Bug 87553 – Incomplete repaint on twitter.com when replying to a tweet

• Component: Layout and Rendering
• Status: RESOLVED FIXED

[Simon Fraser (smfr)]

There's a bad repaint bug when replying to an individual tweet on Twitter.com:

1. Log in to twitter
2. Load an individual tweet, such as https://twitter.com/CityofSunnyvale/status/206160290834944000
3. Hit the Reply link
4. Hit one character in the reply box

The box mostly disappears. As you type, bits of the screen update.

[Simon Fraser (smfr)]

<rdar://problem/11538697>

[Simon Fraser (smfr)]

Fix is something like:


diff --git a/Source/WebCore/rendering/RenderLayerBacking.cpp b/Source/WebCore/rendering/RenderLayerBacking.cpp
index 1085eab..90a4d88 100644
--- a/Source/WebCore/rendering/RenderLayerBacking.cpp
+++ b/Source/WebCore/rendering/RenderLayerBacking.cpp
@@ -1121,6 +1121,19 @@ void RenderLayerBacking::setRequiresOwnBackingStore(bool flag)
     // cached clip rects, so when it changes we have to clear clip rects on descendants.
     m_owningLayer->clearClipRectsIncludingDescendants(PaintingClipRects);
     m_requiresOwnBackingStore = flag;
+
+    // Find our painting ancestor and repaint it
+    RenderLayer* repaintAncestor = m_owningLayer->enclosingCompositingLayerForRepaint();
+    if (repaintAncestor) {
+        ASSERT(repaintAncestor->backing());
+        LayoutRect compBounds = compositedBounds();
+
+        LayoutPoint offset;
+        m_owningLayer->convertToLayerCoords(repaintAncestor, offset);
+        compBounds.moveBy(offset);
+
+        repaintAncestor->setBackingNeedsRepaintInRect(compBounds);
+    }
 }
 
 void RenderLayerBacking::setContentsNeedDisplay()

but this code could be shared with RenderLayerCompositor::layerWillBeRemoved

[Simon Fraser (smfr)]

Created attachment 144608 [details]
Patch

[Simon Fraser (smfr)]

http://trac.webkit.org/changeset/118828