Refactor of Vulkan GPUSurface code (flutter/engine#16224)

Co-authored-by: David Worsham <arbreng@gmail.com>

engine/src/flutter/ci/licenses_golden/licenses_flutter

@@ -603,6 +603,8 @@ FILE: ../../../flutter/shell/gpu/gpu_surface_software_delegate.cc
 FILE: ../../../flutter/shell/gpu/gpu_surface_software_delegate.h
 FILE: ../../../flutter/shell/gpu/gpu_surface_vulkan.cc
 FILE: ../../../flutter/shell/gpu/gpu_surface_vulkan.h
+FILE: ../../../flutter/shell/gpu/gpu_surface_vulkan_delegate.cc
+FILE: ../../../flutter/shell/gpu/gpu_surface_vulkan_delegate.h
 FILE: ../../../flutter/shell/platform/android/AndroidManifest.xml
 FILE: ../../../flutter/shell/platform/android/android_context_gl.cc
 FILE: ../../../flutter/shell/platform/android/android_context_gl.h

engine/src/flutter/shell/gpu/BUILD.gn

@@ -16,6 +16,7 @@ gpu_common_deps = [
 
 source_set("gpu_surface_software") {
   sources = [
+    "$gpu_dir/gpu_surface_delegate.h",
     "$gpu_dir/gpu_surface_software.cc",
     "$gpu_dir/gpu_surface_software.h",
     "$gpu_dir/gpu_surface_software_delegate.cc",
@@ -39,8 +40,11 @@ source_set("gpu_surface_gl") {
 
 source_set("gpu_surface_vulkan") {
   sources = [
+    "$gpu_dir/gpu_surface_delegate.h",
     "$gpu_dir/gpu_surface_vulkan.cc",
     "$gpu_dir/gpu_surface_vulkan.h",
+    "$gpu_dir/gpu_surface_vulkan_delegate.cc",
+    "$gpu_dir/gpu_surface_vulkan_delegate.h",
   ]
 
   deps = gpu_common_deps + [

engine/src/flutter/shell/gpu/gpu_surface_delegate.h

@@ -2,14 +2,24 @@
 #define FLUTTER_SHELL_GPU_GPU_SURFACE_DELEGATE_H_
 
 #include "flutter/flow/embedded_views.h"
-#include "flutter/fml/macros.h"
 
 namespace flutter {
 
 class GPUSurfaceDelegate {
  public:
-  // Get a reference to the external views embedder. This happens on the same
-  // thread that the renderer is operating on.
+  virtual ~GPUSurfaceDelegate() {}
+
+  //----------------------------------------------------------------------------
+  /// @brief      Gets the view embedder that controls how the Flutter layer
+  ///             hierarchy split into multiple chunks should be composited back
+  ///             on-screen. This field is optional and the Flutter rasterizer
+  ///             will render into a single on-screen surface if this call
+  ///             returns a null external view embedder. This happens on the GPU
+  ///             thread.
+  ///
+  /// @return     The external view embedder, or, null if Flutter is rendering
+  ///             into a single on-screen surface.
+  ///
   virtual ExternalViewEmbedder* GetExternalViewEmbedder() = 0;
 };
 

engine/src/flutter/shell/gpu/gpu_surface_gl_delegate.cc

@@ -8,6 +8,8 @@
 
 namespace flutter {
 
+GPUSurfaceGLDelegate::~GPUSurfaceGLDelegate() = default;
+
 bool GPUSurfaceGLDelegate::GLContextFBOResetAfterPresent() const {
   return false;
 }
@@ -95,4 +97,8 @@ GPUSurfaceGLDelegate::GetDefaultPlatformGLInterface() {
   return CreateGLInterface(nullptr);
 }
 
+ExternalViewEmbedder* GPUSurfaceGLDelegate::GetExternalViewEmbedder() {
+  return nullptr;
+}
+
 }  // namespace flutter

engine/src/flutter/shell/gpu/gpu_surface_gl_delegate.h

@@ -15,6 +15,11 @@ namespace flutter {
 
 class GPUSurfaceGLDelegate : public GPUSurfaceDelegate {
  public:
+  ~GPUSurfaceGLDelegate() override;
+
+  // |GPUSurfaceDelegate|
+  ExternalViewEmbedder* GetExternalViewEmbedder() override;
+
   // Called to make the main GL context current on the current thread.
   virtual bool GLContextMakeCurrent() = 0;
 

engine/src/flutter/shell/gpu/gpu_surface_software_delegate.h

@@ -7,6 +7,7 @@
 
 #include "flutter/flow/embedded_views.h"
 #include "flutter/fml/macros.h"
+#include "flutter/shell/gpu/gpu_surface_delegate.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
 namespace flutter {
@@ -24,9 +25,12 @@ namespace flutter {
 /// @see        |IOSurfaceSoftware|, |AndroidSurfaceSoftware|,
 ///             |EmbedderSurfaceSoftware|.
 ///
-class GPUSurfaceSoftwareDelegate {
+class GPUSurfaceSoftwareDelegate : public GPUSurfaceDelegate {
  public:
-  virtual ~GPUSurfaceSoftwareDelegate();
+  ~GPUSurfaceSoftwareDelegate() override;
+
+  // |GPUSurfaceDelegate|
+  ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
   //----------------------------------------------------------------------------
   /// @brief      Called when the GPU surface needs a new buffer to render a new
@@ -48,18 +52,6 @@ class GPUSurfaceSoftwareDelegate {
   ///             the screen.
   ///
   virtual bool PresentBackingStore(sk_sp<SkSurface> backing_store) = 0;
-
-  //----------------------------------------------------------------------------
-  /// @brief      Gets the view embedder that controls how the Flutter layer
-  ///             hierarchy split into multiple chunks should be composited back
-  ///             on-screen. This field is optional and the Flutter rasterizer
-  ///             will render into a single on-screen surface if this call
-  ///             returns a null external view embedder.
-  ///
-  /// @return     The external view embedder, or, null if Flutter is rendering
-  ///             into a single on-screen surface.
-  ///
-  virtual ExternalViewEmbedder* GetExternalViewEmbedder() = 0;
 };
 
 }  // namespace flutter

engine/src/flutter/shell/gpu/gpu_surface_vulkan.cc

@@ -8,21 +8,31 @@
 namespace flutter {
 
 GPUSurfaceVulkan::GPUSurfaceVulkan(
-    fml::RefPtr<vulkan::VulkanProcTable> proc_table,
-    std::unique_ptr<vulkan::VulkanNativeSurface> native_surface)
-    : window_(std::move(proc_table), std::move(native_surface)),
+    GPUSurfaceVulkanDelegate* delegate,
+    std::unique_ptr<vulkan::VulkanNativeSurface> native_surface,
+    bool render_to_surface)
+    : window_(delegate->vk(), std::move(native_surface), render_to_surface),
+      delegate_(delegate),
+      render_to_surface_(render_to_surface),
       weak_factory_(this) {}
 
 GPUSurfaceVulkan::~GPUSurfaceVulkan() = default;
 
-// |Surface|
 bool GPUSurfaceVulkan::IsValid() {
   return window_.IsValid();
 }
 
-// |Surface|
 std::unique_ptr<SurfaceFrame> GPUSurfaceVulkan::AcquireFrame(
     const SkISize& size) {
+  // TODO(38466): Refactor GPU surface APIs take into account the fact that an
+  // external view embedder may want to render to the root surface.
+  if (!render_to_surface_) {
+    return std::make_unique<SurfaceFrame>(
+        nullptr, true, [](const SurfaceFrame& surface_frame, SkCanvas* canvas) {
+          return true;
+        });
+  }
+
   auto surface = window_.AcquireSurface();
 
   if (surface == nullptr) {
@@ -44,7 +54,6 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceVulkan::AcquireFrame(
                                         std::move(callback));
 }
 
-// |Surface|
 SkMatrix GPUSurfaceVulkan::GetRootTransformation() const {
   // This backend does not support delegating to the underlying platform to
   // query for root surface transformations. Just return identity.
@@ -53,9 +62,12 @@ SkMatrix GPUSurfaceVulkan::GetRootTransformation() const {
   return matrix;
 }
 
-// |Surface|
 GrContext* GPUSurfaceVulkan::GetContext() {
   return window_.GetSkiaGrContext();
 }
 
+flutter::ExternalViewEmbedder* GPUSurfaceVulkan::GetExternalViewEmbedder() {
+  return delegate_->GetExternalViewEmbedder();
+}
+
 }  // namespace flutter

engine/src/flutter/shell/gpu/gpu_surface_vulkan.h

@@ -10,6 +10,7 @@
 #include "flutter/fml/macros.h"
 #include "flutter/fml/memory/weak_ptr.h"
 #include "flutter/shell/common/surface.h"
+#include "flutter/shell/gpu/gpu_surface_vulkan_delegate.h"
 #include "flutter/vulkan/vulkan_native_surface.h"
 #include "flutter/vulkan/vulkan_window.h"
 
@@ -17,8 +18,9 @@ namespace flutter {
 
 class GPUSurfaceVulkan : public Surface {
  public:
-  GPUSurfaceVulkan(fml::RefPtr<vulkan::VulkanProcTable> proc_table,
-                   std::unique_ptr<vulkan::VulkanNativeSurface> native_surface);
+  GPUSurfaceVulkan(GPUSurfaceVulkanDelegate* delegate,
+                   std::unique_ptr<vulkan::VulkanNativeSurface> native_surface,
+                   bool render_to_surface);
 
   ~GPUSurfaceVulkan() override;
 
@@ -34,8 +36,14 @@ class GPUSurfaceVulkan : public Surface {
   // |Surface|
   GrContext* GetContext() override;
 
+  // |Surface|
+  flutter::ExternalViewEmbedder* GetExternalViewEmbedder() override;
+
  private:
   vulkan::VulkanWindow window_;
+  GPUSurfaceVulkanDelegate* delegate_;
+  const bool render_to_surface_;
+
   fml::WeakPtrFactory<GPUSurfaceVulkan> weak_factory_;
 
   FML_DISALLOW_COPY_AND_ASSIGN(GPUSurfaceVulkan);

engine/src/flutter/shell/gpu/gpu_surface_vulkan_delegate.cc

@@ -0,0 +1,15 @@
+// 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/shell/gpu/gpu_surface_vulkan_delegate.h"
+
+namespace flutter {
+
+GPUSurfaceVulkanDelegate::~GPUSurfaceVulkanDelegate() = default;
+
+ExternalViewEmbedder* GPUSurfaceVulkanDelegate::GetExternalViewEmbedder() {
+  return nullptr;
+}
+
+}  // namespace flutter

engine/src/flutter/shell/gpu/gpu_surface_vulkan_delegate.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_SHELL_GPU_GPU_SURFACE_VULKAN_DELEGATE_H_
+#define FLUTTER_SHELL_GPU_GPU_SURFACE_VULKAN_DELEGATE_H_
+
+#include "flutter/fml/memory/ref_ptr.h"
+#include "flutter/shell/gpu/gpu_surface_delegate.h"
+#include "flutter/vulkan/vulkan_proc_table.h"
+
+namespace flutter {
+
+class GPUSurfaceVulkanDelegate : public GPUSurfaceDelegate {
+ public:
+  ~GPUSurfaceVulkanDelegate() override;
+
+  // |GPUSurfaceDelegate|
+  ExternalViewEmbedder* GetExternalViewEmbedder() override;
+
+  // Obtain a reference to the Vulkan implementation's proc table.
+  virtual fml::RefPtr<vulkan::VulkanProcTable> vk() = 0;
+};
+
+}  // namespace flutter
+
+#endif  // FLUTTER_SHELL_GPU_GPU_SURFACE_VULKAN_DELEGATE_H_

engine/src/flutter/shell/platform/android/android_surface_vulkan.cc

@@ -21,12 +21,10 @@ bool AndroidSurfaceVulkan::IsValid() const {
   return proc_table_->HasAcquiredMandatoryProcAddresses();
 }
 
-// |AndroidSurface|
 void AndroidSurfaceVulkan::TeardownOnScreenContext() {
   // Nothing to do.
 }
 
-// |AndroidSurface|
 std::unique_ptr<Surface> AndroidSurfaceVulkan::CreateGPUSurface() {
   if (!IsValid()) {
     return nullptr;
@@ -45,7 +43,7 @@ std::unique_ptr<Surface> AndroidSurfaceVulkan::CreateGPUSurface() {
   }
 
   auto gpu_surface = std::make_unique<GPUSurfaceVulkan>(
-      proc_table_, std::move(vulkan_surface_android));
+      this, std::move(vulkan_surface_android), true);
 
   if (!gpu_surface->IsValid()) {
     return nullptr;
@@ -54,28 +52,32 @@ std::unique_ptr<Surface> AndroidSurfaceVulkan::CreateGPUSurface() {
   return gpu_surface;
 }
 
-// |AndroidSurface|
 bool AndroidSurfaceVulkan::OnScreenSurfaceResize(const SkISize& size) const {
   return true;
 }
 
-// |AndroidSurface|
 bool AndroidSurfaceVulkan::ResourceContextMakeCurrent() {
   FML_DLOG(ERROR) << "The vulkan backend does not support resource contexts.";
   return false;
 }
 
-// |AndroidSurface|
 bool AndroidSurfaceVulkan::ResourceContextClearCurrent() {
   FML_DLOG(ERROR) << "The vulkan backend does not support resource contexts.";
   return false;
 }
 
-// |AndroidSurface|
 bool AndroidSurfaceVulkan::SetNativeWindow(
     fml::RefPtr<AndroidNativeWindow> window) {
   native_window_ = std::move(window);
   return native_window_ && native_window_->IsValid();
 }
 
+ExternalViewEmbedder* AndroidSurfaceVulkan::GetExternalViewEmbedder() {
+  return nullptr;
+}
+
+fml::RefPtr<vulkan::VulkanProcTable> AndroidSurfaceVulkan::vk() {
+  return proc_table_;
+}
+
 }  // namespace flutter

engine/src/flutter/shell/platform/android/android_surface_vulkan.h

@@ -8,13 +8,15 @@
 #include <jni.h>
 #include <memory>
 #include "flutter/fml/macros.h"
+#include "flutter/shell/gpu/gpu_surface_vulkan_delegate.h"
 #include "flutter/shell/platform/android/android_native_window.h"
 #include "flutter/shell/platform/android/android_surface.h"
 #include "flutter/vulkan/vulkan_window.h"
 
 namespace flutter {
 
-class AndroidSurfaceVulkan : public AndroidSurface {
+class AndroidSurfaceVulkan : public AndroidSurface,
+                             public GPUSurfaceVulkanDelegate {
  public:
   AndroidSurfaceVulkan();
 
@@ -41,6 +43,12 @@ class AndroidSurfaceVulkan : public AndroidSurface {
   // |AndroidSurface|
   bool SetNativeWindow(fml::RefPtr<AndroidNativeWindow> window) override;
 
+  // |GPUSurfaceVulkanDelegate|
+  ExternalViewEmbedder* GetExternalViewEmbedder() override;
+
+  // |GPUSurfaceVulkanDelegate|
+  fml::RefPtr<vulkan::VulkanProcTable> vk() override;
+
  private:
   fml::RefPtr<vulkan::VulkanProcTable> proc_table_;
   fml::RefPtr<AndroidNativeWindow> native_window_;

engine/src/flutter/vulkan/vulkan_window.cc

@@ -17,7 +17,8 @@
 namespace vulkan {
 
 VulkanWindow::VulkanWindow(fml::RefPtr<VulkanProcTable> proc_table,
-                           std::unique_ptr<VulkanNativeSurface> native_surface)
+                           std::unique_ptr<VulkanNativeSurface> native_surface,
+                           bool render_to_surface)
     : valid_(false), vk(std::move(proc_table)) {
   if (!vk || !vk->HasAcquiredMandatoryProcAddresses()) {
     FML_DLOG(INFO) << "Proc table has not acquired mandatory proc addresses.";
@@ -58,8 +59,13 @@ VulkanWindow::VulkanWindow(fml::RefPtr<VulkanProcTable> proc_table,
     return;
   }
 
-  // Create the logical surface from the native platform surface.
+  // TODO(38466): Refactor GPU surface APIs take into account the fact that an
+  // external view embedder may want to render to the root surface.
+  if (!render_to_surface) {
+    return;
+  }
 
+  // Create the logical surface from the native platform surface.
   surface_ = std::make_unique<VulkanSurface>(*vk, *application_,
                                              std::move(native_surface));
 

engine/src/flutter/vulkan/vulkan_window.h

@@ -32,7 +32,8 @@ class VulkanBackbuffer;
 class VulkanWindow {
  public:
   VulkanWindow(fml::RefPtr<VulkanProcTable> proc_table,
-               std::unique_ptr<VulkanNativeSurface> native_surface);
+               std::unique_ptr<VulkanNativeSurface> native_surface,
+               bool render_to_surface);
 
   ~VulkanWindow();