Explicitly tell the platform view to update its backing store. (#3181)

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

@@ -14,11 +14,11 @@
 #include "flutter/shell/gpu/gpu_surface_gl.h"
 #include "flutter/shell/platform/darwin/common/platform_mac.h"
 #include "flutter/shell/platform/darwin/common/string_conversions.h"
-#include "flutter/shell/platform/darwin/ios/framework/Source/flutter_touch_mapper.h"
 #include "flutter/shell/platform/darwin/ios/framework/Source/FlutterDartProject_Internal.h"
 #include "flutter/shell/platform/darwin/ios/framework/Source/FlutterPlatformPlugin.h"
 #include "flutter/shell/platform/darwin/ios/framework/Source/FlutterTextInputDelegate.h"
 #include "flutter/shell/platform/darwin/ios/framework/Source/FlutterTextInputPlugin.h"
+#include "flutter/shell/platform/darwin/ios/framework/Source/flutter_touch_mapper.h"
 #include "flutter/shell/platform/darwin/ios/platform_view_ios.h"
 #include "lib/ftl/functional/make_copyable.h"
 #include "lib/ftl/time/time_delta.h"
@@ -330,10 +330,13 @@ static inline PointerChangeMapperPhase PointerChangePhaseFromUITouchPhase(
 
 - (void)updateViewportMetrics {
   blink::Threads::UI()->PostTask([
-    engine = _platformView->engine().GetWeakPtr(), metrics = _viewportMetrics
+    weak_platform_view = _platformView->GetWeakPtr(), metrics = _viewportMetrics
   ] {
-    if (engine.get())
-      engine->SetViewportMetrics(metrics);
+    if (!weak_platform_view) {
+      return;
+    }
+    weak_platform_view->UpdateSurfaceSize();
+    weak_platform_view->engine().SetViewportMetrics(metrics);
   });
 }
 

shell/platform/darwin/ios/platform_view_ios.h

@@ -38,6 +38,10 @@ class PlatformViewIOS : public PlatformView, public GPUSurfaceGLDelegate {
     return platform_message_router_;
   }
 
+  ftl::WeakPtr<PlatformViewIOS> GetWeakPtr();
+
+  void UpdateSurfaceSize();
+
   VsyncWaiter* GetVsyncWaiter() override;
 
   bool ResourceContextMakeCurrent() override;
@@ -64,6 +68,7 @@ class PlatformViewIOS : public PlatformView, public GPUSurfaceGLDelegate {
   sky::SkyEnginePtr engine_;
   PlatformMessageRouter platform_message_router_;
   std::unique_ptr<AccessibilityBridge> accessibility_bridge_;
+  ftl::WeakPtrFactory<PlatformViewIOS> weak_factory_;
 
   void SetupAndLoadFromSource(const std::string& main,
                               const std::string& packages,

shell/platform/darwin/ios/platform_view_ios.mm

@@ -3,16 +3,14 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/platform/darwin/ios/platform_view_ios.h"
-
 #import <OpenGLES/EAGL.h>
 #import <OpenGLES/ES2/gl.h>
 #import <OpenGLES/ES2/glext.h>
 #import <QuartzCore/CAEAGLLayer.h>
-
 #include <utility>
-
 #include "base/mac/scoped_nsautorelease_pool.h"
 #include "base/trace_event/trace_event.h"
+#include "flutter/common/threads.h"
 #include "flutter/shell/gpu/gpu_rasterizer.h"
 #include "flutter/shell/platform/darwin/ios/framework/Source/vsync_waiter_ios.h"
 #include "lib/ftl/synchronization/waitable_event.h"
@@ -170,32 +168,6 @@ class IOSGLContext {
 
   GLuint framebuffer() const { return framebuffer_; }
 
-  bool MakeCurrent() {
-    base::mac::ScopedNSAutoreleasePool pool;
-
-    return UpdateStorageSizeIfNecessary() &&
-           [EAGLContext setCurrentContext:context_.get()];
-  }
-
-  bool ResourceMakeCurrent() {
-    base::mac::ScopedNSAutoreleasePool pool;
-
-    return [EAGLContext setCurrentContext:resource_context_.get()];
-  }
-
- private:
-  base::scoped_nsobject<CAEAGLLayer> layer_;
-  base::scoped_nsobject<EAGLContext> context_;
-  base::scoped_nsobject<EAGLContext> resource_context_;
-
-  GLuint framebuffer_;
-  GLuint colorbuffer_;
-  GLuint depthbuffer_;
-  GLuint stencilbuffer_;
-  GLuint depth_stencil_packed_buffer_;
-
-  GLintSize storage_size_;
-
   bool UpdateStorageSizeIfNecessary() {
     GLintSize size([layer_.get() bounds].size);
 
@@ -270,12 +242,37 @@ class IOSGLContext {
     return true;
   }
 
+  bool MakeCurrent() {
+    base::mac::ScopedNSAutoreleasePool pool;
+
+    return UpdateStorageSizeIfNecessary() &&
+           [EAGLContext setCurrentContext:context_.get()];
+  }
+
+  bool ResourceMakeCurrent() {
+    base::mac::ScopedNSAutoreleasePool pool;
+
+    return [EAGLContext setCurrentContext:resource_context_.get()];
+  }
+
+ private:
+  base::scoped_nsobject<CAEAGLLayer> layer_;
+  base::scoped_nsobject<EAGLContext> context_;
+  base::scoped_nsobject<EAGLContext> resource_context_;
+  GLuint framebuffer_;
+  GLuint colorbuffer_;
+  GLuint depthbuffer_;
+  GLuint stencilbuffer_;
+  GLuint depth_stencil_packed_buffer_;
+  GLintSize storage_size_;
+
   FTL_DISALLOW_COPY_AND_ASSIGN(IOSGLContext);
 };
 
 PlatformViewIOS::PlatformViewIOS(CAEAGLLayer* layer)
     : PlatformView(std::make_unique<GPURasterizer>()),
-      context_(std::make_unique<IOSGLContext>(surface_config_, layer)) {
+      context_(std::make_unique<IOSGLContext>(surface_config_, layer)),
+      weak_factory_(this) {
   CreateEngine();
 
   NSArray* paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory,
@@ -313,6 +310,18 @@ void PlatformViewIOS::SetupAndLoadFromSource(
   engine_->RunFromFile(main, packages, assets_directory);
 }
 
+ftl::WeakPtr<PlatformViewIOS> PlatformViewIOS::GetWeakPtr() {
+  return weak_factory_.GetWeakPtr();
+}
+
+void PlatformViewIOS::UpdateSurfaceSize() {
+  blink::Threads::Gpu()->PostTask([self = GetWeakPtr()]() {
+    if (self && self->context_ != nullptr) {
+      self->context_->UpdateStorageSizeIfNecessary();
+    }
+  });
+}
+
 VsyncWaiter* PlatformViewIOS::GetVsyncWaiter() {
   if (!vsync_waiter_)
     vsync_waiter_ = std::make_unique<VsyncWaiterIOS>();