Bug 1355602 - Decouple pushing scroll layers from pushing stacking contexts. r=jrmuizel

This removes the call to push_scroll_layer in wr_push_stacking_context, so that
it's now possible to push a stacking context without necessarily pushing a
scroll layer. There is already a separate function to push a scroll layer so the
call sites can do that. This patch just changes all the call sites that were
pushing a stacking context to also push a scroll layer, so there should be no
functional change. Future patches can remove the spurious scroll layers.

MozReview-Commit-ID: FtCkc9JQd8l

gfx/layers/wr/WebRenderCanvasLayer.cpp

@@ -87,13 +87,15 @@ WebRenderCanvasLayer::RenderLayer(wr::DisplayListBuilder& aBuilder)
   WrBridge()->AddWebRenderParentCommand(OpAddExternalImage(mExternalImageId, key));
 
   aBuilder.PushStackingContext(wr::ToWrRect(relBounds),
-                               wr::ToWrRect(overflow),
-                               mask.ptrOr(nullptr),
                                1.0f,
                                //GetAnimations(),
                                transform,
                                mixBlendMode);
+  aBuilder.PushScrollLayer(wr::ToWrRect(overflow),
+                           wr::ToWrRect(overflow),
+                           mask.ptrOr(nullptr));
   aBuilder.PushImage(wr::ToWrRect(rect), clip, filter, key);
+  aBuilder.PopScrollLayer();
   aBuilder.PopStackingContext();
 }
 

gfx/layers/wr/WebRenderColorLayer.cpp

@@ -34,13 +34,15 @@ WebRenderColorLayer::RenderLayer(wr::DisplayListBuilder& aBuilder)
   DumpLayerInfo("ColorLayer", rect);
 
   aBuilder.PushStackingContext(wr::ToWrRect(relBounds),
-                              wr::ToWrRect(overflow),
-                              mask.ptrOr(nullptr),
                               1.0f,
                               //GetAnimations(),
                               transform,
                               mixBlendMode);
+  aBuilder.PushScrollLayer(wr::ToWrRect(overflow),
+                           wr::ToWrRect(overflow),
+                           mask.ptrOr(nullptr));
   aBuilder.PushRect(wr::ToWrRect(rect), clip, wr::ToWrColor(mColor));
+  aBuilder.PopScrollLayer();
   aBuilder.PopStackingContext();
 }
 

gfx/layers/wr/WebRenderContainerLayer.cpp

@@ -36,18 +36,20 @@ WebRenderContainerLayer::RenderLayer(wr::DisplayListBuilder& aBuilder)
                   Stringify(mixBlendMode).c_str());
   }
   aBuilder.PushStackingContext(wr::ToWrRect(relBounds),
-                               wr::ToWrRect(overflow),
-                               mask.ptrOr(nullptr),
                                GetLocalOpacity(),
                                //GetLayer()->GetAnimations(),
                                transform,
                                mixBlendMode);
+  aBuilder.PushScrollLayer(wr::ToWrRect(overflow),
+                           wr::ToWrRect(overflow),
+                           mask.ptrOr(nullptr));
   for (LayerPolygon& child : children) {
     if (child.layer->IsBackfaceHidden()) {
       continue;
     }
     ToWebRenderLayer(child.layer)->RenderLayer(aBuilder);
   }
+  aBuilder.PopScrollLayer();
   aBuilder.PopStackingContext();
 }
 

gfx/layers/wr/WebRenderImageLayer.cpp

@@ -159,13 +159,15 @@ WebRenderImageLayer::RenderLayer(wr::DisplayListBuilder& aBuilder)
   WrBridge()->AddWebRenderParentCommand(OpAddExternalImage(mExternalImageId, key));
 
   aBuilder.PushStackingContext(wr::ToWrRect(relBounds),
-                            wr::ToWrRect(overflow),
-                            mask.ptrOr(nullptr),
                             1.0f,
                             //GetAnimations(),
                             transform,
                             mixBlendMode);
+  aBuilder.PushScrollLayer(wr::ToWrRect(overflow),
+                           wr::ToWrRect(overflow),
+                           mask.ptrOr(nullptr));
   aBuilder.PushImage(wr::ToWrRect(rect), clip, filter, key);
+  aBuilder.PopScrollLayer();
   aBuilder.PopStackingContext();
 
   //mContainer->SetImageFactory(originalIF);

gfx/layers/wr/WebRenderPaintedLayer.cpp

@@ -204,13 +204,15 @@ WebRenderPaintedLayer::RenderLayer(wr::DisplayListBuilder& aBuilder)
   WrBridge()->AddWebRenderParentCommand(OpAddExternalImage(mExternalImageId, key));
 
   aBuilder.PushStackingContext(wr::ToWrRect(relBounds),
-                              wr::ToWrRect(overflow),
-                              mask.ptrOr(nullptr),
                               1.0f,
                               //GetAnimations(),
                               transform,
                               mixBlendMode);
+  aBuilder.PushScrollLayer(wr::ToWrRect(overflow),
+                           wr::ToWrRect(overflow),
+                           mask.ptrOr(nullptr));
   aBuilder.PushImage(wr::ToWrRect(rect), clip, wr::ImageRendering::Auto, key);
+  aBuilder.PopScrollLayer();
   aBuilder.PopStackingContext();
 }
 

gfx/webrender_bindings/WebRenderAPI.cpp

@@ -526,13 +526,11 @@ DisplayListBuilder::Finalize()
 
 void
 DisplayListBuilder::PushStackingContext(const WrRect& aBounds,
-                                        const WrRect& aOverflow,
-                                        const WrImageMask* aMask,
                                         const float aOpacity,
                                         const gfx::Matrix4x4& aTransform,
                                         const WrMixBlendMode& aMixBlendMode)
 {
-  wr_dp_push_stacking_context(mWrState, aBounds, aOverflow, aMask, aOpacity,
+  wr_dp_push_stacking_context(mWrState, aBounds, aOpacity,
                               ToWrMatrix(aTransform), aMixBlendMode);
 }
 

gfx/webrender_bindings/WebRenderAPI.h

@@ -138,8 +138,6 @@ public:
   wr::BuiltDisplayList Finalize();
 
   void PushStackingContext(const WrRect& aBounds, // TODO: We should work with strongly typed rects
-                           const WrRect& aOverflow,
-                           const WrImageMask* aMask, // TODO: needs a wrapper.
                            const float aOpacity,
                            const gfx::Matrix4x4& aTransform,
                            const WrMixBlendMode& aMixBlendMode);

gfx/webrender_bindings/src/bindings.rs

@@ -1097,8 +1097,6 @@ pub extern "C" fn wr_dp_new_clip_region(state: &mut WrState,
 #[no_mangle]
 pub extern "C" fn wr_dp_push_stacking_context(state: &mut WrState,
                                               bounds: WrRect,
-                                              overflow: WrRect,
-                                              mask: *const WrImageMask,
                                               opacity: f32,
                                               transform: WrMatrix,
                                               mix_blend_mode: WrMixBlendMode) {
@@ -1106,20 +1104,6 @@ pub extern "C" fn wr_dp_push_stacking_context(state: &mut WrState,
     state.z_index += 1;
 
     let bounds = bounds.to_rect();
-    let overflow = overflow.to_rect();
-
-    // convert from the C type to the Rust type
-    let mask = unsafe {
-        mask.as_ref().map(|&WrImageMask { image, ref rect, repeat }| {
-            ImageMask {
-                image: image,
-                rect: rect.to_rect(),
-                repeat: repeat,
-            }
-        })
-    };
-
-    let clip_region = state.frame_builder.dl_builder.new_clip_region(&overflow, vec![], mask);
 
     let mut filters: Vec<FilterOp> = Vec::new();
     if opacity < 1.0 {
@@ -1136,17 +1120,12 @@ pub extern "C" fn wr_dp_push_stacking_context(state: &mut WrState,
                                None,
                                mix_blend_mode,
                                filters);
-
-    let clip_bounds = LayoutRect::new(LayoutPoint::new(0.0, 0.0), bounds.size);
-    state.frame_builder.dl_builder.push_scroll_layer(clip_region, clip_bounds, None);
 }
 
 #[no_mangle]
 pub extern "C" fn wr_dp_pop_stacking_context(state: &mut WrState) {
     assert!(unsafe { is_in_main_thread() });
-    state.frame_builder.dl_builder.pop_scroll_layer();
     state.frame_builder.dl_builder.pop_stacking_context();
-    //println!("pop_stacking {:?}", state.pipeline_id);
 }
 
 #[no_mangle]

gfx/webrender_bindings/webrender_ffi.h

@@ -634,7 +634,6 @@ WR_FUNC;
 
 WR_INLINE void
 wr_dp_push_stacking_context(WrState *wrState, WrRect bounds,
-                            WrRect overflow, const WrImageMask *mask,
                             float opacity, WrMatrix transform,
                             WrMixBlendMode mixBlendMode)
 WR_FUNC;