canvas: pop many clips on restore (#38496)

When restoring context/state we need to pop all clips from current
state, before we just poped one (even if there was none).

Testing: Added new WPT tests

---------

Signed-off-by: sagudev <16504129+sagudev@users.noreply.github.com>

components/canvas/canvas_data.rs

@@ -749,8 +749,10 @@ impl<DrawTarget: GenericDrawTarget> CanvasData<DrawTarget> {
         }
     }
 
-    pub(crate) fn pop_clip(&mut self) {
-        self.drawtarget.pop_clip();
+    pub(crate) fn pop_clips(&mut self, clips: usize) {
+        for _ in 0..clips {
+            self.drawtarget.pop_clip();
+        }
     }
 }
 

components/canvas/canvas_paint_thread.rs

@@ -282,7 +282,7 @@ impl CanvasPaintThread {
                 self.canvas(canvas_id).update_image_rendering();
                 sender.send(()).unwrap();
             },
-            Canvas2dMsg::PopClip => self.canvas(canvas_id).pop_clip(),
+            Canvas2dMsg::PopClips(clips) => self.canvas(canvas_id).pop_clips(clips),
         }
     }
 
@@ -348,14 +348,14 @@ impl Canvas {
         }
     }
 
-    fn pop_clip(&mut self) {
+    fn pop_clips(&mut self, clips: usize) {
         match self {
             #[cfg(feature = "raqote")]
-            Canvas::Raqote(canvas_data) => canvas_data.pop_clip(),
+            Canvas::Raqote(canvas_data) => canvas_data.pop_clips(clips),
             #[cfg(feature = "vello")]
-            Canvas::Vello(canvas_data) => canvas_data.pop_clip(),
+            Canvas::Vello(canvas_data) => canvas_data.pop_clips(clips),
             #[cfg(feature = "vello_cpu")]
-            Canvas::VelloCPU(canvas_data) => canvas_data.pop_clip(),
+            Canvas::VelloCPU(canvas_data) => canvas_data.pop_clips(clips),
             _ => unreachable!(),
         }
     }

components/script/canvas_state.rs

@@ -119,6 +119,9 @@ pub(crate) struct CanvasContextState {
     text_baseline: TextBaseline,
     #[no_trace]
     direction: Direction,
+    /// The number of clips pushed onto the context while in this state.
+    /// When restoring old state, same number of clips will be popped to restore state.
+    clips_pushed: usize,
 }
 
 impl CanvasContextState {
@@ -146,6 +149,7 @@ impl CanvasContextState {
             direction: Default::default(),
             line_dash: Vec::new(),
             line_dash_offset: 0.0,
+            clips_pushed: 0,
         }
     }
 
@@ -1320,12 +1324,15 @@ impl CanvasState {
     }
 
     #[cfg_attr(crown, allow(crown::unrooted_must_root))]
-    // https://html.spec.whatwg.org/multipage/#dom-context-2d-restore
+    /// <https://html.spec.whatwg.org/multipage/#dom-context-2d-restore>
     pub(crate) fn restore(&self) {
         let mut saved_states = self.saved_states.borrow_mut();
         if let Some(state) = saved_states.pop() {
+            let clips_to_pop = self.state.borrow().clips_pushed;
+            if clips_to_pop != 0 {
+                self.send_canvas_2d_msg(Canvas2dMsg::PopClips(clips_to_pop));
+            }
             self.state.borrow_mut().clone_from(&state);
-            self.send_canvas_2d_msg(Canvas2dMsg::PopClip);
         }
     }
 
@@ -1940,6 +1947,7 @@ impl CanvasState {
 
     // https://html.spec.whatwg.org/multipage/#dom-context-2d-clip
     pub(crate) fn clip_(&self, path: Path, fill_rule: CanvasFillRule) {
+        self.state.borrow_mut().clips_pushed += 1;
         self.send_canvas_2d_msg(Canvas2dMsg::ClipPath(
             path,
             fill_rule.convert(),

components/shared/canvas/canvas.rs

@@ -483,7 +483,7 @@ pub enum Canvas2dMsg {
     ),
     ClearRect(Rect<f32>, Transform2D<f32>),
     ClipPath(Path, FillRule, Transform2D<f32>),
-    PopClip,
+    PopClips(usize),
     FillPath(
         FillOrStrokeStyle,
         Path,