Changeset 287757 in webkit

Timestamp:

Jan 7, 2022, 10:06:43 AM (4 years ago)

Author:

Simon Fraser

Message:

REGRESSION (Safari 14): background-attachment: local does not work
​https://bugs.webkit.org/show_bug.cgi?id=219324
Source/WebCore:

<rdar://71808922>

Reviewed by Antti Koivisto.

With async overflow scrolling, we need to trigger a repaint if the scrolling element
has any background layer with background-attachment: local.

The background won't always be synchronized with the scrolling, but a little jitter
is better than a broken CSS behavior (and this is what Firefox does).

Test: fast/repaint/background-attachment-local-scroll.html

• rendering/RenderLayerBacking.cpp:

(WebCore::RenderLayerBacking::needsRepaintOnCompositedScroll const):

• rendering/style/RenderStyle.cpp:

(WebCore::RenderStyle::hasAnyLocalBackground const):

• rendering/style/RenderStyle.h:

LayoutTests:

Reviewed by Antti Koivisto.

Skip the test on platforms without async overflow scroll.

• TestExpectations:
• fast/repaint/background-attachment-local-scroll-expected.txt: Added.
• fast/repaint/background-attachment-local-scroll.html: Added.
• platform/ios-wk2/TestExpectations:
• platform/mac-wk2/TestExpectations:

Location:

trunk

Files:

• LayoutTests/ChangeLog (modified) (1 diff)
• LayoutTests/TestExpectations (modified) (1 diff)
• LayoutTests/fast/repaint/background-attachment-local-scroll-expected.txt (added)
• LayoutTests/fast/repaint/background-attachment-local-scroll.html (added)
• LayoutTests/platform/ios-wk2/TestExpectations (modified) (1 diff)
• LayoutTests/platform/mac-wk2/TestExpectations (modified) (1 diff)
• Source/WebCore/ChangeLog (modified) (1 diff)
• Source/WebCore/rendering/RenderLayerBacking.cpp (modified) (1 diff)
• Source/WebCore/rendering/style/RenderStyle.cpp (modified) (1 diff)
• Source/WebCore/rendering/style/RenderStyle.h (modified) (1 diff)

trunk/LayoutTests/ChangeLog

@@ +1 @@
+2022-01-07  Simon Fraser  <simon.fraser@apple.com>
+
+        REGRESSION (Safari 14): background-attachment: local does not work
+        https://bugs.webkit.org/show_bug.cgi?id=219324
+
+        Reviewed by Antti Koivisto.
+
+        Skip the test on platforms without async overflow scroll.
+
+        * TestExpectations:
+        * fast/repaint/background-attachment-local-scroll-expected.txt: Added.
+        * fast/repaint/background-attachment-local-scroll.html: Added.
+        * platform/ios-wk2/TestExpectations:
+        * platform/mac-wk2/TestExpectations:
+
 2022-01-07  Kate Cheney  <katherine_cheney@apple.com>
 

trunk/LayoutTests/TestExpectations

@@ -92 +92 @@
 compositing/scrolling/async-overflow-scrolling [ Skip ]
 compositing/layer-creation/clipping-scope [ Skip ]
+fast/repaint/background-attachment-local-scroll.html [ Skip ]
 
 # WebKit2 only.

trunk/LayoutTests/platform/ios-wk2/TestExpectations

@@ -42 +42 @@
 fast/media/mq-prefers-contrast-live-update.html [ Pass ]
 
+fast/repaint/background-attachment-local-scroll.html [ Pass ]
 fast/repaint/placeholder-after-caps-lock-hidden.html [ Pass ]
 

trunk/LayoutTests/platform/mac-wk2/TestExpectations

@@ -43 +43 @@
 fast/media/mq-prefers-contrast.html [ Pass ]
 
+fast/repaint/background-attachment-local-scroll.html [ Pass ]
 fast/scrolling/unfocusing-page-while-keyboard-scrolling.html [ Pass ]
 

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2022-01-07  Simon Fraser  <simon.fraser@apple.com>
+
+        REGRESSION (Safari 14): background-attachment: local does not work
+        https://bugs.webkit.org/show_bug.cgi?id=219324
+        <rdar://71808922>
+
+        Reviewed by Antti Koivisto.
+
+        With async overflow scrolling, we need to trigger a repaint if the scrolling element
+        has any background layer with `background-attachment: local`.
+
+        The background won't always be synchronized with the scrolling, but a little jitter
+        is better than a broken CSS behavior (and this is what Firefox does).
+
+        Test: fast/repaint/background-attachment-local-scroll.html
+
+        * rendering/RenderLayerBacking.cpp:
+        (WebCore::RenderLayerBacking::needsRepaintOnCompositedScroll const):
+        * rendering/style/RenderStyle.cpp:
+        (WebCore::RenderStyle::hasAnyLocalBackground const):
+        * rendering/style/RenderStyle.h:
+
 2022-01-07  Kate Cheney  <katherine_cheney@apple.com>
 

trunk/Source/WebCore/rendering/RenderLayerBacking.cpp

@@ -2035 +2035 @@
         return false;
 
+    if (renderer().style().hasAnyLocalBackground())
+        return true;
+
     if (auto scrollingCoordinator = m_owningLayer.page().scrollingCoordinator())
         return scrollingCoordinator->hasSynchronousScrollingReasons(m_scrollingNodeID);
-    
+
     return false;
 }

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

@@ -1665 +1665 @@
 {
     return allLayersAreFixed(backgroundLayers());
+}
+
+bool RenderStyle::hasAnyLocalBackground() const
+{
+    for (auto* layer = &backgroundLayers(); layer; layer = layer->next()) {
+        if (layer->image() && layer->attachment() == FillAttachment::LocalBackground)
+            return true;
+    }
+    return false;
 }
 

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

@@ -215 +215 @@
 
     bool hasEntirelyFixedBackground() const;
+    bool hasAnyLocalBackground() const;
 
     bool hasAppearance() const { return appearance() != NoControlPart; }