Changeset 109386 in webkit

Timestamp:

Mar 1, 2012 12:04:09 PM (12 years ago)

Author:

andersca@apple.com

Message:

Glitchy scrolling on pages where the scroll layer needs to be updated on the main thread
​https://bugs.webkit.org/show_bug.cgi?id=80038
<rdar://problem/10933831>

Reviewed by Simon Fraser.

When we need to update the scroll layer position on the main thread, we need to cache the
scroll position we sent to the main thread and assume that that's the correct scroll position.

• page/scrolling/mac/ScrollingTreeNodeMac.h:

(ScrollingTreeNodeMac):

• page/scrolling/mac/ScrollingTreeNodeMac.mm:

(WebCore::ScrollingTreeNodeMac::update):
(WebCore::ScrollingTreeNodeMac::setScrollPosition):
(WebCore::ScrollingTreeNodeMac::scrollPosition):

Location:

trunk/Source/WebCore

Files:

• ChangeLog (modified) (1 diff)
• page/scrolling/mac/ScrollingTreeNodeMac.h (modified) (1 diff)
• page/scrolling/mac/ScrollingTreeNodeMac.mm (modified) (3 diffs)

trunk/Source/WebCore/ChangeLog

@@ +1 @@
+2012-03-01  Anders Carlsson  <andersca@apple.com>
+
+        Glitchy scrolling on pages where the scroll layer needs to be updated on the main thread
+        https://bugs.webkit.org/show_bug.cgi?id=80038
+        <rdar://problem/10933831>
+
+        Reviewed by Simon Fraser.
+
+        When we need to update the scroll layer position on the main thread, we need to cache the
+        scroll position we sent to the main thread and assume that that's the correct scroll position.
+
+        * page/scrolling/mac/ScrollingTreeNodeMac.h:
+        (ScrollingTreeNodeMac):
+        * page/scrolling/mac/ScrollingTreeNodeMac.mm:
+        (WebCore::ScrollingTreeNodeMac::update):
+        (WebCore::ScrollingTreeNodeMac::setScrollPosition):
+        (WebCore::ScrollingTreeNodeMac::scrollPosition):
+
 2012-03-01  Julien Chaffraix  <jchaffraix@webkit.org>
 

trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeNodeMac.h

@@ -77 +77 @@
 
     RetainPtr<CALayer> m_scrollLayer;
+    IntPoint m_probableMainThreadScrollPosition;
 };
 

trunk/Source/WebCore/page/scrolling/mac/ScrollingTreeNodeMac.mm

@@ -61 +61 @@
     if (state->changedProperties() & (ScrollingTreeState::ScrollLayer | ScrollingTreeState::ContentsSize | ScrollingTreeState::ViewportRect))
         updateMainFramePinState(scrollPosition());
+
+    if ((state->changedProperties() & ScrollingTreeState::ShouldUpdateScrollLayerPositionOnMainThread) && shouldUpdateScrollLayerPositionOnMainThread()) {
+        // We're transitioning to the slow "update scroll layer position on the main thread" mode.
+        // Initialize the probable main thread scroll position with the current scroll layer position.
+        CGPoint scrollLayerPosition = m_scrollLayer.get().position;
+        m_probableMainThreadScrollPosition = IntPoint(-scrollLayerPosition.x, -scrollLayerPosition.y);
+    }
 }
 
@@ -74 +81 @@
 
     if (shouldUpdateScrollLayerPositionOnMainThread()) {
+        m_probableMainThreadScrollPosition = scrollPosition;
         scrollingTree()->updateMainFrameScrollPositionAndScrollLayerPosition(scrollPosition);
         return;
@@ -216 +224 @@
 IntPoint ScrollingTreeNodeMac::scrollPosition() const
 {
+    if (shouldUpdateScrollLayerPositionOnMainThread())
+        return m_probableMainThreadScrollPosition;
+
     CGPoint scrollLayerPosition = m_scrollLayer.get().position;
     return IntPoint(-scrollLayerPosition.x, -scrollLayerPosition.y);