RendererContextSwitch guard flutter's gl context rework. (#13812)

ci/licenses_golden/licenses_flutter

@@ -514,6 +514,8 @@ FILE: ../../../flutter/shell/common/pointer_data_dispatcher.cc
 FILE: ../../../flutter/shell/common/pointer_data_dispatcher.h
 FILE: ../../../flutter/shell/common/rasterizer.cc
 FILE: ../../../flutter/shell/common/rasterizer.h
+FILE: ../../../flutter/shell/common/renderer_context_switch_manager.cc
+FILE: ../../../flutter/shell/common/renderer_context_switch_manager.h
 FILE: ../../../flutter/shell/common/run_configuration.cc
 FILE: ../../../flutter/shell/common/run_configuration.h
 FILE: ../../../flutter/shell/common/shell.cc
@@ -803,6 +805,8 @@ FILE: ../../../flutter/shell/platform/darwin/ios/ios_external_texture_gl.h
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_external_texture_gl.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_gl_context.h
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_gl_context.mm
+FILE: ../../../flutter/shell/platform/darwin/ios/ios_gl_context_switch_manager.h
+FILE: ../../../flutter/shell/platform/darwin/ios/ios_gl_context_switch_manager.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_gl_render_target.h
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_gl_render_target.mm
 FILE: ../../../flutter/shell/platform/darwin/ios/ios_surface.h

shell/common/BUILD.gn

@@ -78,6 +78,8 @@ source_set("common") {
     "pointer_data_dispatcher.h",
     "rasterizer.cc",
     "rasterizer.h",
+    "renderer_context_switch_manager.cc",
+    "renderer_context_switch_manager.h",
     "run_configuration.cc",
     "run_configuration.h",
     "shell.cc",

shell/common/rasterizer.cc

@@ -163,7 +163,9 @@ sk_sp<SkImage> Rasterizer::MakeRasterSnapshot(sk_sp<SkPicture> picture,
     // happen in case of software rendering.
     surface = SkSurface::MakeRaster(image_info);
   } else {
-    if (!surface_->MakeRenderContextCurrent()) {
+    std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+        context_switch = surface_->MakeRenderContextCurrent();
+    if (!context_switch->GetSwitchResult()) {
       return nullptr;
     }
 
@@ -377,7 +379,7 @@ static sk_sp<SkSurface> CreateSnapshotSurface(GrContext* surface_context,
   return SkSurface::MakeRaster(image_info);
 }
 
-static sk_sp<SkData> ScreenshotLayerTreeAsImage(
+sk_sp<SkData> Rasterizer::ScreenshotLayerTreeAsImage(
     flutter::LayerTree* tree,
     flutter::CompositorContext& compositor_context,
     GrContext* surface_context,
@@ -402,21 +404,20 @@ static sk_sp<SkData> ScreenshotLayerTreeAsImage(
   auto frame = compositor_context.AcquireFrame(surface_context, canvas, nullptr,
                                                root_surface_transformation,
                                                false, nullptr);
+
   canvas->clear(SK_ColorTRANSPARENT);
   frame->Raster(*tree, true);
-  canvas->flush();
+  ScreenshotFlushCanvas(*canvas);
 
   // Prepare an image from the surface, this image may potentially be on th GPU.
-  auto potentially_gpu_snapshot = snapshot_surface->makeImageSnapshot();
+  auto potentially_gpu_snapshot = MakeImageSnapshot(snapshot_surface);
   if (!potentially_gpu_snapshot) {
-    FML_LOG(ERROR) << "Screenshot: unable to make image screenshot";
     return nullptr;
   }
 
   // Copy the GPU image snapshot into CPU memory.
-  auto cpu_snapshot = potentially_gpu_snapshot->makeRasterImage();
+  auto cpu_snapshot = MakeRasterImage(potentially_gpu_snapshot);
   if (!cpu_snapshot) {
-    FML_LOG(ERROR) << "Screenshot: unable to make raster image";
     return nullptr;
   }
 
@@ -436,6 +437,47 @@ static sk_sp<SkData> ScreenshotLayerTreeAsImage(
   return SkData::MakeWithCopy(pixmap.addr32(), pixmap.computeByteSize());
 }
 
+sk_sp<SkImage> Rasterizer::MakeImageSnapshot(
+    sk_sp<SkSurface> snapshot_surface) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = surface_->MakeRenderContextCurrent();
+  if (!context_switch->GetSwitchResult()) {
+    return nullptr;
+  }
+  auto potentially_gpu_snapshot = snapshot_surface->makeImageSnapshot();
+  if (!potentially_gpu_snapshot) {
+    FML_LOG(ERROR) << "Screenshot: unable to make image screenshot";
+    return nullptr;
+  }
+  return potentially_gpu_snapshot;
+}
+
+sk_sp<SkImage> Rasterizer::MakeRasterImage(
+    sk_sp<SkImage> potentially_gpu_snapshot) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = surface_->MakeRenderContextCurrent();
+  if (!context_switch->GetSwitchResult()) {
+    return nullptr;
+  }
+  auto cpu_snapshot = potentially_gpu_snapshot->makeRasterImage();
+  if (!cpu_snapshot) {
+    FML_LOG(ERROR) << "Screenshot: unable to make raster image";
+    return nullptr;
+  }
+  return cpu_snapshot;
+}
+
+void Rasterizer::ScreenshotFlushCanvas(SkCanvas& canvas) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = surface_->MakeRenderContextCurrent();
+  if (!context_switch->GetSwitchResult()) {
+    FML_LOG(ERROR)
+        << "Screenshot: unable to switch gl context to flutter's context";
+    return;
+  }
+  canvas.flush();
+}
+
 Rasterizer::Screenshot Rasterizer::ScreenshotLastLayerTree(
     Rasterizer::ScreenshotType type,
     bool base64_encode) {

shell/common/rasterizer.h

@@ -432,6 +432,15 @@ class Rasterizer final : public SnapshotDelegate {
 
   void FireNextFrameCallbackIfPresent();
 
+  sk_sp<SkData> ScreenshotLayerTreeAsImage(
+      flutter::LayerTree* tree,
+      flutter::CompositorContext& compositor_context,
+      GrContext* surface_context,
+      bool compressed);
+  sk_sp<SkImage> MakeImageSnapshot(sk_sp<SkSurface> snapshot_surface);
+  sk_sp<SkImage> MakeRasterImage(sk_sp<SkImage> potentially_gpu_snapshot);
+  void ScreenshotFlushCanvas(SkCanvas& canvas);
+
   FML_DISALLOW_COPY_AND_ASSIGN(Rasterizer);
 };
 

shell/common/renderer_context_switch_manager.cc

@@ -0,0 +1,30 @@
+// 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 "renderer_context_switch_manager.h"
+
+namespace flutter {
+
+RendererContextSwitchManager::RendererContextSwitchManager() = default;
+
+RendererContextSwitchManager::~RendererContextSwitchManager() = default;
+
+RendererContextSwitchManager::RendererContextSwitch::RendererContextSwitch() =
+    default;
+
+RendererContextSwitchManager::RendererContextSwitch::~RendererContextSwitch(){};
+
+RendererContextSwitchManager::RendererContextSwitchPureResult::
+    RendererContextSwitchPureResult(bool switch_result)
+    : switch_result_(switch_result){};
+
+RendererContextSwitchManager::RendererContextSwitchPureResult::
+    ~RendererContextSwitchPureResult() = default;
+
+bool RendererContextSwitchManager::RendererContextSwitchPureResult::
+    GetSwitchResult() {
+  return switch_result_;
+}
+
+}  // namespace flutter

shell/common/renderer_context_switch_manager.h

@@ -0,0 +1,116 @@
+// 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_COMMON_GL_CONTEXT_SWITCH_MANAGER_H_
+#define FLUTTER_SHELL_COMMON_GL_CONTEXT_SWITCH_MANAGER_H_
+
+#include <memory>
+#include "flutter/fml/macros.h"
+
+namespace flutter {
+
+//------------------------------------------------------------------------------
+/// Manages `RendererContextSwitch`.
+///
+/// Should be subclassed for platforms that uses GL and requires context
+/// switching. Always use `MakeCurrent` and `ResourceMakeCurrent` in the
+/// `RendererContextSwitchManager` to set gl contexts.
+///
+class RendererContextSwitchManager {
+ public:
+  //------------------------------------------------------------------------------
+  /// Switches the gl context to the flutter's contexts.
+  ///
+  /// Should be subclassed for each platform embedder that uses GL.
+  /// In construction, it should set the current context to a flutter's context
+  /// In destruction, it should rest the current context.
+  ///
+  class RendererContextSwitch {
+   public:
+    RendererContextSwitch();
+
+    virtual ~RendererContextSwitch();
+
+    virtual bool GetSwitchResult() = 0;
+
+    FML_DISALLOW_COPY_AND_ASSIGN(RendererContextSwitch);
+  };
+
+  RendererContextSwitchManager();
+  ~RendererContextSwitchManager();
+
+  //----------------------------------------------------------------------------
+  /// @brief      Creates a shell instance using the provided settings. The
+  ///             callbacks to create the various shell subcomponents will be
+  ///             called on the appropriate threads before this method returns.
+  ///             If this is the first instance of a shell in the process, this
+  ///             call also bootstraps the Dart VM.
+  ///
+  /// @param[in]  task_runners             The task runners
+  /// @param[in]  settings                 The settings
+  /// @param[in]  on_create_platform_view  The callback that must return a
+  ///                                      platform view. This will be called on
+  ///                                      the platform task runner before this
+  ///                                      method returns.
+  /// @param[in]  on_create_rasterizer     That callback that must provide a
+  ///                                      valid rasterizer. This will be called
+  ///                                      on the render task runner before this
+  ///                                      method returns.
+  ///
+  /// @return     A full initialized shell if the settings and callbacks are
+  ///             valid. The root isolate has been created but not yet launched.
+  ///             It may be launched by obtaining the engine weak pointer and
+  ///             posting a task onto the UI task runner with a valid run
+  ///             configuration to run the isolate. The embedder must always
+  ///             check the validity of the shell (using the IsSetup call)
+  ///             immediately after getting a pointer to it.
+  ///
+
+  //----------------------------------------------------------------------------
+  /// @brief      Make the flutter's context as current context.
+  ///
+  /// @return     A `RendererContextSwitch` with `GetSwitchResult` returning
+  /// true if the setting process is succesful.
+  virtual std::unique_ptr<RendererContextSwitch> MakeCurrent() = 0;
+
+  //----------------------------------------------------------------------------
+  /// @brief      Make the flutter's resources context as current context.
+  ///
+  /// @return     A `RendererContextSwitch` with `GetSwitchResult` returning
+  /// true if the setting process is succesful.
+  virtual std::unique_ptr<RendererContextSwitch> ResourceMakeCurrent() = 0;
+
+  //------------------------------------------------------------------------------
+  /// A representation of a `RendererContextSwitch` that doesn't require actual
+  /// context switching.
+  ///
+  class RendererContextSwitchPureResult final : public RendererContextSwitch {
+   public:
+    // Constructor that creates an `RendererContextSwitchPureResult`.
+    // The `GetSwitchResult` will return the same value as `switch_result`.
+
+    //----------------------------------------------------------------------------
+    /// @brief      Constructs a  `RendererContextSwitchPureResult`.
+    ///
+    /// @param[in]  switch_result       the switch result that will be returned
+    /// in `GetSwitchResult()`
+    ///
+    RendererContextSwitchPureResult(bool switch_result);
+
+    ~RendererContextSwitchPureResult();
+
+    bool GetSwitchResult() override;
+
+   private:
+    bool switch_result_;
+
+    FML_DISALLOW_COPY_AND_ASSIGN(RendererContextSwitchPureResult);
+  };
+
+  FML_DISALLOW_COPY_AND_ASSIGN(RendererContextSwitchManager);
+};
+
+}  // namespace flutter
+
+#endif

shell/common/shell_test.cc

@@ -355,8 +355,11 @@ PointerDataDispatcherMaker ShellTestPlatformView::GetDispatcherMaker() {
 }
 
 // |GPUSurfaceGLDelegate|
-bool ShellTestPlatformView::GLContextMakeCurrent() {
-  return gl_surface_.MakeCurrent();
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+ShellTestPlatformView::GLContextMakeCurrent() {
+  return std::make_unique<
+      RendererContextSwitchManager::RendererContextSwitchPureResult>(
+      gl_surface_.MakeCurrent());
 }
 
 // |GPUSurfaceGLDelegate|
@@ -387,5 +390,10 @@ ExternalViewEmbedder* ShellTestPlatformView::GetExternalViewEmbedder() {
   return nullptr;
 }
 
+std::shared_ptr<RendererContextSwitchManager>
+ShellTestPlatformView::GetRendererContextSwitchManager() {
+  return nullptr;
+}
+
 }  // namespace testing
 }  // namespace flutter

shell/common/shell_test.h

@@ -144,7 +144,8 @@ class ShellTestPlatformView : public PlatformView, public GPUSurfaceGLDelegate {
   PointerDataDispatcherMaker GetDispatcherMaker() override;
 
   // |GPUSurfaceGLDelegate|
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  GLContextMakeCurrent() override;
 
   // |GPUSurfaceGLDelegate|
   bool GLContextClearCurrent() override;
@@ -161,6 +162,9 @@ class ShellTestPlatformView : public PlatformView, public GPUSurfaceGLDelegate {
   // |GPUSurfaceGLDelegate|
   ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
+  std::shared_ptr<RendererContextSwitchManager>
+  GetRendererContextSwitchManager() override;
+
   FML_DISALLOW_COPY_AND_ASSIGN(ShellTestPlatformView);
 };
 

shell/common/shell_unittests.cc

@@ -952,5 +952,68 @@ TEST_F(ShellTest, IsolateCanAccessPersistentIsolateData) {
   DestroyShell(std::move(shell), std::move(task_runners));
 }
 
+TEST_F(ShellTest, RasterizerScreenshot) {
+  Settings settings = CreateSettingsForFixture();
+  auto configuration = RunConfiguration::InferFromSettings(settings);
+  auto task_runner = CreateNewThread();
+  TaskRunners task_runners("test", task_runner, task_runner, task_runner,
+                           task_runner);
+  std::unique_ptr<Shell> shell =
+      CreateShell(std::move(settings), std::move(task_runners));
+
+  ASSERT_TRUE(ValidateShell(shell.get()));
+  PlatformViewNotifyCreated(shell.get());
+
+  RunEngine(shell.get(), std::move(configuration));
+
+  auto latch = std::make_shared<fml::AutoResetWaitableEvent>();
+
+  PumpOneFrame(shell.get());
+
+  fml::TaskRunner::RunNowOrPostTask(
+      shell->GetTaskRunners().GetGPUTaskRunner(), [&shell, &latch]() {
+        Rasterizer::Screenshot screenshot =
+            shell->GetRasterizer()->ScreenshotLastLayerTree(
+                Rasterizer::ScreenshotType::CompressedImage, true);
+        EXPECT_NE(screenshot.data, nullptr);
+
+        latch->Signal();
+      });
+  latch->Wait();
+  DestroyShell(std::move(shell), std::move(task_runners));
+}
+
+TEST_F(ShellTest, RasterizerMakeRasterSnapshot) {
+  Settings settings = CreateSettingsForFixture();
+  auto configuration = RunConfiguration::InferFromSettings(settings);
+  auto task_runner = CreateNewThread();
+  TaskRunners task_runners("test", task_runner, task_runner, task_runner,
+                           task_runner);
+  std::unique_ptr<Shell> shell =
+      CreateShell(std::move(settings), std::move(task_runners));
+
+  ASSERT_TRUE(ValidateShell(shell.get()));
+  PlatformViewNotifyCreated(shell.get());
+
+  RunEngine(shell.get(), std::move(configuration));
+
+  auto latch = std::make_shared<fml::AutoResetWaitableEvent>();
+
+  PumpOneFrame(shell.get());
+
+  fml::TaskRunner::RunNowOrPostTask(
+      shell->GetTaskRunners().GetGPUTaskRunner(), [&shell, &latch]() {
+        SnapshotDelegate* delegate =
+            reinterpret_cast<Rasterizer*>(shell->GetRasterizer().get());
+        sk_sp<SkImage> image = delegate->MakeRasterSnapshot(
+            SkPicture::MakePlaceholder({0, 0, 50, 50}), SkISize::Make(50, 50));
+        EXPECT_NE(image, nullptr);
+
+        latch->Signal();
+      });
+  latch->Wait();
+  DestroyShell(std::move(shell), std::move(task_runners));
+}
+
 }  // namespace testing
 }  // namespace flutter

shell/common/surface.cc

@@ -60,8 +60,10 @@ flutter::ExternalViewEmbedder* Surface::GetExternalViewEmbedder() {
   return nullptr;
 }
 
-bool Surface::MakeRenderContextCurrent() {
-  return true;
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+Surface::MakeRenderContextCurrent() {
+  return std::make_unique<
+      RendererContextSwitchManager::RendererContextSwitchPureResult>(true);
 }
 
 }  // namespace flutter

shell/common/surface.h

@@ -10,6 +10,7 @@
 #include "flutter/flow/compositor_context.h"
 #include "flutter/flow/embedded_views.h"
 #include "flutter/fml/macros.h"
+#include "flutter/shell/common/renderer_context_switch_manager.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 
 namespace flutter {
@@ -58,7 +59,8 @@ class Surface {
 
   virtual flutter::ExternalViewEmbedder* GetExternalViewEmbedder();
 
-  virtual bool MakeRenderContextCurrent();
+  virtual std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  MakeRenderContextCurrent();
 
  private:
   FML_DISALLOW_COPY_AND_ASSIGN(Surface);

shell/gpu/gpu_surface_gl.cc

@@ -9,6 +9,7 @@
 #include "flutter/fml/size.h"
 #include "flutter/fml/trace_event.h"
 #include "flutter/shell/common/persistent_cache.h"
+#include "flutter/shell/common/renderer_context_switch_manager.h"
 #include "third_party/skia/include/core/SkColorFilter.h"
 #include "third_party/skia/include/core/SkSurface.h"
 #include "third_party/skia/include/gpu/GrBackendSurface.h"
@@ -39,7 +40,10 @@ GPUSurfaceGL::GPUSurfaceGL(GPUSurfaceGLDelegate* delegate,
     : delegate_(delegate),
       render_to_surface_(render_to_surface),
       weak_factory_(this) {
-  if (!delegate_->GLContextMakeCurrent()) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = delegate_->GLContextMakeCurrent();
+
+  if (!context_switch->GetSwitchResult()) {
     FML_LOG(ERROR)
         << "Could not make the context current to setup the gr context.";
     return;
@@ -87,8 +91,6 @@ GPUSurfaceGL::GPUSurfaceGL(GPUSurfaceGLDelegate* delegate,
   }
   FML_LOG(INFO) << "Found " << caches.size() << " SkSL shaders; precompiled "
                 << compiled_count;
-
-  delegate_->GLContextClearCurrent();
 }
 
 GPUSurfaceGL::GPUSurfaceGL(sk_sp<GrContext> gr_context,
@@ -98,7 +100,9 @@ GPUSurfaceGL::GPUSurfaceGL(sk_sp<GrContext> gr_context,
       context_(gr_context),
       render_to_surface_(render_to_surface),
       weak_factory_(this) {
-  if (!delegate_->GLContextMakeCurrent()) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = delegate_->GLContextMakeCurrent();
+  if (!context_switch->GetSwitchResult()) {
     FML_LOG(ERROR)
         << "Could not make the context current to setup the gr context.";
     return;
@@ -114,8 +118,9 @@ GPUSurfaceGL::~GPUSurfaceGL() {
   if (!valid_) {
     return;
   }
-
-  if (!delegate_->GLContextMakeCurrent()) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = delegate_->GLContextMakeCurrent();
+  if (!context_switch->GetSwitchResult()) {
     FML_LOG(ERROR) << "Could not make the context current to destroy the "
                       "GrContext resources.";
     return;
@@ -126,8 +131,6 @@ GPUSurfaceGL::~GPUSurfaceGL() {
     context_->releaseResourcesAndAbandonContext();
   }
   context_ = nullptr;
-
-  delegate_->GLContextClearCurrent();
 }
 
 // |Surface|
@@ -253,7 +256,9 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGL::AcquireFrame(const SkISize& size) {
     return nullptr;
   }
 
-  if (!delegate_->GLContextMakeCurrent()) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = delegate_->GLContextMakeCurrent();
+  if (!context_switch->GetSwitchResult()) {
     FML_LOG(ERROR)
         << "Could not make the context current to acquire the frame.";
     return nullptr;
@@ -285,7 +290,9 @@ std::unique_ptr<SurfaceFrame> GPUSurfaceGL::AcquireFrame(const SkISize& size) {
         return weak ? weak->PresentSurface(canvas) : false;
       };
 
-  return std::make_unique<SurfaceFrame>(surface, submit_callback);
+  std::unique_ptr<SurfaceFrame> result =
+      std::make_unique<SurfaceFrame>(surface, submit_callback);
+  return result;
 }
 
 bool GPUSurfaceGL::PresentSurface(SkCanvas* canvas) {
@@ -293,6 +300,8 @@ bool GPUSurfaceGL::PresentSurface(SkCanvas* canvas) {
     return false;
   }
 
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+      context_switch = delegate_->GLContextMakeCurrent();
   if (offscreen_surface_ != nullptr) {
     TRACE_EVENT0("flutter", "CopyTextureOnscreen");
     SkPaint paint;
@@ -329,7 +338,6 @@ bool GPUSurfaceGL::PresentSurface(SkCanvas* canvas) {
 
     onscreen_surface_ = std::move(new_onscreen_surface);
   }
-
   return true;
 }
 
@@ -360,7 +368,8 @@ flutter::ExternalViewEmbedder* GPUSurfaceGL::GetExternalViewEmbedder() {
 }
 
 // |Surface|
-bool GPUSurfaceGL::MakeRenderContextCurrent() {
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+GPUSurfaceGL::MakeRenderContextCurrent() {
   return delegate_->GLContextMakeCurrent();
 }
 

shell/gpu/gpu_surface_gl.h

@@ -44,7 +44,8 @@ class GPUSurfaceGL : public Surface {
   flutter::ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
   // |Surface|
-  bool MakeRenderContextCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  MakeRenderContextCurrent() override;
 
  private:
   GPUSurfaceGLDelegate* delegate_;

shell/gpu/gpu_surface_gl_delegate.h

@@ -7,6 +7,7 @@
 
 #include "flutter/flow/embedded_views.h"
 #include "flutter/fml/macros.h"
+#include "flutter/shell/common/renderer_context_switch_manager.h"
 #include "flutter/shell/gpu/gpu_surface_delegate.h"
 #include "third_party/skia/include/core/SkMatrix.h"
 #include "third_party/skia/include/gpu/gl/GrGLInterface.h"
@@ -16,7 +17,8 @@ namespace flutter {
 class GPUSurfaceGLDelegate : public GPUSurfaceDelegate {
  public:
   // Called to make the main GL context current on the current thread.
-  virtual bool GLContextMakeCurrent() = 0;
+  virtual std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  GLContextMakeCurrent() = 0;
 
   // Called to clear the current GL context on the thread. This may be called on
   // either the GPU or IO threads.
@@ -59,6 +61,9 @@ class GPUSurfaceGLDelegate : public GPUSurfaceDelegate {
   // instrumentation to specific GL calls can specify custom GL functions
   // here.
   virtual GLProcResolver GetGLProcResolver() const;
+
+  virtual std::shared_ptr<RendererContextSwitchManager>
+  GetRendererContextSwitchManager() = 0;
 };
 
 }  // namespace flutter

shell/gpu/gpu_surface_metal.h

@@ -49,7 +49,8 @@ class GPUSurfaceMetal : public Surface {
   flutter::ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
   // |Surface|
-  bool MakeRenderContextCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> MakeRenderContextCurrent()
+      override;
 
   void ReleaseUnusedDrawableIfNecessary();
 

shell/gpu/gpu_surface_metal.mm

@@ -175,9 +175,10 @@ flutter::ExternalViewEmbedder* GPUSurfaceMetal::GetExternalViewEmbedder() {
 }
 
 // |Surface|
-bool GPUSurfaceMetal::MakeRenderContextCurrent() {
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+GPUSurfaceMetal::MakeRenderContextCurrent() {
   // This backend has no such concept.
-  return true;
+  return std::make_unique<RendererContextSwitchManager::RendererContextSwitchPureResult>(true);
 }
 
 void GPUSurfaceMetal::ReleaseUnusedDrawableIfNecessary() {

shell/platform/android/android_surface_gl.cc

@@ -104,9 +104,12 @@ bool AndroidSurfaceGL::SetNativeWindow(
   return true;
 }
 
-bool AndroidSurfaceGL::GLContextMakeCurrent() {
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+AndroidSurfaceGL::GLContextMakeCurrent() {
   FML_DCHECK(onscreen_context_ && onscreen_context_->IsValid());
-  return onscreen_context_->MakeCurrent();
+  return std::make_unique<
+      RendererContextSwitchManager::RendererContextSwitchPureResult>(
+      onscreen_context_->MakeCurrent());
 }
 
 bool AndroidSurfaceGL::GLContextClearCurrent() {
@@ -130,4 +133,10 @@ ExternalViewEmbedder* AndroidSurfaceGL::GetExternalViewEmbedder() {
   return nullptr;
 }
 
+// |GPUSurfaceGLDelegate|
+std::shared_ptr<RendererContextSwitchManager>
+AndroidSurfaceGL::GetRendererContextSwitchManager() {
+  return nullptr;
+}
+
 }  // namespace flutter

shell/platform/android/android_surface_gl.h

@@ -47,7 +47,8 @@ class AndroidSurfaceGL final : public GPUSurfaceGLDelegate,
   bool SetNativeWindow(fml::RefPtr<AndroidNativeWindow> window) override;
 
   // |GPUSurfaceGLDelegate|
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  GLContextMakeCurrent() override;
 
   // |GPUSurfaceGLDelegate|
   bool GLContextClearCurrent() override;
@@ -61,6 +62,10 @@ class AndroidSurfaceGL final : public GPUSurfaceGLDelegate,
   // |GPUSurfaceGLDelegate|
   ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
+  // |GPUSurfaceGLDelegate|
+  std::shared_ptr<RendererContextSwitchManager>
+  GetRendererContextSwitchManager() override;
+
  private:
   fml::RefPtr<AndroidContextGL> onscreen_context_;
   fml::RefPtr<AndroidContextGL> offscreen_context_;

shell/platform/darwin/ios/BUILD.gn

@@ -86,6 +86,8 @@ shared_library("create_flutter_framework_dylib") {
     "ios_external_texture_gl.mm",
     "ios_gl_context.h",
     "ios_gl_context.mm",
+    "ios_gl_context_switch_manager.h",
+    "ios_gl_context_switch_manager.mm",
     "ios_gl_render_target.h",
     "ios_gl_render_target.mm",
     "ios_surface.h",

shell/platform/darwin/ios/framework/Source/FlutterEngine.mm

@@ -553,6 +553,7 @@ NSString* const FlutterDefaultDartEntrypoint = nil;
 - (flutter::Rasterizer::Screenshot)takeScreenshot:(flutter::Rasterizer::ScreenshotType)type
                                   asBase64Encoded:(BOOL)base64Encode {
   FML_DCHECK(_shell) << "Cannot takeScreenshot without a shell";
+  NSLog(@"NSLog take screenshoit");
   return _shell->Screenshot(type, base64Encode);
 }
 

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews.mm

@@ -160,6 +160,11 @@ void FlutterPlatformViewsController::SetFrameSize(SkISize frame_size) {
   frame_size_ = frame_size;
 }
 
+void FlutterPlatformViewsController::SetRendererContextSwitchManager(
+    std::shared_ptr<IOSGLContextSwitchManager> gl_context_guard_manager) {
+  renderer_context_switch_manager_ = gl_context_guard_manager;
+}
+
 void FlutterPlatformViewsController::CancelFrame() {
   composition_order_.clear();
 }
@@ -368,7 +373,12 @@ bool FlutterPlatformViewsController::SubmitFrame(GrContext* gr_context,
 
   bool did_submit = true;
   for (int64_t view_id : composition_order_) {
-    EnsureOverlayInitialized(view_id, gl_context, gr_context);
+    if (renderer_context_switch_manager_ != nullptr) {
+      std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> contextSwitch =
+          renderer_context_switch_manager_->MakeCurrent();
+    }
+
+    EnsureOverlayInitialized(view_id, std::move(gl_context), gr_context);
     auto frame = overlays_[view_id]->surface->AcquireFrame(frame_size_);
     SkCanvas* canvas = frame->SkiaCanvas();
     canvas->drawPicture(picture_recorders_[view_id]->finishRecordingAsPicture());
@@ -455,6 +465,10 @@ void FlutterPlatformViewsController::EnsureOverlayInitialized(
     std::shared_ptr<IOSGLContext> gl_context,
     GrContext* gr_context) {
   FML_DCHECK(flutter_view_);
+  if (renderer_context_switch_manager_ != nullptr) {
+    std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> contextSwitch =
+        renderer_context_switch_manager_->MakeCurrent();
+  }
 
   auto overlay_it = overlays_.find(overlay_id);
 

shell/platform/darwin/ios/framework/Source/FlutterPlatformViews_Internal.h

@@ -11,6 +11,7 @@
 #include "flutter/shell/platform/darwin/common/framework/Headers/FlutterBinaryMessenger.h"
 #include "flutter/shell/platform/darwin/common/framework/Headers/FlutterChannels.h"
 #include "flutter/shell/platform/darwin/ios/framework/Headers/FlutterPlatformViews.h"
+#include "flutter/shell/platform/darwin/ios/ios_gl_context_switch_manager.h"
 
 // A UIView that is used as the parent for embedded UIViews.
 //
@@ -80,6 +81,9 @@ class FlutterPlatformViewsController {
 
   void SetFlutterViewController(UIViewController* flutter_view_controller);
 
+  void SetRendererContextSwitchManager(
+      std::shared_ptr<IOSGLContextSwitchManager> gl_context_guard_manager);
+
   void RegisterViewFactory(NSObject<FlutterPlatformViewFactory>* factory, NSString* factoryId);
 
   void SetFrameSize(SkISize frame_size);
@@ -204,6 +208,8 @@ class FlutterPlatformViewsController {
   void ApplyMutators(const MutatorsStack& mutators_stack, UIView* embedded_view);
   void CompositeWithParams(int view_id, const EmbeddedViewParams& params);
 
+  std::shared_ptr<IOSGLContextSwitchManager> renderer_context_switch_manager_;
+
   FML_DISALLOW_COPY_AND_ASSIGN(FlutterPlatformViewsController);
 };
 

shell/platform/darwin/ios/ios_gl_context.h

@@ -26,16 +26,25 @@ class IOSGLContext {
   std::unique_ptr<IOSGLRenderTarget> CreateRenderTarget(
       fml::scoped_nsobject<CAEAGLLayer> layer);
 
-  bool MakeCurrent();
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  MakeCurrent();
 
-  bool ResourceMakeCurrent();
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  ResourceMakeCurrent();
+
+  std::shared_ptr<IOSGLContextSwitchManager> GetIOSGLContextSwitchManager() {
+    return renderer_context_switch_manager_;
+  }
 
   sk_sp<SkColorSpace> ColorSpace() const { return color_space_; }
 
+  fml::scoped_nsobject<EAGLContext> GetContext() const {
+    return renderer_context_switch_manager_->GetContext();
+  }
+
  private:
-  fml::scoped_nsobject<EAGLContext> context_;
-  fml::scoped_nsobject<EAGLContext> resource_context_;
   sk_sp<SkColorSpace> color_space_;
+  std::shared_ptr<IOSGLContextSwitchManager> renderer_context_switch_manager_;
 
   FML_DISALLOW_COPY_AND_ASSIGN(IOSGLContext);
 };

shell/platform/darwin/ios/ios_gl_context.mm

@@ -13,15 +13,7 @@
 namespace flutter {
 
 IOSGLContext::IOSGLContext() {
-  resource_context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES3]);
-  if (resource_context_ != nullptr) {
-    context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES3
-                                         sharegroup:resource_context_.get().sharegroup]);
-  } else {
-    resource_context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2]);
-    context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2
-                                         sharegroup:resource_context_.get().sharegroup]);
-  }
+  renderer_context_switch_manager_ = std::make_shared<IOSGLContextSwitchManager>();
 
   // TODO:
   // iOS displays are more variable than just P3 or sRGB.  Reading the display
@@ -48,16 +40,16 @@ IOSGLContext::~IOSGLContext() = default;
 
 std::unique_ptr<IOSGLRenderTarget> IOSGLContext::CreateRenderTarget(
     fml::scoped_nsobject<CAEAGLLayer> layer) {
-  return std::make_unique<IOSGLRenderTarget>(std::move(layer), context_.get(),
-                                             resource_context_.get());
+  return std::make_unique<IOSGLRenderTarget>(std::move(layer), renderer_context_switch_manager_);
 }
 
-bool IOSGLContext::MakeCurrent() {
-  return [EAGLContext setCurrentContext:context_.get()];
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> IOSGLContext::MakeCurrent() {
+  return renderer_context_switch_manager_->MakeCurrent();
 }
 
-bool IOSGLContext::ResourceMakeCurrent() {
-  return [EAGLContext setCurrentContext:resource_context_.get()];
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSGLContext::ResourceMakeCurrent() {
+  return renderer_context_switch_manager_->ResourceMakeCurrent();
 }
 
 }  // namespace flutter

shell/platform/darwin/ios/ios_gl_context_switch_manager.h

@@ -0,0 +1,65 @@
+// 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_PLATFORM_DARWIN_IOS_IOS_GL_CONTEXT_SWITCH_MANAGER_H_
+#define FLUTTER_SHELL_PLATFORM_DARWIN_IOS_IOS_GL_CONTEXT_SWITCH_MANAGER_H_
+
+#define GLES_SILENCE_DEPRECATION
+
+#import <OpenGLES/EAGL.h>
+#include "flutter/fml/platform/darwin/scoped_nsobject.h"
+#include "flutter/shell/common/renderer_context_switch_manager.h"
+
+namespace flutter {
+
+//------------------------------------------------------------------------------
+/// The iOS implementation of `RendererContextSwitchManager`.
+///
+/// On `IOSGLContextSwitch`'s construction, it pushes the current EAGLContext to a stack and
+/// sets the flutter's gl context as current.
+/// On `IOSGLContextSwitch`'s desstruction, it pops a EAGLContext from the stack and set it to
+/// current.
+///
+class IOSGLContextSwitchManager final : public RendererContextSwitchManager {
+ public:
+  class IOSGLContextSwitch final : public RendererContextSwitch {
+   public:
+    IOSGLContextSwitch(IOSGLContextSwitchManager& manager,
+                       fml::scoped_nsobject<EAGLContext> context);
+
+    ~IOSGLContextSwitch();
+
+    bool GetSwitchResult() override;
+
+   private:
+    IOSGLContextSwitchManager& manager_;
+    bool switch_result_;
+    bool has_pushed_context_;
+
+    FML_DISALLOW_COPY_AND_ASSIGN(IOSGLContextSwitch);
+  };
+
+  IOSGLContextSwitchManager();
+
+  ~IOSGLContextSwitchManager();
+
+  std::unique_ptr<RendererContextSwitch> MakeCurrent() override;
+  std::unique_ptr<RendererContextSwitch> ResourceMakeCurrent() override;
+
+  fml::scoped_nsobject<EAGLContext> GetContext();
+
+ private:
+  fml::scoped_nsobject<EAGLContext> context_;
+  fml::scoped_nsobject<EAGLContext> resource_context_;
+  fml::scoped_nsobject<NSMutableArray> stored_;
+
+  bool PushContext(fml::scoped_nsobject<EAGLContext> context);
+  void PopContext();
+
+  FML_DISALLOW_COPY_AND_ASSIGN(IOSGLContextSwitchManager);
+};
+
+}
+
+#endif

shell/platform/darwin/ios/ios_gl_context_switch_manager.mm

@@ -0,0 +1,79 @@
+// 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 "ios_gl_context_switch_manager.h"
+
+namespace flutter {
+
+IOSGLContextSwitchManager::IOSGLContextSwitchManager() {
+  resource_context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES3]);
+  stored_ = fml::scoped_nsobject<NSMutableArray>([[NSMutableArray new] retain]);
+  resource_context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES3]);
+  if (resource_context_ != nullptr) {
+    context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES3
+                                         sharegroup:resource_context_.get().sharegroup]);
+  } else {
+    resource_context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2]);
+    context_.reset([[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES2
+                                         sharegroup:resource_context_.get().sharegroup]);
+  }
+};
+
+IOSGLContextSwitchManager::~IOSGLContextSwitchManager() = default;
+
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSGLContextSwitchManager::MakeCurrent() {
+  return std::make_unique<IOSGLContextSwitchManager::IOSGLContextSwitch>(*this, context_);
+}
+
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSGLContextSwitchManager::ResourceMakeCurrent() {
+  return std::make_unique<IOSGLContextSwitchManager::IOSGLContextSwitch>(*this, resource_context_);
+}
+
+fml::scoped_nsobject<EAGLContext> IOSGLContextSwitchManager::GetContext() {
+  return context_;
+}
+
+bool IOSGLContextSwitchManager::PushContext(fml::scoped_nsobject<EAGLContext> context) {
+  EAGLContext* current = [EAGLContext currentContext];
+  if (current == nil) {
+    [stored_.get() addObject:[NSNull null]];
+  } else {
+    [stored_.get() addObject:current];
+  }
+  bool result = [EAGLContext setCurrentContext:context.get()];
+  return result;
+}
+
+void IOSGLContextSwitchManager::PopContext() {
+  EAGLContext* last = [stored_.get() lastObject];
+  [stored_.get() removeLastObject];
+  if ([last isEqual:[NSNull null]]) {
+    [EAGLContext setCurrentContext:nil];
+    return;
+  }
+  [EAGLContext setCurrentContext:last];
+}
+
+IOSGLContextSwitchManager::IOSGLContextSwitch::IOSGLContextSwitch(
+    IOSGLContextSwitchManager& manager,
+    fml::scoped_nsobject<EAGLContext> context)
+    : manager_(manager) {
+  bool result = manager_.PushContext(context);
+  has_pushed_context_ = true;
+  switch_result_ = result;
+}
+
+IOSGLContextSwitchManager::IOSGLContextSwitch::~IOSGLContextSwitch() {
+  if (!has_pushed_context_) {
+    return;
+  }
+  manager_.PopContext();
+}
+
+bool IOSGLContextSwitchManager::IOSGLContextSwitch::GetSwitchResult() {
+  return switch_result_;
+}
+}

shell/platform/darwin/ios/ios_gl_render_target.h

@@ -13,14 +13,15 @@
 #include "flutter/fml/macros.h"
 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
 #include "flutter/shell/common/platform_view.h"
+#include "flutter/shell/platform/darwin/ios/ios_gl_context_switch_manager.h"
 
 namespace flutter {
 
 class IOSGLRenderTarget {
  public:
-  IOSGLRenderTarget(fml::scoped_nsobject<CAEAGLLayer> layer,
-                    EAGLContext* context,
-                    EAGLContext* resource_context);
+  IOSGLRenderTarget(
+      fml::scoped_nsobject<CAEAGLLayer> layer,
+      std::shared_ptr<IOSGLContextSwitchManager> gl_context_guard_manager);
 
   ~IOSGLRenderTarget();
 
@@ -32,16 +33,17 @@ class IOSGLRenderTarget {
 
   bool UpdateStorageSizeIfNecessary();
 
-  bool MakeCurrent();
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  MakeCurrent();
 
-  bool ResourceMakeCurrent();
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  ResourceMakeCurrent();
 
   sk_sp<SkColorSpace> ColorSpace() const { return color_space_; }
 
  private:
   fml::scoped_nsobject<CAEAGLLayer> layer_;
-  fml::scoped_nsobject<EAGLContext> context_;
-  fml::scoped_nsobject<EAGLContext> resource_context_;
+  std::shared_ptr<IOSGLContextSwitchManager> renderer_context_switch_manager_;
   GLuint framebuffer_;
   GLuint colorbuffer_;
   GLint storage_size_width_;

shell/platform/darwin/ios/ios_gl_render_target.mm

@@ -12,22 +12,20 @@
 
 namespace flutter {
 
-IOSGLRenderTarget::IOSGLRenderTarget(fml::scoped_nsobject<CAEAGLLayer> layer,
-                                     EAGLContext* context,
-                                     EAGLContext* resource_context)
+IOSGLRenderTarget::IOSGLRenderTarget(
+    fml::scoped_nsobject<CAEAGLLayer> layer,
+    std::shared_ptr<IOSGLContextSwitchManager> gl_context_guard_manager)
     : layer_(std::move(layer)),
-      context_([context retain]),
-      resource_context_([resource_context retain]),
+      renderer_context_switch_manager_(gl_context_guard_manager),
       framebuffer_(GL_NONE),
       colorbuffer_(GL_NONE),
       storage_size_width_(0),
       storage_size_height_(0),
       valid_(false) {
   FML_DCHECK(layer_ != nullptr);
-  FML_DCHECK(context_ != nullptr);
-  FML_DCHECK(resource_context_ != nullptr);
-
-  bool context_current = [EAGLContext setCurrentContext:context_];
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> context_switch =
+      renderer_context_switch_manager_->MakeCurrent();
+  bool context_current = context_switch->GetSwitchResult();
 
   FML_DCHECK(context_current);
   FML_DCHECK(glGetError() == GL_NO_ERROR);
@@ -62,8 +60,8 @@ IOSGLRenderTarget::IOSGLRenderTarget(fml::scoped_nsobject<CAEAGLLayer> layer,
 }
 
 IOSGLRenderTarget::~IOSGLRenderTarget() {
-  EAGLContext* context = EAGLContext.currentContext;
-  [EAGLContext setCurrentContext:context_];
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> context_switch =
+      renderer_context_switch_manager_->MakeCurrent();
   FML_DCHECK(glGetError() == GL_NO_ERROR);
 
   // Deletes on GL_NONEs are ignored
@@ -71,7 +69,6 @@ IOSGLRenderTarget::~IOSGLRenderTarget() {
   glDeleteRenderbuffers(1, &colorbuffer_);
 
   FML_DCHECK(glGetError() == GL_NO_ERROR);
-  [EAGLContext setCurrentContext:context];
 }
 
 bool IOSGLRenderTarget::IsValid() const {
@@ -104,8 +101,9 @@ bool IOSGLRenderTarget::UpdateStorageSizeIfNecessary() {
   FML_DLOG(INFO) << "Updating render buffer storage size.";
 
   FML_DCHECK(glGetError() == GL_NO_ERROR);
-
-  if (![EAGLContext setCurrentContext:context_]) {
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> context_switch =
+      renderer_context_switch_manager_->MakeCurrent();
+  if (!context_switch->GetSwitchResult()) {
     return false;
   }
 
@@ -116,7 +114,8 @@ bool IOSGLRenderTarget::UpdateStorageSizeIfNecessary() {
   glBindRenderbuffer(GL_RENDERBUFFER, colorbuffer_);
   FML_DCHECK(glGetError() == GL_NO_ERROR);
 
-  if (![context_.get() renderbufferStorage:GL_RENDERBUFFER fromDrawable:layer_.get()]) {
+  if (![renderer_context_switch_manager_->GetContext().get() renderbufferStorage:GL_RENDERBUFFER
+                                                                    fromDrawable:layer_.get()]) {
     return false;
   }
 
@@ -132,12 +131,18 @@ bool IOSGLRenderTarget::UpdateStorageSizeIfNecessary() {
   return true;
 }
 
-bool IOSGLRenderTarget::MakeCurrent() {
-  return UpdateStorageSizeIfNecessary() && [EAGLContext setCurrentContext:context_.get()];
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSGLRenderTarget::MakeCurrent() {
+  bool isUpdateSuccessful = UpdateStorageSizeIfNecessary();
+  if (!isUpdateSuccessful) {
+    return std::make_unique<RendererContextSwitchManager::RendererContextSwitchPureResult>(false);
+  }
+  return renderer_context_switch_manager_->MakeCurrent();
 }
 
-bool IOSGLRenderTarget::ResourceMakeCurrent() {
-  return [EAGLContext setCurrentContext:resource_context_.get()];
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSGLRenderTarget::ResourceMakeCurrent() {
+  return renderer_context_switch_manager_->ResourceMakeCurrent();
 }
 
 }  // namespace flutter

shell/platform/darwin/ios/ios_surface.h

@@ -12,6 +12,7 @@
 #include "flutter/fml/macros.h"
 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
 #include "flutter/shell/common/surface.h"
+#include "flutter/shell/platform/darwin/ios/ios_gl_context_switch_manager.h"
 
 namespace flutter {
 
@@ -27,7 +28,8 @@ class IOSSurface {
 
   virtual bool IsValid() const = 0;
 
-  virtual bool ResourceContextMakeCurrent() = 0;
+  virtual std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  ResourceContextMakeCurrent() = 0;
 
   virtual void UpdateStorageSizeIfNecessary() = 0;
 

shell/platform/darwin/ios/ios_surface_gl.h

@@ -9,6 +9,7 @@
 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
 #include "flutter/shell/gpu/gpu_surface_gl.h"
 #include "flutter/shell/platform/darwin/ios/ios_gl_context.h"
+#include "flutter/shell/platform/darwin/ios/ios_gl_context_switch_manager.h"
 #include "flutter/shell/platform/darwin/ios/ios_gl_render_target.h"
 #include "flutter/shell/platform/darwin/ios/ios_surface.h"
 
@@ -32,7 +33,8 @@ class IOSSurfaceGL final : public IOSSurface,
   bool IsValid() const override;
 
   // |IOSSurface|
-  bool ResourceContextMakeCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> ResourceContextMakeCurrent()
+      override;
 
   // |IOSSurface|
   void UpdateStorageSizeIfNecessary() override;
@@ -40,7 +42,8 @@ class IOSSurfaceGL final : public IOSSurface,
   // |IOSSurface|
   std::unique_ptr<Surface> CreateGPUSurface(GrContext* gr_context = nullptr) override;
 
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> GLContextMakeCurrent()
+      override;
 
   bool GLContextClearCurrent() override;
 
@@ -53,6 +56,9 @@ class IOSSurfaceGL final : public IOSSurface,
   // |GPUSurfaceGLDelegate|
   ExternalViewEmbedder* GetExternalViewEmbedder() override;
 
+  // |GPUSurfaceGLDelegate|
+  std::shared_ptr<RendererContextSwitchManager> GetRendererContextSwitchManager() override;
+
   // |ExternalViewEmbedder|
   SkCanvas* GetRootCanvas() override;
 

shell/platform/darwin/ios/ios_surface_gl.mm

@@ -28,7 +28,8 @@ bool IOSSurfaceGL::IsValid() const {
   return render_target_->IsValid();
 }
 
-bool IOSSurfaceGL::ResourceContextMakeCurrent() {
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSSurfaceGL::ResourceContextMakeCurrent() {
   return context_->ResourceMakeCurrent();
 }
 
@@ -56,11 +57,12 @@ bool IOSSurfaceGL::UseOffscreenSurface() const {
   return true;
 }
 
-bool IOSSurfaceGL::GLContextMakeCurrent() {
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSSurfaceGL::GLContextMakeCurrent() {
   if (!IsValid()) {
-    return false;
+    return std::make_unique<RendererContextSwitchManager::RendererContextSwitchPureResult>(false);
   }
-  return render_target_->UpdateStorageSizeIfNecessary() && context_->MakeCurrent();
+  return render_target_->MakeCurrent();
 }
 
 bool IOSSurfaceGL::GLContextClearCurrent() {
@@ -73,6 +75,11 @@ bool IOSSurfaceGL::GLContextPresent() {
   return IsValid() && render_target_->PresentRenderBuffer();
 }
 
+// |GPUSurfaceGLDelegate|
+std::shared_ptr<RendererContextSwitchManager> IOSSurfaceGL::GetRendererContextSwitchManager() {
+  return context_->GetIOSGLContextSwitchManager();
+}
+
 // |ExternalViewEmbedder|
 SkCanvas* IOSSurfaceGL::GetRootCanvas() {
   // On iOS, the root surface is created from the on-screen render target. Only the surfaces for the
@@ -144,7 +151,8 @@ bool IOSSurfaceGL::SubmitFrame(GrContext* context) {
   if (platform_views_controller == nullptr) {
     return true;
   }
-
+  platform_views_controller->SetRendererContextSwitchManager(
+      context_->GetIOSGLContextSwitchManager());
   bool submitted = platform_views_controller->SubmitFrame(std::move(context), context_);
   [CATransaction commit];
   return submitted;

shell/platform/darwin/ios/ios_surface_metal.h

@@ -30,7 +30,8 @@ class IOSSurfaceMetal final : public IOSSurface,
   bool IsValid() const override;
 
   // |IOSSurface|
-  bool ResourceContextMakeCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> ResourceContextMakeCurrent()
+      override;
 
   // |IOSSurface|
   void UpdateStorageSizeIfNecessary() override;

shell/platform/darwin/ios/ios_surface_metal.mm

@@ -22,8 +22,9 @@ bool IOSSurfaceMetal::IsValid() const {
 }
 
 // |IOSSurface|
-bool IOSSurfaceMetal::ResourceContextMakeCurrent() {
-  return false;
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSSurfaceMetal::ResourceContextMakeCurrent() {
+  return std::make_unique<RendererContextSwitchManager::RendererContextSwitchPureResult>(false);
 }
 
 // |IOSSurface|

shell/platform/darwin/ios/ios_surface_software.h

@@ -8,9 +8,9 @@
 #include "flutter/flow/embedded_views.h"
 #include "flutter/fml/macros.h"
 #include "flutter/fml/platform/darwin/scoped_nsobject.h"
+#include "flutter/shell/common/renderer_context_switch_manager.h"
 #include "flutter/shell/gpu/gpu_surface_software.h"
 #include "flutter/shell/platform/darwin/ios/ios_surface.h"
-
 @class CALayer;
 
 namespace flutter {
@@ -28,7 +28,8 @@ class IOSSurfaceSoftware final : public IOSSurface,
   bool IsValid() const override;
 
   // |IOSSurface|
-  bool ResourceContextMakeCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> ResourceContextMakeCurrent()
+      override;
 
   // |IOSSurface|
   void UpdateStorageSizeIfNecessary() override;

shell/platform/darwin/ios/ios_surface_software.mm

@@ -27,8 +27,9 @@ bool IOSSurfaceSoftware::IsValid() const {
   return layer_;
 }
 
-bool IOSSurfaceSoftware::ResourceContextMakeCurrent() {
-  return false;
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+IOSSurfaceSoftware::ResourceContextMakeCurrent() {
+  return std::make_unique<RendererContextSwitchManager::RendererContextSwitchPureResult>(false);
 }
 
 void IOSSurfaceSoftware::UpdateStorageSizeIfNecessary() {

shell/platform/darwin/ios/platform_view_ios.mm

@@ -107,15 +107,18 @@ std::unique_ptr<Surface> PlatformViewIOS::CreateRenderingSurface() {
 // |PlatformView|
 sk_sp<GrContext> PlatformViewIOS::CreateResourceContext() const {
   FML_DCHECK(task_runners_.GetIOTaskRunner()->RunsTasksOnCurrentThread());
-  if (!gl_context_ || !gl_context_->ResourceMakeCurrent()) {
-    FML_DLOG(INFO) << "Could not make resource context current on IO thread. "
-                      "Async texture uploads will be disabled. On Simulators, "
-                      "this is expected.";
-    return nullptr;
+  if (gl_context_ != nullptr) {
+    std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch> context_switch =
+        gl_context_->ResourceMakeCurrent();
+    if (context_switch->GetSwitchResult()) {
+      return ShellIOManager::CreateCompatibleResourceLoadingContext(
+          GrBackend::kOpenGL_GrBackend, GPUSurfaceGLDelegate::GetDefaultPlatformGLInterface());
+    }
   }
-
-  return ShellIOManager::CreateCompatibleResourceLoadingContext(
-      GrBackend::kOpenGL_GrBackend, GPUSurfaceGLDelegate::GetDefaultPlatformGLInterface());
+  FML_DLOG(INFO) << "Could not make resource context current on IO thread. "
+                    "Async texture uploads will be disabled. On Simulators, "
+                    "this is expected.";
+  return nullptr;
 }
 
 // |PlatformView|

shell/platform/embedder/embedder_surface_gl.cc

@@ -34,8 +34,11 @@ bool EmbedderSurfaceGL::IsValid() const {
 }
 
 // |GPUSurfaceGLDelegate|
-bool EmbedderSurfaceGL::GLContextMakeCurrent() {
-  return gl_dispatch_table_.gl_make_current_callback();
+std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+EmbedderSurfaceGL::GLContextMakeCurrent() {
+  return std::make_unique<
+      RendererContextSwitchManager::RendererContextSwitchPureResult>(
+      gl_dispatch_table_.gl_make_current_callback());
 }
 
 // |GPUSurfaceGLDelegate|
@@ -79,6 +82,12 @@ EmbedderSurfaceGL::GLProcResolver EmbedderSurfaceGL::GetGLProcResolver() const {
   return gl_dispatch_table_.gl_proc_resolver;
 }
 
+// |GPUSurfaceGLDelegate|
+std::shared_ptr<RendererContextSwitchManager>
+EmbedderSurfaceGL::GetRendererContextSwitchManager() {
+  return nullptr;
+}
+
 // |EmbedderSurface|
 std::unique_ptr<Surface> EmbedderSurfaceGL::CreateGPUSurface() {
   const bool render_to_surface = !external_view_embedder_;

shell/platform/embedder/embedder_surface_gl.h

@@ -50,7 +50,8 @@ class EmbedderSurfaceGL final : public EmbedderSurface,
   sk_sp<GrContext> CreateResourceContext() const override;
 
   // |GPUSurfaceGLDelegate|
-  bool GLContextMakeCurrent() override;
+  std::unique_ptr<RendererContextSwitchManager::RendererContextSwitch>
+  GLContextMakeCurrent() override;
 
   // |GPUSurfaceGLDelegate|
   bool GLContextClearCurrent() override;
@@ -73,6 +74,10 @@ class EmbedderSurfaceGL final : public EmbedderSurface,
   // |GPUSurfaceGLDelegate|
   GLProcResolver GetGLProcResolver() const override;
 
+  // |GPUSurfaceGLDelegate|
+  std::shared_ptr<RendererContextSwitchManager>
+  GetRendererContextSwitchManager() override;
+
   FML_DISALLOW_COPY_AND_ASSIGN(EmbedderSurfaceGL);
 };
 

testing/scenario_app/ios/Scenarios/Scenarios.xcodeproj/project.pbxproj

@@ -40,6 +40,8 @@
 		6816DBAC2318696600A51400 /* golden_platform_view_opacity_iPhone SE_simulator.png in Resources */ = {isa = PBXBuildFile; fileRef = 6816DBA72318696600A51400 /* golden_platform_view_opacity_iPhone SE_simulator.png */; };
 		6816DBAD2318696600A51400 /* golden_platform_view_cliprect_iPhone SE_simulator.png in Resources */ = {isa = PBXBuildFile; fileRef = 6816DBA82318696600A51400 /* golden_platform_view_cliprect_iPhone SE_simulator.png */; };
 		6816DBAE2318696600A51400 /* golden_platform_view_cliprrect_iPhone SE_simulator.png in Resources */ = {isa = PBXBuildFile; fileRef = 6816DBA92318696600A51400 /* golden_platform_view_cliprrect_iPhone SE_simulator.png */; };
+		68396B28235FA0D700D5E655 /* GLTestPlatformView.m in Sources */ = {isa = PBXBuildFile; fileRef = 68396B27235FA0D700D5E655 /* GLTestPlatformView.m */; };
+		68396B2A235FBEA600D5E655 /* PlatformViewGLTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 68396B29235FBEA600D5E655 /* PlatformViewGLTests.m */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXContainerItemProxy section */
@@ -136,6 +138,9 @@
 		6816DBA72318696600A51400 /* golden_platform_view_opacity_iPhone SE_simulator.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "golden_platform_view_opacity_iPhone SE_simulator.png"; sourceTree = "<group>"; };
 		6816DBA82318696600A51400 /* golden_platform_view_cliprect_iPhone SE_simulator.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "golden_platform_view_cliprect_iPhone SE_simulator.png"; sourceTree = "<group>"; };
 		6816DBA92318696600A51400 /* golden_platform_view_cliprrect_iPhone SE_simulator.png */ = {isa = PBXFileReference; lastKnownFileType = image.png; path = "golden_platform_view_cliprrect_iPhone SE_simulator.png"; sourceTree = "<group>"; };
+		68396B26235FA0D700D5E655 /* GLTestPlatformView.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GLTestPlatformView.h; sourceTree = "<group>"; };
+		68396B27235FA0D700D5E655 /* GLTestPlatformView.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = GLTestPlatformView.m; sourceTree = "<group>"; };
+		68396B29235FBEA600D5E655 /* PlatformViewGLTests.m */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.objc; path = PlatformViewGLTests.m; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -202,6 +207,8 @@
 				0A57B3BC2323C4BD00DD9521 /* ScreenBeforeFlutter.m */,
 				0A57B3BE2323C74200DD9521 /* FlutterEngine+ScenariosTest.m */,
 				0A57B3C02323C74D00DD9521 /* FlutterEngine+ScenariosTest.h */,
+				68396B26235FA0D700D5E655 /* GLTestPlatformView.h */,
+				68396B27235FA0D700D5E655 /* GLTestPlatformView.m */,
 			);
 			path = Scenarios;
 			sourceTree = "<group>";
@@ -239,6 +246,7 @@
 				6816DBA02317573300A51400 /* GoldenImage.m */,
 				6816DBA22318358200A51400 /* PlatformViewGoldenTestManager.h */,
 				6816DBA32318358200A51400 /* PlatformViewGoldenTestManager.m */,
+				68396B29235FBEA600D5E655 /* PlatformViewGLTests.m */,
 			);
 			path = ScenariosUITests;
 			sourceTree = "<group>";
@@ -398,6 +406,7 @@
 			files = (
 				248D76DA22E388380012F0C1 /* main.m in Sources */,
 				24F1FB89230B4579005ACE7C /* TextPlatformView.m in Sources */,
+				68396B28235FA0D700D5E655 /* GLTestPlatformView.m in Sources */,
 				248D76CC22E388370012F0C1 /* AppDelegate.m in Sources */,
 				0A57B3BF2323C74200DD9521 /* FlutterEngine+ScenariosTest.m in Sources */,
 				0A57B3BD2323C4BD00DD9521 /* ScreenBeforeFlutter.m in Sources */,
@@ -418,6 +427,7 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				68396B2A235FBEA600D5E655 /* PlatformViewGLTests.m in Sources */,
 				6816DBA12317573300A51400 /* GoldenImage.m in Sources */,
 				6816DB9E231750ED00A51400 /* GoldenPlatformViewTests.m in Sources */,
 				6816DBA42318358200A51400 /* PlatformViewGoldenTestManager.m in Sources */,
@@ -492,7 +502,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 12.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = INCLUDE_SOURCE;
 				MTL_FAST_MATH = YES;
 				ONLY_ACTIVE_ARCH = YES;
@@ -545,7 +555,7 @@
 				GCC_WARN_UNINITIALIZED_AUTOS = YES_AGGRESSIVE;
 				GCC_WARN_UNUSED_FUNCTION = YES;
 				GCC_WARN_UNUSED_VARIABLE = YES;
-				IPHONEOS_DEPLOYMENT_TARGET = 12.0;
+				IPHONEOS_DEPLOYMENT_TARGET = 9.0;
 				MTL_ENABLE_DEBUG_INFO = NO;
 				MTL_FAST_MATH = YES;
 				SDKROOT = iphoneos;
@@ -561,6 +571,7 @@
 				CODE_SIGN_IDENTITY = "iPhone Developer";
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = S8QB4VV633;
+				ENABLE_BITCODE = NO;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)",
@@ -584,6 +595,7 @@
 				CODE_SIGN_IDENTITY = "iPhone Developer";
 				CODE_SIGN_STYLE = Automatic;
 				DEVELOPMENT_TEAM = S8QB4VV633;
+				ENABLE_BITCODE = NO;
 				FRAMEWORK_SEARCH_PATHS = (
 					"$(inherited)",
 					"$(PROJECT_DIR)",

testing/scenario_app/ios/Scenarios/Scenarios.xcodeproj/xcshareddata/xcschemes/Scenarios.xcscheme

@@ -27,6 +27,15 @@
       selectedDebuggerIdentifier = "Xcode.DebuggerFoundation.Debugger.LLDB"
       selectedLauncherIdentifier = "Xcode.DebuggerFoundation.Launcher.LLDB"
       shouldUseLaunchSchemeArgsEnv = "YES">
+      <MacroExpansion>
+         <BuildableReference
+            BuildableIdentifier = "primary"
+            BlueprintIdentifier = "248D76C622E388370012F0C1"
+            BuildableName = "Scenarios.app"
+            BlueprintName = "Scenarios"
+            ReferencedContainer = "container:Scenarios.xcodeproj">
+         </BuildableReference>
+      </MacroExpansion>
       <Testables>
          <TestableReference
             skipped = "NO"
@@ -51,17 +60,6 @@
             </BuildableReference>
          </TestableReference>
       </Testables>
-      <MacroExpansion>
-         <BuildableReference
-            BuildableIdentifier = "primary"
-            BlueprintIdentifier = "248D76C622E388370012F0C1"
-            BuildableName = "Scenarios.app"
-            BlueprintName = "Scenarios"
-            ReferencedContainer = "container:Scenarios.xcodeproj">
-         </BuildableReference>
-      </MacroExpansion>
-      <AdditionalOptions>
-      </AdditionalOptions>
    </TestAction>
    <LaunchAction
       buildConfiguration = "Debug"
@@ -93,8 +91,6 @@
             isEnabled = "NO">
          </CommandLineArgument>
       </CommandLineArguments>
-      <AdditionalOptions>
-      </AdditionalOptions>
    </LaunchAction>
    <ProfileAction
       buildConfiguration = "Release"

testing/scenario_app/ios/Scenarios/Scenarios/AppDelegate.m

@@ -4,6 +4,7 @@
 
 #include "AppDelegate.h"
 #import "FlutterEngine+ScenariosTest.h"
+#import "GLTestPlatformView.h"
 #import "ScreenBeforeFlutter.h"
 #import "TextPlatformView.h"
 
@@ -50,6 +51,8 @@
     [self readyContextForPlatformViewTests:goldenTestName];
   } else if ([[[NSProcessInfo processInfo] arguments] containsObject:@"--screen-before-flutter"]) {
     self.window.rootViewController = [[ScreenBeforeFlutter alloc] initWithEngineRunCompletion:nil];
+  } else if ([[[NSProcessInfo processInfo] arguments] containsObject:@"--platform-view-gl"]) {
+    [self readyContextForGLPlatformViewTests:@"platform_view_eaglcontext"];
   } else {
     self.window.rootViewController = [[UIViewController alloc] init];
   }
@@ -79,4 +82,25 @@
   self.window.rootViewController = flutterViewController;
 }
 
+- (void)readyContextForGLPlatformViewTests:(NSString*)scenarioIdentifier {
+  FlutterEngine* engine = [[FlutterEngine alloc] initWithName:@"PlatformViewTest" project:nil];
+  [engine runWithEntrypoint:nil];
+
+  FlutterViewController* flutterViewController =
+      [[NoStatusBarFlutterViewController alloc] initWithEngine:engine nibName:nil bundle:nil];
+  [engine.binaryMessenger
+      setMessageHandlerOnChannel:@"scenario_status"
+            binaryMessageHandler:^(NSData* _Nullable message, FlutterBinaryReply _Nonnull reply) {
+              [engine.binaryMessenger
+                  sendOnChannel:@"set_scenario"
+                        message:[scenarioIdentifier dataUsingEncoding:NSUTF8StringEncoding]];
+            }];
+  GLTestPlatformViewFactory* platformViewFactory =
+      [[GLTestPlatformViewFactory alloc] initWithMessenger:flutterViewController.binaryMessenger];
+  NSObject<FlutterPluginRegistrar>* registrar =
+      [flutterViewController.engine registrarForPlugin:@"scenarios/glTestPlatformViewPlugin"];
+  [registrar registerViewFactory:platformViewFactory withId:@"scenarios/glTestPlatformView"];
+  self.window.rootViewController = flutterViewController;
+}
+
 @end

testing/scenario_app/ios/Scenarios/Scenarios/GLTestPlatformView.h

@@ -0,0 +1,30 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import <Flutter/Flutter.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface GLTestPlatformView : NSObject <FlutterPlatformView>
+
+- (instancetype)initWithFrame:(CGRect)frame
+               viewIdentifier:(int64_t)viewId
+                    arguments:(id _Nullable)args
+              binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger;
+
+- (UIView*)view;
+
+@end
+
+@interface GLTestPlatformViewFactory : NSObject <FlutterPlatformViewFactory>
+
+- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger>*)messenger;
+
+@end
+
+@interface GLTestView : UIView
+
+@end
+
+NS_ASSUME_NONNULL_END

testing/scenario_app/ios/Scenarios/Scenarios/GLTestPlatformView.m

@@ -0,0 +1,90 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#import "GLTestPlatformView.h"
+
+#define GLES_SILENCE_DEPRECATION
+
+@implementation GLTestPlatformView {
+  int64_t _viewId;
+  GLTestView* _view;
+}
+
+- (instancetype)initWithFrame:(CGRect)frame
+               viewIdentifier:(int64_t)viewId
+                    arguments:(id)args
+              binaryMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
+  if ([super init]) {
+    _viewId = viewId;
+    _view = [[GLTestView alloc] initWithFrame:CGRectMake(50.0, 50.0, 250.0, 100.0)];
+  }
+  return self;
+}
+
+- (UIView*)view {
+  return _view;
+}
+
+@end
+
+@implementation GLTestPlatformViewFactory {
+  NSObject<FlutterBinaryMessenger>* _messenger;
+}
+
+- (instancetype)initWithMessenger:(NSObject<FlutterBinaryMessenger>*)messenger {
+  self = [super init];
+  if (self) {
+    _messenger = messenger;
+  }
+  return self;
+}
+
+- (NSObject<FlutterPlatformView>*)createWithFrame:(CGRect)frame
+                                   viewIdentifier:(int64_t)viewId
+                                        arguments:(id _Nullable)args {
+  GLTestPlatformView* platformView = [[GLTestPlatformView alloc] initWithFrame:frame
+                                                                viewIdentifier:viewId
+                                                                     arguments:args
+                                                               binaryMessenger:_messenger];
+  return platformView;
+}
+
+- (NSObject<FlutterMessageCodec>*)createArgsCodec {
+  return [FlutterStringCodec sharedInstance];
+}
+
+@end
+
+@interface GLTestView ()
+
+@property(strong, nonatomic) EAGLContext* context;
+
+@end
+
+@implementation GLTestView
+
+- (instancetype)initWithFrame:(CGRect)frame {
+  self = [super initWithFrame:frame];
+  if (self) {
+    _context = [[EAGLContext alloc] initWithAPI:kEAGLRenderingAPIOpenGLES3];
+    _context.debugLabel = @"platform view context";
+    [EAGLContext setCurrentContext:_context];
+    self.backgroundColor = [UIColor redColor];
+    dispatch_after(dispatch_time(DISPATCH_TIME_NOW, (int64_t)(1 * NSEC_PER_SEC)),
+                   dispatch_get_main_queue(), ^{
+                     [self checkEAGLContext];
+                   });
+  }
+  return self;
+}
+
+- (void)checkEAGLContext {
+  if ([EAGLContext currentContext] != _context) {
+    self.accessibilityIdentifier = @"gl_platformview_wrong_context";
+  } else {
+    self.accessibilityIdentifier = @"gl_platformview_correct_context";
+  }
+}
+
+@end

testing/scenario_app/ios/Scenarios/ScenariosUITests/PlatformViewGLTests.m

@@ -0,0 +1,39 @@
+// 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.
+
+#import <XCTest/XCTest.h>
+
+@interface PlatformViewGLTests : XCTestCase
+
+@property(nonatomic, strong) XCUIApplication* application;
+
+@end
+
+@implementation PlatformViewGLTests
+
+- (void)setUp {
+  self.continueAfterFailure = NO;
+
+  self.application = [[XCUIApplication alloc] init];
+  self.application.launchArguments = @[ @"--platform-view-gl" ];
+  [self.application launch];
+}
+
+- (void)testExample {
+  NSPredicate* predicateToFindPlatformView =
+      [NSPredicate predicateWithBlock:^BOOL(id _Nullable evaluatedObject,
+                                            NSDictionary<NSString*, id>* _Nullable bindings) {
+        XCUIElement* element = evaluatedObject;
+        return [element.identifier isEqualToString:@"gl_platformview_wrong_context"] ||
+               [element.identifier isEqualToString:@"gl_platformview_correct_context"];
+      }];
+  XCUIElement* firstElement =
+      [self.application.otherElements elementMatchingPredicate:predicateToFindPlatformView];
+  if (![firstElement waitForExistenceWithTimeout:30]) {
+    XCTFail(@"Failed due to not able to find platform view with 30 seconds");
+  }
+  XCTAssertEqualObjects(firstElement.identifier, @"gl_platformview_correct_context");
+}
+
+@end

testing/scenario_app/lib/main.dart

@@ -25,6 +25,7 @@ Map<String, Scenario> _scenarios = <String, Scenario>{
   'platform_view_multiple': MultiPlatformViewScenario(window, firstId: 6, secondId: 7),
   'platform_view_multiple_background_foreground': MultiPlatformViewBackgroundForegroundScenario(window, firstId: 8, secondId: 9),
   'poppable_screen': PoppableScreenScenario(window),
+  'platform_view_eaglcontext': PlatformViewGLScenario(window, 'null', id:6),
 };
 
 Scenario _currentScenario = _scenarios['animated_color_square'];

testing/scenario_app/lib/src/platform_view.dart

@@ -34,7 +34,7 @@ class PlatformViewScenario extends Scenario with _BasePlatformViewScenarioMixin
   PlatformViewScenario(Window window, String text, {int id = 0})
       : assert(window != null),
         super(window) {
-    createPlatformView(window, text, id);
+    createPlatformView(window, text, id, 'scenarios/textPlatformView');
   }
 
   @override
@@ -55,8 +55,8 @@ class MultiPlatformViewScenario extends Scenario with _BasePlatformViewScenarioM
   MultiPlatformViewScenario(Window window, {this.firstId, this.secondId})
       : assert(window != null),
         super(window) {
-    createPlatformView(window, 'platform view 1', firstId);
-    createPlatformView(window, 'platform view 2', secondId);
+    createPlatformView(window, 'platform view 1', firstId, 'scenarios/textPlatformView');
+    createPlatformView(window, 'platform view 2', secondId, 'scenarios/textPlatformView');
   }
 
   /// The platform view identifier to use for the first platform view.
@@ -91,8 +91,8 @@ class MultiPlatformViewBackgroundForegroundScenario extends Scenario with _BaseP
   MultiPlatformViewBackgroundForegroundScenario(Window window, {this.firstId, this.secondId})
       : assert(window != null),
         super(window) {
-    createPlatformView(window, 'platform view 1', firstId);
-    createPlatformView(window, 'platform view 2', secondId);
+    createPlatformView(window, 'platform view 1', firstId, 'scenarios/textPlatformView');
+    createPlatformView(window, 'platform view 2', secondId, 'scenarios/textPlatformView');
     _nextFrame = _firstFrame;
   }
 
@@ -177,7 +177,7 @@ class PlatformViewClipRectScenario extends Scenario with _BasePlatformViewScenar
   PlatformViewClipRectScenario(Window window, String text, {int id = 0})
       : assert(window != null),
         super(window) {
-    createPlatformView(window, text, id);
+    createPlatformView(window, text, id, 'scenarios/textPlatformView');
   }
 
   @override
@@ -281,6 +281,24 @@ class PlatformViewOpacityScenario extends PlatformViewScenario {
   }
 }
 
+/// Platform view scenario for testing EAGLContext on iOS.
+class PlatformViewGLScenario extends Scenario with _BasePlatformViewScenarioMixin {
+  /// Constructs a platform view to test EAGLContext on iOS.
+  PlatformViewGLScenario(Window window, String text, {int id = 0})
+      : assert(window != null),
+        super(window) {
+            createPlatformView(window, text, id, 'scenarios/glTestPlatformView');
+      }
+
+  @override
+  void onBeginFrame(Duration duration) {
+    final SceneBuilder builder = SceneBuilder();
+
+    builder.pushOffset(0, 0);
+    finishBuilderByAddingPlatformViewAndPicture(builder, 6);
+  }
+}
+
 mixin _BasePlatformViewScenarioMixin on Scenario {
   int _textureId;
 
@@ -289,7 +307,7 @@ mixin _BasePlatformViewScenarioMixin on Scenario {
   /// It prepare a TextPlatformView so it can be added to the SceneBuilder in `onBeginFrame`.
   /// Call this method in the constructor of the platform view related scenarios
   /// to perform necessary set up.
-  void createPlatformView(Window window, String text, int id) {
+  void createPlatformView(Window window, String text, int id, String viewType) {
     const int _valueInt32 = 3;
     const int _valueFloat64 = 6;
     const int _valueString = 7;
@@ -313,8 +331,8 @@ mixin _BasePlatformViewScenarioMixin on Scenario {
       'viewType'.length,
       ...utf8.encode('viewType'),
       _valueString,
-      'scenarios/textPlatformView'.length,
-      ...utf8.encode('scenarios/textPlatformView'),
+      viewType.length,
+      ...utf8.encode(viewType),
       if (Platform.isAndroid) ...<int>[
         _valueString,
         'width'.length,