[Impeller] Add a CommandBuffer::WaitUntilScheduled API

impeller/renderer/backend/gles/command_buffer_gles.cc

@@ -38,6 +38,11 @@ bool CommandBufferGLES::OnSubmitCommands(CompletionCallback callback) {
   return result;
 }
 
+// |CommandBuffer|
+void CommandBufferGLES::OnWaitUntilScheduled() {
+  reactor_->GetProcTable().Flush();
+}
+
 // |CommandBuffer|
 std::shared_ptr<RenderPass> CommandBufferGLES::OnCreateRenderPass(
     RenderTarget target) {

impeller/renderer/backend/gles/command_buffer_gles.h

@@ -34,6 +34,9 @@ class CommandBufferGLES final : public CommandBuffer {
   // |CommandBuffer|
   bool OnSubmitCommands(CompletionCallback callback) override;
 
+  // |CommandBuffer|
+  void OnWaitUntilScheduled() override;
+
   // |CommandBuffer|
   std::shared_ptr<RenderPass> OnCreateRenderPass(RenderTarget target) override;
 

impeller/renderer/backend/gles/proc_table_gles.h

@@ -119,6 +119,7 @@ struct GLProc {
   PROC(DrawElements);                        \
   PROC(Enable);                              \
   PROC(EnableVertexAttribArray);             \
+  PROC(Flush);                               \
   PROC(FramebufferRenderbuffer);             \
   PROC(FramebufferTexture2D);                \
   PROC(FrontFace);                           \

impeller/renderer/backend/metal/command_buffer_mtl.h

@@ -33,6 +33,9 @@ class CommandBufferMTL final : public CommandBuffer {
   // |CommandBuffer|
   bool OnSubmitCommands(CompletionCallback callback) override;
 
+  // |CommandBuffer|
+  void OnWaitUntilScheduled() override;
+
   // |CommandBuffer|
   std::shared_ptr<RenderPass> OnCreateRenderPass(RenderTarget target) override;
 

impeller/renderer/backend/metal/command_buffer_mtl.mm

@@ -192,6 +192,8 @@ static bool LogMTLCommandBufferErrorIfPresent(id<MTLCommandBuffer> buffer) {
   return true;
 }
 
+void CommandBufferMTL::OnWaitUntilScheduled() {}
+
 std::shared_ptr<RenderPass> CommandBufferMTL::OnCreateRenderPass(
     RenderTarget target) {
   if (!buffer_) {

impeller/renderer/backend/vulkan/command_buffer_vk.cc

@@ -55,6 +55,8 @@ bool CommandBufferVK::OnSubmitCommands(CompletionCallback callback) {
   return submit;
 }
 
+void CommandBufferVK::OnWaitUntilScheduled() {}
+
 std::shared_ptr<RenderPass> CommandBufferVK::OnCreateRenderPass(
     RenderTarget target) {
   auto context = context_.lock();

impeller/renderer/backend/vulkan/command_buffer_vk.h

@@ -41,6 +41,9 @@ class CommandBufferVK final
   // |CommandBuffer|
   bool OnSubmitCommands(CompletionCallback callback) override;
 
+  // |CommandBuffer|
+  void OnWaitUntilScheduled() override;
+
   // |CommandBuffer|
   std::shared_ptr<RenderPass> OnCreateRenderPass(RenderTarget target) override;
 

impeller/renderer/command_buffer.cc

@@ -32,6 +32,10 @@ bool CommandBuffer::SubmitCommands() {
   return SubmitCommands(nullptr);
 }
 
+void CommandBuffer::WaitUntilScheduled() {
+  return OnWaitUntilScheduled();
+}
+
 std::shared_ptr<RenderPass> CommandBuffer::CreateRenderPass(
     const RenderTarget& render_target) {
   auto pass = OnCreateRenderPass(render_target);

impeller/renderer/command_buffer.h

@@ -65,6 +65,11 @@ class CommandBuffer {
 
   [[nodiscard]] bool SubmitCommands();
 
+  //----------------------------------------------------------------------------
+  /// @brief      Force execution of pending GPU commands.
+  ///
+  void WaitUntilScheduled();
+
   //----------------------------------------------------------------------------
   /// @brief      Create a render pass to record render commands into.
   ///
@@ -102,6 +107,8 @@ class CommandBuffer {
 
   [[nodiscard]] virtual bool OnSubmitCommands(CompletionCallback callback) = 0;
 
+  virtual void OnWaitUntilScheduled() = 0;
+
   virtual std::shared_ptr<ComputePass> OnCreateComputePass() const = 0;
 
  private:

impeller/renderer/testing/mocks.h

@@ -78,6 +78,7 @@ class MockCommandBuffer : public CommandBuffer {
   MOCK_CONST_METHOD1(SetLabel, void(const std::string& label));
   MOCK_CONST_METHOD0(OnCreateBlitPass, std::shared_ptr<BlitPass>());
   MOCK_METHOD1(OnSubmitCommands, bool(CompletionCallback callback));
+  MOCK_METHOD0(OnWaitUntilScheduled, void());
   MOCK_CONST_METHOD0(OnCreateComputePass, std::shared_ptr<ComputePass>());
   MOCK_METHOD1(OnCreateRenderPass,
                std::shared_ptr<RenderPass>(RenderTarget render_target));

lib/ui/painting/image_decoder_impeller.cc

@@ -362,6 +362,7 @@ sk_sp<DlImage> ImageDecoderImpeller::UploadTextureToShared(
       FML_DLOG(ERROR) << "Failed to submit blit pass command buffer.";
       return nullptr;
     }
+    command_buffer->WaitUntilScheduled();
   }
 
   return impeller::DlImageImpeller::Make(std::move(texture));