Auto merge of #1773 - glennw:fix-clip-rotated, r=kvark

Fix rounded clips on rotated rects.

We can only safely (for now) apply the clip mask corner optimization
if the primitive is axis aligned. In the future, we can handle this
once we improve how inner rect calculations work.

Fixes #1729

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Author: bors-servo

webrender/src/prim_store.rs

@@ -18,7 +18,7 @@ use render_task::{ClipWorkItem, RenderTask, RenderTaskId, RenderTaskTree};
 use renderer::MAX_VERTEX_TEXTURE_WIDTH;
 use resource_cache::{ImageProperties, ResourceCache};
 use std::{mem, usize};
-use util::{pack_as_float, recycle_vec, TransformedRect};
+use util::{MatrixHelpers, pack_as_float, recycle_vec, TransformedRect};
 
 #[derive(Debug, Copy, Clone)]
 pub struct PrimitiveOpacity {
@@ -1142,6 +1142,7 @@ impl PrimitiveStore {
 
         // Try to create a mask if we may need to.
         let prim_clips = clip_store.get(&metadata.clip_sources);
+        let is_axis_aligned = prim_context.packed_layer.transform.preserves_2d_axis_alignment();
         let clip_task = if prim_clips.is_masking() {
             // Take into account the actual clip info of the primitive, and
             // mutate the current bounds accordingly.
@@ -1169,6 +1170,7 @@ impl PrimitiveStore {
                 Some(extra),
                 prim_screen_rect,
                 clip_store,
+                is_axis_aligned,
             )
         } else if !prim_context.current_clip_stack.is_empty() {
             // If the primitive doesn't have a specific clip, key the task ID off the
@@ -1182,6 +1184,7 @@ impl PrimitiveStore {
                 None,
                 prim_screen_rect,
                 clip_store,
+                is_axis_aligned,
             )
         } else {
             None

webrender/src/render_task.rs

@@ -307,6 +307,7 @@ impl RenderTask {
         extra_clip: Option<ClipWorkItem>,
         prim_rect: DeviceIntRect,
         clip_store: &ClipStore,
+        is_axis_aligned: bool,
     ) -> Option<RenderTask> {
         // Filter out all the clip instances that don't contribute to the result
         let mut inner_rect = Some(task_rect);
@@ -358,7 +359,7 @@ impl RenderTask {
             if inner_rect.contains_rect(&prim_rect) {
                 return None;
             }
-            if clips.len() == 1 {
+            if is_axis_aligned && clips.len() == 1 {
                 geometry_kind = clips[0].get_geometry_kind(clip_store);
             }
         }

wrench/reftests/transforms/reftest.list

@@ -1,2 +1,3 @@
 == local-clip.yaml local-clip.png
+== rotated-clip.yaml rotated-clip.png
 

wrench/reftests/transforms/rotated-clip.png

@@ -0,0 +1,17 @@
+---
+root:
+  items:
+    -
+      bounds: 100 100 100 100
+      items:
+        - type: clip
+          bounds: [20, 20, 100, 100]
+          complex:
+            - rect: [20, 20, 100, 100]
+              radius: 32
+          items:
+          - type: rect
+            bounds: 20 20 100 100
+            color: blue
+      type: stacking-context
+      transform: rotate(30)