Move CanvasKit files from parts to libraries (#26139)

lib/web_ui/lib/src/engine.dart

@@ -15,9 +15,9 @@ library engine;
 // - https://github.com/flutter/engine/blob/master/web_sdk/sdk_rewriter.dart
 
 import 'dart:async';
+// Some of these names are used in services/buffers.dart for example.
+// ignore: unused_import
 import 'dart:collection'
-    // Some of these names are used in services/buffers.dart for example.
-    // ignore: unused_shown_name
     show ListBase, IterableBase, DoubleLinkedQueue, DoubleLinkedQueueEntry;
 import 'dart:convert' hide Codec;
 import 'dart:developer' as developer;
@@ -147,39 +147,74 @@ export 'engine/vector_math.dart';
 import 'engine/web_experiments.dart';
 export 'engine/web_experiments.dart';
 
+export 'engine/canvaskit/canvas.dart';
+
+import 'engine/canvaskit/canvaskit_api.dart';
+export 'engine/canvaskit/canvaskit_api.dart';
+
+export 'engine/canvaskit/canvaskit_canvas.dart';
+
+import 'engine/canvaskit/color_filter.dart';
+export 'engine/canvaskit/color_filter.dart';
+
+import 'engine/canvaskit/embedded_views.dart';
+export 'engine/canvaskit/embedded_views.dart';
+
+export 'engine/canvaskit/fonts.dart';
+
+export 'engine/canvaskit/font_fallbacks.dart';
+
+export 'engine/canvaskit/image.dart';
+
+export 'engine/canvaskit/image_filter.dart';
+
+import 'engine/canvaskit/initialization.dart';
+export 'engine/canvaskit/initialization.dart';
+
+export 'engine/canvaskit/interval_tree.dart';
+
+import 'engine/canvaskit/layer.dart';
+export 'engine/canvaskit/layer.dart';
+
+import 'engine/canvaskit/layer_scene_builder.dart';
+export 'engine/canvaskit/layer_scene_builder.dart';
+
+export 'engine/canvaskit/layer_tree.dart';
+
+export 'engine/canvaskit/mask_filter.dart';
+
+export 'engine/canvaskit/n_way_canvas.dart';
+
+export 'engine/canvaskit/painting.dart';
+
+export 'engine/canvaskit/path.dart';
+
+export 'engine/canvaskit/path_metrics.dart';
+
+export 'engine/canvaskit/picture.dart';
+
+export 'engine/canvaskit/picture_recorder.dart';
+
+import 'engine/canvaskit/rasterizer.dart';
+export 'engine/canvaskit/rasterizer.dart';
+
+export 'engine/canvaskit/raster_cache.dart';
+
+export 'engine/canvaskit/shader.dart';
+
+export 'engine/canvaskit/skia_object_cache.dart';
+
+import 'engine/canvaskit/surface.dart';
+export 'engine/canvaskit/surface.dart';
+
+export 'engine/canvaskit/text.dart';
+
+export 'engine/canvaskit/util.dart';
+
+export 'engine/canvaskit/vertices.dart';
+
 part 'engine/assets.dart';
 part 'engine/html/bitmap_canvas.dart';
-part 'engine/canvaskit/canvas.dart';
-part 'engine/canvaskit/canvaskit_canvas.dart';
-part 'engine/canvaskit/canvaskit_api.dart';
-part 'engine/canvaskit/color_filter.dart';
-part 'engine/canvaskit/embedded_views.dart';
-part 'engine/canvaskit/fonts.dart';
-part 'engine/canvaskit/font_fallbacks.dart';
-part 'engine/canvaskit/image.dart';
-part 'engine/canvaskit/image_filter.dart';
-part 'engine/canvaskit/initialization.dart';
-part 'engine/canvaskit/interval_tree.dart';
-part 'engine/canvaskit/layer.dart';
-part 'engine/canvaskit/layer_scene_builder.dart';
-part 'engine/canvaskit/layer_tree.dart';
-part 'engine/canvaskit/mask_filter.dart';
-part 'engine/canvaskit/n_way_canvas.dart';
-part 'engine/canvaskit/path.dart';
-part 'engine/canvaskit/painting.dart';
-part 'engine/canvaskit/path_metrics.dart';
-part 'engine/canvaskit/picture.dart';
-part 'engine/canvaskit/picture_recorder.dart';
-part 'engine/canvaskit/platform_message.dart';
-part 'engine/canvaskit/raster_cache.dart';
-part 'engine/canvaskit/rasterizer.dart';
-part 'engine/canvaskit/shader.dart';
-part 'engine/canvaskit/skia_object_cache.dart';
-part 'engine/canvaskit/surface.dart';
-part 'engine/canvaskit/text.dart';
-part 'engine/canvaskit/util.dart';
-part 'engine/canvaskit/vertices.dart';
-part 'engine/canvaskit/viewport_metrics.dart';
 part 'engine/canvas_pool.dart';
 part 'engine/clipboard.dart';
 part 'engine/color_filter.dart';
@@ -251,8 +286,11 @@ const bool kReleaseMode =
 const bool kProfileMode =
     bool.fromEnvironment('dart.vm.profile', defaultValue: false);
 const bool kDebugMode = !kReleaseMode && !kProfileMode;
-String get buildMode =>
-    kReleaseMode ? 'release' : kProfileMode ? 'profile' : 'debug';
+String get buildMode => kReleaseMode
+    ? 'release'
+    : kProfileMode
+        ? 'profile'
+        : 'debug';
 
 /// A benchmark metric that includes frame-related computations prior to
 /// submitting layer and picture operations to the underlying renderer, such as
@@ -370,7 +408,7 @@ void _addUrlStrategyListener() {
   });
 }
 
-class _NullTreeSanitizer implements html.NodeTreeSanitizer {
+class NullTreeSanitizer implements html.NodeTreeSanitizer {
   @override
   void sanitizeTree(html.Node node) {}
 }

lib/web_ui/lib/src/engine/canvaskit/canvas.dart

@@ -2,7 +2,20 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:math' as math;
+import 'dart:typed_data';
+
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'image.dart';
+import 'image_filter.dart';
+import 'painting.dart';
+import 'path.dart';
+import 'picture.dart';
+import 'text.dart';
+import 'util.dart';
+import 'vertices.dart';
 
 /// Memoized value for ClipOp.Intersect, so we don't have to hit JS-interop
 /// every time we need it.
@@ -158,7 +171,8 @@ class CkCanvas {
     }
   }
 
-  void drawImageNine(CkImage image, ui.Rect center, ui.Rect dst, CkPaint paint) {
+  void drawImageNine(
+      CkImage image, ui.Rect center, ui.Rect dst, CkPaint paint) {
     skCanvas.drawImageNine(
       image.skImage,
       toSkRect(center),
@@ -268,13 +282,14 @@ class CkCanvas {
     skCanvas.saveLayer(paint?.skiaObject, null, null, null);
   }
 
-  void saveLayerWithFilter(ui.Rect bounds, ui.ImageFilter filter, [ CkPaint? paint ]) {
-    final _CkManagedSkImageFilterConvertible convertible =
-        filter as _CkManagedSkImageFilterConvertible;
+  void saveLayerWithFilter(ui.Rect bounds, ui.ImageFilter filter,
+      [CkPaint? paint]) {
+    final CkManagedSkImageFilterConvertible convertible =
+        filter as CkManagedSkImageFilterConvertible;
     return skCanvas.saveLayer(
       paint?.skiaObject,
       toSkRect(bounds),
-      convertible._imageFilter.skiaObject,
+      convertible.imageFilter.skiaObject,
       0,
     );
   }
@@ -504,7 +519,8 @@ class RecordingCkCanvas extends CkCanvas {
   }
 
   @override
-  void saveLayerWithFilter(ui.Rect bounds, ui.ImageFilter filter, [ CkPaint? paint ]) {
+  void saveLayerWithFilter(ui.Rect bounds, ui.ImageFilter filter,
+      [CkPaint? paint]) {
     super.saveLayerWithFilter(bounds, filter, paint);
     _addCommand(CkSaveLayerWithFilterCommand(bounds, filter, paint));
   }
@@ -1128,12 +1144,12 @@ class CkSaveLayerWithFilterCommand extends CkPaintCommand {
 
   @override
   void apply(SkCanvas canvas) {
-    final _CkManagedSkImageFilterConvertible convertible =
-        filter as _CkManagedSkImageFilterConvertible;
+    final CkManagedSkImageFilterConvertible convertible =
+        filter as CkManagedSkImageFilterConvertible;
     return canvas.saveLayer(
       paint?.skiaObject,
       toSkRect(bounds),
-      convertible._imageFilter.skiaObject,
+      convertible.imageFilter.skiaObject,
       0,
     );
   }

lib/web_ui/lib/src/engine/canvaskit/canvaskit_api.dart

@@ -6,8 +6,17 @@
 ///
 /// Prefer keeping the original CanvasKit names so it is easier to locate
 /// the API behind these bindings in the Skia source code.
+@JS()
+library canvaskit_api;
+
+import 'dart:async';
+import 'dart:html' as html;
+import 'dart:js' as js;
+import 'dart:typed_data';
 
-part of engine;
+import 'package:js/js.dart';
+import 'package:ui/src/engine.dart';
+import 'package:ui/ui.dart' as ui;
 
 /// Entrypoint into the CanvasKit API.
 late CanvasKit canvasKit;

lib/web_ui/lib/src/engine/canvaskit/canvaskit_canvas.dart

@@ -2,7 +2,22 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show toMatrix32;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvas.dart';
+import 'canvaskit_api.dart';
+import 'image.dart';
+import 'painting.dart';
+import 'path.dart';
+import 'picture.dart';
+import 'picture_recorder.dart';
+import 'text.dart';
+import 'vertices.dart';
+
+import '../validators.dart';
 
 /// An implementation of [ui.Canvas] that is backed by a CanvasKit canvas.
 class CanvasKitCanvas implements ui.Canvas {

lib/web_ui/lib/src/engine/canvaskit/color_filter.dart

@@ -2,18 +2,25 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show listEquals, EngineColorFilter;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'image_filter.dart';
+import 'skia_object_cache.dart';
 
 /// A concrete [ManagedSkiaObject] subclass that owns a [SkColorFilter] and
 /// manages its lifecycle.
 ///
 /// Seealso:
 ///
-/// * [CkPaint.colorFilter], which uses a [_ManagedSkColorFilter] to manage
+/// * [CkPaint.colorFilter], which uses a [ManagedSkColorFilter] to manage
 ///   the lifecycle of its [SkColorFilter].
-class _ManagedSkColorFilter extends ManagedSkiaObject<SkColorFilter> {
-  _ManagedSkColorFilter(CkColorFilter ckColorFilter)
-    : this.ckColorFilter = ckColorFilter;
+class ManagedSkColorFilter extends ManagedSkiaObject<SkColorFilter> {
+  ManagedSkColorFilter(CkColorFilter ckColorFilter)
+      : this.ckColorFilter = ckColorFilter;
 
   final CkColorFilter ckColorFilter;
 
@@ -33,10 +40,11 @@ class _ManagedSkColorFilter extends ManagedSkiaObject<SkColorFilter> {
 
   @override
   bool operator ==(Object other) {
-    if (runtimeType != other.runtimeType)
+    if (runtimeType != other.runtimeType) {
       return false;
-    return other is _ManagedSkColorFilter
-        && other.ckColorFilter == ckColorFilter;
+    }
+    return other is ManagedSkColorFilter &&
+        other.ckColorFilter == ckColorFilter;
   }
 
   @override
@@ -47,24 +55,29 @@ class _ManagedSkColorFilter extends ManagedSkiaObject<SkColorFilter> {
 ///
 /// Additionally, this class provides the interface for converting itself to a
 /// [ManagedSkiaObject] that manages a skia image filter.
-abstract class CkColorFilter implements _CkManagedSkImageFilterConvertible<SkImageFilter>, EngineColorFilter {
+abstract class CkColorFilter
+    implements
+        CkManagedSkImageFilterConvertible<SkImageFilter>,
+        EngineColorFilter {
   const CkColorFilter();
 
   /// Called by [ManagedSkiaObject.createDefault] and
   /// [ManagedSkiaObject.resurrect] to create a new [SKImageFilter], when this
   /// filter is used as an [ImageFilter].
-  SkImageFilter _initRawImageFilter() => canvasKit.ImageFilter.MakeColorFilter(_initRawColorFilter(), null);
+  SkImageFilter initRawImageFilter() =>
+      canvasKit.ImageFilter.MakeColorFilter(_initRawColorFilter(), null);
 
   /// Called by [ManagedSkiaObject.createDefault] and
   /// [ManagedSkiaObject.resurrect] to create a new [SKColorFilter], when this
   /// filter is used as a [ColorFilter].
   SkColorFilter _initRawColorFilter();
 
-  ManagedSkiaObject<SkImageFilter> get _imageFilter => _CkColorFilterImageFilter(colorFilter: this);
+  ManagedSkiaObject<SkImageFilter> get imageFilter =>
+      CkColorFilterImageFilter(colorFilter: this);
 }
 
-class _CkBlendModeColorFilter extends CkColorFilter {
-  const _CkBlendModeColorFilter(this.color, this.blendMode);
+class CkBlendModeColorFilter extends CkColorFilter {
+  const CkBlendModeColorFilter(this.color, this.blendMode);
 
   final ui.Color color;
   final ui.BlendMode blendMode;
@@ -82,28 +95,30 @@ class _CkBlendModeColorFilter extends CkColorFilter {
 
   @override
   bool operator ==(Object other) {
-    if (runtimeType != other.runtimeType)
+    if (runtimeType != other.runtimeType) {
       return false;
-    return other is _CkBlendModeColorFilter
-        && other.color == color
-        && other.blendMode == blendMode;
+    }
+    return other is CkBlendModeColorFilter &&
+        other.color == color &&
+        other.blendMode == blendMode;
   }
 
   @override
   String toString() => 'ColorFilter.mode($color, $blendMode)';
 }
 
-class _CkMatrixColorFilter extends CkColorFilter {
-  const _CkMatrixColorFilter(this.matrix);
+class CkMatrixColorFilter extends CkColorFilter {
+  const CkMatrixColorFilter(this.matrix);
 
   final List<double> matrix;
 
   @override
   SkColorFilter _initRawColorFilter() {
-    assert(this.matrix.length == 20,  'Color Matrix must have 20 entries.');
+    assert(this.matrix.length == 20, 'Color Matrix must have 20 entries.');
     final List<double> matrix = this.matrix;
-    if (matrix is Float32List)
+    if (matrix is Float32List) {
       return canvasKit.ColorFilter.MakeMatrix(matrix);
+    }
     final Float32List float32Matrix = Float32List(20);
     for (int i = 0; i < 20; i++) {
       float32Matrix[i] = matrix[i];
@@ -116,19 +131,20 @@ class _CkMatrixColorFilter extends CkColorFilter {
 
   @override
   bool operator ==(Object other) {
-    return runtimeType == other.runtimeType
-      && other is _CkMatrixColorFilter
-      && _listEquals<double>(matrix, other.matrix);
+    return runtimeType == other.runtimeType &&
+        other is CkMatrixColorFilter &&
+        listEquals<double>(matrix, other.matrix);
   }
 
   @override
   String toString() => 'ColorFilter.matrix($matrix)';
 }
 
-class _CkLinearToSrgbGammaColorFilter extends CkColorFilter {
-  const _CkLinearToSrgbGammaColorFilter();
+class CkLinearToSrgbGammaColorFilter extends CkColorFilter {
+  const CkLinearToSrgbGammaColorFilter();
   @override
-  SkColorFilter _initRawColorFilter() => canvasKit.ColorFilter.MakeLinearToSRGBGamma();
+  SkColorFilter _initRawColorFilter() =>
+      canvasKit.ColorFilter.MakeLinearToSRGBGamma();
 
   @override
   bool operator ==(Object other) => runtimeType == other.runtimeType;
@@ -137,10 +153,11 @@ class _CkLinearToSrgbGammaColorFilter extends CkColorFilter {
   String toString() => 'ColorFilter.linearToSrgbGamma()';
 }
 
-class _CkSrgbToLinearGammaColorFilter extends CkColorFilter {
-  const _CkSrgbToLinearGammaColorFilter();
+class CkSrgbToLinearGammaColorFilter extends CkColorFilter {
+  const CkSrgbToLinearGammaColorFilter();
   @override
-  SkColorFilter _initRawColorFilter() => canvasKit.ColorFilter.MakeSRGBToLinearGamma();
+  SkColorFilter _initRawColorFilter() =>
+      canvasKit.ColorFilter.MakeSRGBToLinearGamma();
 
   @override
   bool operator ==(Object other) => runtimeType == other.runtimeType;

lib/web_ui/lib/src/engine/canvaskit/embedded_views.dart

@@ -2,7 +2,21 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:html' as html;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show window, NullTreeSanitizer;
+import 'package:ui/ui.dart' as ui;
+
+import '../html/path_to_svg_clip.dart';
+import '../services.dart';
+import '../util.dart';
+import '../vector_math.dart';
+import 'canvas.dart';
+import 'initialization.dart';
+import 'path.dart';
+import 'picture_recorder.dart';
+import 'surface.dart';
 
 /// This composites HTML views into the [ui.Scene].
 class HtmlViewEmbedder {
@@ -130,11 +144,11 @@ class HtmlViewEmbedder {
     callback(codec.encodeSuccessEnvelope(null));
   }
 
-  List<CkCanvas?> getCurrentCanvases() {
-    final List<CkCanvas?> canvases = <CkCanvas?>[];
+  List<CkCanvas> getCurrentCanvases() {
+    final List<CkCanvas> canvases = <CkCanvas>[];
     for (int i = 0; i < _compositionOrder.length; i++) {
       final int viewId = _compositionOrder[i];
-      canvases.add(_pictureRecorders[viewId]!.recordingCanvas);
+      canvases.add(_pictureRecorders[viewId]!.recordingCanvas!);
     }
     return canvases;
   }
@@ -268,7 +282,7 @@ class HtmlViewEmbedder {
               '<clipPath id="svgClip$_clipPathCount">'
               '<path d="${path.toSvgString()}">'
               '</path></clipPath>',
-              treeSanitizer: _NullTreeSanitizer(),
+              treeSanitizer: NullTreeSanitizer(),
             );
             pathDefs.append(newClipPath);
             clipView.style.clipPath = 'url(#svgClip$_clipPathCount)';
@@ -282,7 +296,7 @@ class HtmlViewEmbedder {
               '<clipPath id="svgClip$_clipPathCount">'
               '<path d="${path.toSvgString()}">'
               '</path></clipPath>',
-              treeSanitizer: _NullTreeSanitizer(),
+              treeSanitizer: NullTreeSanitizer(),
             );
             pathDefs.append(newClipPath);
             clipView.style.clipPath = 'url(#svgClip$_clipPathCount)';
@@ -304,7 +318,8 @@ class HtmlViewEmbedder {
     // pixels, so scale down the head element to match the logical resolution.
     final double scale = window.devicePixelRatio;
     final double inverseScale = 1 / scale;
-    final Matrix4 scaleMatrix = Matrix4.diagonal3Values(inverseScale, inverseScale, 1);
+    final Matrix4 scaleMatrix =
+        Matrix4.diagonal3Values(inverseScale, inverseScale, 1);
     headTransform = scaleMatrix.multiplied(headTransform);
     head.style.transform = float64ListToCssTransform(headTransform.storage);
   }
@@ -330,7 +345,7 @@ class HtmlViewEmbedder {
     }
     _svgPathDefs = html.Element.html(
       '$kSvgResourceHeader<defs id="sk_path_defs"></defs></svg>',
-      treeSanitizer: _NullTreeSanitizer(),
+      treeSanitizer: NullTreeSanitizer(),
     );
     skiaSceneHost!.append(_svgPathDefs!);
   }
@@ -341,8 +356,7 @@ class HtmlViewEmbedder {
     for (int i = 0; i < _compositionOrder.length; i++) {
       int viewId = _compositionOrder[i];
       _ensureOverlayInitialized(viewId);
-      final SurfaceFrame frame =
-          _overlays[viewId]!.acquireFrame(_frameSize);
+      final SurfaceFrame frame = _overlays[viewId]!.acquireFrame(_frameSize);
       final CkCanvas canvas = frame.skiaCanvas;
       canvas.drawPicture(
         _pictureRecorders[viewId]!.endRecording(),
@@ -350,7 +364,7 @@ class HtmlViewEmbedder {
       frame.submit();
     }
     _pictureRecorders.clear();
-    if (_listEquals(_compositionOrder, _activeCompositionOrder)) {
+    if (listEquals(_compositionOrder, _activeCompositionOrder)) {
       _compositionOrder.clear();
       return;
     }
@@ -628,7 +642,7 @@ class MutatorsStack extends Iterable<Mutator> {
       return true;
     }
     return other is MutatorsStack &&
-        _listEquals<Mutator>(other._mutators, _mutators);
+        listEquals<Mutator>(other._mutators, _mutators);
   }
 
   int get hashCode => ui.hashList(_mutators);

lib/web_ui/lib/src/engine/canvaskit/font_fallbacks.dart

@@ -2,7 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:async';
+import 'dart:convert';
+import 'dart:html' as html;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show sendFontChangeMessage;
+import 'package:ui/ui.dart' as ui;
+
+import '../util.dart';
+import 'canvaskit_api.dart';
+import 'fonts.dart';
+import 'initialization.dart';
+import 'interval_tree.dart';
 
 /// Global static font fallback data.
 class FontFallbackData {
@@ -52,7 +64,7 @@ class FontFallbackData {
   }
 
   /// Fallback fonts which have been registered and loaded.
-  final List<_RegisteredFont> registeredFallbackFonts = <_RegisteredFont>[];
+  final List<RegisteredFont> registeredFallbackFonts = <RegisteredFont>[];
 
   final List<String> globalFontFallbacks = <String>['Roboto'];
 
@@ -69,8 +81,7 @@ class FontFallbackData {
     int fontFallbackTag = fontFallbackCounts[family]!;
     fontFallbackCounts[family] = fontFallbackCounts[family]! + 1;
     String countedFamily = '$family $fontFallbackTag';
-    registeredFallbackFonts
-        .add(_RegisteredFont(bytes, countedFamily, typeface));
+    registeredFallbackFonts.add(RegisteredFont(bytes, countedFamily, typeface));
     globalFontFallbacks.add(countedFamily);
   }
 }

lib/web_ui/lib/src/engine/canvaskit/fonts.dart

@@ -2,7 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:convert';
+import 'dart:html' as html;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show AssetManager, AssetManagerException;
+
+import '../util.dart';
+import 'canvaskit_api.dart';
+import 'font_fallbacks.dart';
 
 // This URL was found by using the Google Fonts Developer API to find the URL
 // for Roboto. The API warns that this URL is not stable. In order to update
@@ -15,11 +23,11 @@ const String _robotoUrl =
 /// Manages the fonts used in the Skia-based backend.
 class SkiaFontCollection {
   /// Fonts that have been registered but haven't been loaded yet.
-  final List<Future<_RegisteredFont?>> _unloadedFonts =
-      <Future<_RegisteredFont?>>[];
+  final List<Future<RegisteredFont?>> _unloadedFonts =
+      <Future<RegisteredFont?>>[];
 
   /// Fonts which have been registered and loaded.
-  final List<_RegisteredFont> _registeredFonts = <_RegisteredFont>[];
+  final List<RegisteredFont> _registeredFonts = <RegisteredFont>[];
 
   final Map<String, List<SkTypeface>> familyToTypefaceMap =
       <String, List<SkTypeface>>{};
@@ -55,9 +63,8 @@ class SkiaFontCollection {
     if (_unloadedFonts.isEmpty) {
       return;
     }
-    final List<_RegisteredFont?> loadedFonts =
-        await Future.wait(_unloadedFonts);
-    for (_RegisteredFont? font in loadedFonts) {
+    final List<RegisteredFont?> loadedFonts = await Future.wait(_unloadedFonts);
+    for (RegisteredFont? font in loadedFonts) {
       if (font != null) {
         _registeredFonts.add(font);
       }
@@ -77,7 +84,7 @@ class SkiaFontCollection {
     final SkTypeface? typeface =
         canvasKit.FontMgr.RefDefault().MakeTypefaceFromData(list);
     if (typeface != null) {
-      _registeredFonts.add(_RegisteredFont(list, fontFamily, typeface));
+      _registeredFonts.add(RegisteredFont(list, fontFamily, typeface));
       await ensureFontsLoaded();
     } else {
       printWarning('Failed to parse font family "$fontFamily"');
@@ -134,7 +141,7 @@ class SkiaFontCollection {
     }
   }
 
-  Future<_RegisteredFont?> _registerFont(String url, String family) async {
+  Future<RegisteredFont?> _registerFont(String url, String family) async {
     ByteBuffer buffer;
     try {
       buffer = await html.window.fetch(url).then(_getArrayBuffer);
@@ -148,7 +155,7 @@ class SkiaFontCollection {
     SkTypeface? typeface =
         canvasKit.FontMgr.RefDefault().MakeTypefaceFromData(bytes);
     if (typeface != null) {
-      return _RegisteredFont(bytes, family, typeface);
+      return RegisteredFont(bytes, family, typeface);
     } else {
       printWarning('Failed to load font $family at $url');
       printWarning('Verify that $url contains a valid font.');
@@ -175,7 +182,7 @@ class SkiaFontCollection {
 }
 
 /// Represents a font that has been registered.
-class _RegisteredFont {
+class RegisteredFont {
   /// The font family name for this font.
   final String family;
 
@@ -187,7 +194,7 @@ class _RegisteredFont {
   /// This is used to determine which code points are supported by this font.
   final SkTypeface typeface;
 
-  _RegisteredFont(this.bytes, this.family, this.typeface) {
+  RegisteredFont(this.bytes, this.family, this.typeface) {
     // This is a hack which causes Skia to cache the decoded font.
     SkFont skFont = SkFont(typeface);
     skFont.getGlyphBounds([0], null, null);

lib/web_ui/lib/src/engine/canvaskit/image.dart

@@ -2,7 +2,16 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:async';
+import 'dart:html' as html;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show WebOnlyImageCodecChunkCallback;
+import 'package:ui/ui.dart' as ui;
+
+import '../util.dart';
+import 'canvaskit_api.dart';
+import 'skia_object_cache.dart';
 
 /// Instantiates a [ui.Codec] backed by an `SkAnimatedImage` from Skia.
 ui.Codec skiaInstantiateImageCodec(Uint8List list,

lib/web_ui/lib/src/engine/canvaskit/image_filter.dart

@@ -2,7 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'color_filter.dart';
+import 'skia_object_cache.dart';
 
 /// An [ImageFilter] that can create a managed skia [SkImageFilter] object.
 ///
@@ -11,21 +15,27 @@ part of engine;
 /// whenever possible.
 ///
 /// Currently implemented by [CkImageFilter] and [CkColorFilter].
-abstract class _CkManagedSkImageFilterConvertible<T extends Object> implements ui.ImageFilter {
-  ManagedSkiaObject<SkImageFilter> get _imageFilter;
+abstract class CkManagedSkImageFilterConvertible<T extends Object>
+    implements ui.ImageFilter {
+  ManagedSkiaObject<SkImageFilter> get imageFilter;
 }
 
 /// The CanvasKit implementation of [ui.ImageFilter].
 ///
 /// Currently only supports `blur`.
-abstract class CkImageFilter extends ManagedSkiaObject<SkImageFilter> implements _CkManagedSkImageFilterConvertible<SkImageFilter> {
-  factory CkImageFilter.blur({ required double sigmaX, required double sigmaY, required ui.TileMode tileMode }) = _CkBlurImageFilter;
-  factory CkImageFilter.color({ required CkColorFilter colorFilter }) = _CkColorFilterImageFilter;
+abstract class CkImageFilter extends ManagedSkiaObject<SkImageFilter>
+    implements CkManagedSkImageFilterConvertible<SkImageFilter> {
+  factory CkImageFilter.blur(
+      {required double sigmaX,
+      required double sigmaY,
+      required ui.TileMode tileMode}) = _CkBlurImageFilter;
+  factory CkImageFilter.color({required CkColorFilter colorFilter}) =
+      CkColorFilterImageFilter;
 
   CkImageFilter._();
 
   @override
-  ManagedSkiaObject<SkImageFilter> get _imageFilter => this;
+  ManagedSkiaObject<SkImageFilter> get imageFilter => this;
 
   SkImageFilter _initSkiaObject();
 
@@ -41,23 +51,24 @@ abstract class CkImageFilter extends ManagedSkiaObject<SkImageFilter> implements
   }
 }
 
-class _CkColorFilterImageFilter extends CkImageFilter {
-  _CkColorFilterImageFilter({ required this.colorFilter }) : super._();
+class CkColorFilterImageFilter extends CkImageFilter {
+  CkColorFilterImageFilter({required this.colorFilter}) : super._();
 
   final CkColorFilter colorFilter;
 
   @override
-  SkImageFilter _initSkiaObject() => colorFilter._initRawImageFilter();
+  SkImageFilter _initSkiaObject() => colorFilter.initRawImageFilter();
 
   @override
   int get hashCode => colorFilter.hashCode;
 
   @override
   bool operator ==(Object other) {
-    if (runtimeType != other.runtimeType)
+    if (runtimeType != other.runtimeType) {
       return false;
-    return other is _CkColorFilterImageFilter
-        && other.colorFilter == colorFilter;
+    }
+    return other is CkColorFilterImageFilter &&
+        other.colorFilter == colorFilter;
   }
 
   @override
@@ -65,7 +76,9 @@ class _CkColorFilterImageFilter extends CkImageFilter {
 }
 
 class _CkBlurImageFilter extends CkImageFilter {
-  _CkBlurImageFilter({ required this.sigmaX, required this.sigmaY, required this.tileMode }) : super._();
+  _CkBlurImageFilter(
+      {required this.sigmaX, required this.sigmaY, required this.tileMode})
+      : super._();
 
   final double sigmaX;
   final double sigmaY;
@@ -73,10 +86,14 @@ class _CkBlurImageFilter extends CkImageFilter {
 
   String get _modeString {
     switch (tileMode) {
-      case ui.TileMode.clamp: return 'clamp';
-      case ui.TileMode.mirror: return 'mirror';
-      case ui.TileMode.repeated: return 'repeated';
-      case ui.TileMode.decal: return 'decal';
+      case ui.TileMode.clamp:
+        return 'clamp';
+      case ui.TileMode.mirror:
+        return 'mirror';
+      case ui.TileMode.repeated:
+        return 'repeated';
+      case ui.TileMode.decal:
+        return 'decal';
     }
   }
 
@@ -92,12 +109,13 @@ class _CkBlurImageFilter extends CkImageFilter {
 
   @override
   bool operator ==(Object other) {
-    if (runtimeType != other.runtimeType)
+    if (runtimeType != other.runtimeType) {
       return false;
-    return other is _CkBlurImageFilter
-        && other.sigmaX == sigmaX
-        && other.sigmaY == sigmaY
-        && other.tileMode == tileMode;
+    }
+    return other is _CkBlurImageFilter &&
+        other.sigmaX == sigmaX &&
+        other.sigmaY == sigmaY &&
+        other.tileMode == tileMode;
   }
 
   @override
@@ -108,4 +126,3 @@ class _CkBlurImageFilter extends CkImageFilter {
     return 'ImageFilter.blur($sigmaX, $sigmaY, $_modeString)';
   }
 }
-

lib/web_ui/lib/src/engine/canvaskit/initialization.dart

 // Copyright 2013 The Flutter Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
+@JS()
+library canvaskit_initialization;
 
-part of engine;
+import 'dart:async';
+import 'dart:html' as html;
+import 'dart:js' as js;
+
+import 'package:js/js.dart';
+import 'package:ui/src/engine.dart' show isDesktop, kProfileMode, domRenderer;
+
+import 'canvaskit_api.dart';
+import 'fonts.dart';
 
 /// A JavaScript entrypoint that allows developer to set rendering backend
 /// at runtime before launching the application.
@@ -10,7 +20,7 @@ part of engine;
 external String? get requestedRendererType;
 
 /// Whether to use CanvasKit as the rendering backend.
-bool get useCanvasKit => _autoDetect ? _detectRenderer() : _useSkia;
+bool get useCanvasKit => flutterWebAutoDetect ? _detectRenderer() : _useSkia;
 
 /// Returns true if CanvasKit is used.
 ///
@@ -28,7 +38,7 @@ bool _detectRenderer() {
 ///
 /// Using flutter tools option "--web-render=auto" or not specifying one
 /// would set the value to true. Otherwise, it would be false.
-const bool _autoDetect =
+const bool flutterWebAutoDetect =
     bool.fromEnvironment('FLUTTER_WEB_AUTO_DETECT', defaultValue: true);
 
 /// Enable the Skia-based rendering backend.

lib/web_ui/lib/src/engine/canvaskit/interval_tree.dart

@@ -2,7 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:math' as math;
+
+import 'font_fallbacks.dart' show CodeunitRange;
 
 /// A tree which stores a set of intervals that can be queried for intersection.
 class IntervalTree<T> {

lib/web_ui/lib/src/engine/canvaskit/layer.dart

@@ -2,7 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'package:ui/src/engine.dart' show transformRect, Matrix4;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvas.dart';
+import 'embedded_views.dart';
+import 'n_way_canvas.dart';
+import 'painting.dart';
+import 'path.dart';
+import 'picture.dart';
+import 'raster_cache.dart';
+import 'util.dart';
 
 /// A layer to be composed into a scene.
 ///
@@ -149,7 +159,8 @@ class RootLayer extends ContainerLayer {
   }
 }
 
-class BackdropFilterEngineLayer extends ContainerLayer implements ui.BackdropFilterEngineLayer {
+class BackdropFilterEngineLayer extends ContainerLayer
+    implements ui.BackdropFilterEngineLayer {
   final ui.ImageFilter _filter;
   final ui.BlendMode _blendMode;
 
@@ -164,14 +175,16 @@ class BackdropFilterEngineLayer extends ContainerLayer implements ui.BackdropFil
   @override
   void paint(PaintContext context) {
     CkPaint paint = CkPaint()..blendMode = _blendMode;
-    context.internalNodesCanvas.saveLayerWithFilter(paintBounds, _filter, paint);
+    context.internalNodesCanvas
+        .saveLayerWithFilter(paintBounds, _filter, paint);
     paintChildren(context);
     context.internalNodesCanvas.restore();
   }
 }
 
 /// A layer that clips its child layers by a given [Path].
-class ClipPathEngineLayer extends ContainerLayer implements ui.ClipPathEngineLayer {
+class ClipPathEngineLayer extends ContainerLayer
+    implements ui.ClipPathEngineLayer {
   /// The path used to clip child layers.
   final CkPath _clipPath;
   final ui.Clip _clipBehavior;
@@ -210,7 +223,8 @@ class ClipPathEngineLayer extends ContainerLayer implements ui.ClipPathEngineLay
 }
 
 /// A layer that clips its child layers by a given [Rect].
-class ClipRectEngineLayer extends ContainerLayer implements ui.ClipRectEngineLayer {
+class ClipRectEngineLayer extends ContainerLayer
+    implements ui.ClipRectEngineLayer {
   /// The rectangle used to clip child layers.
   final ui.Rect _clipRect;
   final ui.Clip _clipBehavior;
@@ -250,7 +264,8 @@ class ClipRectEngineLayer extends ContainerLayer implements ui.ClipRectEngineLay
 }
 
 /// A layer that clips its child layers by a given [RRect].
-class ClipRRectEngineLayer extends ContainerLayer implements ui.ClipRRectEngineLayer {
+class ClipRRectEngineLayer extends ContainerLayer
+    implements ui.ClipRRectEngineLayer {
   /// The rounded rectangle used to clip child layers.
   final ui.RRect _clipRRect;
   final ui.Clip? _clipBehavior;
@@ -287,7 +302,8 @@ class ClipRRectEngineLayer extends ContainerLayer implements ui.ClipRRectEngineL
 }
 
 /// A layer that paints its children with the given opacity.
-class OpacityEngineLayer extends ContainerLayer implements ui.OpacityEngineLayer {
+class OpacityEngineLayer extends ContainerLayer
+    implements ui.OpacityEngineLayer {
   final int _alpha;
   final ui.Offset _offset;
 
@@ -327,7 +343,8 @@ class OpacityEngineLayer extends ContainerLayer implements ui.OpacityEngineLayer
 }
 
 /// A layer that transforms its child layers by the given transform matrix.
-class TransformEngineLayer extends ContainerLayer implements ui.TransformEngineLayer {
+class TransformEngineLayer extends ContainerLayer
+    implements ui.TransformEngineLayer {
   /// The matrix with which to transform the child layers.
   final Matrix4 _transform;
 
@@ -358,12 +375,15 @@ class TransformEngineLayer extends ContainerLayer implements ui.TransformEngineL
 /// This is a thin wrapper over [TransformEngineLayer] just so the framework
 /// gets the "OffsetEngineLayer" when calling `runtimeType.toString()`. This is
 /// better for debugging.
-class OffsetEngineLayer extends TransformEngineLayer implements ui.OffsetEngineLayer {
-  OffsetEngineLayer(double dx, double dy) : super(Matrix4.translationValues(dx, dy, 0.0));
+class OffsetEngineLayer extends TransformEngineLayer
+    implements ui.OffsetEngineLayer {
+  OffsetEngineLayer(double dx, double dy)
+      : super(Matrix4.translationValues(dx, dy, 0.0));
 }
 
 /// A layer that applies an [ui.ImageFilter] to its children.
-class ImageFilterEngineLayer extends ContainerLayer implements ui.ImageFilterEngineLayer {
+class ImageFilterEngineLayer extends ContainerLayer
+    implements ui.ImageFilterEngineLayer {
   ImageFilterEngineLayer(this._filter);
 
   final ui.ImageFilter _filter;
@@ -379,8 +399,10 @@ class ImageFilterEngineLayer extends ContainerLayer implements ui.ImageFilterEng
   }
 }
 
-class ShaderMaskEngineLayer extends ContainerLayer implements ui.ShaderMaskEngineLayer {
-  ShaderMaskEngineLayer(this.shader, this.maskRect, this.blendMode, this.filterQuality);
+class ShaderMaskEngineLayer extends ContainerLayer
+    implements ui.ShaderMaskEngineLayer {
+  ShaderMaskEngineLayer(
+      this.shader, this.maskRect, this.blendMode, this.filterQuality);
 
   final ui.Shader shader;
   final ui.Rect maskRect;
@@ -467,7 +489,8 @@ class PhysicalShapeEngineLayer extends ContainerLayer
   @override
   void preroll(PrerollContext prerollContext, Matrix4 matrix) {
     prerollChildren(prerollContext, matrix);
-    paintBounds = computeSkShadowBounds(_path, _elevation, ui.window.devicePixelRatio, matrix);
+    paintBounds = computeSkShadowBounds(
+        _path, _elevation, ui.window.devicePixelRatio, matrix);
   }
 
   @override
@@ -524,7 +547,8 @@ class PhysicalShapeEngineLayer extends ContainerLayer
 }
 
 /// A layer which contains a [ui.ColorFilter].
-class ColorFilterEngineLayer extends ContainerLayer implements ui.ColorFilterEngineLayer {
+class ColorFilterEngineLayer extends ContainerLayer
+    implements ui.ColorFilterEngineLayer {
   ColorFilterEngineLayer(this.filter);
 
   final ui.ColorFilter filter;

lib/web_ui/lib/src/engine/canvaskit/layer_scene_builder.dart

@@ -2,7 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show toMatrix32, Matrix4;
+import 'package:ui/ui.dart' as ui;
+
+import 'layer.dart';
+import 'layer_tree.dart';
+import 'picture.dart';
+import 'path.dart';
 
 class LayerScene implements ui.Scene {
   final LayerTree layerTree;
@@ -115,7 +123,8 @@ class LayerSceneBuilder implements ui.SceneBuilder {
     ui.Clip clipBehavior = ui.Clip.antiAlias,
     ui.EngineLayer? oldLayer,
   }) {
-    return pushLayer<ClipPathEngineLayer>(ClipPathEngineLayer(path as CkPath, clipBehavior));
+    return pushLayer<ClipPathEngineLayer>(
+        ClipPathEngineLayer(path as CkPath, clipBehavior));
   }
 
   @override
@@ -124,7 +133,8 @@ class LayerSceneBuilder implements ui.SceneBuilder {
     ui.Clip? clipBehavior,
     ui.EngineLayer? oldLayer,
   }) {
-    return pushLayer<ClipRRectEngineLayer>(ClipRRectEngineLayer(rrect, clipBehavior));
+    return pushLayer<ClipRRectEngineLayer>(
+        ClipRRectEngineLayer(rrect, clipBehavior));
   }
 
   @override
@@ -133,7 +143,8 @@ class LayerSceneBuilder implements ui.SceneBuilder {
     ui.Clip clipBehavior = ui.Clip.antiAlias,
     ui.EngineLayer? oldLayer,
   }) {
-    return pushLayer<ClipRectEngineLayer>(ClipRectEngineLayer(rect, clipBehavior));
+    return pushLayer<ClipRectEngineLayer>(
+        ClipRectEngineLayer(rect, clipBehavior));
   }
 
   @override
@@ -197,8 +208,8 @@ class LayerSceneBuilder implements ui.SceneBuilder {
     ui.EngineLayer? oldLayer,
     ui.FilterQuality filterQuality = ui.FilterQuality.low,
   }) {
-    return pushLayer<ShaderMaskEngineLayer>(ShaderMaskEngineLayer(
-        shader, maskRect, blendMode, filterQuality));
+    return pushLayer<ShaderMaskEngineLayer>(
+        ShaderMaskEngineLayer(shader, maskRect, blendMode, filterQuality));
   }
 
   @override

lib/web_ui/lib/src/engine/canvaskit/layer_tree.dart

@@ -2,7 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'package:ui/src/engine.dart' show timeAction;
+import 'package:ui/ui.dart' as ui;
+
+import '../../engine.dart' show kProfilePrerollFrame, kProfileApplyFrame;
+import '../vector_math.dart';
+import 'canvas.dart';
+import 'embedded_views.dart';
+import 'layer.dart';
+import 'n_way_canvas.dart';
+import 'picture_recorder.dart';
+import 'raster_cache.dart';
 
 /// A tree of [Layer]s that, together with a [Size] compose a frame.
 class LayerTree {
@@ -38,7 +48,7 @@ class LayerTree {
   void paint(Frame frame, {bool ignoreRasterCache = false}) {
     final CkNWayCanvas internalNodesCanvas = CkNWayCanvas();
     internalNodesCanvas.addCanvas(frame.canvas);
-    final List<CkCanvas?> overlayCanvases =
+    final List<CkCanvas> overlayCanvases =
         frame.viewEmbedder!.getCurrentCanvases();
     for (int i = 0; i < overlayCanvases.length; i++) {
       internalNodesCanvas.addCanvas(overlayCanvases[i]);

lib/web_ui/lib/src/engine/canvaskit/mask_filter.dart

@@ -2,7 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'canvaskit_api.dart';
+import 'skia_object_cache.dart';
+
+import 'package:ui/ui.dart' as ui;
 
 /// The CanvasKit implementation of [ui.MaskFilter].
 class CkMaskFilter extends ManagedSkiaObject<SkMaskFilter> {

lib/web_ui/lib/src/engine/canvaskit/n_way_canvas.dart

@@ -2,14 +2,19 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
+
+import 'package:ui/ui.dart' as ui;
+
+import 'canvas.dart';
+import 'painting.dart';
+import 'path.dart';
 
 /// A virtual canvas that applies operations to multiple canvases at once.
 class CkNWayCanvas {
-  // TODO(yjbanov): make this List<CkCanvas>
-  final List<CkCanvas?> _canvases = <CkCanvas?>[];
+  final List<CkCanvas> _canvases = <CkCanvas>[];
 
-  void addCanvas(CkCanvas? canvas) {
+  void addCanvas(CkCanvas canvas) {
     _canvases.add(canvas);
   }
 
@@ -17,7 +22,7 @@ class CkNWayCanvas {
   int save() {
     int saveCount = 0;
     for (int i = 0; i < _canvases.length; i++) {
-      saveCount = _canvases[i]!.save();
+      saveCount = _canvases[i].save();
     }
     return saveCount;
   }
@@ -25,63 +30,64 @@ class CkNWayCanvas {
   /// Calls [saveLayer] on all canvases.
   void saveLayer(ui.Rect bounds, CkPaint? paint) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.saveLayer(bounds, paint);
+      _canvases[i].saveLayer(bounds, paint);
     }
   }
 
   /// Calls [saveLayerWithFilter] on all canvases.
-  void saveLayerWithFilter(ui.Rect bounds, ui.ImageFilter filter, [ CkPaint? paint ]) {
+  void saveLayerWithFilter(ui.Rect bounds, ui.ImageFilter filter,
+      [CkPaint? paint]) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.saveLayerWithFilter(bounds, filter, paint);
+      _canvases[i].saveLayerWithFilter(bounds, filter, paint);
     }
   }
 
   /// Calls [restore] on all canvases.
   void restore() {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.restore();
+      _canvases[i].restore();
     }
   }
 
   /// Calls [restoreToCount] on all canvases.
   void restoreToCount(int count) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.restoreToCount(count);
+      _canvases[i].restoreToCount(count);
     }
   }
 
   /// Calls [translate] on all canvases.
   void translate(double dx, double dy) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.translate(dx, dy);
+      _canvases[i].translate(dx, dy);
     }
   }
 
   /// Calls [transform] on all canvases.
   void transform(Float32List matrix) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.transform(matrix);
+      _canvases[i].transform(matrix);
     }
   }
 
   /// Calls [clipPath] on all canvases.
   void clipPath(CkPath path, bool doAntiAlias) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.clipPath(path, doAntiAlias);
+      _canvases[i].clipPath(path, doAntiAlias);
     }
   }
 
   /// Calls [clipRect] on all canvases.
   void clipRect(ui.Rect rect, ui.ClipOp clipOp, bool doAntiAlias) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.clipRect(rect, clipOp, doAntiAlias);
+      _canvases[i].clipRect(rect, clipOp, doAntiAlias);
     }
   }
 
   /// Calls [clipRRect] on all canvases.
   void clipRRect(ui.RRect rrect, bool doAntiAlias) {
     for (int i = 0; i < _canvases.length; i++) {
-      _canvases[i]!.clipRRect(rrect, doAntiAlias);
+      _canvases[i].clipRRect(rrect, doAntiAlias);
     }
   }
 }

lib/web_ui/lib/src/engine/canvaskit/painting.dart

@@ -2,7 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'color_filter.dart';
+import 'image_filter.dart';
+import 'mask_filter.dart';
+import 'shader.dart';
+import 'skia_object_cache.dart';
 
 /// The implementation of [ui.Paint] used by the CanvasKit backend.
 ///
@@ -175,12 +182,12 @@ class CkPaint extends ManagedSkiaObject<SkPaint> implements ui.Paint {
     if (value == null) {
       _managedColorFilter = null;
     } else {
-      _managedColorFilter = _ManagedSkColorFilter(value as CkColorFilter);
+      _managedColorFilter = ManagedSkColorFilter(value as CkColorFilter);
     }
     skiaObject.setColorFilter(_managedColorFilter?.skiaObject);
   }
 
-  _ManagedSkColorFilter? _managedColorFilter;
+  ManagedSkColorFilter? _managedColorFilter;
 
   @override
   double get strokeMiterLimit => _strokeMiterLimit;
@@ -203,12 +210,12 @@ class CkPaint extends ManagedSkiaObject<SkPaint> implements ui.Paint {
       return;
     }
 
-    _imageFilter = value as _CkManagedSkImageFilterConvertible?;
-    _managedImageFilter = _imageFilter?._imageFilter;
+    _imageFilter = value as CkManagedSkImageFilterConvertible?;
+    _managedImageFilter = _imageFilter?.imageFilter;
     skiaObject.setImageFilter(_managedImageFilter?.skiaObject);
   }
 
-  _CkManagedSkImageFilterConvertible? _imageFilter;
+  CkManagedSkImageFilterConvertible? _imageFilter;
   ManagedSkiaObject<SkImageFilter>? _managedImageFilter;
 
   @override

lib/web_ui/lib/src/engine/canvaskit/path.dart

@@ -2,7 +2,15 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:math' as math;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show Matrix4;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'path_metrics.dart';
+import 'skia_object_cache.dart';
 
 /// An implementation of [ui.Path] which is backed by an `SkPath`.
 ///
@@ -16,7 +24,7 @@ class CkPath extends ManagedSkiaObject<SkPath> implements ui.Path {
     skiaObject.setFillType(toSkFillType(_fillType));
   }
 
-  CkPath._fromSkPath(SkPath skPath, this._fillType) : super(skPath) {
+  CkPath.fromSkPath(SkPath skPath, this._fillType) : super(skPath) {
     skiaObject.setFillType(toSkFillType(_fillType));
   }
 
@@ -254,7 +262,7 @@ class CkPath extends ManagedSkiaObject<SkPath> implements ui.Path {
     // path and call `transform` on it.
     final SkPath newPath = skiaObject.copy();
     newPath.transform(1.0, 0.0, offset.dx, 0.0, 1.0, offset.dy, 0.0, 0.0, 0.0);
-    return CkPath._fromSkPath(newPath, _fillType);
+    return CkPath.fromSkPath(newPath, _fillType);
   }
 
   static CkPath combine(
@@ -269,7 +277,7 @@ class CkPath extends ManagedSkiaObject<SkPath> implements ui.Path {
       path2.skiaObject,
       toSkPathOp(operation),
     );
-    return CkPath._fromSkPath(newPath, path1._fillType);
+    return CkPath.fromSkPath(newPath, path1._fillType);
   }
 
   @override
@@ -287,7 +295,7 @@ class CkPath extends ManagedSkiaObject<SkPath> implements ui.Path {
       m[7],
       m[8],
     );
-    return CkPath._fromSkPath(newPath, _fillType);
+    return CkPath.fromSkPath(newPath, _fillType);
   }
 
   String? toSvgString() {

lib/web_ui/lib/src/engine/canvaskit/path_metrics.dart

@@ -2,7 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:collection';
+import 'dart:typed_data';
+
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'path.dart';
+import 'skia_object_cache.dart';
 
 class CkPathMetrics extends IterableBase<ui.PathMetric>
     implements ui.PathMetrics {
@@ -14,11 +21,12 @@ class CkPathMetrics extends IterableBase<ui.PathMetric>
   /// The [CkPath.isEmpty] case is special-cased to avoid booting the WASM machinery just to find out there are no contours.
   @override
   Iterator<ui.PathMetric> get iterator => _path.isEmpty
-    ? const CkPathMetricIteratorEmpty._()
-    : CkContourMeasureIter(this);
+      ? const CkPathMetricIteratorEmpty._()
+      : CkContourMeasureIter(this);
 }
 
-class CkContourMeasureIter extends ManagedSkiaObject<SkContourMeasureIter> implements Iterator<ui.PathMetric> {
+class CkContourMeasureIter extends ManagedSkiaObject<SkContourMeasureIter>
+    implements Iterator<ui.PathMetric> {
   CkContourMeasureIter(this._metrics);
 
   final CkPathMetrics _metrics;
@@ -33,13 +41,13 @@ class CkContourMeasureIter extends ManagedSkiaObject<SkContourMeasureIter> imple
     final ui.PathMetric? currentMetric = _current;
     if (currentMetric == null) {
       throw RangeError(
-        'PathMetricIterator is not pointing to a PathMetric. This can happen in two situations:\n'
-        '- The iteration has not started yet. If so, call "moveNext" to start iteration.'
-        '- The iterator ran out of elements. If so, check that "moveNext" returns true prior to calling "current".'
-      );
+          'PathMetricIterator is not pointing to a PathMetric. This can happen in two situations:\n'
+          '- The iteration has not started yet. If so, call "moveNext" to start iteration.'
+          '- The iterator ran out of elements. If so, check that "moveNext" returns true prior to calling "current".');
     }
     return currentMetric;
   }
+
   CkContourMeasure? _current;
 
   @override
@@ -50,7 +58,8 @@ class CkContourMeasureIter extends ManagedSkiaObject<SkContourMeasureIter> imple
       return false;
     }
 
-    _current = CkContourMeasure(_metrics, skContourMeasure, _contourIndexCounter);
+    _current =
+        CkContourMeasure(_metrics, skContourMeasure, _contourIndexCounter);
     _contourIndexCounter += 1;
     return true;
   }
@@ -83,9 +92,10 @@ class CkContourMeasureIter extends ManagedSkiaObject<SkContourMeasureIter> imple
   }
 }
 
-class CkContourMeasure extends ManagedSkiaObject<SkContourMeasure> implements ui.PathMetric {
+class CkContourMeasure extends ManagedSkiaObject<SkContourMeasure>
+    implements ui.PathMetric {
   CkContourMeasure(this._metrics, SkContourMeasure jsObject, this.contourIndex)
-    : super(jsObject);
+      : super(jsObject);
 
   /// The path metrics used to create this measure.
   ///
@@ -98,7 +108,7 @@ class CkContourMeasure extends ManagedSkiaObject<SkContourMeasure> implements ui
   @override
   ui.Path extractPath(double start, double end, {bool startWithMoveTo = true}) {
     final SkPath skPath = skiaObject.getSegment(start, end, startWithMoveTo);
-    return CkPath._fromSkPath(skPath, _metrics._path._fillType);
+    return CkPath.fromSkPath(skPath, _metrics._path.fillType);
   }
 
   @override
@@ -130,7 +140,8 @@ class CkContourMeasure extends ManagedSkiaObject<SkContourMeasure> implements ui
 
   @override
   SkContourMeasure resurrect() {
-    final CkContourMeasureIter iterator = _metrics.iterator as CkContourMeasureIter;
+    final CkContourMeasureIter iterator =
+        _metrics.iterator as CkContourMeasureIter;
     final SkContourMeasureIter skIterator = iterator.skiaObject;
 
     // When resurrecting we must advance the iterator to the last known

lib/web_ui/lib/src/engine/canvaskit/picture.dart

@@ -2,7 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvas.dart';
+import 'canvaskit_api.dart';
+import 'image.dart';
+import 'skia_object_cache.dart';
 
 class CkPicture extends ManagedSkiaObject<SkPicture> implements ui.Picture {
   final ui.Rect? cullRect;
@@ -10,7 +15,8 @@ class CkPicture extends ManagedSkiaObject<SkPicture> implements ui.Picture {
 
   CkPicture(SkPicture picture, this.cullRect, this._snapshot) : super(picture) {
     assert(
-      browserSupportsFinalizationRegistry && _snapshot == null || _snapshot != null,
+      browserSupportsFinalizationRegistry && _snapshot == null ||
+          _snapshot != null,
       'If the browser does not support FinalizationRegistry (WeakRef), then we must have a picture snapshot to be able to resurrect it.',
     );
   }

lib/web_ui/lib/src/engine/canvaskit/picture_recorder.dart

@@ -2,7 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
+
+import 'package:ui/ui.dart' as ui;
+
+import 'canvas.dart';
+import 'canvaskit_api.dart';
+import 'picture.dart';
 
 class CkPictureRecorder implements ui.PictureRecorder {
   ui.Rect? _cullRect;
@@ -15,8 +21,8 @@ class CkPictureRecorder implements ui.PictureRecorder {
     final Float32List skRect = toSkRect(bounds);
     final SkCanvas skCanvas = recorder.beginRecording(skRect);
     return _recordingCanvas = browserSupportsFinalizationRegistry
-      ? CkCanvas(skCanvas)
-      : RecordingCkCanvas(skCanvas, bounds);
+        ? CkCanvas(skCanvas)
+        : RecordingCkCanvas(skCanvas, bounds);
   }
 
   CkCanvas? get recordingCanvas => _recordingCanvas;

lib/web_ui/lib/src/engine/canvaskit/platform_message.dart

@@ -2,8 +2,9 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
 
+// TODO(hterkelsen): Delete this once the slots change lands?
 class PlatformMessage {
   final String channel;
   final ByteData data;

lib/web_ui/lib/src/engine/canvaskit/raster_cache.dart

@@ -2,7 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'package:ui/src/engine.dart' show Matrix4;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvas.dart';
 
 /// A cache of [Picture]s that have already been rasterized.
 ///

lib/web_ui/lib/src/engine/canvaskit/rasterizer.dart

@@ -2,7 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'package:ui/src/engine.dart' show frameReferences;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvas.dart';
+import 'layer_tree.dart';
+import 'surface.dart';
 
 /// A class that can rasterize [LayerTree]s into a given [Surface].
 class Rasterizer {
@@ -13,7 +18,7 @@ class Rasterizer {
   Rasterizer(this.surface);
 
   void setSkiaResourceCacheMaxBytes(int bytes) =>
-    surface.setSkiaResourceCacheMaxBytes(bytes);
+      surface.setSkiaResourceCacheMaxBytes(bytes);
 
   /// Creates a new frame from this rasterizer's surface, draws the given
   /// [LayerTree] into it, and then submits the frame.
@@ -48,9 +53,9 @@ class Rasterizer {
       final ui.VoidCallback callback = _postFrameCallbacks[i];
       callback();
     }
-    for (int i = 0; i < _frameReferences.length; i++) {
-      _frameReferences[i].value = null;
+    for (int i = 0; i < frameReferences.length; i++) {
+      frameReferences[i].value = null;
     }
-    _frameReferences.clear();
+    frameReferences.clear();
   }
 }

lib/web_ui/lib/src/engine/canvaskit/shader.dart

@@ -2,7 +2,17 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:math' as math;
+import 'dart:typed_data';
+
+import 'package:ui/ui.dart' as ui;
+
+import '../util.dart';
+import '../validators.dart';
+import 'canvaskit_api.dart';
+import 'image.dart';
+import 'initialization.dart';
+import 'skia_object_cache.dart';
 
 abstract class CkShader extends ManagedSkiaObject<SkShader>
     implements ui.Shader {
@@ -165,7 +175,8 @@ class CkGradientConical extends CkShader implements ui.Gradient {
 }
 
 class CkImageShader extends CkShader implements ui.ImageShader {
-  CkImageShader(ui.Image image, this.tileModeX, this.tileModeY, this.matrix4, this.filterQuality)
+  CkImageShader(ui.Image image, this.tileModeX, this.tileModeY, this.matrix4,
+      this.filterQuality)
       : _image = image as CkImage;
 
   final ui.TileMode tileModeX;

lib/web_ui/lib/src/engine/canvaskit/skia_object_cache.dart

@@ -2,7 +2,13 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:collection';
+
+import 'package:meta/meta.dart';
+import '../../engine.dart' show EnginePlatformDispatcher, Instrumentation;
+
+import 'canvaskit_api.dart';
+import '../util.dart';
 
 /// A cache of Skia objects whose memory Flutter manages.
 ///
@@ -248,7 +254,8 @@ typedef Resurrector<T> = T Function();
 /// prior to being deleted permanently. A temporary deletion may effectively
 /// be permanent if this object is garbage collected. This is safe because a
 /// temporarily deleted object has no C++ resources to collect.
-class SkiaObjectBox<R extends StackTraceDebugger, T extends Object> extends SkiaObject<T> {
+class SkiaObjectBox<R extends StackTraceDebugger, T extends Object>
+    extends SkiaObject<T> {
   /// Creates an object box that's memory-managed using [SkFinalizationRegistry].
   ///
   /// This constructor must only be used if [browserSupportsFinalizationRegistry] is true.
@@ -261,7 +268,8 @@ class SkiaObjectBox<R extends StackTraceDebugger, T extends Object> extends Skia
   /// Creates an object box that's memory-managed using a [Resurrector].
   ///
   /// This constructor must only be used if [browserSupportsFinalizationRegistry] is false.
-  SkiaObjectBox.resurrectable(R debugReferrer, T initialValue, this._resurrector) {
+  SkiaObjectBox.resurrectable(
+      R debugReferrer, T initialValue, this._resurrector) {
     assert(!browserSupportsFinalizationRegistry);
     _initialize(debugReferrer, initialValue);
     SkiaObjects.manageExpensive(this);
@@ -362,14 +370,16 @@ class SkiaObjectBox<R extends StackTraceDebugger, T extends Object> extends Skia
 
   /// Whether the underlying [rawSkiaObject] has been deleted, but it may still
   /// be resurrected (see [SkiaObjectBox.resurrectable]).
-  bool get isDeletedTemporarily => rawSkiaObject == null && !_isDeletedPermanently;
+  bool get isDeletedTemporarily =>
+      rawSkiaObject == null && !_isDeletedPermanently;
 
   /// Increases the reference count of this box because a new object began
   /// sharing ownership of the underlying [skiaObject].
   ///
   /// Clones must be [dispose]d when finished.
   void ref(R debugReferrer) {
-    assert(!_isDeletedPermanently, 'Cannot increment ref count on a deleted handle.');
+    assert(!_isDeletedPermanently,
+        'Cannot increment ref count on a deleted handle.');
     assert(_refCount > 0);
     assert(
       debugReferrers.add(debugReferrer),
@@ -386,7 +396,8 @@ class SkiaObjectBox<R extends StackTraceDebugger, T extends Object> extends Skia
   /// If this causes the reference count to drop to zero, deletes the
   /// [skObject].
   void unref(R debugReferrer) {
-    assert(!_isDeletedPermanently, 'Attempted to unref an already deleted Skia object.');
+    assert(!_isDeletedPermanently,
+        'Attempted to unref an already deleted Skia object.');
     assert(
       debugReferrers.remove(debugReferrer),
       'Attempted to decrement ref count by the same referrer more than once.',
@@ -435,7 +446,11 @@ class SkiaObjects {
     if (_addedCleanupCallback) {
       return;
     }
-    EnginePlatformDispatcher.instance.rasterizer!.addPostFrameCallback(postFrameCleanUp);
+    // This method is @visibleForTesting but we're getting a warning about
+    // using a @visibleForTesting member.
+    // ignore: invalid_use_of_visible_for_testing_member
+    EnginePlatformDispatcher.instance.rasterizer!
+        .addPostFrameCallback(postFrameCleanUp);
     _addedCleanupCallback = true;
   }
 

lib/web_ui/lib/src/engine/canvaskit/surface.dart

@@ -2,7 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:html' as html;
+
+import 'package:ui/src/engine.dart' show window, EnginePlatformDispatcher;
+import 'package:ui/ui.dart' as ui;
+
+import '../browser_detection.dart';
+import '../util.dart';
+import 'canvas.dart';
+import 'canvaskit_api.dart';
+import 'embedded_views.dart';
+import 'initialization.dart';
+import 'util.dart';
 
 typedef SubmitCallback = bool Function(SurfaceFrame, CkCanvas);
 

lib/web_ui/lib/src/engine/canvaskit/text.dart

@@ -2,7 +2,18 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
+
+import 'package:meta/meta.dart';
+import 'package:ui/ui.dart' as ui;
+
+import '../util.dart';
+import 'canvaskit_api.dart';
+import 'font_fallbacks.dart';
+import 'initialization.dart';
+import 'painting.dart';
+import 'skia_object_cache.dart';
+import 'util.dart';
 
 @immutable
 class CkParagraphStyle implements ui.ParagraphStyle {
@@ -76,7 +87,7 @@ class CkParagraphStyle implements ui.ParagraphStyle {
   }
 
   static SkStrutStyleProperties toSkStrutStyleProperties(ui.StrutStyle value, ui.TextHeightBehavior? paragraphHeightBehavior) {
-    EngineStrutStyle style = value as EngineStrutStyle;
+    CkStrutStyle style = value as CkStrutStyle;
     final SkStrutStyleProperties skStrutStyle = SkStrutStyleProperties();
     skStrutStyle.fontFamilies =
         _getEffectiveFontFamilies(style._fontFamily, style._fontFamilyFallback);
@@ -439,6 +450,69 @@ class CkTextStyle implements ui.TextStyle {
   }();
 }
 
+class CkStrutStyle implements ui.StrutStyle {
+  CkStrutStyle({
+    String? fontFamily,
+    List<String>? fontFamilyFallback,
+    double? fontSize,
+    double? height,
+    //TODO(LongCatIsLooong): implement leadingDistribution.
+    ui.TextLeadingDistribution? leadingDistribution,
+    double? leading,
+    ui.FontWeight? fontWeight,
+    ui.FontStyle? fontStyle,
+    bool? forceStrutHeight,
+  })  : _fontFamily = fontFamily,
+        _fontFamilyFallback = fontFamilyFallback,
+        _fontSize = fontSize,
+        _height = height,
+        _leadingDistribution = leadingDistribution,
+        _leading = leading,
+        _fontWeight = fontWeight,
+        _fontStyle = fontStyle,
+        _forceStrutHeight = forceStrutHeight;
+
+  final String? _fontFamily;
+  final List<String>? _fontFamilyFallback;
+  final double? _fontSize;
+  final double? _height;
+  final double? _leading;
+  final ui.FontWeight? _fontWeight;
+  final ui.FontStyle? _fontStyle;
+  final bool? _forceStrutHeight;
+  final ui.TextLeadingDistribution? _leadingDistribution;
+
+  @override
+  bool operator ==(Object other) {
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is CkStrutStyle &&
+        other._fontFamily == _fontFamily &&
+        other._fontSize == _fontSize &&
+        other._height == _height &&
+        other._leading == _leading &&
+        other._leadingDistribution == _leadingDistribution &&
+        other._fontWeight == _fontWeight &&
+        other._fontStyle == _fontStyle &&
+        other._forceStrutHeight == _forceStrutHeight &&
+        listEquals<String>(other._fontFamilyFallback, _fontFamilyFallback);
+  }
+
+  @override
+  int get hashCode => ui.hashValues(
+        _fontFamily,
+        _fontFamilyFallback,
+        _fontSize,
+        _height,
+        _leading,
+        _leadingDistribution,
+        _fontWeight,
+        _fontStyle,
+        _forceStrutHeight,
+      );
+}
+
 SkFontStyle toSkFontStyle(ui.FontWeight? fontWeight, ui.FontStyle? fontStyle) {
   final style = SkFontStyle();
   if (fontWeight != null) {

lib/web_ui/lib/src/engine/canvaskit/util.dart

@@ -2,7 +2,14 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:math' as math;
+import 'dart:typed_data';
+
+import 'package:ui/src/engine.dart' show transformRect, Matrix4;
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'path.dart';
 
 /// An error related to the CanvasKit rendering backend.
 class CanvasKitError extends Error {
@@ -26,7 +33,8 @@ Float32List makeFreshSkColor(ui.Color color) {
 }
 
 ui.TextPosition fromPositionWithAffinity(SkTextPosition positionWithAffinity) {
-  final ui.TextAffinity affinity = ui.TextAffinity.values[positionWithAffinity.affinity.value];
+  final ui.TextAffinity affinity =
+      ui.TextAffinity.values[positionWithAffinity.affinity.value];
   return ui.TextPosition(
     offset: positionWithAffinity.pos,
     affinity: affinity,
@@ -53,10 +61,12 @@ class SkiaShadowFlags {
   static const int kDirectionalLight_ShadowFlag = 0x04;
 
   /// Complete value for the `flags` argument for opaque occluder.
-  static const int kDefaultShadowFlags = kDirectionalLight_ShadowFlag | kNone_ShadowFlag;
+  static const int kDefaultShadowFlags =
+      kDirectionalLight_ShadowFlag | kNone_ShadowFlag;
 
   /// Complete value for the `flags` argument for transparent occluder.
-  static const int kTransparentOccluderShadowFlags = kDirectionalLight_ShadowFlag | kTransparentOccluder_ShadowFlag;
+  static const int kTransparentOccluderShadowFlags =
+      kDirectionalLight_ShadowFlag | kTransparentOccluder_ShadowFlag;
 }
 
 // These numbers have been chosen empirically to give a result closest to the
@@ -115,7 +125,8 @@ ui.Rect computeSkShadowBounds(
   left = left - 1 + (spotOffsetX - ambientBlur - spotBlur) * devicePixelRatio;
   top = top - 1 + (spotOffsetY - ambientBlur - spotBlur) * devicePixelRatio;
   right = right + 1 + (spotOffsetX + ambientBlur + spotBlur) * devicePixelRatio;
-  bottom = bottom + 1 + (spotOffsetY + ambientBlur + spotBlur) * devicePixelRatio;
+  bottom =
+      bottom + 1 + (spotOffsetY + ambientBlur + spotBlur) * devicePixelRatio;
 
   final ui.Rect shadowBounds = ui.Rect.fromLTRB(left, top, right, bottom);
 
@@ -134,10 +145,12 @@ ui.Rect computeSkShadowBounds(
 
 const double kAmbientHeightFactor = 1.0 / 128.0;
 const double kAmbientGeomFactor = 64.0;
-const double kMaxAmbientRadius = 300 * kAmbientHeightFactor * kAmbientGeomFactor;
+const double kMaxAmbientRadius =
+    300 * kAmbientHeightFactor * kAmbientGeomFactor;
 
 double ambientBlurRadius(double height) {
-  return math.min(height * kAmbientHeightFactor * kAmbientGeomFactor, kMaxAmbientRadius);
+  return math.min(
+      height * kAmbientHeightFactor * kAmbientGeomFactor, kMaxAmbientRadius);
 }
 
 void drawSkShadow(
@@ -149,10 +162,11 @@ void drawSkShadow(
   double devicePixelRatio,
 ) {
   final int flags = transparentOccluder
-    ? SkiaShadowFlags.kTransparentOccluderShadowFlags
-    : SkiaShadowFlags.kDefaultShadowFlags;
+      ? SkiaShadowFlags.kTransparentOccluderShadowFlags
+      : SkiaShadowFlags.kDefaultShadowFlags;
 
-  ui.Color inAmbient = color.withAlpha((color.alpha * ckShadowAmbientAlpha).round());
+  ui.Color inAmbient =
+      color.withAlpha((color.alpha * ckShadowAmbientAlpha).round());
   ui.Color inSpot = color.withAlpha((color.alpha * ckShadowSpotAlpha).round());
 
   final SkTonalColors inTonalColors = SkTonalColors(
@@ -160,13 +174,11 @@ void drawSkShadow(
     spot: makeFreshSkColor(inSpot),
   );
 
-  final SkTonalColors tonalColors =
-      canvasKit.computeTonalColors(inTonalColors);
+  final SkTonalColors tonalColors = canvasKit.computeTonalColors(inTonalColors);
 
   skCanvas.drawShadow(
     path.skiaObject,
-    Float32List(3)
-      ..[2] = devicePixelRatio * elevation,
+    Float32List(3)..[2] = devicePixelRatio * elevation,
     Float32List(3)
       ..[0] = ckShadowLightXOffset
       ..[1] = ckShadowLightYOffset

lib/web_ui/lib/src/engine/canvaskit/vertices.dart

@@ -2,7 +2,12 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
+import 'dart:typed_data';
+
+import 'package:ui/ui.dart' as ui;
+
+import 'canvaskit_api.dart';
+import 'skia_object_cache.dart';
 
 class CkVertices extends ManagedSkiaObject<SkVertices> implements ui.Vertices {
   factory CkVertices(

lib/web_ui/lib/src/engine/canvaskit/viewport_metrics.dart

@@ -2,8 +2,6 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-part of engine;
-
 class ViewportMetrics {
   final double devicePixelRatio;
   final double physicalWidth;

lib/web_ui/lib/src/engine/color_filter.dart

@@ -20,7 +20,8 @@ class EngineColorFilter implements ui.ColorFilter {
   /// The output of this filter is then composited into the background according
   /// to the [Paint.blendMode], using the output of this filter as the source
   /// and the background as the destination.
-  const factory EngineColorFilter.mode(ui.Color color, ui.BlendMode blendMode) = _CkBlendModeColorFilter;
+  const factory EngineColorFilter.mode(ui.Color color, ui.BlendMode blendMode) =
+      CkBlendModeColorFilter;
 
   /// Construct a color filter that transforms a color by a 5x5 matrix, where
   /// the fifth row is implicitly added in an identity configuration.
@@ -82,13 +83,16 @@ class EngineColorFilter implements ui.ColorFilter {
   ///   0,      0,      0,      1, 0,
   /// ]);
   /// ```
-  const factory EngineColorFilter.matrix(List<double> matrix) = _CkMatrixColorFilter;
+  const factory EngineColorFilter.matrix(List<double> matrix) =
+      CkMatrixColorFilter;
 
   /// Construct a color filter that applies the sRGB gamma curve to the RGB
   /// channels.
-  const factory EngineColorFilter.linearToSrgbGamma() = _CkLinearToSrgbGammaColorFilter;
+  const factory EngineColorFilter.linearToSrgbGamma() =
+      CkLinearToSrgbGammaColorFilter;
 
   /// Creates a color filter that applies the inverse of the sRGB gamma curve
   /// to the RGB channels.
-  const factory EngineColorFilter.srgbToLinearGamma() = _CkSrgbToLinearGammaColorFilter;
+  const factory EngineColorFilter.srgbToLinearGamma() =
+      CkSrgbToLinearGammaColorFilter;
 }

lib/web_ui/lib/src/engine/dom_renderer.dart

@@ -366,7 +366,7 @@ flt-glass-pane * {
     setElementAttribute(
       bodyElement,
       'flt-renderer',
-      '${useCanvasKit ? 'canvaskit' : 'html'} (${_autoDetect ? 'auto-selected' : 'requested explicitly'})',
+      '${useCanvasKit ? 'canvaskit' : 'html'} (${flutterWebAutoDetect ? 'auto-selected' : 'requested explicitly'})',
     );
     setElementAttribute(bodyElement, 'flt-build-mode', buildMode);
 

lib/web_ui/lib/src/engine/frame_reference.dart

@@ -9,7 +9,7 @@ part of engine;
 /// Used for debugging only.
 int _debugFrameNumber = 1;
 
-List<FrameReference<dynamic>> _frameReferences = <FrameReference<dynamic>>[];
+List<FrameReference<dynamic>> frameReferences = <FrameReference<dynamic>>[];
 
 /// A temporary reference to a value of type [V].
 ///
@@ -21,7 +21,7 @@ List<FrameReference<dynamic>> _frameReferences = <FrameReference<dynamic>>[];
 class FrameReference<V> {
   /// Creates a frame reference to a value.
   FrameReference([this.value]) {
-    _frameReferences.add(this);
+    frameReferences.add(this);
   }
 
   /// The current value of this reference.

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

@@ -630,12 +630,12 @@ class BitmapCanvas extends EngineCanvas {
     final EngineColorFilter? colorFilter =
         paint.colorFilter as EngineColorFilter?;
     html.HtmlElement imgElement;
-    if (colorFilter is _CkBlendModeColorFilter) {
-      imgElement = _createImageElementWithBlend(image,
-          colorFilter.color, colorFilter.blendMode, paint);
-    } else if (colorFilter is _CkMatrixColorFilter) {
+    if (colorFilter is CkBlendModeColorFilter) {
+      imgElement = _createImageElementWithBlend(
+          image, colorFilter.color, colorFilter.blendMode, paint);
+    } else if (colorFilter is CkMatrixColorFilter) {
       imgElement = _createImageElementWithSvgColorMatrixFilter(
-          image, colorFilter.matrix , paint);
+          image, colorFilter.matrix, paint);
     } else {
       // No Blending, create an image by cloning original loaded image.
       imgElement = _reuseOrCreateImage(htmlImage);
@@ -665,8 +665,8 @@ class BitmapCanvas extends EngineCanvas {
     return imgElement;
   }
 
-  html.HtmlElement _createImageElementWithBlend(HtmlImage image,
-      ui.Color color, ui.BlendMode blendMode, SurfacePaintData paint) {
+  html.HtmlElement _createImageElementWithBlend(HtmlImage image, ui.Color color,
+      ui.BlendMode blendMode, SurfacePaintData paint) {
     switch (blendMode) {
       case ui.BlendMode.colorBurn:
       case ui.BlendMode.colorDodge:
@@ -685,8 +685,7 @@ class BitmapCanvas extends EngineCanvas {
         return _createImageElementWithSvgBlendFilter(
             image, color, blendMode, paint);
       default:
-        return _createBackgroundImageWithBlend(
-            image, color, blendMode, paint);
+        return _createBackgroundImageWithBlend(image, color, blendMode, paint);
     }
   }
 
@@ -827,7 +826,7 @@ class BitmapCanvas extends EngineCanvas {
     String? svgFilter =
         svgFilterFromBlendMode(filterColor, colorFilterBlendMode);
     final html.Element filterElement =
-        html.Element.html(svgFilter, treeSanitizer: _NullTreeSanitizer());
+        html.Element.html(svgFilter, treeSanitizer: NullTreeSanitizer());
     rootElement.append(filterElement);
     _children.add(filterElement);
     final html.HtmlElement imgElement = _reuseOrCreateImage(image);
@@ -840,13 +839,11 @@ class BitmapCanvas extends EngineCanvas {
 
   // Creates an image element and an svg color matrix filter to apply on the element.
   html.HtmlElement _createImageElementWithSvgColorMatrixFilter(
-      HtmlImage image,
-      List<double> matrix,
-      SurfacePaintData paint) {
+      HtmlImage image, List<double> matrix, SurfacePaintData paint) {
     // For srcIn blendMode, we use an svg filter to apply to image element.
     String? svgFilter = svgFilterFromColorMatrix(matrix);
     final html.Element filterElement =
-    html.Element.html(svgFilter, treeSanitizer: _NullTreeSanitizer());
+        html.Element.html(svgFilter, treeSanitizer: NullTreeSanitizer());
     rootElement.append(filterElement);
     _children.add(filterElement);
     final html.HtmlElement imgElement = _reuseOrCreateImage(image);
@@ -968,7 +965,8 @@ class BitmapCanvas extends EngineCanvas {
     final Int32List? colors = vertices.colors;
     final ui.VertexMode mode = vertices.mode;
     html.CanvasRenderingContext2D? ctx = _canvasPool.context;
-    if (colors == null && paint.style != ui.PaintingStyle.fill &&
+    if (colors == null &&
+        paint.style != ui.PaintingStyle.fill &&
         paint.shader == null) {
       final Float32List positions = mode == ui.VertexMode.triangles
           ? vertices.positions
@@ -1240,7 +1238,7 @@ List<html.Element> _clipContent(List<_SaveClipEntry> clipStack,
         String svgClipPath =
             createSvgClipDef(curElement as html.HtmlElement, entry.path!);
         final html.Element clipElement =
-            html.Element.html(svgClipPath, treeSanitizer: _NullTreeSanitizer());
+            html.Element.html(svgClipPath, treeSanitizer: NullTreeSanitizer());
         clipDefs.add(clipElement);
       }
     }

lib/web_ui/lib/src/engine/html/clip.dart

@@ -342,7 +342,7 @@ class PersistedPhysicalShape extends PersistedContainerSurface
     _clipElement?.remove();
     _svgElement?.remove();
     _clipElement =
-        html.Element.html(svgClipPath, treeSanitizer: _NullTreeSanitizer());
+        html.Element.html(svgClipPath, treeSanitizer: NullTreeSanitizer());
     domRenderer.append(rootElement!, _clipElement!);
     if (elevation == 0.0) {
       DomRenderer.setClipPath(rootElement!, createSvgClipUrl());
@@ -469,7 +469,7 @@ class PersistedClipPath extends PersistedContainerSurface
     final String svgClipPath =
         createSvgClipDef(childContainer as html.HtmlElement, clipPath);
     _clipElement =
-        html.Element.html(svgClipPath, treeSanitizer: _NullTreeSanitizer());
+        html.Element.html(svgClipPath, treeSanitizer: NullTreeSanitizer());
     domRenderer.append(childContainer!, _clipElement!);
   }
 

lib/web_ui/lib/src/engine/html/color_filter.dart

@@ -59,16 +59,16 @@ class PersistedColorFilter extends PersistedContainerSurface
       childContainer?.style.visibility = 'visible';
       return;
     }
-    if (engineValue is _CkBlendModeColorFilter) {
+    if (engineValue is CkBlendModeColorFilter) {
       _applyBlendModeFilter(engineValue);
-    } else if (engineValue is _CkMatrixColorFilter) {
+    } else if (engineValue is CkMatrixColorFilter) {
       _applyMatrixColorFilter(engineValue);
     } else {
       childContainer?.style.visibility = 'visible';
     }
   }
 
-  void _applyBlendModeFilter(_CkBlendModeColorFilter colorFilter) {
+  void _applyBlendModeFilter(CkBlendModeColorFilter colorFilter) {
     ui.Color filterColor = colorFilter.color;
     ui.BlendMode colorFilterBlendMode = colorFilter.blendMode;
     html.CssStyleDeclaration style = rootElement!.style;
@@ -119,7 +119,7 @@ class PersistedColorFilter extends PersistedContainerSurface
         svgFilterFromBlendMode(filterColor, colorFilterBlendMode);
     if (svgFilter != null) {
       _filterElement =
-          html.Element.html(svgFilter, treeSanitizer: _NullTreeSanitizer());
+          html.Element.html(svgFilter, treeSanitizer: NullTreeSanitizer());
       rootElement!.append(_filterElement!);
       rootElement!.style.filter = 'url(#_fcf${_filterIdCounter})';
       if (colorFilterBlendMode == ui.BlendMode.saturation ||
@@ -130,11 +130,11 @@ class PersistedColorFilter extends PersistedContainerSurface
     }
   }
 
-  void _applyMatrixColorFilter(_CkMatrixColorFilter colorFilter) {
+  void _applyMatrixColorFilter(CkMatrixColorFilter colorFilter) {
     String? svgFilter = svgFilterFromColorMatrix(colorFilter.matrix);
     if (svgFilter != null) {
       _filterElement =
-          html.Element.html(svgFilter, treeSanitizer: _NullTreeSanitizer());
+          html.Element.html(svgFilter, treeSanitizer: NullTreeSanitizer());
       rootElement!.append(_filterElement!);
       rootElement!.style.filter = 'url(#_fcf${_filterIdCounter})';
     }

lib/web_ui/lib/src/engine/html/dom_canvas.dart

@@ -6,7 +6,6 @@ part of engine;
 
 /// A canvas that renders to DOM elements and CSS properties.
 class DomCanvas extends EngineCanvas with SaveElementStackTracking {
-
   @override
   final html.Element rootElement;
 
@@ -61,14 +60,14 @@ class DomCanvas extends EngineCanvas with SaveElementStackTracking {
 
   @override
   void drawRect(ui.Rect rect, SurfacePaintData paint) {
-    currentElement.append(_buildDrawRectElement(rect, paint, 'draw-rect',
-        currentTransform));
+    currentElement.append(
+        _buildDrawRectElement(rect, paint, 'draw-rect', currentTransform));
   }
 
   @override
   void drawRRect(ui.RRect rrect, SurfacePaintData paint) {
-    html.Element element = _buildDrawRectElement(rrect.outerRect,
-        paint, 'draw-rrect', currentTransform);
+    html.Element element = _buildDrawRectElement(
+        rrect.outerRect, paint, 'draw-rrect', currentTransform);
     _applyRRectBorderRadius(element.style, rrect);
     currentElement.append(element);
   }
@@ -112,8 +111,9 @@ class DomCanvas extends EngineCanvas with SaveElementStackTracking {
 
   @override
   void drawParagraph(ui.Paragraph paragraph, ui.Offset offset) {
-    final html.Element paragraphElement =
-        _drawParagraphElement(paragraph as EngineParagraph, offset, transform: currentTransform);
+    final html.Element paragraphElement = _drawParagraphElement(
+        paragraph as EngineParagraph, offset,
+        transform: currentTransform);
     currentElement.append(paragraphElement);
   }
 
@@ -124,7 +124,8 @@ class DomCanvas extends EngineCanvas with SaveElementStackTracking {
   }
 
   @override
-  void drawPoints(ui.PointMode pointMode, Float32List points, SurfacePaintData paint) {
+  void drawPoints(
+      ui.PointMode pointMode, Float32List points, SurfacePaintData paint) {
     throw UnimplementedError();
   }
 
@@ -139,16 +140,16 @@ class DomCanvas extends EngineCanvas with SaveElementStackTracking {
 ///
 /// Returns a color for box-shadow based on blur filter at sigma.
 ui.Color blurColor(ui.Color color, double sigma) {
-  final double strength = math.min(
-      math.sqrt(sigma) / (math.pi * 2.0), 1.0);
+  final double strength = math.min(math.sqrt(sigma) / (math.pi * 2.0), 1.0);
   final int reducedAlpha = ((1.0 - strength) * color.alpha).round();
   return ui.Color((reducedAlpha & 0xff) << 24 | (color.value & 0x00ffffff));
 }
 
-html.HtmlElement _buildDrawRectElement(ui.Rect rect, SurfacePaintData paint, String tagName,
-    Matrix4 transform) {
+html.HtmlElement _buildDrawRectElement(
+    ui.Rect rect, SurfacePaintData paint, String tagName, Matrix4 transform) {
   assert(paint.shader == null);
-  final html.HtmlElement rectangle = domRenderer.createElement(tagName) as html.HtmlElement;
+  final html.HtmlElement rectangle =
+      domRenderer.createElement(tagName) as html.HtmlElement;
   assert(() {
     rectangle.setAttribute('flt-rect', '$rect');
     rectangle.setAttribute('flt-paint', '$paint');
@@ -164,7 +165,7 @@ html.HtmlElement _buildDrawRectElement(ui.Rect rect, SurfacePaintData paint, Str
   if (transform.isIdentity()) {
     if (isStroke) {
       effectiveTransform =
-      'translate(${left - (strokeWidth / 2.0)}px, ${top - (strokeWidth / 2.0)}px)';
+          'translate(${left - (strokeWidth / 2.0)}px, ${top - (strokeWidth / 2.0)}px)';
     } else {
       effectiveTransform = 'translate(${left}px, ${top}px)';
     }
@@ -245,8 +246,8 @@ String _borderStrokeToCssUnit(double value) {
   return '${value.toStringAsFixed(3)}px';
 }
 
-html.Element _pathToSvgElement(SurfacePath path, SurfacePaintData paint,
-    String width, String height) {
+html.Element _pathToSvgElement(
+    SurfacePath path, SurfacePaintData paint, String width, String height) {
   final StringBuffer sb = StringBuffer();
   sb.write(
       '<svg viewBox="0 0 $width $height" width="${width}px" height="${height}px">');
@@ -254,7 +255,8 @@ html.Element _pathToSvgElement(SurfacePath path, SurfacePaintData paint,
   final ui.Color color = paint.color ?? const ui.Color(0xFF000000);
   if (paint.style == ui.PaintingStyle.stroke ||
       (paint.style != ui.PaintingStyle.fill &&
-      paint.strokeWidth != 0 && paint.strokeWidth != null)) {
+          paint.strokeWidth != 0 &&
+          paint.strokeWidth != null)) {
     sb.write('stroke="${colorToCssString(color)}" ');
     sb.write('stroke-width="${paint.strokeWidth ?? 1.0}" ');
     sb.write('fill="none" ');
@@ -270,5 +272,5 @@ html.Element _pathToSvgElement(SurfacePath path, SurfacePaintData paint,
   pathToSvg(path.pathRef, sb);
   sb.write('"></path>');
   sb.write('</svg>');
-  return html.Element.html(sb.toString(), treeSanitizer: _NullTreeSanitizer());
+  return html.Element.html(sb.toString(), treeSanitizer: NullTreeSanitizer());
 }

lib/web_ui/lib/src/engine/html/shader_mask.dart

@@ -149,7 +149,7 @@ class PersistedShaderMask extends PersistedContainerSurface
           imageUrl, blendModeTemp, maskRect.width, maskRect.height)!;
 
       _shaderElement =
-          html.Element.html(code, treeSanitizer: _NullTreeSanitizer());
+          html.Element.html(code, treeSanitizer: NullTreeSanitizer());
       if (isWebKit) {
         _childContainer!.style.filter = 'url(#_fmf${_maskFilterIdCounter}';
       } else {

lib/web_ui/lib/src/engine/html/surface.dart

@@ -5,6 +5,7 @@
 /// When `true` prints statistics about what happened to the surface tree when
 
 part of engine;
+
 /// it was composited.
 ///
 /// Also paints an on-screen overlay with the numbers visualized as a timeline.
@@ -77,10 +78,10 @@ void commitScene(PersistedScene scene) {
     return true;
   }());
 
-  for (int i = 0; i < _frameReferences.length; i++) {
-    _frameReferences[i].value = null;
+  for (int i = 0; i < frameReferences.length; i++) {
+    frameReferences[i].value = null;
   }
-  _frameReferences = <FrameReference<dynamic>>[];
+  frameReferences = <FrameReference<dynamic>>[];
 
   if (_debugExplainSurfaceStats) {
     _surfaceStats = <PersistedSurface, _DebugSurfaceStats>{};
@@ -187,7 +188,7 @@ bool debugAssertSurfaceState(
 abstract class PersistedSurface implements ui.EngineLayer {
   /// Creates a persisted surface.
   PersistedSurface(PersistedSurface? oldLayer)
-    : _oldLayer = FrameReference<PersistedSurface>(
+      : _oldLayer = FrameReference<PersistedSurface>(
             oldLayer != null && oldLayer.isActive ? oldLayer : null);
 
   /// The surface that is being updated using this surface.
@@ -380,7 +381,8 @@ abstract class PersistedSurface implements ui.EngineLayer {
         PersistedSurfaceState.pendingUpdate));
     assert(() {
       if (oldSurface.isPendingUpdate) {
-        final PersistedContainerSurface self = this as PersistedContainerSurface;
+        final PersistedContainerSurface self =
+            this as PersistedContainerSurface;
         assert(identical(self.oldLayer, oldSurface));
       }
       return true;
@@ -568,7 +570,8 @@ abstract class PersistedSurface implements ui.EngineLayer {
     buffer.writeln('>');
     debugPrintChildren(buffer, indent);
     if (rootElement != null) {
-      buffer.writeln('${'  ' * indent}</${rootElement!.tagName.toLowerCase()}>');
+      buffer
+          .writeln('${'  ' * indent}</${rootElement!.tagName.toLowerCase()}>');
     } else {
       buffer.writeln('${'  ' * indent}</$runtimeType>');
     }
@@ -773,7 +776,8 @@ abstract class PersistedContainerSurface extends PersistedSurface {
             newChild, PersistedSurfaceState.pendingRetention));
       } else if (newChild is PersistedContainerSurface &&
           newChild.oldLayer != null) {
-        final PersistedContainerSurface oldLayer = newChild.oldLayer as PersistedContainerSurface;
+        final PersistedContainerSurface oldLayer =
+            newChild.oldLayer as PersistedContainerSurface;
         assert(debugAssertSurfaceState(
             oldLayer, PersistedSurfaceState.pendingUpdate));
         newChild.update(oldLayer);
@@ -837,7 +841,8 @@ abstract class PersistedContainerSurface extends PersistedSurface {
       assert(newChild.rootElement == null);
       assert(newChild.oldLayer!.rootElement != null);
 
-      final PersistedContainerSurface oldLayer = newChild.oldLayer as PersistedContainerSurface;
+      final PersistedContainerSurface oldLayer =
+          newChild.oldLayer as PersistedContainerSurface;
 
       // Move the HTML node if necessary.
       if (oldLayer.rootElement!.parent != childContainer) {
@@ -936,7 +941,8 @@ abstract class PersistedContainerSurface extends PersistedSurface {
             newChild, PersistedSurfaceState.pendingRetention));
       } else if (newChild is PersistedContainerSurface &&
           newChild.oldLayer != null) {
-        final PersistedContainerSurface oldLayer = newChild.oldLayer as PersistedContainerSurface;
+        final PersistedContainerSurface oldLayer =
+            newChild.oldLayer as PersistedContainerSurface;
         isReparenting = oldLayer.rootElement!.parent != containerElement;
         matchedOldChild = oldLayer;
         assert(debugAssertSurfaceState(
@@ -950,7 +956,8 @@ abstract class PersistedContainerSurface extends PersistedSurface {
         if (matchedOldChild != null) {
           assert(debugAssertSurfaceState(
               matchedOldChild, PersistedSurfaceState.active));
-          isReparenting = matchedOldChild.rootElement!.parent != containerElement;
+          isReparenting =
+              matchedOldChild.rootElement!.parent != containerElement;
           newChild.update(matchedOldChild);
           assert(debugAssertSurfaceState(
               matchedOldChild, PersistedSurfaceState.released));
@@ -1018,7 +1025,8 @@ abstract class PersistedContainerSurface extends PersistedSurface {
   /// Performs the minimum number of DOM moves necessary to put all children in
   /// the right place in the DOM.
   void _insertChildDomNodes(List<int>? indexMapNew, List<int> indexMapOld) {
-    final List<int?> stationaryIndices = longestIncreasingSubsequence(indexMapOld);
+    final List<int?> stationaryIndices =
+        longestIncreasingSubsequence(indexMapOld);
 
     // Convert to stationary new indices
     for (int i = 0; i < stationaryIndices.length; i++) {
@@ -1029,9 +1037,11 @@ abstract class PersistedContainerSurface extends PersistedSurface {
     final html.Element? containerElement = childContainer;
     for (int i = _children.length - 1; i >= 0; i -= 1) {
       final int indexInNew = indexMapNew!.indexOf(i);
-      final bool isStationary = indexInNew != -1 && stationaryIndices.contains(i);
+      final bool isStationary =
+          indexInNew != -1 && stationaryIndices.contains(i);
       final PersistedSurface child = _children[i];
-      final html.HtmlElement childElement = child.rootElement as html.HtmlElement;
+      final html.HtmlElement childElement =
+          child.rootElement as html.HtmlElement;
       assert(childElement != null); // ignore: unnecessary_null_comparison
       if (!isStationary) {
         if (refNode == null) {

lib/web_ui/lib/src/engine/text/paragraph.dart

@@ -37,7 +37,7 @@ class EngineLineMetrics implements ui.LineMetrics {
     required this.widthWithTrailingSpaces,
     required this.left,
     required this.lineNumber,
-  })  : assert(displayText != null), // ignore: unnecessary_null_comparison
+  })  : assert(displayText != null), // ignore: unnecessary_null_comparison,
         assert(startIndex != null), // ignore: unnecessary_null_comparison
         assert(endIndex != null), // ignore: unnecessary_null_comparison
         assert(endIndexWithoutNewlines != null), // ignore: unnecessary_null_comparison
@@ -167,33 +167,33 @@ class EngineLineMetrics implements ui.LineMetrics {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is EngineLineMetrics
-        && other.displayText == displayText
-        && other.startIndex == startIndex
-        && other.endIndex == endIndex
-        && other.hardBreak == hardBreak
-        && other.ascent == ascent
-        && other.descent == descent
-        && other.unscaledAscent == unscaledAscent
-        && other.height == height
-        && other.width == width
-        && other.left == left
-        && other.baseline == baseline
-        && other.lineNumber == lineNumber;
+    return other is EngineLineMetrics &&
+        other.displayText == displayText &&
+        other.startIndex == startIndex &&
+        other.endIndex == endIndex &&
+        other.hardBreak == hardBreak &&
+        other.ascent == ascent &&
+        other.descent == descent &&
+        other.unscaledAscent == unscaledAscent &&
+        other.height == height &&
+        other.width == width &&
+        other.left == left &&
+        other.baseline == baseline &&
+        other.lineNumber == lineNumber;
   }
 
   @override
   String toString() {
     if (assertionsEnabled) {
       return 'LineMetrics(hardBreak: $hardBreak, '
-                        'ascent: $ascent, '
-                        'descent: $descent, '
-                        'unscaledAscent: $unscaledAscent, '
-                        'height: $height, '
-                        'width: $width, '
-                        'left: $left, '
-                        'baseline: $baseline, '
-                        'lineNumber: $lineNumber)';
+          'ascent: $ascent, '
+          'descent: $descent, '
+          'unscaledAscent: $unscaledAscent, '
+          'height: $height, '
+          'width: $width, '
+          'left: $left, '
+          'baseline: $baseline, '
+          'lineNumber: $lineNumber)';
     } else {
       return super.toString();
     }
@@ -367,7 +367,8 @@ class DomParagraph implements EngineParagraph {
     _measurementResult = _measurementService.measure(this, constraints);
     if (Profiler.isBenchmarkMode) {
       stopwatch.stop();
-      Profiler.instance.benchmark('text_layout', stopwatch.elapsedMicroseconds.toDouble());
+      Profiler.instance
+          .benchmark('text_layout', stopwatch.elapsedMicroseconds.toDouble());
     }
 
     _lastUsedConstraints = constraints;
@@ -413,7 +414,8 @@ class DomParagraph implements EngineParagraph {
     // Paint the background first.
     final SurfacePaint? background = _background;
     if (background != null) {
-      final ui.Rect rect = ui.Rect.fromLTWH(offset.dx, offset.dy, width, height);
+      final ui.Rect rect =
+          ui.Rect.fromLTWH(offset.dx, offset.dy, width, height);
       canvas.drawRect(rect, background.paintData);
     }
 
@@ -837,7 +839,8 @@ class EngineParagraphStyle implements ui.ParagraphStyle {
 
   // The effective style attributes should be consistent with paragraph_style.h.
   ui.TextAlign get _effectiveTextAlign => _textAlign ?? ui.TextAlign.start;
-  ui.TextDirection get _effectiveTextDirection => _textDirection ?? ui.TextDirection.ltr;
+  ui.TextDirection get _effectiveTextDirection =>
+      _textDirection ?? ui.TextDirection.ltr;
 
   String get _effectiveFontFamily {
     if (assertionsEnabled) {
@@ -880,18 +883,18 @@ class EngineParagraphStyle implements ui.ParagraphStyle {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is EngineParagraphStyle
-        && other._textAlign == _textAlign
-        && other._textDirection == _textDirection
-        && other._fontWeight == _fontWeight
-        && other._fontStyle == _fontStyle
-        && other._maxLines == _maxLines
-        && other._fontFamily == _fontFamily
-        && other._fontSize == _fontSize
-        && other._height == _height
-        && other._textHeightBehavior == _textHeightBehavior
-        && other._ellipsis == _ellipsis
-        && other._locale == _locale;
+    return other is EngineParagraphStyle &&
+        other._textAlign == _textAlign &&
+        other._textDirection == _textDirection &&
+        other._fontWeight == _fontWeight &&
+        other._fontStyle == _fontStyle &&
+        other._maxLines == _maxLines &&
+        other._fontFamily == _fontFamily &&
+        other._fontSize == _fontSize &&
+        other._height == _height &&
+        other._textHeightBehavior == _textHeightBehavior &&
+        other._ellipsis == _ellipsis &&
+        other._locale == _locale;
   }
 
   @override
@@ -1096,24 +1099,24 @@ class EngineTextStyle implements ui.TextStyle {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is EngineTextStyle
-        && other._color == _color
-        && other._decoration == _decoration
-        && other._decorationColor == _decorationColor
-        && other._decorationStyle == _decorationStyle
-        && other._fontWeight == _fontWeight
-        && other._fontStyle == _fontStyle
-        && other._textBaseline == _textBaseline
-        && other._fontFamily == _fontFamily
-        && other._fontSize == _fontSize
-        && other._letterSpacing == _letterSpacing
-        && other._wordSpacing == _wordSpacing
-        && other._height == _height
-        && other._locale == _locale
-        && other._background == _background
-        && other._foreground == _foreground
-        && _listEquals<ui.Shadow>(other._shadows, _shadows)
-        && _listEquals<String>(other._fontFamilyFallback, _fontFamilyFallback);
+    return other is EngineTextStyle &&
+        other._color == _color &&
+        other._decoration == _decoration &&
+        other._decorationColor == _decorationColor &&
+        other._decorationStyle == _decorationStyle &&
+        other._fontWeight == _fontWeight &&
+        other._fontStyle == _fontStyle &&
+        other._textBaseline == _textBaseline &&
+        other._fontFamily == _fontFamily &&
+        other._fontSize == _fontSize &&
+        other._letterSpacing == _letterSpacing &&
+        other._wordSpacing == _wordSpacing &&
+        other._height == _height &&
+        other._locale == _locale &&
+        other._background == _background &&
+        other._foreground == _foreground &&
+        listEquals<ui.Shadow>(other._shadows, _shadows) &&
+        listEquals<String>(other._fontFamilyFallback, _fontFamilyFallback);
   }
 
   @override
@@ -1170,41 +1173,6 @@ class EngineTextStyle implements ui.TextStyle {
 
 /// The web implementation of [ui.StrutStyle].
 class EngineStrutStyle implements ui.StrutStyle {
-  /// Creates a new StrutStyle object.
-  ///
-  /// * `fontFamily`: The name of the font to use when painting the text (e.g.,
-  ///   Roboto).
-  ///
-  /// * `fontFamilyFallback`: An ordered list of font family names that will be searched for when
-  ///    the font in `fontFamily` cannot be found.
-  ///
-  /// * `fontSize`: The size of glyphs (in logical pixels) to use when painting
-  ///   the text.
-  ///
-  /// * `lineHeight`: The minimum height of the line boxes, as a multiple of the
-  ///   font size. The lines of the paragraph will be at least
-  ///   `(lineHeight + leading) * fontSize` tall when fontSize
-  ///   is not null. When fontSize is null, there is no minimum line height. Tall
-  ///   glyphs due to baseline alignment or large [TextStyle.fontSize] may cause
-  ///   the actual line height after layout to be taller than specified here.
-  ///   [fontSize] must be provided for this property to take effect.
-  ///
-  /// * `leading`: The minimum amount of leading between lines as a multiple of
-  ///   the font size. [fontSize] must be provided for this property to take effect.
-  ///
-  /// * `fontWeight`: The typeface thickness to use when painting the text
-  ///   (e.g., bold).
-  ///
-  /// * `fontStyle`: The typeface variant to use when drawing the letters (e.g.,
-  ///   italics).
-  ///
-  /// * `forceStrutHeight`: When true, the paragraph will force all lines to be exactly
-  ///   `(lineHeight + leading) * fontSize` tall from baseline to baseline.
-  ///   [TextStyle] is no longer able to influence the line height, and any tall
-  ///   glyphs may overlap with lines above. If a [fontFamily] is specified, the
-  ///   total ascent of the first line will be the min of the `Ascent + half-leading`
-  ///   of the [fontFamily] and `(lineHeight + leading) * fontSize`. Otherwise, it
-  ///   will be determined by the Ascent + half-leading of the first text.
   EngineStrutStyle({
     String? fontFamily,
     List<String>? fontFamilyFallback,
@@ -1243,16 +1211,16 @@ class EngineStrutStyle implements ui.StrutStyle {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is EngineStrutStyle
-        && other._fontFamily == _fontFamily
-        && other._fontSize == _fontSize
-        && other._height == _height
-        && other._leading == _leading
-        && other._leadingDistribution == _leadingDistribution
-        && other._fontWeight == _fontWeight
-        && other._fontStyle == _fontStyle
-        && other._forceStrutHeight == _forceStrutHeight
-        && _listEquals<String>(other._fontFamilyFallback, _fontFamilyFallback);
+    return other is EngineStrutStyle &&
+        other._fontFamily == _fontFamily &&
+        other._fontSize == _fontSize &&
+        other._height == _height &&
+        other._leading == _leading &&
+        other._leadingDistribution == _leadingDistribution &&
+        other._fontWeight == _fontWeight &&
+        other._fontStyle == _fontStyle &&
+        other._forceStrutHeight == _forceStrutHeight &&
+        listEquals<String>(other._fontFamilyFallback, _fontFamilyFallback);
   }
 
   @override
@@ -1274,7 +1242,8 @@ class DomParagraphBuilder implements ui.ParagraphBuilder {
   /// Marks a call to the [pop] method in the [_ops] list.
   static final Object _paragraphBuilderPop = Object();
 
-  final html.HtmlElement _paragraphElement = domRenderer.createElement('p') as html.HtmlElement;
+  final html.HtmlElement _paragraphElement =
+      domRenderer.createElement('p') as html.HtmlElement;
   final EngineParagraphStyle _paragraphStyle;
   final List<dynamic> _ops = <dynamic>[];
 
@@ -1324,7 +1293,9 @@ class DomParagraphBuilder implements ui.ParagraphBuilder {
     // Require a baseline to be specified if using a baseline-based alignment.
     assert((alignment == ui.PlaceholderAlignment.aboveBaseline ||
             alignment == ui.PlaceholderAlignment.belowBaseline ||
-            alignment == ui.PlaceholderAlignment.baseline) ? baseline != null : true);
+            alignment == ui.PlaceholderAlignment.baseline)
+        ? baseline != null
+        : true);
 
     _placeholderCount++;
     _placeholderScales.add(scale);
@@ -1394,12 +1365,14 @@ class DomParagraphBuilder implements ui.ParagraphBuilder {
     ui.FontWeight? fontWeight = _paragraphStyle._fontWeight;
     ui.FontStyle? fontStyle = _paragraphStyle._fontStyle;
     ui.TextBaseline? textBaseline;
-    String fontFamily = _paragraphStyle._fontFamily ?? DomRenderer.defaultFontFamily;
+    String fontFamily =
+        _paragraphStyle._fontFamily ?? DomRenderer.defaultFontFamily;
     List<String>? fontFamilyFallback;
     List<ui.FontFeature>? fontFeatures;
     double fontSize = _paragraphStyle._fontSize ?? DomRenderer.defaultFontSize;
     final ui.TextAlign textAlign = _paragraphStyle._effectiveTextAlign;
-    final ui.TextDirection textDirection = _paragraphStyle._effectiveTextDirection;
+    final ui.TextDirection textDirection =
+        _paragraphStyle._effectiveTextDirection;
     double? letterSpacing;
     double? wordSpacing;
     double? height;
@@ -1604,7 +1577,8 @@ class DomParagraphBuilder implements ui.ParagraphBuilder {
     for (int i = 0; i < _ops.length; i++) {
       final dynamic op = _ops[i];
       if (op is EngineTextStyle) {
-        final html.SpanElement span = domRenderer.createElement('span') as html.SpanElement;
+        final html.SpanElement span =
+            domRenderer.createElement('span') as html.SpanElement;
         _applyTextStyleToElement(element: span, style: op, isSpan: true);
         if (op._background != null) {
           _applyTextBackgroundToElement(element: span, style: op);
@@ -1789,8 +1763,7 @@ void _applyTextStyleToElement({
   if (isSpan && !ui.debugEmulateFlutterTesterEnvironment) {
     cssStyle.fontFamily = canonicalizeFontFamily(style._fontFamily);
   } else {
-    cssStyle.fontFamily =
-        canonicalizeFontFamily(style._effectiveFontFamily);
+    cssStyle.fontFamily = canonicalizeFontFamily(style._effectiveFontFamily);
   }
   if (style._letterSpacing != null) {
     cssStyle.letterSpacing = '${style._letterSpacing}px';
@@ -2002,7 +1975,8 @@ String? textDirectionIndexToCss(int textDirectionIndex) {
 /// ```css
 /// text-align: right;
 /// ```
-String textAlignToCssValue(ui.TextAlign? align, ui.TextDirection textDirection) {
+String textAlignToCssValue(
+    ui.TextAlign? align, ui.TextDirection textDirection) {
   switch (align) {
     case ui.TextAlign.left:
       return 'left';
@@ -2031,23 +2005,3 @@ String textAlignToCssValue(ui.TextAlign? align, ui.TextDirection textDirection)
       return '';
   }
 }
-
-/// Determines if lists [a] and [b] are deep equivalent.
-///
-/// Returns true if the lists are both null, or if they are both non-null, have
-/// the same length, and contain the same elements in the same order. Returns
-/// false otherwise.
-bool _listEquals<T>(List<T>? a, List<T>? b) {
-  if (a == null) {
-    return b == null;
-  }
-  if (b == null || a.length != b.length) {
-    return false;
-  }
-  for (int index = 0; index < a.length; index += 1) {
-    if (a[index] != b[index]) {
-      return false;
-    }
-  }
-  return true;
-}

lib/web_ui/lib/src/engine/util.dart

@@ -293,21 +293,25 @@ void transformLTRB(Matrix4 transform, Float32List ltrb) {
   }
 
   ltrb[0] = math.min(
-      math.min(
-          math.min(_tempPointData[0], _tempPointData[1]), _tempPointData[2]),
-      _tempPointData[3]) / w;
+          math.min(math.min(_tempPointData[0], _tempPointData[1]),
+              _tempPointData[2]),
+          _tempPointData[3]) /
+      w;
   ltrb[1] = math.min(
-      math.min(
-          math.min(_tempPointData[4], _tempPointData[5]), _tempPointData[6]),
-      _tempPointData[7]) / w;
+          math.min(math.min(_tempPointData[4], _tempPointData[5]),
+              _tempPointData[6]),
+          _tempPointData[7]) /
+      w;
   ltrb[2] = math.max(
-      math.max(
-          math.max(_tempPointData[0], _tempPointData[1]), _tempPointData[2]),
-      _tempPointData[3]) / w;
+          math.max(math.max(_tempPointData[0], _tempPointData[1]),
+              _tempPointData[2]),
+          _tempPointData[3]) /
+      w;
   ltrb[3] = math.max(
-      math.max(
-          math.max(_tempPointData[4], _tempPointData[5]), _tempPointData[6]),
-      _tempPointData[7]) / w;
+          math.max(math.max(_tempPointData[4], _tempPointData[5]),
+              _tempPointData[6]),
+          _tempPointData[7]) /
+      w;
 }
 
 /// Returns true if [rect] contains every point that is also contained by the
@@ -528,3 +532,23 @@ int clampInt(int value, int min, int max) {
 /// This function can be overridden in tests. This could be useful, for example,
 /// to verify that warnings are printed under certain circumstances.
 void Function(String) printWarning = html.window.console.warn;
+
+/// Determines if lists [a] and [b] are deep equivalent.
+///
+/// Returns true if the lists are both null, or if they are both non-null, have
+/// the same length, and contain the same elements in the same order. Returns
+/// false otherwise.
+bool listEquals<T>(List<T>? a, List<T>? b) {
+  if (a == null) {
+    return b == null;
+  }
+  if (b == null || a.length != b.length) {
+    return false;
+  }
+  for (int index = 0; index < a.length; index += 1) {
+    if (a[index] != b[index]) {
+      return false;
+    }
+  }
+  return true;
+}

lib/web_ui/lib/src/ui/canvas.dart

@@ -87,7 +87,8 @@ abstract class Canvas {
     if (engine.useCanvasKit) {
       return engine.CanvasKitCanvas(recorder, cullRect);
     } else {
-      return engine.SurfaceCanvas(recorder as engine.EnginePictureRecorder, cullRect);
+      return engine.SurfaceCanvas(
+          recorder as engine.EnginePictureRecorder, cullRect);
     }
   }
   void save();
@@ -99,7 +100,8 @@ abstract class Canvas {
   void rotate(double radians);
   void skew(double sx, double sy);
   void transform(Float64List matrix4);
-  void clipRect(Rect rect, {ClipOp clipOp = ClipOp.intersect, bool doAntiAlias = true});
+  void clipRect(Rect rect,
+      {ClipOp clipOp = ClipOp.intersect, bool doAntiAlias = true});
   void clipRRect(RRect rrect, {bool doAntiAlias = true});
   void clipPath(Path path, {bool doAntiAlias = true});
   void drawColor(Color color, BlendMode blendMode);
@@ -110,7 +112,8 @@ abstract class Canvas {
   void drawDRRect(RRect outer, RRect inner, Paint paint);
   void drawOval(Rect rect, Paint paint);
   void drawCircle(Offset c, double radius, Paint paint);
-  void drawArc(Rect rect, double startAngle, double sweepAngle, bool useCenter, Paint paint);
+  void drawArc(Rect rect, double startAngle, double sweepAngle, bool useCenter,
+      Paint paint);
   void drawPath(Path path, Paint paint);
   void drawImage(Image image, Offset offset, Paint paint);
   void drawImageRect(Image image, Rect src, Rect dst, Paint paint);

lib/web_ui/lib/src/ui/text.dart

@@ -45,9 +45,15 @@ class FontWeight {
   ];
   static FontWeight? lerp(FontWeight? a, FontWeight? b, double t) {
     assert(t != null); // ignore: unnecessary_null_comparison
-    if (a == null && b == null)
+    if (a == null && b == null) {
       return null;
-    return values[engine.clampInt(lerpDouble(a?.index ?? normal.index, b?.index ?? normal.index, t)!.round(), 0, 8)];
+    }
+    return values[engine.clampInt(
+      lerpDouble(a?.index ?? normal.index, b?.index ?? normal.index, t)!
+          .round(),
+      0,
+      8,
+    )];
   }
 
   @override
@@ -67,59 +73,103 @@ class FontWeight {
 }
 
 class FontFeature {
-  const FontFeature(
-    this.feature,
-    [ this.value = 1 ]
-  ) : assert(feature != null), // ignore: unnecessary_null_comparison
-      assert(feature.length == 4, 'Feature tag must be exactly four characters long.'),
-      assert(value != null), // ignore: unnecessary_null_comparison
-      assert(value >= 0, 'Feature value must be zero or a positive integer.');
+  const FontFeature(this.feature, [this.value = 1])
+      : assert(feature != null), // ignore: unnecessary_null_comparison
+        assert(feature.length == 4,
+            'Feature tag must be exactly four characters long.'),
+        assert(value != null), // ignore: unnecessary_null_comparison
+        assert(value >= 0, 'Feature value must be zero or a positive integer.');
   const FontFeature.enable(String feature) : this(feature, 1);
   const FontFeature.disable(String feature) : this(feature, 0);
   const FontFeature.alternative(this.value) : feature = 'aalt';
-  const FontFeature.alternativeFractions() : feature = 'afrc', value = 1;
-  const FontFeature.contextualAlternates() : feature = 'calt', value = 1;
-  const FontFeature.caseSensitiveForms() : feature = 'case', value = 1;
+  const FontFeature.alternativeFractions()
+      : feature = 'afrc',
+        value = 1;
+  const FontFeature.contextualAlternates()
+      : feature = 'calt',
+        value = 1;
+  const FontFeature.caseSensitiveForms()
+      : feature = 'case',
+        value = 1;
   factory FontFeature.characterVariant(int value) {
     assert(value >= 1);
     assert(value <= 20);
     return FontFeature('cv${value.toString().padLeft(2, "0")}');
   }
-  const FontFeature.denominator() : feature = 'dnom', value = 1;
-  const FontFeature.fractions() : feature = 'frac', value = 1;
-  const FontFeature.historicalForms() : feature = 'hist', value = 1;
-  const FontFeature.historicalLigatures() : feature = 'hlig', value = 1;
-  const FontFeature.liningFigures() : feature = 'lnum', value = 1;
-  const FontFeature.localeAware({ bool enable = true }) : feature = 'locl', value = enable ? 1 : 0;
-  const FontFeature.notationalForms([this.value = 1]) : feature = 'nalt', assert(value >= 0);
-  const FontFeature.numerators() : feature = 'numr', value = 1;
-  const FontFeature.oldstyleFigures() : feature = 'onum', value = 1;
-  const FontFeature.ordinalForms() : feature = 'ordn', value = 1;
-  const FontFeature.proportionalFigures() : feature = 'pnum', value = 1;
-  const FontFeature.randomize() : feature = 'rand', value = 1;
-  const FontFeature.stylisticAlternates() : feature = 'salt', value = 1;
-  const FontFeature.scientificInferiors() : feature = 'sinf', value = 1;
+  const FontFeature.denominator()
+      : feature = 'dnom',
+        value = 1;
+  const FontFeature.fractions()
+      : feature = 'frac',
+        value = 1;
+  const FontFeature.historicalForms()
+      : feature = 'hist',
+        value = 1;
+  const FontFeature.historicalLigatures()
+      : feature = 'hlig',
+        value = 1;
+  const FontFeature.liningFigures()
+      : feature = 'lnum',
+        value = 1;
+  const FontFeature.localeAware({bool enable = true})
+      : feature = 'locl',
+        value = enable ? 1 : 0;
+  const FontFeature.notationalForms([this.value = 1])
+      : feature = 'nalt',
+        assert(value >= 0);
+  const FontFeature.numerators()
+      : feature = 'numr',
+        value = 1;
+  const FontFeature.oldstyleFigures()
+      : feature = 'onum',
+        value = 1;
+  const FontFeature.ordinalForms()
+      : feature = 'ordn',
+        value = 1;
+  const FontFeature.proportionalFigures()
+      : feature = 'pnum',
+        value = 1;
+  const FontFeature.randomize()
+      : feature = 'rand',
+        value = 1;
+  const FontFeature.stylisticAlternates()
+      : feature = 'salt',
+        value = 1;
+  const FontFeature.scientificInferiors()
+      : feature = 'sinf',
+        value = 1;
   factory FontFeature.stylisticSet(int value) {
     assert(value >= 1);
     assert(value <= 20);
     return FontFeature('ss${value.toString().padLeft(2, "0")}');
   }
-  const FontFeature.subscripts() : feature = 'subs', value = 1;
-  const FontFeature.superscripts() : feature = 'sups', value = 1;
-  const FontFeature.swash([this.value = 1]) : feature = 'swsh', assert(value >= 0);
-  const FontFeature.tabularFigures() : feature = 'tnum', value = 1;
-  const FontFeature.slashedZero() : feature = 'zero', value = 1;
+  const FontFeature.subscripts()
+      : feature = 'subs',
+        value = 1;
+  const FontFeature.superscripts()
+      : feature = 'sups',
+        value = 1;
+  const FontFeature.swash([this.value = 1])
+      : feature = 'swsh',
+        assert(value >= 0);
+  const FontFeature.tabularFigures()
+      : feature = 'tnum',
+        value = 1;
+  const FontFeature.slashedZero()
+      : feature = 'zero',
+        value = 1;
 
   final String feature;
   final int value;
 
   @override
   bool operator ==(Object other) {
-    if (other.runtimeType != runtimeType)
+    if (other.runtimeType != runtimeType) {
       return false;
-    return other is FontFeature
-        && other.feature == feature
-        && other.value == value;
+    }
+    return other is FontFeature &&
+        other.feature == feature &&
+        other.value == value;
   }
 
   @override
@@ -166,8 +216,7 @@ class TextDecoration {
 
   @override
   bool operator ==(Object other) {
-    return other is TextDecoration
-        && other._mask == _mask;
+    return other is TextDecoration && other._mask == _mask;
   }
 
   @override
@@ -195,13 +244,7 @@ class TextDecoration {
   }
 }
 
-enum TextDecorationStyle {
-  solid,
-  double,
-  dotted,
-  dashed,
-  wavy
-}
+enum TextDecorationStyle { solid, double, dotted, dashed, wavy }
 
 enum TextLeadingDistribution {
   proportional,
@@ -220,12 +263,13 @@ class TextHeightBehavior {
 
   @override
   bool operator ==(Object other) {
-    if (other.runtimeType != runtimeType)
-     return false;
-    return other is TextHeightBehavior
-        && other.applyHeightToFirstAscent == applyHeightToFirstAscent
-        && other.applyHeightToLastDescent == applyHeightToLastDescent
-        && other.leadingDistribution == leadingDistribution;
+    if (other.runtimeType != runtimeType) {
+      return false;
+    }
+    return other is TextHeightBehavior &&
+        other.applyHeightToFirstAscent == applyHeightToFirstAscent &&
+        other.applyHeightToLastDescent == applyHeightToLastDescent &&
+        other.leadingDistribution == leadingDistribution;
   }
 
   @override
@@ -239,10 +283,10 @@ class TextHeightBehavior {
   @override
   String toString() {
     return 'TextHeightBehavior('
-             'applyHeightToFirstAscent: $applyHeightToFirstAscent, '
-             'applyHeightToLastDescent: $applyHeightToLastDescent, '
-             'leadingDistribution: $leadingDistribution'
-           ')';
+        'applyHeightToFirstAscent: $applyHeightToFirstAscent, '
+        'applyHeightToLastDescent: $applyHeightToLastDescent, '
+        'leadingDistribution: $leadingDistribution'
+        ')';
   }
 }
 
@@ -369,6 +413,41 @@ abstract class ParagraphStyle {
 }
 
 abstract class StrutStyle {
+  /// Creates a new StrutStyle object.
+  ///
+  /// * `fontFamily`: The name of the font to use when painting the text (e.g.,
+  ///   Roboto).
+  ///
+  /// * `fontFamilyFallback`: An ordered list of font family names that will be searched for when
+  ///    the font in `fontFamily` cannot be found.
+  ///
+  /// * `fontSize`: The size of glyphs (in logical pixels) to use when painting
+  ///   the text.
+  ///
+  /// * `lineHeight`: The minimum height of the line boxes, as a multiple of the
+  ///   font size. The lines of the paragraph will be at least
+  ///   `(lineHeight + leading) * fontSize` tall when fontSize
+  ///   is not null. When fontSize is null, there is no minimum line height. Tall
+  ///   glyphs due to baseline alignment or large [TextStyle.fontSize] may cause
+  ///   the actual line height after layout to be taller than specified here.
+  ///   [fontSize] must be provided for this property to take effect.
+  ///
+  /// * `leading`: The minimum amount of leading between lines as a multiple of
+  ///   the font size. [fontSize] must be provided for this property to take effect.
+  ///
+  /// * `fontWeight`: The typeface thickness to use when painting the text
+  ///   (e.g., bold).
+  ///
+  /// * `fontStyle`: The typeface variant to use when drawing the letters (e.g.,
+  ///   italics).
+  ///
+  /// * `forceStrutHeight`: When true, the paragraph will force all lines to be exactly
+  ///   `(lineHeight + leading) * fontSize` tall from baseline to baseline.
+  ///   [TextStyle] is no longer able to influence the line height, and any tall
+  ///   glyphs may overlap with lines above. If a [fontFamily] is specified, the
+  ///   total ascent of the first line will be the min of the `Ascent + half-leading`
+  ///   of the [fontFamily] and `(lineHeight + leading) * fontSize`. Otherwise, it
+  ///   will be determined by the Ascent + half-leading of the first text.
   factory StrutStyle({
     String? fontFamily,
     List<String>? fontFamilyFallback,
@@ -379,7 +458,33 @@ abstract class StrutStyle {
     FontWeight? fontWeight,
     FontStyle? fontStyle,
     bool? forceStrutHeight,
-  }) = engine.EngineStrutStyle;
+  }) {
+    if (engine.useCanvasKit) {
+      return engine.CkStrutStyle(
+        fontFamily: fontFamily,
+        fontFamilyFallback: fontFamilyFallback,
+        fontSize: fontSize,
+        height: height,
+        leadingDistribution: leadingDistribution,
+        leading: leading,
+        fontWeight: fontWeight,
+        fontStyle: fontStyle,
+        forceStrutHeight: forceStrutHeight,
+      );
+    } else {
+      return engine.EngineStrutStyle(
+        fontFamily: fontFamily,
+        fontFamilyFallback: fontFamilyFallback,
+        fontSize: fontSize,
+        height: height,
+        leadingDistribution: leadingDistribution,
+        leading: leading,
+        fontWeight: fontWeight,
+        fontStyle: fontStyle,
+        forceStrutHeight: forceStrutHeight,
+      );
+    }
+  }
 }
 
 // The order of this enum must match the order of the values in TextDirection.h's TextDirection.
@@ -418,12 +523,12 @@ class TextBox {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is TextBox
-        && other.left == left
-        && other.top == top
-        && other.right == right
-        && other.bottom == bottom
-        && other.direction == direction;
+    return other is TextBox &&
+        other.left == left &&
+        other.top == top &&
+        other.right == right &&
+        other.bottom == bottom &&
+        other.direction == direction;
   }
 
   @override
@@ -454,9 +559,9 @@ class TextPosition {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is TextPosition
-        && other.offset == offset
-        && other.affinity == affinity;
+    return other is TextPosition &&
+        other.offset == offset &&
+        other.affinity == affinity;
   }
 
   @override
@@ -472,10 +577,10 @@ class TextRange {
   const TextRange({
     required this.start,
     required this.end,
-  })  : assert(start != null && start >= -1), // ignore: unnecessary_null_comparison
-        assert(end != null && end >= -1); // ignore: unnecessary_null_comparison
+  })  : assert(start >= -1),
+        assert(end >= -1);
   const TextRange.collapsed(int offset)
-      : assert(offset != null && offset >= -1), // ignore: unnecessary_null_comparison
+      : assert(offset >= -1),
         start = offset,
         end = offset;
   static const TextRange empty = TextRange(start: -1, end: -1);
@@ -504,9 +609,7 @@ class TextRange {
     if (identical(this, other)) {
       return true;
     }
-    return other is TextRange
-        && other.start == start
-        && other.end == end;
+    return other is TextRange && other.start == start && other.end == end;
   }
 
   @override
@@ -530,8 +633,7 @@ class ParagraphConstraints {
     if (other.runtimeType != runtimeType) {
       return false;
     }
-    return other is ParagraphConstraints
-        && other.width == width;
+    return other is ParagraphConstraints && other.width == width;
   }
 
   @override
@@ -605,7 +707,8 @@ abstract class ParagraphBuilder {
     if (engine.useCanvasKit) {
       return engine.CkParagraphBuilder(style);
     } else if (engine.WebExperiments.instance!.useCanvasRichText) {
-      return engine.CanvasParagraphBuilder(style as engine.EngineParagraphStyle);
+      return engine.CanvasParagraphBuilder(
+          style as engine.EngineParagraphStyle);
     } else {
       return engine.DomParagraphBuilder(style as engine.EngineParagraphStyle);
     }
@@ -628,12 +731,12 @@ abstract class ParagraphBuilder {
 
 Future<void> loadFontFromList(Uint8List list, {String? fontFamily}) {
   if (engine.useCanvasKit) {
-    return engine.skiaFontCollection.loadFontFromList(list, fontFamily: fontFamily).then(
-      (_) => engine.sendFontChangeMessage()
-    );
+    return engine.skiaFontCollection
+        .loadFontFromList(list, fontFamily: fontFamily)
+        .then((_) => engine.sendFontChangeMessage());
   } else {
-    return _fontCollection!.loadFontFromList(list, fontFamily: fontFamily!).then(
-      (_) => engine.sendFontChangeMessage()
-    );
+    return _fontCollection!
+        .loadFontFromList(list, fontFamily: fontFamily!)
+        .then((_) => engine.sendFontChangeMessage());
   }
 }

lib/web_ui/test/golden_tests/engine/path_to_svg_golden_test.dart

@@ -24,18 +24,21 @@ enum PaintMode {
 }
 
 void testMain() async {
-  final Rect region = Rect.fromLTWH(8, 8, 600, 400); // Compensate for old scuba tester padding
+  final Rect region =
+      Rect.fromLTWH(8, 8, 600, 400); // Compensate for old scuba tester padding
 
   Future<void> testPath(Path path, String scubaFileName,
-      {Paint paint, double maxDiffRatePercent = null, bool write = false,
+      {Paint paint,
+      double maxDiffRatePercent = null,
+      bool write = false,
       PaintMode mode = PaintMode.kStrokeAndFill}) async {
     const Rect canvasBounds = Rect.fromLTWH(0, 0, 600, 400);
-    final BitmapCanvas bitmapCanvas = BitmapCanvas(canvasBounds,
-        RenderStrategy());
+    final BitmapCanvas bitmapCanvas =
+        BitmapCanvas(canvasBounds, RenderStrategy());
     final RecordingCanvas canvas = RecordingCanvas(canvasBounds);
 
-    bool enableFill = mode == PaintMode.kStrokeAndFill ||
-        mode == PaintMode.kFill;
+    bool enableFill =
+        mode == PaintMode.kStrokeAndFill || mode == PaintMode.kFill;
     if (enableFill) {
       paint ??= Paint()
         ..color = const Color(0x807F7F7F)
@@ -46,8 +49,7 @@ void testMain() async {
     if (mode == PaintMode.kStrokeAndFill || mode == PaintMode.kStroke) {
       paint = Paint()
         ..strokeWidth = 2
-        ..color = enableFill ? const Color(0xFFFF0000) :
-            const Color(0xFF000000)
+        ..color = enableFill ? const Color(0xFFFF0000) : const Color(0xFF000000)
         ..style = PaintingStyle.stroke;
     }
 
@@ -59,8 +61,7 @@ void testMain() async {
 
     canvas.drawPath(path, paint);
 
-    final html.Element svgElement = pathToSvgElement(path, paint,
-        enableFill);
+    final html.Element svgElement = pathToSvgElement(path, paint, enableFill);
 
     html.document.body.append(bitmapCanvas.rootElement);
     html.document.body.append(svgElement);
@@ -68,8 +69,8 @@ void testMain() async {
     canvas.endRecording();
     canvas.apply(bitmapCanvas, canvasBounds);
 
-    await matchGoldenFile('$scubaFileName.png', region: region,
-        maxDiffRatePercent: maxDiffRatePercent, write: write);
+    await matchGoldenFile('$scubaFileName.png',
+        region: region, maxDiffRatePercent: maxDiffRatePercent, write: write);
 
     bitmapCanvas.rootElement.remove();
     svgElement.remove();
@@ -180,18 +181,15 @@ void testMain() async {
     final Path path = Path();
     path.moveTo(20, 20);
     path.lineTo(200, 200);
-    await testPath(path, 'svg_stroke_width',
-        mode: PaintMode.kStrokeWidthOnly);
+    await testPath(path, 'svg_stroke_width', mode: PaintMode.kStrokeWidthOnly);
   });
 }
 
-html.Element pathToSvgElement(Path path, Paint paint,
-    bool enableFill) {
+html.Element pathToSvgElement(Path path, Paint paint, bool enableFill) {
   final Rect bounds = path.getBounds();
   final StringBuffer sb = StringBuffer();
-  sb.write(
-      '<svg viewBox="0 0 ${bounds.right} ${bounds.bottom}" '
-          'width="${bounds.right}" height="${bounds.bottom}">');
+  sb.write('<svg viewBox="0 0 ${bounds.right} ${bounds.bottom}" '
+      'width="${bounds.right}" height="${bounds.bottom}">');
   sb.write('<path ');
   if (paint.style == PaintingStyle.stroke ||
       (paint.strokeWidth != null && paint.strokeWidth != 0.0)) {
@@ -209,16 +207,11 @@ html.Element pathToSvgElement(Path path, Paint paint,
   sb.write('"></path>');
   sb.write('</svg>');
   final html.Element svgElement =
-      html.Element.html(sb.toString(), treeSanitizer: _NullTreeSanitizer());
+      html.Element.html(sb.toString(), treeSanitizer: NullTreeSanitizer());
   svgElement.style.transform = 'translate(200px, 0px)';
   return svgElement;
 }
 
-class _NullTreeSanitizer implements html.NodeTreeSanitizer {
-  @override
-  void sanitizeTree(html.Node node) {}
-}
-
 class ArcSample {
   final Offset offset;
   final bool largeArc;