Changeset 277579 in webkit

Timestamp:

May 17, 2021 3:09:03 AM (14 months ago)

Author:

ntim@apple.com

Message:

will-change: position should not create a containing block for position: fixed elements
​https://bugs.webkit.org/show_bug.cgi?id=225443

Reviewed by Antti Koivisto.

This partially undoes r276627 which made will-change: position create a CB for all out-of-flow elements:

• Removed CSSPropertyPosition from createsContainingBlockForOutOfFlowPositioned() to not create a containing block

for position: fixed; children.

• Added createsContainingBlockForAbsolutelyPositioned() with CSSPropertyPosition to still create a containing block

for position: absolute; children.

Enabled WPT (which covers both cases): css/css-will-change/will-change-fixpos-cb-position-1.html

Source/WebCore:

• rendering/RenderElement.h:

(WebCore::RenderElement::canContainAbsolutelyPositionedObjects const):

• rendering/style/WillChangeData.cpp:

(WebCore::WillChangeData::createsContainingBlockForAbsolutelyPositioned const):
(WebCore::WillChangeData::createsContainingBlockForOutOfFlowPositioned const):

• rendering/style/WillChangeData.h:

LayoutTests:

• TestExpectations:

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/TestExpectations (modified) (1 diff)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderElement.h (modified) (1 diff)
• Source/WebCore/rendering/style/WillChangeData.cpp (modified) (1 diff)
• Source/WebCore/rendering/style/WillChangeData.h (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2021-05-17  Tim Nguyen  <ntim@apple.com>
+
+        will-change: position should not create a containing block for position: fixed elements
+        https://bugs.webkit.org/show_bug.cgi?id=225443
+
+        Reviewed by Antti Koivisto.
+
+        This partially undoes r276627 which made will-change: position create a CB for all out-of-flow elements:
+
+        - Removed CSSPropertyPosition from createsContainingBlockForOutOfFlowPositioned() to not create a containing block
+        for position: fixed; children.
+        - Added createsContainingBlockForAbsolutelyPositioned() with CSSPropertyPosition to still create a containing block
+        for position: absolute; children.
+
+        Enabled WPT (which covers both cases): css/css-will-change/will-change-fixpos-cb-position-1.html
+
+        * TestExpectations:
+
 2021-05-16  Cameron McCormack  <heycam@apple.com>
 

trunk/LayoutTests/TestExpectations

@@ -4858 +4858 @@
 webkit.org/b/225034 imported/w3c/web-platform-tests/css/css-will-change/will-change-fixedpos-cb-003.html [ ImageOnlyFailure ]
 webkit.org/b/225442 imported/w3c/web-platform-tests/css/css-will-change/will-change-fixpos-cb-contain-1.html [ ImageOnlyFailure ]
-webkit.org/b/225443 imported/w3c/web-platform-tests/css/css-will-change/will-change-fixpos-cb-position-1.html [ ImageOnlyFailure ]
 webkit.org/b/224902 [ Debug ] imported/w3c/web-platform-tests/css/css-will-change/parsing/will-change-invalid.html [ Skip ]
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2021-05-17  Tim Nguyen  <ntim@apple.com>
+
+        will-change: position should not create a containing block for position: fixed elements
+        https://bugs.webkit.org/show_bug.cgi?id=225443
+
+        Reviewed by Antti Koivisto.
+
+        This partially undoes r276627 which made will-change: position create a CB for all out-of-flow elements:
+
+        - Removed CSSPropertyPosition from createsContainingBlockForOutOfFlowPositioned() to not create a containing block
+        for position: fixed; children.
+        - Added createsContainingBlockForAbsolutelyPositioned() with CSSPropertyPosition to still create a containing block
+        for position: absolute; children.
+
+        Enabled WPT (which covers both cases): css/css-will-change/will-change-fixpos-cb-position-1.html
+
+        * rendering/RenderElement.h:
+        (WebCore::RenderElement::canContainAbsolutelyPositionedObjects const):
+        * rendering/style/WillChangeData.cpp:
+        (WebCore::WillChangeData::createsContainingBlockForAbsolutelyPositioned const):
+        (WebCore::WillChangeData::createsContainingBlockForOutOfFlowPositioned const):
+        * rendering/style/WillChangeData.h:
+
 2021-05-17  Zan Dobersek  <zdobersek@igalia.com>
 

trunk/Source/WebCore/rendering/RenderElement.h

@@ -450 +450 @@
         || (isRenderBlock() && hasTransformRelatedProperty())
         // FIXME: will-change should create containing blocks on inline boxes (bug 225035)
-        || (isRenderBlock() && style().willChange() && style().willChange()->createsContainingBlockForOutOfFlowPositioned())
+        || (isRenderBlock() && style().willChange() && style().willChange()->createsContainingBlockForAbsolutelyPositioned())
         || isSVGForeignObject()
         || shouldApplyLayoutContainment(*this)

trunk/Source/WebCore/rendering/style/WillChangeData.cpp

@@ -61 +61 @@
 }
 
+bool WillChangeData::createsContainingBlockForAbsolutelyPositioned() const
+{
+    return createsContainingBlockForOutOfFlowPositioned()
+        || containsProperty(CSSPropertyPosition);
+}
+
 bool WillChangeData::createsContainingBlockForOutOfFlowPositioned() const
 {
-    return containsProperty(CSSPropertyPosition)
-        || containsProperty(CSSPropertyPerspective)
+    return containsProperty(CSSPropertyPerspective)
         // CSS transforms
         || containsProperty(CSSPropertyTransform)

trunk/Source/WebCore/rendering/style/WillChangeData.h

@@ -53 +53 @@
     bool containsProperty(CSSPropertyID) const;
 
+    bool createsContainingBlockForAbsolutelyPositioned() const;
     bool createsContainingBlockForOutOfFlowPositioned() const;
     bool canCreateStackingContext() const { return m_canCreateStackingContext; }