Title: [266664] trunk/Source/WebCore
- Revision
- 266664
- Author
- [email protected]
- Date
- 2020-09-05 10:55:35 -0700 (Sat, 05 Sep 2020)
Log Message
REGRESSION (r260571): Scrolling on weather.com in Safari causes the gradient background to flicker (fixed backgrounds)
https://bugs.webkit.org/show_bug.cgi?id=216192
<rdar://problem/68192010>
Reviewed by Tim Horton.
If a page has slow-scrolling reasons, like background-attachment:fixed on a non-root element,
then we should never update layer positions on the scrolling thread, since this results
in scroll position being out of sync with the painted background position.
* page/scrolling/ThreadedScrollingTree.cpp:
(WebCore::ThreadedScrollingTree::canUpdateLayersOnScrollingThread const):
(WebCore::ThreadedScrollingTree::waitForRenderingUpdateCompletionOrTimeout):
(WebCore::ThreadedScrollingTree::delayedRenderingUpdateDetectionTimerFired):
(WebCore::ThreadedScrollingTree::displayDidRefreshOnScrollingThread):
* page/scrolling/ThreadedScrollingTree.h:
Modified Paths
Diff
Modified: trunk/Source/WebCore/ChangeLog (266663 => 266664)
--- trunk/Source/WebCore/ChangeLog 2020-09-05 17:51:09 UTC (rev 266663)
+++ trunk/Source/WebCore/ChangeLog 2020-09-05 17:55:35 UTC (rev 266664)
@@ -1,3 +1,22 @@
+2020-09-04 Simon Fraser <[email protected]>
+
+ REGRESSION (r260571): Scrolling on weather.com in Safari causes the gradient background to flicker (fixed backgrounds)
+ https://bugs.webkit.org/show_bug.cgi?id=216192
+ <rdar://problem/68192010>
+
+ Reviewed by Tim Horton.
+
+ If a page has slow-scrolling reasons, like background-attachment:fixed on a non-root element,
+ then we should never update layer positions on the scrolling thread, since this results
+ in scroll position being out of sync with the painted background position.
+
+ * page/scrolling/ThreadedScrollingTree.cpp:
+ (WebCore::ThreadedScrollingTree::canUpdateLayersOnScrollingThread const):
+ (WebCore::ThreadedScrollingTree::waitForRenderingUpdateCompletionOrTimeout):
+ (WebCore::ThreadedScrollingTree::delayedRenderingUpdateDetectionTimerFired):
+ (WebCore::ThreadedScrollingTree::displayDidRefreshOnScrollingThread):
+ * page/scrolling/ThreadedScrollingTree.h:
+
2020-09-05 Myles C. Maxfield <[email protected]>
[Cocoa] Unify implementation of custom font name aliases between all Cocoa platforms
Modified: trunk/Source/WebCore/page/scrolling/ThreadedScrollingTree.cpp (266663 => 266664)
--- trunk/Source/WebCore/page/scrolling/ThreadedScrollingTree.cpp 2020-09-05 17:51:09 UTC (rev 266663)
+++ trunk/Source/WebCore/page/scrolling/ThreadedScrollingTree.cpp 2020-09-05 17:55:35 UTC (rev 266664)
@@ -116,6 +116,12 @@
}
}
+bool ThreadedScrollingTree::canUpdateLayersOnScrollingThread() const
+{
+ auto* rootNode = this->rootNode();
+ return !(rootNode && rootNode->hasSynchronousScrollingReasons());
+}
+
void ThreadedScrollingTree::scrollingTreeNodeDidScroll(ScrollingTreeScrollingNode& node, ScrollingLayerPositionAction scrollingLayerPositionAction)
{
if (!m_scrollingCoordinator)
@@ -258,7 +264,8 @@
m_state = SynchronizationState::Desynchronized;
// At this point we know the main thread is taking too long in the rendering update,
// so we give up trying to sync with the main thread and update layers here on the scrolling thread.
- applyLayerPositionsInternal();
+ if (canUpdateLayersOnScrollingThread())
+ applyLayerPositionsInternal();
tracePoint(ScrollingThreadRenderUpdateSyncEnd, 1);
} else
tracePoint(ScrollingThreadRenderUpdateSyncEnd);
@@ -291,7 +298,8 @@
ASSERT(ScrollingThread::isCurrentThread());
LockHolder treeLocker(m_treeMutex);
- applyLayerPositionsInternal();
+ if (canUpdateLayersOnScrollingThread())
+ applyLayerPositionsInternal();
m_state = SynchronizationState::Desynchronized;
}
@@ -302,7 +310,7 @@
LockHolder treeLocker(m_treeMutex);
- if (m_state != SynchronizationState::Idle)
+ if (m_state != SynchronizationState::Idle && canUpdateLayersOnScrollingThread())
applyLayerPositionsInternal();
switch (m_state) {
Modified: trunk/Source/WebCore/page/scrolling/ThreadedScrollingTree.h (266663 => 266664)
--- trunk/Source/WebCore/page/scrolling/ThreadedScrollingTree.h 2020-09-05 17:51:09 UTC (rev 266663)
+++ trunk/Source/WebCore/page/scrolling/ThreadedScrollingTree.h 2020-09-05 17:55:35 UTC (rev 266664)
@@ -81,6 +81,8 @@
void displayDidRefreshOnScrollingThread();
void waitForRenderingUpdateCompletionOrTimeout();
+
+ bool canUpdateLayersOnScrollingThread() const;
void scheduleDelayedRenderingUpdateDetectionTimer(Seconds);
void delayedRenderingUpdateDetectionTimerFired();
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