Set up scroll and clip parents

Source/core/rendering/RenderLayerBacking.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 153 matching lines @@
         if (page && page->mainFrame() == &frame) {
             m_isMainFrameRenderViewLayer = true;
         }
     }
 
     createPrimaryGraphicsLayer();
 }
 
 RenderLayerBacking::~RenderLayerBacking()
 {
-    updateClippingLayers(false, false);
+    updateClippingLayers(false, false, false);
     updateOverflowControlsLayers(false, false, false);
     updateForegroundLayer(false);
     updateBackgroundLayer(false);
     updateMaskLayer(false);
     updateScrollingLayers(false);
     destroyGraphicsLayers();
 }
 
 PassOwnPtr<GraphicsLayer> RenderLayerBacking::createGraphicsLayer(CompositingReasons reasons)
 {
@@ skipping 226 matching lines @@
 
     if (updateForegroundLayer(compositor->needsContentsCompositingLayer(m_owningLayer)))
         layerConfigChanged = true;
 
     bool needsDescendentsClippingLayer = compositor->clipsCompositingDescendants(m_owningLayer);
 
     // Our scrolling layer will clip.
     if (m_owningLayer->needsCompositedScrolling())
         needsDescendentsClippingLayer = false;
 
-    if (updateClippingLayers(compositor->clippedByAncestor(m_owningLayer), needsDescendentsClippingLayer))
+    RenderLayer* scrollParent = m_owningLayer->scrollParent();
+    bool needsAncestorClip = compositor->clippedByAncestor(m_owningLayer);
+    bool needsScrollClip = !!scrollParent;
+    if (updateClippingLayers(needsAncestorClip, needsDescendentsClippingLayer, needsScrollClip))
         layerConfigChanged = true;
 
     if (updateOverflowControlsLayers(requiresHorizontalScrollbarLayer(), requiresVerticalScrollbarLayer(), requiresScrollCornerLayer()))
         layerConfigChanged = true;
 
     if (updateScrollingLayers(m_owningLayer->needsCompositedScrolling()))
         layerConfigChanged = true;
 
+    updateScrollParent(scrollParent);
+    updateClipParent(m_owningLayer->clipParent());
+
     if (layerConfigChanged)
         updateInternalHierarchy();
 
     if (updateMaskLayer(renderer->hasMask()))
         m_graphicsLayer->setMaskLayer(m_maskLayer.get());
 
     if (m_owningLayer->hasReflection()) {
         if (m_owningLayer->reflectionLayer()->backing()) {
             GraphicsLayer* reflectionLayer = m_owningLayer->reflectionLayer()->backing()->graphicsLayer();
             m_graphicsLayer->setReplicatedByLayer(reflectionLayer);
@@ skipping 96 matching lines @@
     else
         graphicsLayerParentLocation = renderer()->view()->documentRect().location();
 
     if (compAncestor && compAncestor->needsCompositedScrolling()) {
         RenderBox* renderBox = toRenderBox(compAncestor->renderer());
         IntSize scrollOffset = compAncestor->scrolledContentOffset();
         IntPoint scrollOrigin(renderBox->borderLeft(), renderBox->borderTop());
         graphicsLayerParentLocation = scrollOrigin - scrollOffset;
     }
 
+    if (compAncestor && m_ancestorScrollClippingLayer) {
+        // Our scroll parent must have been processed before us.

[hartmanng, 2013/09/06 01:46:38]

I think a slightly longer comment explaining why our we know our parent has
already been processed might be useful here.

[Ian Vollick, 2013/09/06 02:38:11]

Done.

+        RenderLayer* scrollParent = m_owningLayer->ancestorScrollingLayer();
+        GraphicsLayer* scrollParentClippingLayer = scrollParent->backing()->scrollingLayer();
+
+        // Not relative to our parent graphics layer.
+        FloatPoint position;
+        GraphicsLayer* scrollParentChildForSuperlayers = scrollParent->backing()->childForSuperlayers();
+
+        for (GraphicsLayer* scrollAncestor = scrollParentClippingLayer; scrollAncestor; scrollAncestor = scrollAncestor->parent()) {
+            position = position + toFloatSize(scrollAncestor->position());
+            if (scrollAncestor == scrollParentChildForSuperlayers)
+                break;
+        }
+
+        m_ancestorScrollClippingLayer->setPosition(position);
+        m_ancestorScrollClippingLayer->setSize(scrollParentClippingLayer->size());
+        m_ancestorScrollClippingLayer->setOffsetFromRenderer(toIntSize(roundedIntPoint(-position)));
+
+        graphicsLayerParentLocation = roundedIntPoint(position);
+    }
+
     if (compAncestor && m_ancestorClippingLayer) {
         // Call calculateRects to get the backgroundRect which is what is used to clip the contents of this
         // layer. Note that we call it with temporaryClipRects = true because normally when computing clip rects
         // for a compositing layer, rootLayer is the layer itself.
         RenderLayer::ClipRectsContext clipRectsContext(compAncestor, 0, TemporaryClipRects, IgnoreOverlayScrollbarSize, IgnoreOverflowClip);
         IntRect parentClipRect = pixelSnappedIntRect(m_owningLayer->backgroundClipRect(clipRectsContext).rect()); // FIXME: Incorrect for CSS regions.
         ASSERT(parentClipRect != PaintInfo::infiniteRect());
         m_ancestorClippingLayer->setPosition(FloatPoint(parentClipRect.location() - graphicsLayerParentLocation));
         m_ancestorClippingLayer->setSize(parentClipRect.size());
 
@@ skipping 186 matching lines @@
 
     // Page scale is applied as a transform on the root render view layer. Because the scroll
     // layer is further up in the hierarchy, we need to avoid marking the root render view
     // layer as a container.
     bool isContainer = m_owningLayer->hasTransform() && !m_owningLayer->isRootLayer();
     scrollingCoordinator->setLayerIsContainerForFixedPositionLayers(childForSuperlayers(), isContainer);
 }
 
 void RenderLayerBacking::updateInternalHierarchy()
 {
+    if (m_ancestorScrollClippingLayer)
+        m_ancestorScrollClippingLayer->removeAllChildren();
+
     // m_foregroundLayer has to be inserted in the correct order with child layers,
     // so it's not inserted here.
     if (m_ancestorClippingLayer)
         m_ancestorClippingLayer->removeAllChildren();
 
     m_graphicsLayer->removeFromParent();
 
     if (m_ancestorClippingLayer)
         m_ancestorClippingLayer->addChild(m_graphicsLayer.get());
 
+    if (m_ancestorScrollClippingLayer) {
+        if (m_ancestorClippingLayer)
+            m_ancestorScrollClippingLayer->addChild(m_ancestorClippingLayer.get());
+        else
+            m_ancestorScrollClippingLayer->addChild(m_graphicsLayer.get());
+    }
+
     if (m_childContainmentLayer) {
         m_childContainmentLayer->removeFromParent();
         m_graphicsLayer->addChild(m_childContainmentLayer.get());
     }
 
     if (m_scrollingLayer) {
         GraphicsLayer* superlayer = m_childContainmentLayer ? m_childContainmentLayer.get() : m_graphicsLayer.get();
         m_scrollingLayer->removeFromParent();
         superlayer->addChild(m_scrollingLayer.get());
     }
@@ skipping 58 matching lines @@
     // FIXME: we could refine this to only allocate backing for one of these layers if possible.
     m_graphicsLayer->setDrawsContent(hasPaintedContent);
     if (m_foregroundLayer)
         m_foregroundLayer->setDrawsContent(hasPaintedContent);
 
     if (m_backgroundLayer)
         m_backgroundLayer->setDrawsContent(hasPaintedContent);
 }
 
 // Return true if the layers changed.
-bool RenderLayerBacking::updateClippingLayers(bool needsAncestorClip, bool needsDescendantClip)
+bool RenderLayerBacking::updateClippingLayers(bool needsAncestorClip, bool needsDescendantClip, bool needsScrollClip)
 {
     bool layersChanged = false;
 
     if (needsAncestorClip) {
         if (!m_ancestorClippingLayer) {
             m_ancestorClippingLayer = createGraphicsLayer(CompositingReasonLayerForClip);
             m_ancestorClippingLayer->setMasksToBounds(true);
             layersChanged = true;
         }
     } else if (m_ancestorClippingLayer) {
         m_ancestorClippingLayer->removeFromParent();
         m_ancestorClippingLayer = nullptr;
         layersChanged = true;
     }
 
     if (needsDescendantClip) {
         // We don't need a child containment layer if we're the main frame render view
         // layer. It's redundant as the frame clip above us will handle this clipping.
         if (!m_childContainmentLayer && !m_isMainFrameRenderViewLayer) {
             m_childContainmentLayer = createGraphicsLayer(CompositingReasonLayerForClip);
             m_childContainmentLayer->setMasksToBounds(true);
             layersChanged = true;
         }
     } else if (hasClippingLayer()) {
         m_childContainmentLayer->removeFromParent();
         m_childContainmentLayer = nullptr;
         layersChanged = true;
     }
 
+    if (needsScrollClip) {
+        if (!m_ancestorScrollClippingLayer) {
+            m_ancestorScrollClippingLayer = createGraphicsLayer(CompositingReasonLayerForClip);
+            m_ancestorScrollClippingLayer->setMasksToBounds(true);
+            layersChanged = true;
+        }
+    } else if (m_ancestorScrollClippingLayer) {
+        m_ancestorScrollClippingLayer->removeFromParent();
+        m_ancestorScrollClippingLayer = nullptr;
+        layersChanged = true;
+    }
+
     return layersChanged;
 }
 
 void RenderLayerBacking::setBackgroundLayerPaintsFixedRootBackground(bool backgroundLayerPaintsFixedRootBackground)
 {
     m_backgroundLayerPaintsFixedRootBackground = backgroundLayerPaintsFixedRootBackground;
 }
 
 bool RenderLayerBacking::updateOverflowControlsLayers(bool needsHorizontalScrollbarLayer, bool needsVerticalScrollbarLayer, bool needsScrollCornerLayer)
 {
@@ skipping 202 matching lines @@
         updateInternalHierarchy();
         m_graphicsLayer->setPaintingPhase(paintingPhaseForPrimaryLayer());
         m_graphicsLayer->setNeedsDisplay();
         if (renderer()->view())
             compositor()->scrollingLayerDidChange(m_owningLayer);
     }
 
     return layerChanged;
 }
 
+void RenderLayerBacking::updateScrollParent(RenderLayer* scrollParent)
+{
+    if (ScrollingCoordinator* scrollingCoordinator = scrollingCoordinatorFromLayer(m_owningLayer))
+        scrollingCoordinator->updateScrollParentForLayer(m_owningLayer, scrollParent);
+}
+
+void RenderLayerBacking::updateClipParent(RenderLayer* clipParent)
+{
+    if (ScrollingCoordinator* scrollingCoordinator = scrollingCoordinatorFromLayer(m_owningLayer))
+        scrollingCoordinator->updateClipParentForLayer(m_owningLayer, clipParent);
+}
+
 GraphicsLayerPaintingPhase RenderLayerBacking::paintingPhaseForPrimaryLayer() const
 {
     unsigned phase = 0;
     if (!m_backgroundLayer)
         phase |= GraphicsLayerPaintBackground;
     if (!m_foregroundLayer)
         phase |= GraphicsLayerPaintForeground;
     if (!m_maskLayer)
         phase |= GraphicsLayerPaintMask;
 
     if (m_scrollingContentsLayer) {
         phase &= ~GraphicsLayerPaintForeground;
         phase |= GraphicsLayerPaintCompositedScroll;
     }
 
+    if (m_owningLayer->compositingReasons() & CompositingReasonOverflowScrollingParent)
+        phase |= GraphicsLayerPaintCompositedScroll;
+
     return static_cast<GraphicsLayerPaintingPhase>(phase);
 }
 
 float RenderLayerBacking::compositingOpacity(float rendererOpacity) const
 {
     float finalOpacity = rendererOpacity;
 
     for (RenderLayer* curr = m_owningLayer->parent(); curr; curr = curr->parent()) {
         // We only care about parents that are stacking contexts.
         // Recall that opacity creates stacking context.
@@ skipping 317 matching lines @@
 GraphicsLayer* RenderLayerBacking::parentForSublayers() const
 {
     if (m_scrollingContentsLayer)
         return m_scrollingContentsLayer.get();
 
     return m_childContainmentLayer ? m_childContainmentLayer.get() : m_graphicsLayer.get();
 }
 
 GraphicsLayer* RenderLayerBacking::childForSuperlayers() const
 {
+    if (m_ancestorScrollClippingLayer)
+        return m_ancestorScrollClippingLayer.get();
+
     if (m_ancestorClippingLayer)
         return m_ancestorClippingLayer.get();
 
     return m_graphicsLayer.get();
 }
 
 void RenderLayerBacking::setRequiresOwnBackingStore(bool requiresOwnBacking)
 {
     if (requiresOwnBacking == m_requiresOwnBackingStore)
         return;
@@ skipping 446 matching lines @@
         backingMemory += m_layerForScrollCorner->backingStoreMemoryEstimate();
 
     return backingMemory;
 }
 
 String RenderLayerBacking::debugName(const GraphicsLayer* graphicsLayer)
 {
     String name;
     if (graphicsLayer == m_graphicsLayer.get()) {
         name = m_owningLayer->debugName();
+    } else if (graphicsLayer == m_ancestorScrollClippingLayer.get()) {
+        name = "Ancestor Scroll Clipping Layer";
     } else if (graphicsLayer == m_ancestorClippingLayer.get()) {
         name = "Ancestor Clipping Layer";
     } else if (graphicsLayer == m_foregroundLayer.get()) {
         name = m_owningLayer->debugName() + " (foreground) Layer";
     } else if (graphicsLayer == m_backgroundLayer.get()) {
         name = m_owningLayer->debugName() + " (background) Layer";
     } else if (graphicsLayer == m_childContainmentLayer.get()) {
         name = "Child Containment Layer";
     } else if (graphicsLayer == m_maskLayer.get()) {
         name = "Mask Layer";
     } else if (graphicsLayer == m_layerForHorizontalScrollbar.get()) {
         name = "Horizontal Scrollbar Layer";
     } else if (graphicsLayer == m_layerForVerticalScrollbar.get()) {
         name = "Vertical Scrollbar Layer";
     } else if (graphicsLayer == m_layerForScrollCorner.get()) {
         name = "Scroll Corner Layer";
     } else if (graphicsLayer == m_scrollingLayer.get()) {
         name = "Scrolling Layer";
     } else if (graphicsLayer == m_scrollingContentsLayer.get()) {
         name = "Scrolling Contents Layer";
     } else {
         ASSERT_NOT_REACHED();
     }
 
     return name;
 }
 
 } // namespace WebCore