Fix a picture caching race condition.

webrender/src/frame_builder.rs

@@ -490,8 +490,9 @@ impl FrameBuilder {
                 &mut z_generator,
             );
 
-            if let RenderPassKind::OffScreen { ref texture_cache, .. } = pass.kind {
+            if let RenderPassKind::OffScreen { ref texture_cache, ref color, .. } = pass.kind {
                 has_texture_cache_tasks |= !texture_cache.is_empty();
+                has_texture_cache_tasks |= color.must_be_drawn();
             }
         }
 

webrender/src/picture.rs

@@ -732,13 +732,23 @@ impl TileCache {
 
         let prim_data = &resources.as_common_data(&prim_instance);
 
-        let prim_rect = LayoutRect::new(
-            prim_instance.prim_origin,
-            prim_data.prim_size,
-        );
-        let clip_rect = prim_data
-            .prim_relative_clip_rect
-            .translate(&prim_instance.prim_origin.to_vector());
+        let (prim_rect, clip_rect) = match prim_instance.kind {
+            PrimitiveInstanceKind::Picture { pic_index, .. } => {
+                let pic = &pictures[pic_index.0];
+                (pic.local_rect, LayoutRect::max_rect())
+            }
+            _ => {
+                let prim_rect = LayoutRect::new(
+                    prim_instance.prim_origin,
+                    prim_data.prim_size,
+                );
+                let clip_rect = prim_data
+                    .prim_relative_clip_rect
+                    .translate(&prim_instance.prim_origin.to_vector());
+
+                (prim_rect, clip_rect)
+            }
+        };
 
         // Map the primitive local rect into the picture space.
         // TODO(gw): We should maybe store this in the primitive template
@@ -850,7 +860,7 @@ impl TileCache {
             // We only care about clip nodes that have transforms that are children
             // of the surface, since clips that are positioned by parents will be
             // handled by the clip collector when these tiles are composited.
-            if clip_chain_node.spatial_node_index > surface_spatial_node_index {
+            if clip_chain_node.spatial_node_index >= surface_spatial_node_index {
                 clip_chain_spatial_nodes.push(clip_chain_node.spatial_node_index);
                 clip_chain_uids.push(clip_chain_node.handle.uid());
             }

webrender/src/tiling.rs

@@ -110,6 +110,7 @@ pub trait RenderTarget {
     );
 
     fn needs_depth(&self) -> bool;
+    fn must_be_drawn(&self) -> bool;
 
     fn used_rect(&self) -> DeviceIntRect;
     fn add_used(&mut self, rect: DeviceIntRect);
@@ -258,6 +259,10 @@ impl<T: RenderTarget> RenderTargetList<T> {
         self.targets.iter().any(|target| target.needs_depth())
     }
 
+    pub fn must_be_drawn(&self) -> bool {
+        self.targets.iter().any(|target| target.must_be_drawn())
+    }
+
     pub fn check_ready(&self, t: &Texture) {
         let dimensions = t.get_dimensions();
         assert!(dimensions.width >= self.max_dynamic_size.width);
@@ -544,6 +549,10 @@ impl RenderTarget for ColorRenderTarget {
         }
     }
 
+    fn must_be_drawn(&self) -> bool {
+        !self.tile_blits.is_empty()
+    }
+
     fn needs_depth(&self) -> bool {
         self.alpha_batch_containers.iter().any(|ab| {
             !ab.opaque_batches.is_empty()
@@ -674,6 +683,10 @@ impl RenderTarget for AlphaRenderTarget {
         false
     }
 
+    fn must_be_drawn(&self) -> bool {
+        false
+    }
+
     fn used_rect(&self) -> DeviceIntRect {
         self.used_rect
     }