[web] Implement sweep gradient

ci/licenses_golden/licenses_flutter

@@ -489,6 +489,7 @@ FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/recording_canvas.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/render_vertices.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/scene.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/scene_builder.dart
+FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/shaders/normalized_gradient.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/shaders/shader.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/shaders/shader_builder.dart
 FILE: ../../../flutter/lib/web_ui/lib/src/engine/html/surface.dart

lib/web_ui/dev/goldens_lock.yaml

@@ -1,2 +1,2 @@
 repository: https://github.com/flutter/goldens.git
-revision: 672510dc52daa5b059081f6990582bccdb4ea48f
+revision: 7171fa6b2844b39d08aab87ca5b4e923c18e3b39

lib/web_ui/lib/src/engine.dart

@@ -89,6 +89,7 @@ part 'engine/html/recording_canvas.dart';
 part 'engine/html/render_vertices.dart';
 part 'engine/html/scene.dart';
 part 'engine/html/scene_builder.dart';
+part 'engine/html/shaders/normalized_gradient.dart';
 part 'engine/html/shaders/shader.dart';
 part 'engine/html/shaders/shader_builder.dart';
 part 'engine/html/surface.dart';

lib/web_ui/lib/src/engine/bitmap_canvas.dart

@@ -208,8 +208,8 @@ class BitmapCanvas extends EngineCanvas {
   }
 
   /// Sets the global paint styles to correspond to [paint].
-  void _setUpPaint(SurfacePaintData paint) {
-    _canvasPool.contextHandle.setUpPaint(paint);
+  void _setUpPaint(SurfacePaintData paint, ui.Rect? shaderBounds) {
+    _canvasPool.contextHandle.setUpPaint(paint, shaderBounds);
   }
 
   void _tearDownPaint() {
@@ -292,56 +292,61 @@ class BitmapCanvas extends EngineCanvas {
 
   @override
   void drawLine(ui.Offset p1, ui.Offset p2, SurfacePaintData paint) {
-    _setUpPaint(paint);
+    ui.Rect? shaderBounds = (paint.shader != null) ?
+        ui.Rect.fromPoints(p1, p2) : null;
+    _setUpPaint(paint, shaderBounds);
     _canvasPool.strokeLine(p1, p2);
     _tearDownPaint();
   }
 
   @override
   void drawPaint(SurfacePaintData paint) {
-    _setUpPaint(paint);
+    ui.Rect? shaderBounds = (paint.shader != null) ?
+        _computeScreenBounds(_canvasPool._currentTransform) : null;
+    _setUpPaint(paint, shaderBounds);
     _canvasPool.fill();
     _tearDownPaint();
   }
 
   @override
   void drawRect(ui.Rect rect, SurfacePaintData paint) {
-    _setUpPaint(paint);
+    _setUpPaint(paint, rect);
     _canvasPool.drawRect(rect, paint.style);
     _tearDownPaint();
   }
 
   @override
   void drawRRect(ui.RRect rrect, SurfacePaintData paint) {
-    _setUpPaint(paint);
+    _setUpPaint(paint, rrect.outerRect);
     _canvasPool.drawRRect(rrect, paint.style);
     _tearDownPaint();
   }
 
   @override
   void drawDRRect(ui.RRect outer, ui.RRect inner, SurfacePaintData paint) {
-    _setUpPaint(paint);
+    _setUpPaint(paint, outer.outerRect);
     _canvasPool.drawDRRect(outer, inner, paint.style);
     _tearDownPaint();
   }
 
   @override
   void drawOval(ui.Rect rect, SurfacePaintData paint) {
-    _setUpPaint(paint);
+    _setUpPaint(paint, rect);
     _canvasPool.drawOval(rect, paint.style);
     _tearDownPaint();
   }
 
   @override
   void drawCircle(ui.Offset c, double radius, SurfacePaintData paint) {
-    _setUpPaint(paint);
+    _setUpPaint(paint, paint.shader != null
+        ? ui.Rect.fromCircle(center: c, radius: radius) : null);
     _canvasPool.drawCircle(c, radius, paint.style);
     _tearDownPaint();
   }
 
   @override
   void drawPath(ui.Path path, SurfacePaintData paint) {
-    _setUpPaint(paint);
+    _setUpPaint(paint, paint.shader != null ? path.getBounds() : null);
     _canvasPool.drawPath(path, paint.style);
     _tearDownPaint();
   }
@@ -655,7 +660,7 @@ class BitmapCanvas extends EngineCanvas {
         ctx.font = style.cssFontString;
         _cachedLastStyle = style;
       }
-      _setUpPaint(paragraph._paint!.paintData);
+      _setUpPaint(paragraph._paint!.paintData, null);
       double y = offset.dy + paragraph.alphabeticBaseline;
       final int len = lines.length;
       for (int i = 0; i < len; i++) {
@@ -761,7 +766,7 @@ class BitmapCanvas extends EngineCanvas {
     _drawPointsPaint.strokeWidth = paint.strokeWidth;
     _drawPointsPaint.maskFilter = paint.maskFilter;
 
-    _setUpPaint(_drawPointsPaint);
+    _setUpPaint(_drawPointsPaint, null);
     _canvasPool.drawPoints(pointMode, points, paint.strokeWidth! / 2.0);
     _tearDownPaint();
   }
@@ -771,6 +776,34 @@ class BitmapCanvas extends EngineCanvas {
     _canvasPool.endOfPaint();
     _elementCache?.commitFrame();
   }
+
+  /// Computes paint bounds given [targetTransform] to completely cover window
+  /// viewport.
+  ui.Rect _computeScreenBounds(Matrix4 targetTransform) {
+    final Matrix4 inverted = targetTransform.clone()..invert();
+    final double dpr = ui.window.devicePixelRatio;
+    final double width = ui.window.physicalSize.width * dpr;
+    final double height = ui.window.physicalSize.height * dpr;
+    Vector3 topLeft = inverted.perspectiveTransform(Vector3(0, 0, 0));
+    Vector3 topRight = inverted.perspectiveTransform(Vector3(width, 0, 0));
+    Vector3 bottomRight =
+    inverted.perspectiveTransform(Vector3(width, height, 0));
+    Vector3 bottomLeft = inverted.perspectiveTransform(Vector3(0, height, 0));
+    return ui.Rect.fromLTRB(
+      math.min(topLeft.x,
+          math.min(topRight.x, math.min(bottomRight.x, bottomLeft.x))) -
+          bounds.left,
+      math.min(topLeft.y,
+          math.min(topRight.y, math.min(bottomRight.y, bottomLeft.y))) -
+          bounds.top,
+      math.max(topLeft.x,
+          math.max(topRight.x, math.max(bottomRight.x, bottomLeft.x))) -
+          bounds.left,
+      math.max(topLeft.y,
+          math.max(topRight.y, math.max(bottomRight.y, bottomLeft.y))) -
+          bounds.top,
+    );
+  }
 }
 
 String? _stringForBlendMode(ui.BlendMode? blendMode) {
@@ -966,3 +999,4 @@ String _maskFilterToCanvasFilter(ui.MaskFilter? maskFilter) {
   }
 }
 
+

lib/web_ui/lib/src/engine/canvas_pool.dart

@@ -761,7 +761,7 @@ class ContextStateHandle {
   /// Sets paint properties on the current canvas.
   ///
   /// [tearDownPaint] must be called after calling this method.
-  void setUpPaint(SurfacePaintData paint) {
+  void setUpPaint(SurfacePaintData paint, ui.Rect? shaderBounds) {
     if (assertionsEnabled) {
       assert(!_debugIsPaintSetUp);
       _debugIsPaintSetUp = true;
@@ -776,7 +776,7 @@ class ContextStateHandle {
     if (paint.shader != null) {
       final EngineGradient engineShader = paint.shader as EngineGradient;
       final Object paintStyle =
-          engineShader.createPaintStyle(_canvasPool.context);
+          engineShader.createPaintStyle(_canvasPool.context, shaderBounds);
       fillStyle = paintStyle;
       strokeStyle = paintStyle;
     } else if (paint.color != null) {