Changeset 243786 in webkit

Timestamp:

Apr 2, 2019, 9:20:24 PM (7 years ago)

Author:

Simon Fraser

Message:

REGRESSION (r238266): Exchange 2013 Outlook Web Access displays partially blank page when creating new e-mail
​https://bugs.webkit.org/show_bug.cgi?id=196522
Source/WebCore:

rdar://problem/49472941

Reviewed by Zalan Bujtas.

In this content a layer is composited to clip descendants, and has negative z-order children,
so we compute that it "paints into ancestor", and has a foreground layer. This combination doesn't
make sense, and when the layer becomes scrollable, we end up with bad paint phases on layers, and
fail to paint the contents.

Fix by ensuring that a layer has its own backing store if it requires a foreground layer
by virtue of having negative z-order children.

Test: compositing/backing/foreground-layer-no-paints-into-ancestor.html

• rendering/RenderLayerCompositor.cpp:

(WebCore::RenderLayerCompositor::requiresOwnBackingStore const):

LayoutTests:

Reviewed by Zalan Bujtas.

• compositing/backing/foreground-layer-no-paints-into-ancestor-expected.html: Added.
• compositing/backing/foreground-layer-no-paints-into-ancestor.html: Added.

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/compositing/backing/foreground-layer-no-paints-into-ancestor-expected.html (added)
• LayoutTests/compositing/backing/foreground-layer-no-paints-into-ancestor.html (added)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderLayerCompositor.cpp (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2019-04-02  Simon Fraser  <simon.fraser@apple.com>
+
+        REGRESSION (r238266): Exchange 2013 Outlook Web Access displays partially blank page when creating new e-mail
+        https://bugs.webkit.org/show_bug.cgi?id=196522
+
+        Reviewed by Zalan Bujtas.
+
+        * compositing/backing/foreground-layer-no-paints-into-ancestor-expected.html: Added.
+        * compositing/backing/foreground-layer-no-paints-into-ancestor.html: Added.
+
 2019-04-02  Said Abou-Hallawa  <sabouhallawa@apple.com>
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2019-04-02  Simon Fraser  <simon.fraser@apple.com>
+
+        REGRESSION (r238266): Exchange 2013 Outlook Web Access displays partially blank page when creating new e-mail
+        https://bugs.webkit.org/show_bug.cgi?id=196522
+        rdar://problem/49472941
+
+        Reviewed by Zalan Bujtas.
+
+        In this content a layer is composited to clip descendants, and has negative z-order children,
+        so we compute that it "paints into ancestor", and has a foreground layer. This combination doesn't
+        make sense, and when the layer becomes scrollable, we end up with bad paint phases on layers, and
+        fail to paint the contents.
+
+        Fix by ensuring that a layer has its own backing store if it requires a foreground layer
+        by virtue of having negative z-order children.
+
+        Test: compositing/backing/foreground-layer-no-paints-into-ancestor.html
+
+        * rendering/RenderLayerCompositor.cpp:
+        (WebCore::RenderLayerCompositor::requiresOwnBackingStore const):
+
 2019-04-02  Timothy Hatcher  <timothy@apple.com>
 

trunk/Source/WebCore/rendering/RenderLayerCompositor.cpp

@@ -2222 +2222 @@
         || requiresCompositingForEditableImage(renderer)
         || requiresCompositingForOverflowScrolling(layer, queryData)
+        || needsContentsCompositingLayer(layer)
         || renderer.isTransparent()
         || renderer.hasMask()