Bug 1360246 - Remove the RelativeToParent functions by propagating StackingContextHelper chains. r=nical

The only remaining callers of RelativeToParent() are in
StackingContextHelper itself, which we can remove now by having the SCH
take a parent SCH and use it instead of RelativeToParent(). This patch
implements this change.

This makes a failing test pass, because of how preserve-3d container
layers work. Specifically, preserve-3d container layers render their
descendants in z-order, not in tree order. If those children were assuming
that their parent had already pushed a stacking context, that assumption
may have been false because the parent might have not yet been rendered
because of z-ordering. By using the StackingContextHelper chain instead
of the layer tree ancestry, we fix the stacking-context-relative coordinates
being used in the descendant subtree of preserve-3d container layers.

MozReview-Commit-ID: HzZvBuAlMdB

gfx/layers/wr/StackingContextHelper.cpp

@@ -17,30 +17,32 @@ StackingContextHelper::StackingContextHelper()
   // mOrigin remains at 0,0
 }
 
-StackingContextHelper::StackingContextHelper(wr::DisplayListBuilder& aBuilder,
+StackingContextHelper::StackingContextHelper(const StackingContextHelper& aParentSC,
+                                             wr::DisplayListBuilder& aBuilder,
                                              WebRenderLayer* aLayer,
                                              const Maybe<gfx::Matrix4x4>& aTransform)
   : mBuilder(&aBuilder)
 {
-  LayerRect scBounds = aLayer->RelativeToParent(aLayer->BoundsForStackingContext());
+  LayerRect scBounds = aLayer->BoundsForStackingContext();
   Layer* layer = aLayer->GetLayer();
   gfx::Matrix4x4 transform = aTransform.valueOr(layer->GetTransform());
-  mBuilder->PushStackingContext(wr::ToWrRect(scBounds),
+  mBuilder->PushStackingContext(aParentSC.ToRelativeWrRect(scBounds),
                                 1.0f,
                                 transform,
                                 wr::ToWrMixBlendMode(layer->GetMixBlendMode()));
   mOrigin = aLayer->Bounds().TopLeft();
 }
 
-StackingContextHelper::StackingContextHelper(wr::DisplayListBuilder& aBuilder,
+StackingContextHelper::StackingContextHelper(const StackingContextHelper& aParentSC,
+                                             wr::DisplayListBuilder& aBuilder,
                                              WebRenderLayer* aLayer,
                                              uint64_t aAnimationsId,
                                              float* aOpacityPtr,
                                              gfx::Matrix4x4* aTransformPtr)
   : mBuilder(&aBuilder)
 {
-  LayerRect scBounds = aLayer->RelativeToParent(aLayer->BoundsForStackingContext());
+  LayerRect scBounds = aLayer->BoundsForStackingContext();
-  mBuilder->PushStackingContext(wr::ToWrRect(scBounds),
+  mBuilder->PushStackingContext(aParentSC.ToRelativeWrRect(scBounds),
                                 aAnimationsId,
                                 aOpacityPtr,
                                 aTransformPtr,

gfx/layers/wr/StackingContextHelper.h

@@ -28,12 +28,14 @@ public:
   // the transform if provided, otherwise takes the transform from the layer.
   // It also takes the mix-blend-mode and bounds from the layer, and uses 1.0
   // for the opacity.
-  StackingContextHelper(wr::DisplayListBuilder& aBuilder,
+  StackingContextHelper(const StackingContextHelper& aParentSC,
+                        wr::DisplayListBuilder& aBuilder,
                         WebRenderLayer* aLayer,
                         const Maybe<gfx::Matrix4x4>& aTransform = Nothing());
   // Alternate constructor which invokes the version of PushStackingContext
   // for animations.
-  StackingContextHelper(wr::DisplayListBuilder& aBuilder,
+  StackingContextHelper(const StackingContextHelper& aParentSC,
+                        wr::DisplayListBuilder& aBuilder,
                         WebRenderLayer* aLayer,
                         uint64_t aAnimationsId,
                         float* aOpacityPtr,

gfx/layers/wr/WebRenderCanvasLayer.cpp

@@ -62,7 +62,7 @@ WebRenderCanvasLayer::RenderLayer(wr::DisplayListBuilder& aBuilder,
     transform = Some(GetTransform().PreTranslate(0, mBounds.height, 0).PreScale(1, -1, 1));
   }
 
-  StackingContextHelper sc(aBuilder, this, transform);
+  StackingContextHelper sc(aSc, aBuilder, this, transform);
 
   LayerRect rect(0, 0, mBounds.width, mBounds.height);
   DumpLayerInfo("CanvasLayer", rect);

gfx/layers/wr/WebRenderColorLayer.cpp

@@ -21,7 +21,7 @@ void
 WebRenderColorLayer::RenderLayer(wr::DisplayListBuilder& aBuilder,
                                  const StackingContextHelper& aSc)
 {
-  StackingContextHelper sc(aBuilder, this);
+  StackingContextHelper sc(aSc, aBuilder, this);
 
   LayerRect rect = Bounds();
   DumpLayerInfo("ColorLayer", rect);

gfx/layers/wr/WebRenderContainerLayer.cpp

@@ -88,7 +88,7 @@ WebRenderContainerLayer::RenderLayer(wr::DisplayListBuilder& aBuilder,
     WrBridge()->AddWebRenderParentCommand(anim);
   }
 
-  StackingContextHelper sc(aBuilder, this, animationsId, opacityForSC, transformForSC);
+  StackingContextHelper sc(aSc, aBuilder, this, animationsId, opacityForSC, transformForSC);
 
   LayerRect rect = Bounds();
   DumpLayerInfo("ContainerLayer", rect);

gfx/layers/wr/WebRenderImageLayer.cpp

@@ -165,7 +165,7 @@ WebRenderImageLayer::RenderLayer(wr::DisplayListBuilder& aBuilder,
     return;
   }
 
-  StackingContextHelper sc(aBuilder, this);
+  StackingContextHelper sc(aSc, aBuilder, this);
 
   LayerRect rect(0, 0, size.width, size.height);
   if (mScaleMode != ScaleMode::SCALE_NONE) {

gfx/layers/wr/WebRenderLayer.cpp

@@ -51,19 +51,6 @@ WebRenderLayer::ParentBounds()
   return LayerRect();
 }
 
-LayerRect
-WebRenderLayer::RelativeToParent(const LayerRect& aRect)
-{
-  return aRect - ParentBounds().TopLeft();
-}
-
-LayerRect
-WebRenderLayer::RelativeToParent(const LayoutDeviceRect& aRect)
-{
-  return RelativeToParent(ViewAs<LayerPixel>(
-      aRect, PixelCastJustification::WebRenderHasUnitResolution));
-}
-
 gfx::Rect
 WebRenderLayer::TransformedVisibleBoundsRelativeToParent()
 {

gfx/layers/wr/WebRenderLayer.h

@@ -48,9 +48,6 @@ public:
   WebRenderBridgeChild* WrBridge();
   WrImageKey GetImageKey();
 
-  LayerRect RelativeToParent(const LayerRect& aRect);
-  LayerRect RelativeToParent(const LayoutDeviceRect& aRect);
-
   LayerRect Bounds();
   LayerRect BoundsForStackingContext();
 protected:

gfx/layers/wr/WebRenderPaintedLayer.cpp

@@ -89,9 +89,10 @@ WebRenderPaintedLayer::UpdateImageClient()
 }
 
 void
-WebRenderPaintedLayer::CreateWebRenderDisplayList(wr::DisplayListBuilder& aBuilder)
+WebRenderPaintedLayer::CreateWebRenderDisplayList(wr::DisplayListBuilder& aBuilder,
+                                                  const StackingContextHelper& aSc)
 {
-  StackingContextHelper sc(aBuilder, this);
+  StackingContextHelper sc(aSc, aBuilder, this);
 
   LayerRect rect = Bounds();
   DumpLayerInfo("PaintedLayer", rect);
@@ -145,7 +146,7 @@ WebRenderPaintedLayer::RenderLayer(wr::DisplayListBuilder& aBuilder,
     MOZ_ASSERT(GetInvalidRegion().IsEmpty());
   }
 
-  CreateWebRenderDisplayList(aBuilder);
+  CreateWebRenderDisplayList(aBuilder, aSc);
 }
 
 } // namespace layers

gfx/layers/wr/WebRenderPaintedLayer.h

@@ -55,7 +55,8 @@ public:
 private:
   bool SetupExternalImages();
   bool UpdateImageClient();
-  void CreateWebRenderDisplayList(wr::DisplayListBuilder& aBuilder);
+  void CreateWebRenderDisplayList(wr::DisplayListBuilder& aBuilder,
+                                  const StackingContextHelper& aSc);
 };
 
 } // namespace layers

gfx/layers/wr/WebRenderPaintedLayerBlob.cpp

@@ -22,7 +22,7 @@ using namespace mozilla::gfx;
 
 void
 WebRenderPaintedLayerBlob::RenderLayer(wr::DisplayListBuilder& aBuilder,
-                                       const StackingContextHelper& aHelper)
+                                       const StackingContextHelper& aSc)
 {
   LayerIntRegion visibleRegion = GetVisibleRegion();
   LayerIntRect bounds = visibleRegion.GetBounds();
@@ -78,7 +78,7 @@ WebRenderPaintedLayerBlob::RenderLayer(wr::DisplayListBuilder& aBuilder,
   DebugOnly<bool> ok = recorder->CopyRecording((char*)bytes.AsSlice().begin().get(), bytes.AsSlice().length());
   MOZ_ASSERT(ok);
 
-  StackingContextHelper sc(aBuilder, this);
+  StackingContextHelper sc(aSc, aBuilder, this);
   LayerRect rect = Bounds();
   DumpLayerInfo("PaintedLayer", rect);
 

gfx/layers/wr/WebRenderPaintedLayerBlob.h

@@ -48,7 +48,7 @@ public:
 
   Layer* GetLayer() override { return this; }
   void RenderLayer(wr::DisplayListBuilder& aBuilder,
-                   const StackingContextHelper& aHelper) override;
+                   const StackingContextHelper& aSc) override;
 private:
   RefPtr<ImageContainer> mImageContainer;
   RefPtr<ImageClient> mImageClient;

layout/reftests/transform-3d/reftest.list

@@ -46,7 +46,7 @@ fuzzy-if(winWidget&&!layersGPUAccelerated,1,61) == perspective-origin-3a.html pe
 == perspective-origin-4a.html perspective-origin-4-ref.html
 fails-if(webrender) == perspective-zindex.html green-rect.html
 fails-if(webrender) == perspective-zindex-2.html green-rect.html
-fails-if(webrender) fails-if(stylo) != sorting-1a.html sorting-1-ref.html
+fails-if(stylo) != sorting-1a.html sorting-1-ref.html
 # Parallel planes, different z depth
 fails-if(webrender) == sorting-2a.html sorting-2-ref.html
 # Parallel planes, same z depth (shouldn't be sorted!)