Title: [233399] trunk/Source/WebCore
- Revision
- 233399
- Author
- [email protected]
- Date
- 2018-06-30 11:07:43 -0700 (Sat, 30 Jun 2018)
Log Message
[LFC] Do not add the containing block's offset while computing the out-of-flow static position.
https://bugs.webkit.org/show_bug.cgi?id=187202
Reviewed by Antti Koivisto.
The static position for an out-of-flow elements is
1. the distance from the parent's border box.
2. climbing up on the containing block chain and offset the containers until we reach the out-of-flow element's containing block.
* layout/FormattingContextGeometry.cpp:
(WebCore::Layout::staticVerticalPositionForOutOfFlowPositioned):
(WebCore::Layout::staticHorizontalPositionForOutOfFlowPositioned):
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (233398 => 233399)
--- trunk/Source/WebCore/ChangeLog 2018-06-30 18:06:22 UTC (rev 233398)
+++ trunk/Source/WebCore/ChangeLog 2018-06-30 18:07:43 UTC (rev 233399)
@@ -1,5 +1,20 @@
2018-06-30 Zalan Bujtas <[email protected]>
+ [LFC] Do not add the containing block's offset while computing the out-of-flow static position.
+ https://bugs.webkit.org/show_bug.cgi?id=187202
+
+ Reviewed by Antti Koivisto.
+
+ The static position for an out-of-flow elements is
+ 1. the distance from the parent's border box.
+ 2. climbing up on the containing block chain and offset the containers until we reach the out-of-flow element's containing block.
+
+ * layout/FormattingContextGeometry.cpp:
+ (WebCore::Layout::staticVerticalPositionForOutOfFlowPositioned):
+ (WebCore::Layout::staticHorizontalPositionForOutOfFlowPositioned):
+
+2018-06-30 Zalan Bujtas <[email protected]>
+
[LFC] If the top and bottom margins of a box are adjoining, then it is possible for margins to collapse through it.
https://bugs.webkit.org/show_bug.cgi?id=187220
Modified: trunk/Source/WebCore/layout/FormattingContextGeometry.cpp (233398 => 233399)
--- trunk/Source/WebCore/layout/FormattingContextGeometry.cpp 2018-06-30 18:06:22 UTC (rev 233398)
+++ trunk/Source/WebCore/layout/FormattingContextGeometry.cpp 2018-06-30 18:07:43 UTC (rev 233399)
@@ -79,19 +79,30 @@
{
ASSERT(layoutBox.isOutOfFlowPositioned());
+ // For the purposes of this section and the next, the term "static position" (of an element) refers, roughly, to the position an element would have
+ // had in the normal flow. More precisely, the static position for 'top' is the distance from the top edge of the containing block to the top margin
+ // edge of a hypothetical box that would have been the first box of the element if its specified 'position' value had been 'static' and its specified
+ // 'float' had been 'none' and its specified 'clear' had been 'none'. (Note that due to the rules in section 9.7 this might require also assuming a different
+ // computed value for 'display'.) The value is negative if the hypothetical box is above the containing block.
+
+ // Start with this box's border box offset from the parent's border box.
LayoutUnit top;
- // Add sibling offset
if (auto* previousInFlowSibling = layoutBox.previousInFlowSibling()) {
+ // Add sibling offset
auto& previousInFlowDisplayBox = *layoutContext.displayBoxForLayoutBox(*previousInFlowSibling);
top += previousInFlowDisplayBox.bottom() + previousInFlowDisplayBox.nonCollapsedMarginBottom();
+ } else {
+ ASSERT(layoutBox.parent());
+ top = layoutContext.displayBoxForLayoutBox(*layoutBox.parent())->contentBoxTop();
}
+
// Resolve top all the way up to the containing block.
auto* containingBlock = layoutBox.containingBlock();
- for (auto* parent = layoutBox.parent(); parent; parent = parent->parent()) {
- auto& displayBox = *layoutContext.displayBoxForLayoutBox(*parent);
- top += (displayBox.top() + displayBox.contentBoxTop());
- if (parent == containingBlock)
- break;
+ for (auto* container = layoutBox.parent(); container != containingBlock; container = container->containingBlock()) {
+ auto& displayBox = *layoutContext.displayBoxForLayoutBox(*container);
+ // Display::Box::top is the border box top position in its containing block's coordinate system.
+ top += displayBox.top();
+ ASSERT(!container->isPositioned());
}
// FIXME: floatings need to be taken into account.
return top;
@@ -100,15 +111,19 @@
static LayoutUnit staticHorizontalPositionForOutOfFlowPositioned(const LayoutContext& layoutContext, const Box& layoutBox)
{
ASSERT(layoutBox.isOutOfFlowPositioned());
+ // See staticVerticalPositionForOutOfFlowPositioned for the definition of the static position.
- LayoutUnit left;
+ // Start with this box's border box offset from the parent's border box.
+ ASSERT(layoutBox.parent());
+ auto left = layoutContext.displayBoxForLayoutBox(*layoutBox.parent())->contentBoxLeft();
+
// Resolve left all the way up to the containing block.
auto* containingBlock = layoutBox.containingBlock();
- for (auto* parent = layoutBox.parent(); parent; parent = parent->parent()) {
- auto& displayBox = *layoutContext.displayBoxForLayoutBox(*parent);
- left += (displayBox.left() + displayBox.contentBoxLeft());
- if (parent == containingBlock)
- break;
+ for (auto* container = layoutBox.parent(); container != containingBlock; container = container->containingBlock()) {
+ auto& displayBox = *layoutContext.displayBoxForLayoutBox(*container);
+ // Display::Box::left is the border box left position in its containing block's coordinate system.
+ left += displayBox.left();
+ ASSERT(!container->isPositioned());
}
// FIXME: floatings need to be taken into account.
return left;
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