[UI-side compositing] Scrolling is not as smooth as it should be on 1…

…20Hz displays https://bugs.webkit.org/show_bug.cgi?id=255254 <rdar://107837416> Reviewed by Tim Horton and Matt Woodrow. On 120Hz displays, the scrolling thread would get displayDidRefresh() at 120Hz, but frameDuration() was the default 1/60s, causing RemoteLayerTreeEventDispatcher::waitForRenderingUpdateCompletionOrTimeout() to block for up to 8ms (half the frame duration). No-one called ScrollingTree::windowScreenDidChange(), so fix that by calling it from RemoteLayerTreeEventDispatcher. * Source/WebCore/page/scrolling/ScrollingTree.h: * Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteLayerTreeEventDispatcher.cpp: (WebKit::RemoteLayerTreeEventDispatcher::windowScreenDidChange): Canonical link: https://commits.webkit.org/262801@main
WebKit · Apr 11, 2023 · 80da2ab · 80da2ab
1 parent 0f2621d
commit 80da2ab
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Showing 2 changed files with 4 additions and 1 deletion.
diff --git a/Source/WebCore/page/scrolling/ScrollingTree.h b/Source/WebCore/page/scrolling/ScrollingTree.h
@@ -209,7 +209,7 @@ class ScrollingTree : public ThreadSafeRefCounted<ScrollingTree> {
 
     Lock& treeLock() WTF_RETURNS_LOCK(m_treeLock) { return m_treeLock; }
 
-    void windowScreenDidChange(PlatformDisplayID, std::optional<FramesPerSecond> nominalFramesPerSecond);
+    WEBCORE_EXPORT void windowScreenDidChange(PlatformDisplayID, std::optional<FramesPerSecond> nominalFramesPerSecond);
     PlatformDisplayID displayID();
     WEBCORE_EXPORT virtual void displayDidRefresh(PlatformDisplayID) { }
 

diff --git a/Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteLayerTreeEventDispatcher.cpp b/Source/WebKit/UIProcess/RemoteLayerTree/mac/RemoteLayerTreeEventDispatcher.cpp
@@ -497,6 +497,9 @@ void RemoteLayerTreeEventDispatcher::windowScreenDidChange(PlatformDisplayID dis
     UNUSED_PARAM(displayID);
     UNUSED_PARAM(nominalFramesPerSecond);
 #endif
+    if (auto scrollingTree = this->scrollingTree())
+        scrollingTree->windowScreenDidChange(displayID, nominalFramesPerSecond);
+
     // FIXME: Restart the displayLink if necessary.
 }