[skwasm] Fix platform view occlusion logic.

lib/web_ui/lib/src/engine/layers.dart

@@ -21,10 +21,7 @@ class BackdropFilterOperation implements LayerOperation {
   final ui.BlendMode mode;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect;
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect;
 
   @override
   void pre(SceneCanvas canvas, ui.Rect contentRect) {
@@ -50,10 +47,7 @@ class ClipPathOperation implements LayerOperation {
   final ui.Clip clip;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect.intersect(path.getBounds());
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect.intersect(path.getBounds());
 
   @override
   void pre(SceneCanvas canvas, ui.Rect contentRect) {
@@ -89,10 +83,7 @@ class ClipRectOperation implements LayerOperation {
   final ui.Clip clip;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect.intersect(rect);
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect.intersect(rect);
 
   @override
   void pre(SceneCanvas canvas, ui.Rect contentRect) {
@@ -128,10 +119,7 @@ class ClipRRectOperation implements LayerOperation {
   final ui.Clip clip;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect.intersect(rrect.outerRect);
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect.intersect(rrect.outerRect);
 
   @override
   void pre(SceneCanvas canvas, ui.Rect contentRect) {
@@ -166,10 +154,7 @@ class ColorFilterOperation implements LayerOperation {
   final ui.ColorFilter filter;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect;
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect;
 
   @override
   void pre(SceneCanvas canvas, ui.Rect contentRect) {
@@ -195,10 +180,7 @@ class ImageFilterOperation implements LayerOperation {
   final ui.Offset offset;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => (filter as SceneImageFilter).filterBounds(contentRect);
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => (filter as SceneImageFilter).filterBounds(contentRect);
 
   @override
   void pre(SceneCanvas canvas, ui.Rect contentRect) {
@@ -241,10 +223,7 @@ class OffsetOperation implements LayerOperation {
   final double dy;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect.shift(ui.Offset(dx, dy));
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect.shift(ui.Offset(-dx, -dy));
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect.shift(ui.Offset(dx, dy));
 
   @override
   void pre(SceneCanvas canvas, ui.Rect cullRect) {
@@ -273,10 +252,7 @@ class OpacityOperation implements LayerOperation {
   final ui.Offset offset;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect.shift(offset);
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect.shift(offset);
 
   @override
   void pre(SceneCanvas canvas, ui.Rect cullRect) {
@@ -317,13 +293,7 @@ class TransformOperation implements LayerOperation {
   Matrix4 getMatrix() => Matrix4.fromFloat32List(toMatrix32(transform));
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => getMatrix().transformRect(contentRect);
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) {
-    final Matrix4 matrix = getMatrix()..invert();
-    return matrix.transformRect(rect);
-  }
+  ui.Rect mapRect(ui.Rect contentRect) => getMatrix().transformRect(contentRect);
 
   @override
   void pre(SceneCanvas canvas, ui.Rect cullRect) {
@@ -353,10 +323,7 @@ class ShaderMaskOperation implements LayerOperation {
   final ui.BlendMode blendMode;
 
   @override
-  ui.Rect cullRect(ui.Rect contentRect) => contentRect;
-
-  @override
-  ui.Rect inverseMapRect(ui.Rect rect) => rect;
+  ui.Rect mapRect(ui.Rect contentRect) => contentRect;
 
   @override
   void pre(SceneCanvas canvas, ui.Rect contentRect) {
@@ -444,11 +411,8 @@ abstract class LayerOperation {
   // Given an input content rectangle, this returns a conservative estimate of
   // the covering rectangle of the content after it has been processed by the
   // layer operation.
-  ui.Rect cullRect(ui.Rect contentRect);
+  ui.Rect mapRect(ui.Rect contentRect);
 
-  // Takes a rectangle in the layer's coordinate space and maps it to the parent
-  // coordinate space.
-  ui.Rect inverseMapRect(ui.Rect rect);
   void pre(SceneCanvas canvas, ui.Rect contentRect);
   void post(SceneCanvas canvas, ui.Rect contentRect);
 
@@ -625,7 +589,7 @@ class LayerBuilder {
       // Merge the existing draw commands into a single picture and add a slice
       // with that picture to the slice list.
       final ui.Rect drawnRect = picturesRect ?? ui.Rect.zero;
-      final ui.Rect rect = operation?.cullRect(drawnRect) ?? drawnRect;
+      final ui.Rect rect = operation?.mapRect(drawnRect) ?? drawnRect;
       final (ui.PictureRecorder recorder, SceneCanvas canvas) = _createRecorder(rect);
 
       operation?.pre(canvas, rect);
@@ -649,7 +613,7 @@ class LayerBuilder {
       // slice.
       ui.Rect? occlusionRect = platformViewRect;
       if (occlusionRect != null && operation != null) {
-        occlusionRect = operation!.inverseMapRect(occlusionRect);
+        occlusionRect = operation!.mapRect(occlusionRect);
       }
       layer.slices.add(PlatformViewSlice(pendingPlatformViews, occlusionRect));
     }

lib/web_ui/test/engine/scene_builder_test.dart

@@ -150,6 +150,33 @@ void testMain() {
         PlatformView(1, platformViewRect, const PlatformViewStyling())
       ]));
     });
+
+    test('platform view sandwich (overlapping) with offset layers', () {
+      final EngineSceneBuilder sceneBuilder = EngineSceneBuilder();
+
+      const ui.Rect pictureRect1 = ui.Rect.fromLTRB(100, 100, 200, 200);
+      sceneBuilder.addPicture(ui.Offset.zero, StubPicture(pictureRect1));
+
+      sceneBuilder.pushOffset(150, 150);
+      const ui.Rect platformViewRect = ui.Rect.fromLTRB(0, 0, 100, 100);
+      sceneBuilder.addPlatformView(
+        1,
+        offset: platformViewRect.topLeft,
+        width: platformViewRect.width,
+        height: platformViewRect.height
+      );
+      sceneBuilder.pushOffset(50, 50);
+      sceneBuilder.addPicture(ui.Offset.zero, StubPicture(const ui.Rect.fromLTRB(0, 0, 100, 100)));
+
+      final EngineScene scene = sceneBuilder.build() as EngineScene;
+      final List<LayerSlice> slices = scene.rootLayer.slices;
+      expect(slices.length, 3);
+      expect(slices[0], pictureSliceWithRect(pictureRect1));
+      expect(slices[1], platformViewSliceWithViews(<PlatformView>[
+        PlatformView(1, platformViewRect, const PlatformViewStyling(position: PlatformViewPosition.offset(ui.Offset(150, 150))))
+      ]));
+      expect(slices[2], pictureSliceWithRect(const ui.Rect.fromLTRB(200, 200, 300, 300)));
+    });
   });
 }
 
@@ -209,12 +236,15 @@ class PlatformViewSliceMatcher extends Matcher {
       final PlatformView expectedView = expectedPlatformViews[i];
       final PlatformView actualView = item.views[i];
       if (expectedView.viewId != actualView.viewId) {
+        print('viewID mismatch');
         return false;
       }
       if (expectedView.bounds != actualView.bounds) {
+        print('bounds mismatch');
         return false;
       }
       if (expectedView.styling != actualView.styling) {
+        print('styling mismatch');
         return false;
       }
     }

lib/web_ui/test/engine/scene_builder_utils.dart

@@ -60,9 +60,21 @@ class StubPictureRecorder implements ui.PictureRecorder {
 class StubSceneCanvas implements SceneCanvas {
   List<StubPicture> pictures = <StubPicture>[];
 
+  // We actually use offsets in some of the tests, so we need to track the
+  // translate calls as they are made.
+  List<ui.Offset> offsetStack = <ui.Offset>[ui.Offset.zero];
+
+  ui.Offset get currentOffset {
+    return offsetStack.last;
+  }
+
+  set currentOffset(ui.Offset offset) {
+    offsetStack[offsetStack.length - 1] = offset;
+  }
+
   @override
   void drawPicture(ui.Picture picture) {
-    pictures.add(picture as StubPicture);
+    pictures.add(StubPicture((picture as StubPicture).cullRect.shift(currentOffset)));
   }
 
   @override
@@ -155,7 +167,9 @@ class StubSceneCanvas implements SceneCanvas {
   }
 
   @override
-  void restore() {}
+  void restore() {
+    offsetStack.removeLast();
+  }
 
   @override
   void restoreToCount(int count) {}
@@ -164,7 +178,9 @@ class StubSceneCanvas implements SceneCanvas {
   void rotate(double radians) {}
 
   @override
-  void save() {}
+  void save() {
+    offsetStack.add(currentOffset);
+  }
 
   @override
   void saveLayer(ui.Rect? bounds, ui.Paint paint) {}
@@ -182,5 +198,7 @@ class StubSceneCanvas implements SceneCanvas {
   void transform(Float64List matrix4) {}
 
   @override
-  void translate(double dx, double dy) {}
+  void translate(double dx, double dy) {
+    currentOffset += ui.Offset(dx, dy);
+  }
 }