Bug 1708122 - Fix the radial gradient optimization. r=gfx-reviewers,lsalzman

The bounds of a radial gradient primitive's radius have to be scaled by the end_offset parameter.

Differential Revision: https://phabricator.services.mozilla.com/D114344

gfx/wr/webrender/src/prim_store/gradient/radial.rs

@@ -385,6 +385,7 @@ pub fn optimize_radial_gradient(
     tile_spacing: &mut LayoutSize,
     clip_rect: &LayoutRect,
     radius: LayoutSize,
+    end_offset: f32,
     extend_mode: ExtendMode,
     stops: &[GradientStopKey],
     solid_parts: &mut dyn FnMut(&LayoutRect, ColorU),
@@ -403,8 +404,8 @@ pub fn optimize_radial_gradient(
     }
 
     // Bounding box of the "interesting" part of the gradient.
-    let min = prim_rect.origin + center.to_vector() - radius.to_vector();
-    let max = prim_rect.origin + center.to_vector() + radius.to_vector();
+    let min = prim_rect.origin + center.to_vector() - radius.to_vector() * end_offset;
+    let max = prim_rect.origin + center.to_vector() + radius.to_vector() * end_offset;
 
     // The (non-repeated) gradient primitive rect.
     let gradient_rect = LayoutRect {
@@ -444,7 +445,6 @@ pub fn optimize_radial_gradient(
         if b < threshold { b = 0.0 }
     }
 
-
     if l + t + r + b == 0.0 {
         // No adjustment to make;
         return;

gfx/wr/webrender/src/scene_building.rs

@@ -1322,6 +1322,7 @@ impl<'a> SceneBuilder<'a> {
                     &mut tile_spacing,
                     &layout.clip_rect,
                     info.gradient.radius,
+                    info.gradient.end_offset,
                     info.gradient.extend_mode,
                     &stops,
                     &mut |solid_rect, color| {

gfx/wr/wrench/reftests/gradient/radial-optimized-2-ref.yaml

@@ -0,0 +1,8 @@
+---
+root:
+  items:
+    - type: radial-gradient
+      bounds: 50 50 500 500
+      center: 150 150
+      radius: 80 160
+      stops: [0, red, 1, [0,0,0,0]]

gfx/wr/wrench/reftests/gradient/radial-optimized-2.yaml

@@ -0,0 +1,8 @@
+---
+root:
+  items:
+    - type: radial-gradient
+      bounds: 50 50 500 500
+      center: 150 150
+      radius: 20 40
+      stops: [0, red, 4, [0,0,0,0]]

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

@@ -111,6 +111,7 @@ fuzzy-range(<=1,1) == gradient_cache_hardstop_clip.yaml gradient_cache_hardstop_
 
 # Exercise the radial gradient optimization code path
 == radial-optimized.yaml radial-optimized-ref.yaml
+== radial-optimized-2.yaml radial-optimized-2-ref.yaml
 == radial-tiling-optimized.yaml radial-tiling-optimized-ref.yaml
 
 # Exercise the cached gradient scaling code path