Refactor ColorFilter to have a native wrapper (flutter#9668)

Author: dnfield

ci/licenses_golden/licenses_flutter

@@ -332,6 +332,8 @@ FILE: ../../../flutter/lib/ui/painting/canvas.cc
 FILE: ../../../flutter/lib/ui/painting/canvas.h
 FILE: ../../../flutter/lib/ui/painting/codec.cc
 FILE: ../../../flutter/lib/ui/painting/codec.h
+FILE: ../../../flutter/lib/ui/painting/color_filter.cc
+FILE: ../../../flutter/lib/ui/painting/color_filter.h
 FILE: ../../../flutter/lib/ui/painting/engine_layer.cc
 FILE: ../../../flutter/lib/ui/painting/engine_layer.h
 FILE: ../../../flutter/lib/ui/painting/frame_info.cc

lib/ui/BUILD.gn

@@ -24,6 +24,8 @@ source_set("ui") {
     "painting/canvas.h",
     "painting/codec.cc",
     "painting/codec.h",
+    "painting/color_filter.cc",
+    "painting/color_filter.h",
     "painting/engine_layer.cc",
     "painting/engine_layer.h",
     "painting/frame_info.cc",

lib/ui/dart_ui.cc

@@ -11,6 +11,7 @@
 #include "flutter/lib/ui/isolate_name_server/isolate_name_server_natives.h"
 #include "flutter/lib/ui/painting/canvas.h"
 #include "flutter/lib/ui/painting/codec.h"
+#include "flutter/lib/ui/painting/color_filter.h"
 #include "flutter/lib/ui/painting/engine_layer.h"
 #include "flutter/lib/ui/painting/frame_info.h"
 #include "flutter/lib/ui/painting/gradient.h"
@@ -75,6 +76,7 @@ void DartUI::InitForGlobal() {
     CanvasPath::RegisterNatives(g_natives);
     CanvasPathMeasure::RegisterNatives(g_natives);
     Codec::RegisterNatives(g_natives);
+    ColorFilter::RegisterNatives(g_natives);
     DartRuntimeHooks::RegisterNatives(g_natives);
     EngineLayer::RegisterNatives(g_natives);
     FontCollection::RegisterNatives(g_natives);

lib/ui/painting.dart

@@ -1056,13 +1056,10 @@ class Paint {
   static const int _kStrokeJoinIndex = 6;
   static const int _kStrokeMiterLimitIndex = 7;
   static const int _kFilterQualityIndex = 8;
-  static const int _kColorFilterIndex = 9;
-  static const int _kColorFilterColorIndex = 10;
-  static const int _kColorFilterBlendModeIndex = 11;
-  static const int _kMaskFilterIndex = 12;
-  static const int _kMaskFilterBlurStyleIndex = 13;
-  static const int _kMaskFilterSigmaIndex = 14;
-  static const int _kInvertColorIndex = 15;
+  static const int _kMaskFilterIndex = 9;
+  static const int _kMaskFilterBlurStyleIndex = 10;
+  static const int _kMaskFilterSigmaIndex = 11;
+  static const int _kInvertColorIndex = 12;
 
   static const int _kIsAntiAliasOffset = _kIsAntiAliasIndex << 2;
   static const int _kColorOffset = _kColorIndex << 2;
@@ -1073,20 +1070,17 @@ class Paint {
   static const int _kStrokeJoinOffset = _kStrokeJoinIndex << 2;
   static const int _kStrokeMiterLimitOffset = _kStrokeMiterLimitIndex << 2;
   static const int _kFilterQualityOffset = _kFilterQualityIndex << 2;
-  static const int _kColorFilterOffset = _kColorFilterIndex << 2;
-  static const int _kColorFilterColorOffset = _kColorFilterColorIndex << 2;
-  static const int _kColorFilterBlendModeOffset = _kColorFilterBlendModeIndex << 2;
   static const int _kMaskFilterOffset = _kMaskFilterIndex << 2;
   static const int _kMaskFilterBlurStyleOffset = _kMaskFilterBlurStyleIndex << 2;
   static const int _kMaskFilterSigmaOffset = _kMaskFilterSigmaIndex << 2;
   static const int _kInvertColorOffset = _kInvertColorIndex << 2;
   // If you add more fields, remember to update _kDataByteCount.
-  static const int _kDataByteCount = 75;
+  static const int _kDataByteCount = 52;
 
   // Binary format must match the deserialization code in paint.cc.
   List<dynamic> _objects;
   static const int _kShaderIndex = 0;
-  static const int _kColorFilterMatrixIndex = 1;
+  static const int _kColorFilterIndex = 1;
   static const int _kImageFilterIndex = 2;
   static const int _kObjectCount = 3; // Must be one larger than the largest index.
 
@@ -1342,48 +1336,23 @@ class Paint {
   ///
   /// When a shape is being drawn, [colorFilter] overrides [color] and [shader].
   ColorFilter get colorFilter {
-    switch (_data.getInt32(_kColorFilterOffset, _kFakeHostEndian)) {
-      case ColorFilter._TypeNone:
-        return null;
-      case ColorFilter._TypeMode:
-        return ColorFilter.mode(
-          Color(_data.getInt32(_kColorFilterColorOffset, _kFakeHostEndian)),
-          BlendMode.values[_data.getInt32(_kColorFilterBlendModeOffset, _kFakeHostEndian)],
-        );
-      case ColorFilter._TypeMatrix:
-        return ColorFilter.matrix(_objects[_kColorFilterMatrixIndex]);
-      case ColorFilter._TypeLinearToSrgbGamma:
-        return const ColorFilter.linearToSrgbGamma();
-      case ColorFilter._TypeSrgbToLinearGamma:
-        return const ColorFilter.srgbToLinearGamma();
+    if (_objects == null || _objects[_kColorFilterIndex] == null) {
+      return null;
     }
-
-    return null;
+    return _objects[_kColorFilterIndex].creator;
   }
 
   set colorFilter(ColorFilter value) {
     if (value == null) {
-      _data.setInt32(_kColorFilterOffset, ColorFilter._TypeNone, _kFakeHostEndian);
-      _data.setInt32(_kColorFilterColorOffset, 0, _kFakeHostEndian);
-      _data.setInt32(_kColorFilterBlendModeOffset, 0, _kFakeHostEndian);
-
       if (_objects != null) {
-        _objects[_kColorFilterMatrixIndex] = null;
+        _objects[_kColorFilterIndex] = null;
       }
     } else {
-      _data.setInt32(_kColorFilterOffset, value._type, _kFakeHostEndian);
-
-      if (value._type == ColorFilter._TypeMode) {
-        assert(value._color != null);
-        assert(value._blendMode != null);
-
-        _data.setInt32(_kColorFilterColorOffset, value._color.value, _kFakeHostEndian);
-        _data.setInt32(_kColorFilterBlendModeOffset, value._blendMode.index, _kFakeHostEndian);
-      } else if (value._type == ColorFilter._TypeMatrix) {
-        assert(value._matrix != null);
-
-        _objects ??= List<dynamic>(_kObjectCount);
-        _objects[_kColorFilterMatrixIndex] = Float32List.fromList(value._matrix);
+      if (_objects == null) {
+        _objects = List<dynamic>(_kObjectCount);
+        _objects[_kColorFilterIndex] = value._toNativeColorFilter();
+      } else if (_objects[_kColorFilterIndex]?.creator != value) {
+        _objects[_kColorFilterIndex] = value._toNativeColorFilter();
       }
     }
   }
@@ -2520,7 +2489,9 @@ class ColorFilter {
   /// to the [Paint.blendMode], using the output of this filter as the source
   /// and the background as the destination.
   const ColorFilter.mode(Color color, BlendMode blendMode)
-      : _color = color,
+      : assert(color != null),
+        assert(blendMode != null),
+        _color = color,
         _blendMode = blendMode,
         _matrix = null,
         _type = _TypeMode;
@@ -2529,7 +2500,9 @@ class ColorFilter {
   /// matrix is in row-major order and the translation column is specified in
   /// unnormalized, 0...255, space.
   const ColorFilter.matrix(List<double> matrix)
-      : _color = null,
+      : assert(matrix != null),
+        assert(matrix.length == 20),
+        _color = null,
         _blendMode = null,
         _matrix = matrix,
         _type = _TypeMatrix;
@@ -2580,6 +2553,21 @@ class ColorFilter {
     return _color == typedOther._color && _blendMode == typedOther._blendMode;
   }
 
+  _ColorFilter _toNativeColorFilter() {
+    switch (_type) {
+      case _TypeMode:
+        return _ColorFilter.mode(this);
+      case _TypeMatrix:
+        return _ColorFilter.matrix(this);
+      case _TypeLinearToSrgbGamma:
+        return _ColorFilter.linearToSrgbGamma(this);
+      case _TypeSrgbToLinearGamma:
+        return _ColorFilter.srgbToLinearGamma(this);
+      default:
+        throw StateError('Unknown mode $_type for ColorFilter.');
+    }
+  }
+
   @override
   int get hashCode => hashValues(_color, _blendMode, hashList(_matrix), _type);
 
@@ -2600,6 +2588,51 @@ class ColorFilter {
   }
 }
 
+/// A [ColorFilter] that is backed by a native SkColorFilter.
+///
+/// This is a private class, rather than being the implementation of the public
+/// ColorFilter, because we want ColorFilter to be const constructible and
+/// efficiently comparable, so that widgets can check for ColorFilter equality to
+// avoid repainting.
+class _ColorFilter extends NativeFieldWrapperClass2 {
+  _ColorFilter.mode(this.creator)
+    : assert(creator != null),
+      assert(creator._type == ColorFilter._TypeMode) {
+    _constructor();
+    _initMode(creator._color.value, creator._blendMode.index);
+  }
+
+  _ColorFilter.matrix(this.creator)
+    : assert(creator != null),
+      assert(creator._type == ColorFilter._TypeMatrix) {
+    _constructor();
+    _initMatrix(Float32List.fromList(creator._matrix));
+  }
+  _ColorFilter.linearToSrgbGamma(this.creator)
+    : assert(creator != null),
+      assert(creator._type == ColorFilter._TypeLinearToSrgbGamma) {
+    _constructor();
+    _initLinearToSrgbGamma();
+  }
+
+  _ColorFilter.srgbToLinearGamma(this.creator)
+    : assert(creator != null),
+      assert(creator._type == ColorFilter._TypeSrgbToLinearGamma) {
+    _constructor();
+    _initSrgbToLinearGamma();
+  }
+
+  /// The original Dart object that created the native wrapper, which retains
+  /// the values used for the filter.
+  final ColorFilter creator;
+
+  void _constructor() native 'ColorFilter_constructor';
+  void _initMode(int color, int blendMode) native 'ColorFilter_initMode';
+  void _initMatrix(Float32List matrix) native 'ColorFilter_initMatrix';
+  void _initLinearToSrgbGamma() native 'ColorFilter_initLinearToSrgbGamma';
+  void _initSrgbToLinearGamma() native 'ColorFilter_initSrgbToLinearGamma';
+}
+
 /// A filter operation to apply to a raster image.
 ///
 /// See also:

lib/ui/painting/color_filter.cc

@@ -0,0 +1,70 @@
+// 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.
+
+#include "flutter/lib/ui/painting/color_filter.h"
+
+#include "third_party/tonic/converter/dart_converter.h"
+#include "third_party/tonic/dart_args.h"
+#include "third_party/tonic/dart_binding_macros.h"
+#include "third_party/tonic/dart_library_natives.h"
+
+namespace flutter {
+
+static void ColorFilter_constructor(Dart_NativeArguments args) {
+  DartCallConstructor(&ColorFilter::Create, args);
+}
+
+IMPLEMENT_WRAPPERTYPEINFO(ui, ColorFilter);
+
+#define FOR_EACH_BINDING(V)             \
+  V(ColorFilter, initMode)              \
+  V(ColorFilter, initMatrix)            \
+  V(ColorFilter, initSrgbToLinearGamma) \
+  V(ColorFilter, initLinearToSrgbGamma)
+
+FOR_EACH_BINDING(DART_NATIVE_CALLBACK)
+
+void ColorFilter::RegisterNatives(tonic::DartLibraryNatives* natives) {
+  natives->Register(
+      {{"ColorFilter_constructor", ColorFilter_constructor, 1, true},
+       FOR_EACH_BINDING(DART_REGISTER_NATIVE)});
+}
+
+fml::RefPtr<ColorFilter> ColorFilter::Create() {
+  return fml::MakeRefCounted<ColorFilter>();
+}
+
+void ColorFilter::initMode(int color, int blend_mode) {
+  filter_ = SkColorFilters::Blend(static_cast<SkColor>(color),
+                                  static_cast<SkBlendMode>(blend_mode));
+}
+
+sk_sp<SkColorFilter> ColorFilter::MakeColorMatrixFilter255(
+    const float array[20]) {
+  float tmp[20];
+  memcpy(tmp, array, sizeof(tmp));
+  tmp[4] *= 1.0f / 255;
+  tmp[9] *= 1.0f / 255;
+  tmp[14] *= 1.0f / 255;
+  tmp[19] *= 1.0f / 255;
+  return SkColorFilters::Matrix(tmp);
+}
+
+void ColorFilter::initMatrix(const tonic::Float32List& color_matrix) {
+  FML_CHECK(color_matrix.num_elements() == 20);
+
+  filter_ = MakeColorMatrixFilter255(color_matrix.data());
+}
+
+void ColorFilter::initLinearToSrgbGamma() {
+  filter_ = SkColorFilters::LinearToSRGBGamma();
+}
+
+void ColorFilter::initSrgbToLinearGamma() {
+  filter_ = SkColorFilters::SRGBToLinearGamma();
+}
+
+ColorFilter::~ColorFilter() = default;
+
+}  // namespace flutter

lib/ui/painting/color_filter.h

@@ -0,0 +1,52 @@
+// 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.
+
+#ifndef FLUTTER_LIB_UI_COLOR_FILTER_H_
+#define FLUTTER_LIB_UI_COLOR_FILTER_H_
+
+#include "flutter/lib/ui/dart_wrapper.h"
+#include "third_party/skia/include/core/SkColorFilter.h"
+#include "third_party/tonic/typed_data/typed_list.h"
+
+using tonic::DartPersistentValue;
+
+namespace tonic {
+class DartLibraryNatives;
+}  // namespace tonic
+
+namespace flutter {
+
+// A handle to an SkCodec object.
+//
+// Doesn't mirror SkCodec's API but provides a simple sequential access API.
+class ColorFilter : public RefCountedDartWrappable<ColorFilter> {
+  DEFINE_WRAPPERTYPEINFO();
+  FML_FRIEND_MAKE_REF_COUNTED(ColorFilter);
+
+ public:
+  static fml::RefPtr<ColorFilter> Create();
+
+  // Flutter still defines the matrix to be biased by 255 in the last column
+  // (translate). skia is normalized, treating the last column as 0...1, so we
+  // post-scale here before calling the skia factory.
+  static sk_sp<SkColorFilter> MakeColorMatrixFilter255(const float array[20]);
+
+  void initMode(int color, int blend_mode);
+  void initMatrix(const tonic::Float32List& color_matrix);
+  void initSrgbToLinearGamma();
+  void initLinearToSrgbGamma();
+
+  ~ColorFilter() override;
+
+  sk_sp<SkColorFilter> filter() const { return filter_; }
+
+  static void RegisterNatives(tonic::DartLibraryNatives* natives);
+
+ private:
+  sk_sp<SkColorFilter> filter_;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_LIB_UI_COLOR_FILTER_H_