Picture shader

lib/stub_ui/lib/painting.dart

@@ -1318,6 +1318,7 @@ class Paint {
   ///
   ///  * [Gradient], a shader that paints a color gradient.
   ///  * [ImageShader], a shader that tiles an [Image].
+  ///  * [PictureShader], a shader that tiles a [Picture].
   ///  * [colorFilter], which overrides [shader].
   ///  * [color], which is used if [shader] and [colorFilter] are null.
   Shader get shader {
@@ -2669,6 +2670,13 @@ class ImageShader extends Shader {
     super._();
 }
 
+/// A shader (as used by [Paint.shader]) that tiles a picture.
+class PictureShader extends Shader {
+  /// This class is created by the engine, and should not be instantiated
+  /// or extended directly.
+  PictureShader._() : super._();
+}
+
 /// Defines how a list of points is interpreted when drawing a set of triangles.
 ///
 /// Used by [Canvas.drawVertices].
@@ -3312,6 +3320,15 @@ class Picture {
   Future<Image> toImage(int width, int height) {
     throw UnimplementedError();
   }
+
+  /// Creates a picture shader from this picture.
+  ///
+  /// The shader is returned asynchronously to allow time for the gpu to
+  /// draw the picture and compile a shader.
+  Future<PictureShader> toShader(TileMode tmx, TileMode tmy, Float64List matrix4) {
+    throw UnimplementedError();
+  }
+
   /// Release the resources used by this object. The object is no longer usable
   /// after this method is called.
   void dispose() {

lib/ui/BUILD.gn

@@ -48,6 +48,8 @@ source_set("ui") {
     "painting/picture.h",
     "painting/picture_recorder.cc",
     "painting/picture_recorder.h",
+    "painting/picture_shader.cc",
+    "painting/picture_shader.h",
     "painting/rrect.cc",
     "painting/rrect.h",
     "painting/shader.cc",

lib/ui/painting.dart

@@ -1319,6 +1319,7 @@ class Paint {
   ///
   ///  * [Gradient], a shader that paints a color gradient.
   ///  * [ImageShader], a shader that tiles an [Image].
+  ///  * [PictureShader], a shader that tiles a [Picture].
   ///  * [colorFilter], which overrides [shader].
   ///  * [color], which is used if [shader] and [colorFilter] are null.
   Shader get shader {
@@ -2875,6 +2876,14 @@ class ImageShader extends Shader {
   void _initWithImage(Image image, int tmx, int tmy, Float64List matrix4) native 'ImageShader_initWithImage';
 }
 
+/// A shader (as used by [Paint.shader]) that tiles a picture.
+class PictureShader extends Shader {
+  /// This class is created by the engine, and should not be instantiated
+  /// or extended directly.
+  @pragma('vm:entry-point')
+  PictureShader._() : super._();
+}
+
 /// Defines how a list of points is interpreted when drawing a set of triangles.
 ///
 /// Used by [Canvas.drawVertices].
@@ -3765,6 +3774,23 @@ class Picture extends NativeFieldWrapperClass2 {
 
   String _toImage(int width, int height, _Callback<Image> callback) native 'Picture_toImage';
 
+  /// Creates a picture shader from this picture.
+  ///
+  /// The shader is returned asynchronously to allow time for the gpu to
+  /// draw the picture and compile a shader.
+  Future<PictureShader> toShader(TileMode tmx, TileMode tmy, Float64List matrix4) {
+    assert(tmx != null);
+    assert(tmy != null);
+    assert(matrix4 != null);
+    if (matrix4.length != 16)
+      throw new ArgumentError('"matrix4" must have 16 entries.');
+    return _futurize(
+      (_Callback<PictureShader> callback) => _toShader(tmx, tmy, matrix4, callback)
+    );
+  }
+
+  String _toShader(TileMode tmx, TileMode tmy, Float64List matrix4, _Callback<PictureShader> callback) native 'Picture_toShader';
+
   /// Release the resources used by this object. The object is no longer usable
   /// after this method is called.
   void dispose() native 'Picture_dispose';

lib/ui/painting/picture.cc

@@ -21,6 +21,7 @@ IMPLEMENT_WRAPPERTYPEINFO(ui, Picture);
 
 #define FOR_EACH_BINDING(V) \
   V(Picture, toImage)       \
+  V(Picture, toShader)      \
   V(Picture, dispose)       \
   V(Picture, GetAllocationSize)
 
@@ -46,6 +47,21 @@ Dart_Handle Picture::toImage(uint32_t width,
   return RasterizeToImage(picture_.get(), width, height, raw_image_callback);
 }
 
+Dart_Handle Picture::toShader(SkTileMode tmx,
+                                    SkTileMode tmy,
+                                    const tonic::Float64List& matrix4,
+                                    Dart_Handle raw_shader_callback) {
+  if (!picture_.get()) {
+    return tonic::ToDart("Picture is null");
+  }
+
+  if (picture_.get()->cullRect().isEmpty()) {
+    return tonic::ToDart("Picture cull rect is null");
+  }
+
+  return TransferToShader(picture_.get(), tmx, tmy, matrix4, raw_shader_callback);
+}
+
 void Picture::dispose() {
   ClearDartWrapper();
 }
@@ -126,4 +142,81 @@ Dart_Handle Picture::RasterizeToImage(sk_sp<SkPicture> picture,
   return Dart_Null();
 }
 
+Dart_Handle Picture::TransferToShader(sk_sp<SkPicture> picture,
+                                            SkTileMode tmx,
+                                            SkTileMode tmy,
+                                            const tonic::Float64List& matrix4,
+                                            Dart_Handle raw_shader_callback) {
+  if (Dart_IsNull(raw_shader_callback) || !Dart_IsClosure(raw_shader_callback)) {
+    return tonic::ToDart("Picture shader callback was invalid");
+  }
+
+  auto* dart_state = UIDartState::Current();
+  tonic::DartPersistentValue* shader_callback = new tonic::DartPersistentValue(dart_state, raw_shader_callback);
+  auto unref_queue = dart_state->GetSkiaUnrefQueue();
+  auto ui_task_runner = dart_state->GetTaskRunners().GetUITaskRunner();
+  auto gpu_task_runner = dart_state->GetTaskRunners().GetGPUTaskRunner();
+
+  auto matrix = ToSkMatrix(matrix4);
+
+  auto ui_task = fml::MakeCopyable([shader_callback, unref_queue](
+                                       sk_sp<SkShader> shader) mutable {
+    auto dart_state = shader_callback->dart_state().lock();
+    if (!dart_state) {
+      return;
+    }
+    tonic::DartState::Scope scope(dart_state);
+
+    if (!shader) {
+      tonic::DartInvoke(shader_callback->Get(), {Dart_Null()});
+      return;
+    }
+
+    auto dart_shader = PictureShader::Create();
+    dart_shader->set_shader({std::move(shader), std::move(unref_queue)});
+    auto* raw_dart_shader = tonic::ToDart(std::move(dart_shader));
+
+    tonic::DartInvoke(shader_callback->Get(), {raw_dart_shader});
+
+    delete shader_callback;
+  });
+
+  fml::TaskRunner::RunNowOrPostTask(
+      gpu_task_runner,
+      [ui_task_runner, picture, tmx, tmy, matrix, ui_task] {
+        sk_sp<SkShader> shader;
+
+        SkRect tile = picture->cullRect();
+
+        SkPoint scale;
+
+        scale.set(SkScalarSqrt(matrix.getScaleX() * matrix.getScaleX() + matrix.getSkewX() * matrix.getSkewX()),
+                  SkScalarSqrt(matrix.getScaleY() * matrix.getScaleY() + matrix.getSkewY() * matrix.getSkewY()));
+
+        SkSize scaledSize = SkSize::Make(SkScalarAbs(scale.x() * tile.width()),
+                                         SkScalarAbs(scale.y() * tile.height()));
+
+        const SkISize tileSize = scaledSize.toCeil();
+
+        if (!tileSize.isEmpty()) {
+          SkMatrix tileMatrix;
+          tileMatrix.setRectToRect(tile, SkRect::MakeIWH(tileSize.width(), tileSize.height()), SkMatrix::kFill_ScaleToFit);
+
+          SkImage::BitDepth bitDepth = SkImage::BitDepth::kU8;
+          sk_sp<SkColorSpace> colorSpace = SkColorSpace::MakeSRGB();
+
+          sk_sp<SkImage> tileImage = SkImage::MakeFromPicture(picture, tileSize, &tileMatrix, nullptr, bitDepth, std::move(colorSpace));
+
+          if(tileImage)
+            shader = tileImage->makeShader(tmx, tmy);
+        }
+
+        fml::TaskRunner::RunNowOrPostTask(
+            ui_task_runner,
+            [ui_task, shader]() { ui_task(shader); });
+      });
+
+  return Dart_Null();
+}
+
 }  // namespace flutter

lib/ui/painting/picture.h

@@ -8,7 +8,11 @@
 #include "flutter/flow/skia_gpu_object.h"
 #include "flutter/lib/ui/dart_wrapper.h"
 #include "flutter/lib/ui/painting/image.h"
+#include "flutter/lib/ui/painting/matrix.h"
+#include "flutter/lib/ui/painting/picture_shader.h"
+#include "third_party/skia/include/core/SkImage.h"
 #include "third_party/skia/include/core/SkPicture.h"
+#include "third_party/tonic/typed_data/float64_list.h"
 
 namespace tonic {
 class DartLibraryNatives;
@@ -31,6 +35,11 @@ class Picture : public RefCountedDartWrappable<Picture> {
                       uint32_t height,
                       Dart_Handle raw_image_callback);
 
+  Dart_Handle toShader(SkTileMode tmx,
+                       SkTileMode tmy,
+                       const tonic::Float64List& matrix4,
+                       Dart_Handle raw_shader_callback);
+
   void dispose();
 
   size_t GetAllocationSize() override;
@@ -42,6 +51,12 @@ class Picture : public RefCountedDartWrappable<Picture> {
                                       uint32_t height,
                                       Dart_Handle raw_image_callback);
 
+  static Dart_Handle TransferToShader(sk_sp<SkPicture> picture,
+                                      SkTileMode tmx,
+                                      SkTileMode tmy,
+                                      const tonic::Float64List& matrix4,
+                                      Dart_Handle raw_shader_callback);
+
  private:
   explicit Picture(flutter::SkiaGPUObject<SkPicture> picture);
 

lib/ui/painting/picture_shader.cc

@@ -0,0 +1,19 @@
+// 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/picture_shader.h"
+
+namespace flutter {
+
+IMPLEMENT_WRAPPERTYPEINFO(ui, PictureShader);
+
+fml::RefPtr<PictureShader> PictureShader::Create() {
+  return fml::MakeRefCounted<PictureShader>();
+}
+
+PictureShader::PictureShader() = default;
+
+PictureShader::~PictureShader() = default;
+
+}  // namespace flutter

lib/ui/painting/picture_shader.h

@@ -0,0 +1,27 @@
+// 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_PAINTING_PICTURE_SHADER_H_
+#define FLUTTER_LIB_UI_PAINTING_PICTURE_SHADER_H_
+
+#include "flutter/lib/ui/dart_wrapper.h"
+#include "flutter/lib/ui/painting/shader.h"
+
+namespace flutter {
+
+class PictureShader : public Shader {
+  DEFINE_WRAPPERTYPEINFO();
+  FML_FRIEND_MAKE_REF_COUNTED(PictureShader);
+
+ public:
+  ~PictureShader() override;
+  static fml::RefPtr<PictureShader> Create();
+
+ private:
+  PictureShader();
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_LIB_UI_PAINTING_PICTURE_SHADER_H_