Attachment 369561 Details for Bug 197692 – WIP

[patch] WIP

bug-197692-20190510101719.patch (text/plain), 23.49 KB, created by Simon Fraser (smfr) on 2019-05-10 10:17:20 PDT

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Creator: Simon Fraser (smfr)

Created: 2019-05-10 10:17:20 PDT

Size: 23.49 KB

patch

obsolete

>Subversion Revision: 245170
>diff --git a/Source/WebCore/ChangeLog b/Source/WebCore/ChangeLog
>index 8cb18e7da7c75fd08039c7e663e741ed20889016..b9262b8b069fa293d7a9584aab537b8784cd82c3 100644
>--- a/Source/WebCore/ChangeLog
>+++ b/Source/WebCore/ChangeLog
>@@ -1,3 +1,32 @@
>+2019-05-09  Simon Fraser  <simon.fraser@apple.com>
>+
>+        Backing-sharing layers with transforms render incorrectly
>+        https://bugs.webkit.org/show_bug.cgi?id=197692
>+        <rdar://problem/50652127>
>+
>+        Reviewed by NOBODY (OOPS!).
>+        
>+        When layers that paint into shared backing have effects (transform, filter, opacity), we need
>+        to paint with those effects. That's different from the primary layer, whose effects are normally
>+        mapped to GraphicsLayer properties. (Note that if the primary layer has an effect, that effect will create
>+        stacking context, so descendants will also become z-order descendants and there's no need to do sharing.)
>+
>+        For some reason reflection painting is broken, so just disable sharing in that case.
>+
>+        Tests: compositing/shared-backing/shared-layer-has-filter.html
>+               compositing/shared-backing/shared-layer-has-opacity.html
>+               compositing/shared-backing/shared-layer-has-reflection.html
>+               compositing/shared-backing/shared-layer-has-transform.html
>+
>+        * rendering/RenderLayer.cpp:
>+        (WebCore::RenderLayer::paintLayer):
>+        (WebCore::RenderLayer::paintLayerWithEffects):
>+        * rendering/RenderLayer.h:
>+        * rendering/RenderLayerBacking.cpp:
>+        (WebCore::RenderLayerBacking::paintIntoLayer):
>+        * rendering/RenderLayerCompositor.cpp:
>+        (WebCore::backingProviderLayerCanIncludeLayer):
>+
> 2019-05-09  Simon Fraser  <simon.fraser@apple.com>
> 
>         Implement backing-sharing in compositing layers, allowing overlap layers to paint into the backing store of another layer
>diff --git a/Source/WebCore/platform/Logging.cpp b/Source/WebCore/platform/Logging.cpp
>index 899141ce0d39d4151450cf4e1632cdb4ca85af97..e48fc645355401d3938e26a5c8adbe8130b34e0b 100644
>--- a/Source/WebCore/platform/Logging.cpp
>+++ b/Source/WebCore/platform/Logging.cpp
>@@ -78,6 +78,7 @@ void initializeLogChannelsIfNecessary(Optional<String> logChannelString)
> 
>     String enabledChannelsString = logChannelString ? logChannelString.value() : logLevelString();
>     WTFInitializeLogChannelStatesFromString(logChannels, logChannelCount, enabledChannelsString.utf8().data());
>+    LogCompositing.state = WTFLogChannelState::On;
> }
> 
> WTFLogChannel* getLogChannel(const String& name)
>diff --git a/Source/WebCore/platform/graphics/GraphicsContext.h b/Source/WebCore/platform/graphics/GraphicsContext.h
>index 1c366d51cbd74d0bcedec5790df2ed71aacc7a96..964598b4a414ca808bdcac7b019cae8b32a35ee8 100644
>--- a/Source/WebCore/platform/graphics/GraphicsContext.h
>+++ b/Source/WebCore/platform/graphics/GraphicsContext.h
>@@ -348,6 +348,8 @@ public:
> 
>     WEBCORE_EXPORT void save();
>     WEBCORE_EXPORT void restore();
>+    
>+    unsigned stackSize() const { return m_stack.size(); }
> 
>     // These draw methods will do both stroking and filling.
>     // FIXME: ...except drawRect(), which fills properly but always strokes
>@@ -686,6 +688,27 @@ private:
>     bool m_saveAndRestore;
> };
> 
>+
>+class GraphicsContextStateStackChecker {
>+public:
>+    GraphicsContextStateStackChecker(GraphicsContext& context)
>+        : m_context(context)
>+        , m_stackSize(context.stackSize())
>+    { }
>+    
>+    ~GraphicsContextStateStackChecker()
>+    {
>+        if (m_context.stackSize() != m_stackSize)
>+            WTFLogAlways("GraphicsContext %p stack changed by %d", this, (int)m_context.stackSize() - (int)m_stackSize);
>+    }
>+
>+private:
>+    GraphicsContext& m_context;
>+    unsigned m_stackSize;
>+};
>+
>+
>+
> class InterpolationQualityMaintainer {
> public:
>     explicit InterpolationQualityMaintainer(GraphicsContext& graphicsContext, InterpolationQuality interpolationQualityToUse)
>diff --git a/Source/WebCore/rendering/RenderLayer.cpp b/Source/WebCore/rendering/RenderLayer.cpp
>index a25dbd1abb909e84c6fe51b68ed414c7129da324..9901d46da10e3bc0a62c5df79d84420c15b10f39 100644
>--- a/Source/WebCore/rendering/RenderLayer.cpp
>+++ b/Source/WebCore/rendering/RenderLayer.cpp
>@@ -2056,6 +2056,8 @@ void RenderLayer::beginTransparencyLayers(GraphicsContext& context, const LayerP
>         ancestor->beginTransparencyLayers(context, paintingInfo, dirtyRect);
>     
>     if (paintsWithTransparency(paintingInfo.paintBehavior)) {
>+    
>+        WTFLogAlways("RenderLayer %p beginTransparencyLayers", this);
>         ASSERT(isCSSStackingContext());
>         m_usedTransparency = true;
>         context.save();
>@@ -4100,26 +4102,39 @@ void RenderLayer::paintLayer(GraphicsContext& context, const LayerPaintingInfo&
>         return;
>     }
> 
>+    paintLayerWithEffects(context, paintingInfo, paintFlags);
>+}
>+
>+void RenderLayer::paintLayerWithEffects(GraphicsContext& context, const LayerPaintingInfo& paintingInfo, OptionSet<PaintLayerFlag> paintFlags)
>+{
>+    GraphicsContextStateStackChecker checker(context);
>+
>     // Non self-painting leaf layers don't need to be painted as their renderer() should properly paint itself.
>     if (!isSelfPaintingLayer() && !hasSelfPaintingLayerDescendant())
>         return;
> 
>     if (shouldSuppressPaintingLayer(this))
>         return;
>-    
>+
>     // If this layer is totally invisible then there is nothing to paint.
>     if (!renderer().opacity())
>         return;
> 
>+    WTFLogAlways("-> RenderLayer %p paintLayerWithEffects (paints with transparency %d)", this, paintsWithTransparency(paintingInfo.paintBehavior));
>+
>     if (paintsWithTransparency(paintingInfo.paintBehavior))
>         paintFlags.add(PaintLayerHaveTransparency);
> 
>     // PaintLayerAppliedTransform is used in RenderReplica, to avoid applying the transform twice.
>     if (paintsWithTransform(paintingInfo.paintBehavior) && !(paintFlags & PaintLayerAppliedTransform)) {
>+        GraphicsContextStateStackChecker transformChecker(context);
>+
>         TransformationMatrix layerTransform = renderableTransform(paintingInfo.paintBehavior);
>         // If the transform can't be inverted, then don't paint anything.
>-        if (!layerTransform.isInvertible())
>+        if (!layerTransform.isInvertible()) {
>+            WTFLogAlways("<- RenderLayer %p paintLayerWithEffects 1", this);
>             return;
>+        }
> 
>         // If we have a transparency layer enclosing us and we are the root of a transform, then we need to establish the transparency
>         // layer from the parent now, assuming there is a parent
>@@ -4132,6 +4147,7 @@ void RenderLayer::paintLayer(GraphicsContext& context, const LayerPaintingInfo&
> 
>         if (enclosingPaginationLayer(ExcludeCompositedPaginatedLayers)) {
>             paintTransformedLayerIntoFragments(context, paintingInfo, paintFlags);
>+            WTFLogAlways("<- RenderLayer %p paintLayerWithEffects 2", this);
>             return;
>         }
> 
>@@ -4153,10 +4169,13 @@ void RenderLayer::paintLayer(GraphicsContext& context, const LayerPaintingInfo&
>         if (parent())
>             parent()->restoreClip(context, paintingInfo, clipRect);
> 
>+        WTFLogAlways("<- RenderLayer %p paintLayerWithEffects 3", this);
>         return;
>     }
>     
>     paintLayerContentsAndReflection(context, paintingInfo, paintFlags);
>+
>+    WTFLogAlways("<- RenderLayer %p paintLayerWithEffects", this);
> }
> 
> void RenderLayer::paintLayerContentsAndReflection(GraphicsContext& context, const LayerPaintingInfo& paintingInfo, OptionSet<PaintLayerFlag> paintFlags)
>@@ -4549,7 +4568,9 @@ void RenderLayer::paintLayerContents(GraphicsContext& context, const LayerPainti
>     }
> 
>     // End our transparency layer
>+    WTFLogAlways("RenderLayer %p may endTransparencyLayer - haveTransparency %d, m_usedTransparency %d", this, haveTransparency, m_usedTransparency);
>     if (haveTransparency && m_usedTransparency && !m_paintingInsideReflection) {
>+        WTFLogAlways("RenderLayer %p endTransparencyLayer", this);
>         context.endTransparencyLayer();
>         context.restore();
>         m_usedTransparency = false;
>@@ -4565,6 +4586,9 @@ void RenderLayer::paintLayerContents(GraphicsContext& context, const LayerPainti
> 
> void RenderLayer::paintLayerByApplyingTransform(GraphicsContext& context, const LayerPaintingInfo& paintingInfo, OptionSet<PaintLayerFlag> paintFlags, const LayoutSize& translationOffset)
> {
>+    WTFLogAlways("-> RenderLayer %p paintLayerByApplyingTransform", this);
>+    GraphicsContextStateStackChecker checker(context);
>+
>     // This involves subtracting out the position of the layer in our current coordinate space, but preserving
>     // the accumulated error for sub-pixel layout.
>     float deviceScaleFactor = renderer().document().deviceScaleFactor();
>@@ -4590,6 +4614,8 @@ void RenderLayer::paintLayerByApplyingTransform(GraphicsContext& context, const
>     transformedPaintingInfo.subpixelOffset = adjustedSubpixelOffset;
>     paintLayerContentsAndReflection(context, transformedPaintingInfo, paintFlags);
>     context.setCTM(oldTransfrom);
>+
>+    WTFLogAlways("<- RenderLayer %p paintLayerByApplyingTransform", this);
> }
> 
> void RenderLayer::paintList(LayerList layerIterator, GraphicsContext& context, const LayerPaintingInfo& paintingInfo, OptionSet<PaintLayerFlag> paintFlags)
>diff --git a/Source/WebCore/rendering/RenderLayer.h b/Source/WebCore/rendering/RenderLayer.h
>index da4beb9ac9850608552fafafe7bda20af019ad1b..22be9bcbbfe02dedc4bc25caaada73466ad62756 100644
>--- a/Source/WebCore/rendering/RenderLayer.h
>+++ b/Source/WebCore/rendering/RenderLayer.h
>@@ -1003,6 +1003,8 @@ private:
>     void applyFilters(GraphicsContext& originalContext, const LayerPaintingInfo&, const LayerFragments&);
> 
>     void paintLayer(GraphicsContext&, const LayerPaintingInfo&, OptionSet<PaintLayerFlag>);
>+    void paintLayerWithEffects(GraphicsContext&, const LayerPaintingInfo&, OptionSet<PaintLayerFlag>);
>+
>     void paintLayerContentsAndReflection(GraphicsContext&, const LayerPaintingInfo&, OptionSet<PaintLayerFlag>);
>     void paintLayerByApplyingTransform(GraphicsContext&, const LayerPaintingInfo&, OptionSet<PaintLayerFlag>, const LayoutSize& translationOffset = LayoutSize());
>     void paintLayerContents(GraphicsContext&, const LayerPaintingInfo&, OptionSet<PaintLayerFlag>);
>diff --git a/Source/WebCore/rendering/RenderLayerBacking.cpp b/Source/WebCore/rendering/RenderLayerBacking.cpp
>index 0ed800cf919112e1da9806f86b4dcb74ef101718..7c71cc35eb741fca797dd4de06e7a340f8de4e51 100644
>--- a/Source/WebCore/rendering/RenderLayerBacking.cpp
>+++ b/Source/WebCore/rendering/RenderLayerBacking.cpp
>@@ -2659,16 +2659,21 @@ void RenderLayerBacking::paintIntoLayer(const GraphicsLayer* graphicsLayer, Grap
>     auto paintOneLayer = [&](RenderLayer& layer, OptionSet<RenderLayer::PaintLayerFlag> paintFlags) {
>         InspectorInstrumentation::willPaint(layer.renderer());
> 
>+        GraphicsContextStateStackChecker checker(context);
>+
>         FrameView::PaintingState paintingState;
>         if (layer.isRenderViewLayer())
>             renderer().view().frameView().willPaintContents(context, paintDirtyRect, paintingState);
> 
>         RenderLayer::LayerPaintingInfo paintingInfo(&m_owningLayer, paintDirtyRect, paintBehavior, -m_subpixelOffsetFromRenderer);
> 
>-        layer.paintLayerContents(context, paintingInfo, paintFlags);
>+        if (&layer == &m_owningLayer) {
>+            layer.paintLayerContents(context, paintingInfo, paintFlags);
> 
>-        if (layer.containsDirtyOverlayScrollbars())
>-            layer.paintLayerContents(context, paintingInfo, paintFlags | RenderLayer::PaintLayerPaintingOverlayScrollbars);
>+            if (layer.containsDirtyOverlayScrollbars())
>+                layer.paintLayerContents(context, paintingInfo, paintFlags | RenderLayer::PaintLayerPaintingOverlayScrollbars);
>+        } else
>+            layer.paintLayerWithEffects(context, paintingInfo, paintFlags);
> 
>         if (layer.isRenderViewLayer())
>             renderer().view().frameView().didPaintContents(context, paintDirtyRect, paintingState);
>diff --git a/Source/WebCore/rendering/RenderLayerCompositor.cpp b/Source/WebCore/rendering/RenderLayerCompositor.cpp
>index e3a4c9f3f87abeb4ebe4024fec1e69ac51648d36..a2348ff1a7e327c23d28362939a7c351c0ca07be 100644
>--- a/Source/WebCore/rendering/RenderLayerCompositor.cpp
>+++ b/Source/WebCore/rendering/RenderLayerCompositor.cpp
>@@ -860,6 +860,9 @@ bool RenderLayerCompositor::updateCompositingLayers(CompositingUpdateType update
> 
> static bool backingProviderLayerCanIncludeLayer(const RenderLayer& sharedLayer, const RenderLayer& layer)
> {
>+    // Disable sharing when painting shared layers doesn't work correctly.
>+    if (layer.hasReflection())
>+        return false;
>     return layer.ancestorLayerIsInContainingBlockChain(sharedLayer);
> }
> 
>diff --git a/LayoutTests/ChangeLog b/LayoutTests/ChangeLog
>index 72cecf98bb49ee8e208906cf95b381f17c2d678d..4806f21612dd20a66749e051f8a81f549c330b65 100644
>--- a/LayoutTests/ChangeLog
>+++ b/LayoutTests/ChangeLog
>@@ -1,3 +1,20 @@
>+2019-05-09  Simon Fraser  <simon.fraser@apple.com>
>+
>+        Backing-sharing layers with transforms render incorrectly
>+        https://bugs.webkit.org/show_bug.cgi?id=197692
>+        <rdar://problem/50652127>
>+
>+        Reviewed by NOBODY (OOPS!).
>+
>+        * compositing/shared-backing/shared-layer-has-filter-expected.html: Added.
>+        * compositing/shared-backing/shared-layer-has-filter.html: Added.
>+        * compositing/shared-backing/shared-layer-has-opacity-expected.html: Added.
>+        * compositing/shared-backing/shared-layer-has-opacity.html: Added.
>+        * compositing/shared-backing/shared-layer-has-reflection-expected.html: Added.
>+        * compositing/shared-backing/shared-layer-has-reflection.html: Added.
>+        * compositing/shared-backing/shared-layer-has-transform-expected.html: Added.
>+        * compositing/shared-backing/shared-layer-has-transform.html: Added.
>+
> 2019-05-09  Simon Fraser  <simon.fraser@apple.com>
> 
>         Implement backing-sharing in compositing layers, allowing overlap layers to paint into the backing store of another layer
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-filter-expected.html b/LayoutTests/compositing/shared-backing/shared-layer-has-filter-expected.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..55828317fca87f46603428e80d7ad0fe13d69ae4
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-filter-expected.html
>@@ -0,0 +1,35 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a filtered layer into shared backing</title>
>+    <style>
>+        .scrollable {
>+            position: relative;
>+            z-index: 0;
>+            overflow-y: scroll;
>+            height: 300px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            width: 200px;
>+            height: 200px;
>+            background-color: magenta;
>+            filter: hue-rotate(0.5turn);
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+    </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-filter.html b/LayoutTests/compositing/shared-backing/shared-layer-has-filter.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..40713897176abb1b24b09aea227c71aa012533ed
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-filter.html
>@@ -0,0 +1,33 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a filtered layer into shared backing</title>
>+    <style>
>+        .scrollable {
>+            overflow-y: scroll;
>+            height: 300px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            width: 200px;
>+            height: 200px;
>+            background-color: magenta;
>+            filter: hue-rotate(0.5turn);
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+    </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-opacity-expected.html b/LayoutTests/compositing/shared-backing/shared-layer-has-opacity-expected.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..74c6a3303ce9ebef9d52382a9e19a34b3acf470b
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-opacity-expected.html
>@@ -0,0 +1,35 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a layer with opacity into shared backing</title>
>+    <style>
>+        .scrollable {
>+            position: relative;
>+            z-index: 0;
>+            overflow-y: scroll;
>+            height: 300px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            width: 200px;
>+            height: 200px;
>+            background-color: green;
>+            opacity: 0.5;
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+    </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-opacity.html b/LayoutTests/compositing/shared-backing/shared-layer-has-opacity.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..1abf4e48c3bd300387a2bdef48a4c2bd439a1448
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-opacity.html
>@@ -0,0 +1,33 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a layer with opacity into shared backing</title>
>+    <style>
>+        .scrollable {
>+            overflow-y: scroll;
>+            height: 300px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            width: 200px;
>+            height: 200px;
>+            background-color: green;
>+            opacity: 0.5;
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+    </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-reflection-expected.html b/LayoutTests/compositing/shared-backing/shared-layer-has-reflection-expected.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..4eefd643fb9d4b9572f36742007ecd9822a08669
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-reflection-expected.html
>@@ -0,0 +1,37 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a reflected layer into shared backing</title>
>+    <style>
>+        .scrollable {
>+            position: relative;
>+            z-index: 0;
>+            overflow-y: scroll;
>+            height: 400px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            margin: 20px;
>+            width: 150px;
>+            height: 130px;
>+            background-color: green;
>+            border-bottom: 20px solid orange;
>+            -webkit-box-reflect: below 10px;
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+        </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-reflection.html b/LayoutTests/compositing/shared-backing/shared-layer-has-reflection.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..f584d9ef1a5f3619d88f9e6588b50d1eb3e06d44
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-reflection.html
>@@ -0,0 +1,35 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a reflected layer into shared backing</title>
>+    <style>
>+        .scrollable {
>+            overflow-y: scroll;
>+            height: 400px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            margin: 20px;
>+            width: 150px;
>+            height: 130px;
>+            background-color: green;
>+            border-bottom: 20px solid orange;
>+            -webkit-box-reflect: below 10px;
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+        </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-transform-expected.html b/LayoutTests/compositing/shared-backing/shared-layer-has-transform-expected.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..daccda1b77fc43489e372c97b892ec0b63920b41
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-transform-expected.html
>@@ -0,0 +1,36 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a transformed layer into shared backing</title>
>+    <style>
>+        .scrollable {
>+            position: relative;
>+            z-index: 0;
>+            overflow-y: scroll;
>+            height: 300px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            width: 100px;
>+            height: 100px;
>+            background-color: green;
>+            transform: scale(2);
>+            transform-origin: top left;
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+    </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>
>diff --git a/LayoutTests/compositing/shared-backing/shared-layer-has-transform.html b/LayoutTests/compositing/shared-backing/shared-layer-has-transform.html
>new file mode 100644
>index 0000000000000000000000000000000000000000..7a45c9151b5eb1e0308da5e2d3f9172d054f41dc
>--- /dev/null
>+++ b/LayoutTests/compositing/shared-backing/shared-layer-has-transform.html
>@@ -0,0 +1,34 @@
>+<!DOCTYPE html> 
>+<html>
>+<head>
>+    <title>Tests painting of a transformed layer into shared backing</title>
>+    <style>
>+        .scrollable {
>+            overflow-y: scroll;
>+            height: 300px;
>+            width: 300px;
>+            margin: 10px;
>+            border: 1px solid black;
>+        }
>+
>+        .sharing {
>+            width: 100px;
>+            height: 100px;
>+            background-color: green;
>+            transform: scale(2);
>+            transform-origin: top left;
>+        }
>+    
>+        .spacer {
>+            height: 500px;
>+        }
>+    </style>
>+</head>
>+<body>
>+    <div class="scrollable">
>+        <div class="sharing">
>+        </div>
>+        <div class="spacer"></div>
>+    </div>
>+</body>
>+</html>

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Attachments on bug 197692: 369544 | 369561 | 369637 | 369638 | 369639 | 369641 | 369642 | 369643 | 369644 | 369645 | 369646 | 369647 | 369652