Place item clipping_and_scrolling inside closure

A utility function assures that if the clipping and scrolling are changed
for a display item the old value is later restored.

components/layout/display_list/builder.rs

@@ -17,7 +17,7 @@ use context::LayoutContext;
 use display_list::ToLayout;
 use display_list::background::{build_border_radius, build_image_border_details};
 use display_list::background::{calculate_inner_border_radii, compute_background_placement};
-use display_list::background::{convert_radial_gradient, convert_linear_gradient};
+use display_list::background::{convert_linear_gradient, convert_radial_gradient};
 use display_list::background::{get_cyclic, simple_normal_border};
 use display_list::items::{BaseDisplayItem, BorderDetails, BorderDisplayItem, BLUR_INFLATION_FACTOR};
 use display_list::items::{BoxShadowDisplayItem, ClipScrollNode};
@@ -547,6 +547,13 @@ impl<'a> DisplayListBuildState<'a> {
             list.push(item);
         }
     }
+
+    fn clipping_and_scrolling_scope<R, F: FnOnce(&mut Self) -> R>(&mut self, function: F) -> R {
+        let previous_clipping_and_scrolling = self.current_clipping_and_scrolling;
+        let ret = function(self);
+        self.current_clipping_and_scrolling = previous_clipping_and_scrolling;
+        ret
+    }
 }
 
 /// The logical width of an insertion point: at the moment, a one-pixel-wide line.
@@ -858,7 +865,7 @@ impl FragmentDisplayListBuilding for Fragment {
             },
         }
 
-        let previous_clipping_and_scrolling = state.current_clipping_and_scrolling;
+        state.clipping_and_scrolling_scope(|state| {
             if !border_radii.is_zero() {
                 let clip_id = state.add_late_clip_node(bounds.to_layout(), border_radii);
                 state.current_clipping_and_scrolling = ClippingAndScrolling::simple(clip_id);
@@ -875,8 +882,7 @@ impl FragmentDisplayListBuilding for Fragment {
                 base: base,
                 color: background_color.to_layout(),
             })));
-
-        state.current_clipping_and_scrolling = previous_clipping_and_scrolling;
+        });
 
         // The background image is painted on top of the background color.
         // Implements background image, per spec:
@@ -984,7 +990,7 @@ impl FragmentDisplayListBuilding for Fragment {
             index,
         );
 
-        let previous_clipping_and_scrolling = state.current_clipping_and_scrolling;
+        state.clipping_and_scrolling_scope(|state| {
             if !placement.clip_radii.is_zero() {
                 let clip_id =
                     state.add_late_clip_node(placement.clip_rect.to_layout(), placement.clip_radii);
@@ -1008,8 +1014,7 @@ impl FragmentDisplayListBuilding for Fragment {
                 tile_spacing: placement.tile_spacing.to_layout(),
                 image_rendering: style.get_inheritedbox().image_rendering.to_layout(),
             })));
-
-        state.current_clipping_and_scrolling = previous_clipping_and_scrolling;
+        });
     }
 
     fn get_webrender_image_for_paint_worklet(
@@ -1092,7 +1097,7 @@ impl FragmentDisplayListBuilding for Fragment {
             index,
         );
 
-        let previous_clipping_and_scrolling = state.current_clipping_and_scrolling;
+        state.clipping_and_scrolling_scope(|state| {
             if !placement.clip_radii.is_zero() {
                 let clip_id =
                     state.add_late_clip_node(placement.clip_rect.to_layout(), placement.clip_radii);
@@ -1139,7 +1144,7 @@ impl FragmentDisplayListBuilding for Fragment {
                 },
             };
             state.add_display_item(display_item);
-        state.current_clipping_and_scrolling = previous_clipping_and_scrolling;
+        });
     }
 
     fn build_display_list_for_box_shadow_if_applicable(
@@ -1677,7 +1682,13 @@ impl FragmentDisplayListBuilding for Fragment {
         debug!("Fragment::build_display_list: intersected. Adding display item...");
 
         // Create special per-fragment-type display items.
-        self.build_fragment_type_specific_display_items(state, &stacking_relative_border_box, clip);
+        state.clipping_and_scrolling_scope(|state| {
+            self.build_fragment_type_specific_display_items(
+                state,
+                &stacking_relative_border_box,
+                clip,
+            );
+        });
 
         if opts::get().show_debug_fragment_borders {
             self.build_debug_borders_around_fragment(state, &stacking_relative_border_box, clip)
@@ -1690,8 +1701,6 @@ impl FragmentDisplayListBuilding for Fragment {
         stacking_relative_border_box: &Rect<Au>,
         clip: &Rect<Au>,
     ) {
-        let previous_clipping_and_scrolling = state.current_clipping_and_scrolling;
-
         // Compute the context box position relative to the parent stacking context.
         let stacking_relative_content_box =
             self.stacking_relative_content_box(stacking_relative_border_box);
@@ -1860,8 +1869,6 @@ impl FragmentDisplayListBuilding for Fragment {
                 panic!("Shouldn't see table column fragments here.")
             },
         }
-
-        state.current_clipping_and_scrolling = previous_clipping_and_scrolling;
     }
 
     fn create_stacking_context(

components/layout/display_list/items.rs

@@ -71,10 +71,7 @@ impl ClippingAndScrolling {
         }
     }
 
-    pub fn new(
-        scrolling: ClipScrollNodeIndex,
-        clipping: ClipScrollNodeIndex,
-    ) -> ClippingAndScrolling {
+    pub fn new(scrolling: ClipScrollNodeIndex, clipping: ClipScrollNodeIndex) -> Self {
         ClippingAndScrolling {
             scrolling,
             clipping: Some(clipping),

tests/wpt/metadata/MANIFEST.json

@@ -483718,7 +483718,7 @@
    "support"
   ],
   "css/css-backgrounds/background-rounded-image-clip.html": [
-   "c22edf865829fea1d69a54e34396b4462250585f",
+   "1f3a33ee141f0bf0186875d376bc95414db8dd18",
    "reftest"
   ],
   "css/css-backgrounds/background-size-001.html": [
@@ -485926,7 +485926,7 @@
    "support"
   ],
   "css/css-backgrounds/reference/background-rounded-image-clip.html": [
-   "f5c1af4d9e5b415e762c921c6d93355b2861946c",
+   "0f98f9c82627977b11cde5f7c8ba536104cccdd2",
    "support"
   ],
   "css/css-backgrounds/reference/background-size-002-ref.html": [

tests/wpt/web-platform-tests/css/css-backgrounds/background-rounded-image-clip.html

@@ -28,7 +28,5 @@
         border-color: transparent;
     }
 </style>
-<body>
-    <div id="a"></div>
-    <div id="b"></div>
-</body>
+<div id="a"></div>
+<div id="b"></div>

tests/wpt/web-platform-tests/css/css-backgrounds/reference/background-rounded-image-clip.html

@@ -1,4 +1,6 @@
 <!doctype html>
+<meta charset="utf-8">
+<title>Corner Clipped Background Color</title>
 <style>
     html {
         background-color: green;