Fix Compositing of Opaque Scrolling Layers and Add Tests

third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

 /*
  * Copyright (C) 2009, 2010, 2011 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 293 matching lines @@
         else if (WebLayer* layer = context->platformLayer())
             m_graphicsLayer->setContentsOpaque(!Color(layer->backgroundColor()).hasAlpha());
         else
             m_graphicsLayer->setContentsOpaque(false);
     } else if (m_backgroundLayer) {
         m_graphicsLayer->setContentsOpaque(false);
         m_backgroundLayer->setContentsOpaque(m_owningLayer.backgroundIsKnownToBeOpaqueInRect(compositedBounds()));
     } else {
         // For non-root layers, background is painted by the scrolling contents layer if all backgrounds
         // are background attachment local, otherwise background is painted by the primary graphics layer.
-        if (hasScrollingLayer() && shouldPaintBackgroundOntoScrollingContentsLayer()) {
+        if (hasScrollingLayer() && m_owningLayer.shouldPaintBackgroundOntoScrollingContentsLayer()) {
             // Backgrounds painted onto the foreground are clipped by the padding box rect.
             // TODO(flackr): This should actually check the entire overflow rect within the
             // scrolling contents layer but since we currently only trigger this for solid
             // color backgrounds the answer will be the same.
             m_scrollingContentsLayer->setContentsOpaque(m_owningLayer.backgroundIsKnownToBeOpaqueInRect(toLayoutBox(layoutObject())->paddingBoxRect()));
 
             // When we paint the background onto the scrolling contents layer we are going
             // to leave a hole in the m_graphicsLayer where the background is so it is
             // not opaque.
             m_graphicsLayer->setContentsOpaque(false);
@@ skipping 2126 matching lines @@
     else if (compositor()->fixedRootBackgroundLayer() && m_owningLayer.isRootLayer())
         paintLayerFlags |= PaintLayerPaintingSkipRootBackground;
 
     if (graphicsLayer == m_graphicsLayer.get()
         || graphicsLayer == m_foregroundLayer.get()
         || graphicsLayer == m_backgroundLayer.get()
         || graphicsLayer == m_maskLayer.get()
         || graphicsLayer == m_childClippingMaskLayer.get()
         || graphicsLayer == m_scrollingContentsLayer.get()) {
 
-        bool paintRootBackgroundOntoScrollingContentsLayer = shouldPaintBackgroundOntoScrollingContentsLayer();
+        bool paintRootBackgroundOntoScrollingContentsLayer = m_owningLayer.shouldPaintBackgroundOntoScrollingContentsLayer();
         DCHECK(!paintRootBackgroundOntoScrollingContentsLayer || (!m_backgroundLayer && !m_foregroundLayer));
         if (paintRootBackgroundOntoScrollingContentsLayer) {
             if (graphicsLayer == m_scrollingContentsLayer.get())
                 paintLayerFlags &= ~PaintLayerPaintingSkipRootBackground;
             else
                 paintLayerFlags |= PaintLayerPaintingSkipRootBackground;
         }
         GraphicsLayerPaintInfo paintInfo;
         paintInfo.paintLayer = &m_owningLayer;
         paintInfo.compositedBounds = compositedBounds();
@@ skipping 86 matching lines @@
         if (m_squashedLayers[previousIndex].paintLayer == layerToRemove)
             break;
     }
     if (previousIndex == indexToClear && layerToRemove->groupedMapping() == this) {
         compositor()->paintInvalidationOnCompositingChange(layerToRemove);
         return true;
     }
     return false;
 }
 
-bool CompositedLayerMapping::shouldPaintBackgroundOntoScrollingContentsLayer() const
-{
-    // TODO(flackr): Add support for painting locally attached background images. https://crbug.com/625882
-    const FillLayer& backgroundLayer = m_owningLayer.layoutObject()->style()->backgroundLayers();
-    return !m_owningLayer.isRootLayer()
-        && m_owningLayer.scrollsOverflow()
-        && !backgroundLayer.image()
-        && !backgroundLayer.next()
-        && (backgroundLayer.attachment() == LocalBackgroundAttachment
-            || backgroundLayer.clip() == PaddingFillBox)
-        && !m_owningLayer.stackingNode()->hasNegativeZOrderList();
-}
-
 bool CompositedLayerMapping::updateSquashingLayerAssignment(PaintLayer* squashedLayer, size_t nextSquashedLayerIndex)
 {
     GraphicsLayerPaintInfo paintInfo;
     paintInfo.paintLayer = squashedLayer;
     // NOTE: composited bounds are updated elsewhere
     // NOTE: offsetFromLayoutObject is updated elsewhere
 
     // Change tracking on squashing layers: at the first sign of something changed, just invalidate the layer.
     // FIXME: Perhaps we can find a tighter more clever mechanism later.
     if (nextSquashedLayerIndex < m_squashedLayers.size()) {
@@ skipping 100 matching lines @@
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace blink