Fix repainting of subpixel positioned composited layers

Since the offset-from-renderer includes the pixel snapping based on
subpixel accumulation, we should take the accumulation into account to
calculate the repaint area in layer coordinates.

Task-number: QTBUG-40218
Change-Id: I66f9cb0943ba69bb892c686ecea9ed5fec805a0d
Reviewed-by: Michael Bruning <michael.bruning@digia.com>

1 files changed, 7 insertions, 10 deletions

diff --git a/Source/WebCore/rendering/RenderLayerBacking.cpp b/Source/WebCore/rendering/RenderLayerBacking.cpp
index 143c7d32c..acfc67776 100644
--- a/Source/WebCore/rendering/RenderLayerBacking.cpp
+++ b/Source/WebCore/rendering/RenderLayerBacking.cpp
@@ -1925,35 +1925,32 @@ void RenderLayerBacking::setContentsNeedDisplayInRect(const IntRect& r)
 {
     ASSERT(!paintsIntoCompositedAncestor());
 
+    LayoutRect layerDirtyRect(r);
+    layerDirtyRect.move(m_subpixelAccumulation);
     if (m_graphicsLayer && m_graphicsLayer->drawsContent()) {
-        IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_graphicsLayer->offsetFromRenderer());
-        m_graphicsLayer->setNeedsDisplayInRect(layerDirtyRect);
+        m_graphicsLayer->setNeedsDisplayInRect(enclosingIntRect(layerDirtyRect));
     }
 
     if (m_foregroundLayer && m_foregroundLayer->drawsContent()) {
-        IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_foregroundLayer->offsetFromRenderer());
-        m_foregroundLayer->setNeedsDisplayInRect(layerDirtyRect);
+        m_foregroundLayer->setNeedsDisplayInRect(enclosingIntRect(layerDirtyRect));
     }
 
     // FIXME: need to split out repaints for the background.
     if (m_backgroundLayer && m_backgroundLayer->drawsContent()) {
-        IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_backgroundLayer->offsetFromRenderer());
-        m_backgroundLayer->setNeedsDisplayInRect(layerDirtyRect);
+        m_backgroundLayer->setNeedsDisplayInRect(enclosingIntRect(layerDirtyRect));
     }
 
     if (m_maskLayer && m_maskLayer->drawsContent()) {
-        IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_maskLayer->offsetFromRenderer());
-        m_maskLayer->setNeedsDisplayInRect(layerDirtyRect);
+        m_maskLayer->setNeedsDisplayInRect(enclosingIntRect(layerDirtyRect));
     }
 
     if (m_scrollingContentsLayer && m_scrollingContentsLayer->drawsContent()) {
-        IntRect layerDirtyRect = r;
         layerDirtyRect.move(-m_scrollingContentsLayer->offsetFromRenderer());
-        m_scrollingContentsLayer->setNeedsDisplayInRect(layerDirtyRect);
+        m_scrollingContentsLayer->setNeedsDisplayInRect(enclosingIntRect(layerDirtyRect));
     }
 }