Add setImageSampler (for replacing setSampler)

lib/ui/dart_ui.cc

@@ -174,6 +174,7 @@ typedef CanvasPath Path;
   V(EngineLayer, dispose, 1)                           \
   V(FragmentProgram, initFromAsset, 2)                 \
   V(ReusableFragmentShader, Dispose, 1)                \
+  V(ReusableFragmentShader, SetImageSampler, 3)        \
   V(ReusableFragmentShader, SetSampler, 3)             \
   V(ReusableFragmentShader, ValidateSamplers, 1)       \
   V(Gradient, initLinear, 6)                           \

lib/ui/painting.dart

@@ -4314,13 +4314,27 @@ class FragmentShader extends Shader {
     _floats[index] = value;
   }
 
+  /// Sets the sampler uniform at [index] to [image].
+  ///
+  /// The index provided to setSampler is the index of the sampler uniform defined
+  /// in the fragment program, excluding all non-sampler uniforms.
+  ///
+  /// All the sampler uniforms that a shader expects must be provided or the
+  /// results will be undefined.
+  void setImageSampler(int index, Image image) {
+    assert(!debugDisposed, 'Tried to access uniforms on a disposed Shader: $this');
+    _setImageSampler(index, image);
+  }
+
   /// Sets the sampler uniform at [index] to [sampler].
   ///
   /// The index provided to setSampler is the index of the sampler uniform defined
   /// in the fragment program, excluding all non-sampler uniforms.
   ///
   /// All the sampler uniforms that a shader expects must be provided or the
   /// results will be undefined.
+  ///
+  /// Use of this method may result in poor performance with the Impeller backend.
   void setSampler(int index, ImageShader sampler) {
     assert(!debugDisposed, 'Tried to access uniforms on a disposed Shader: $this');
     _setSampler(index, sampler);
@@ -4341,6 +4355,9 @@ class FragmentShader extends Shader {
   @FfiNative<Handle Function(Handle, Handle, Handle, Handle)>('ReusableFragmentShader::Create')
   external Float32List _constructor(FragmentProgram program, int floatUniforms, int samplerUniforms);
 
+  @FfiNative<Void Function(Pointer<Void>, Handle, Handle)>('ReusableFragmentShader::SetImageSampler')
+  external void _setImageSampler(int index, Image sampler);
+
   @FfiNative<Void Function(Pointer<Void>, Handle, Handle)>('ReusableFragmentShader::SetSampler')
   external void _setSampler(int index, ImageShader sampler);
 

lib/ui/painting/fragment_shader.cc

@@ -7,6 +7,8 @@
 
 #include "flutter/lib/ui/painting/fragment_shader.h"
 
+#include "flutter/display_list/display_list_color_source.h"
+#include "flutter/display_list/display_list_tile_mode.h"
 #include "flutter/lib/ui/dart_wrapper.h"
 #include "flutter/lib/ui/painting/fragment_program.h"
 #include "flutter/lib/ui/ui_dart_state.h"
@@ -61,6 +63,27 @@ bool ReusableFragmentShader::ValidateSamplers() {
   return true;
 }
 
+void ReusableFragmentShader::SetImageSampler(Dart_Handle index_handle,
+                                             Dart_Handle image_handle) {
+  uint64_t index = tonic::DartConverter<uint64_t>::FromDart(index_handle);
+  CanvasImage* image =
+      tonic::DartConverter<CanvasImage*>::FromDart(image_handle);
+  if (index >= samplers_.size()) {
+    Dart_ThrowException(tonic::ToDart("Sampler index out of bounds"));
+  }
+
+  // TODO(115794): Once the DlImageSampling enum is replaced, expose the
+  //               sampling options as a new default parameter for users.
+  samplers_[index] = std::make_shared<DlImageColorSource>(
+      image->image(), DlTileMode::kClamp, DlTileMode::kClamp,
+      DlImageSampling::kNearestNeighbor, nullptr);
+
+  auto* uniform_floats =
+      reinterpret_cast<float*>(uniform_data_->writable_data());
+  uniform_floats[float_count_ + 2 * index] = image->width();
+  uniform_floats[float_count_ + 2 * index + 1] = image->height();
+}
+
 void ReusableFragmentShader::SetSampler(Dart_Handle index_handle,
                                         Dart_Handle sampler_handle) {
   uint64_t index = tonic::DartConverter<uint64_t>::FromDart(index_handle);

lib/ui/painting/fragment_shader.h

@@ -34,6 +34,8 @@ class ReusableFragmentShader : public Shader {
                             Dart_Handle float_count,
                             Dart_Handle sampler_count);
 
+  void SetImageSampler(Dart_Handle index, Dart_Handle image);
+
   void SetSampler(Dart_Handle index, Dart_Handle sampler);
 
   bool ValidateSamplers();