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Unified Diff: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp

Issue 2196583002: Paint local background colors onto foreground layer. (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Incorporate test related cleanups and comments. Created 4 years, 4 months ago
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Index: third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
diff --git a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
index 51159637bc5b210ce7b76982670cd289db156338..09ceb1c33c1b3f76d88ed56428c73b8a96ab7cc8 100644
--- a/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
+++ b/third_party/WebKit/Source/core/layout/compositing/CompositedLayerMapping.cpp
@@ -309,8 +309,22 @@ void CompositedLayerMapping::updateContentsOpaque()
m_graphicsLayer->setContentsOpaque(false);
m_backgroundLayer->setContentsOpaque(m_owningLayer.backgroundIsKnownToBeOpaqueInRect(compositedBounds()));
} else {
- // For non-root layers, background is always painted by the primary graphics layer.
- m_graphicsLayer->setContentsOpaque(m_owningLayer.backgroundIsKnownToBeOpaqueInRect(compositedBounds()));
+ // 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()) {
+ // 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);
+ } else {
+ m_graphicsLayer->setContentsOpaque(m_owningLayer.backgroundIsKnownToBeOpaqueInRect(compositedBounds()));
+ }
}
}
@@ -2413,6 +2427,8 @@ void CompositedLayerMapping::paintContents(const GraphicsLayer* graphicsLayer, G
PaintLayerFlags paintLayerFlags = 0;
if (graphicsLayerPaintingPhase & GraphicsLayerPaintBackground)
paintLayerFlags |= PaintLayerPaintingCompositingBackgroundPhase;
+ else
+ paintLayerFlags |= PaintLayerPaintingSkipRootBackground;
if (graphicsLayerPaintingPhase & GraphicsLayerPaintForeground)
paintLayerFlags |= PaintLayerPaintingCompositingForegroundPhase;
if (graphicsLayerPaintingPhase & GraphicsLayerPaintMask)
@@ -2426,7 +2442,7 @@ void CompositedLayerMapping::paintContents(const GraphicsLayer* graphicsLayer, G
if (graphicsLayer == m_backgroundLayer.get())
paintLayerFlags |= (PaintLayerPaintingRootBackgroundOnly | PaintLayerPaintingCompositingForegroundPhase); // Need PaintLayerPaintingCompositingForegroundPhase to walk child layers.
- else if (compositor()->fixedRootBackgroundLayer())
+ else if (compositor()->fixedRootBackgroundLayer() && m_owningLayer.isRootLayer())
paintLayerFlags |= PaintLayerPaintingSkipRootBackground;
if (graphicsLayer == m_graphicsLayer.get()
@@ -2436,6 +2452,14 @@ void CompositedLayerMapping::paintContents(const GraphicsLayer* graphicsLayer, G
|| graphicsLayer == m_childClippingMaskLayer.get()
|| graphicsLayer == m_scrollingContentsLayer.get()) {
+ bool paintRootBackgroundOntoScrollingContentsLayer = 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();
@@ -2547,6 +2571,19 @@ bool CompositedLayerMapping::invalidateLayerIfNoPrecedingEntry(size_t indexToCle
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;

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