattingContext(parent))
return false;
- // Margins of the root element's box do not collapse.
- if (parent.isDocumentBox() || parent.isInitialContainingBlock())
- return false;
-
if (hasBorderBefore(parent))
return false;
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