Bug 1561447 - Include picture shadow in local rect when building clip chain r=nical

Differential Revision: https://phabricator.services.mozilla.com/D42244

--HG--
extra : moz-landing-system : lando

gfx/wr/webrender/src/prim_store/mod.rs

@@ -2037,12 +2037,13 @@ impl PrimitiveStore {
                 }
 
                 // Inflate the local rect for this primitive by the inflation factor of
-                // the picture context. This ensures that even if the primitive itself
-                // is not visible, any effects from the blur radius will be correctly
-                // taken into account.
+                // the picture context and include the shadow offset. This ensures that
+                // even if the primitive itself is not visible, any effects from the
+                // blur radius or shadow will be correctly taken into account.
                 let inflation_factor = surface.inflation_factor;
                 let local_rect = prim_local_rect
                     .inflate(inflation_factor, inflation_factor)
+                    .union(&prim_shadow_rect)
                     .intersection(&prim_instance.local_clip_rect);
                 let local_rect = match local_rect {
                     Some(local_rect) => local_rect,

gfx/wr/wrench/reftests/filters/filter-drop-shadow-clip-2.yaml

@@ -0,0 +1,17 @@
+# Bug 1561447: If a clip task is created for a picture, it should take into account the rect of the drop shadow
+---
+root:
+  items:
+  - type: clip
+    id: 2
+    bounds: 10 0 300 300
+    clip-rect: 10 0 300 300
+  - type: stacking-context
+    bounds: 30 30 0 0
+    transform: rotate-z(45)
+    filters: drop-shadow([15, 0], 0, red)
+    clip-node: 2
+    items:
+    - type: rect
+      bounds: 0 0 100 100
+      color: blue

gfx/wr/wrench/reftests/filters/reftest.list

@@ -35,6 +35,7 @@ platform(linux,mac) == filter-drop-shadow.yaml filter-drop-shadow.png
 platform(linux,mac) == filter-drop-shadow-on-viewport-edge.yaml filter-drop-shadow-on-viewport-edge.png
 platform(linux,mac) == blend-clipped.yaml blend-clipped.png
 platform(linux,mac) == filter-drop-shadow-clip.yaml filter-drop-shadow-clip.png
+platform(linux,mac) == filter-drop-shadow-clip-2.yaml filter-drop-shadow-clip-2.png
 == filter-segments.yaml filter-segments-ref.yaml
 == iframe-dropshadow.yaml iframe-dropshadow-ref.yaml
 skip_on(android) == filter-mix-blend-mode.yaml filter-mix-blend-mode-ref.yaml  # Android debug: GL error 502 at blit_framebuffer (emulator) or draw_elements_instanced (Pixel2); Android opt: fails