WIP: Smooth window resizing on macOS

shell/platform/darwin/macos/BUILD.gn

@@ -67,6 +67,7 @@ source_set("flutter_framework_source") {
   sources += _flutter_framework_headers
 
   deps = [
+    "//flutter/fml:fml",
     "//flutter/shell/platform/darwin/common:framework_shared",
     "//flutter/shell/platform/embedder:embedder_as_internal_library",
   ]
@@ -80,6 +81,8 @@ source_set("flutter_framework_source") {
   libs = [
     "Cocoa.framework",
     "CoreVideo.framework",
+    "IOSurface.framework",
+    "QuartzCore.framework",
   ]
 }
 

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

@@ -138,9 +138,9 @@ static bool OnPresent(FlutterEngine* engine) {
   return [engine engineCallbackOnPresent];
 }
 
-static uint32_t OnFBO(FlutterEngine* engine) {
-  // There is currently no case where a different FBO is used, so no need to forward.
-  return 0;
+static uint32_t OnFBO(FlutterEngine* engine, const FlutterFrameInfo* info) {
+  return [engine.viewController.flutterView getFrameBufferIdForWidth:info->size.width
+                                                              height:info->size.height];
 }
 
 static bool OnMakeResourceCurrent(FlutterEngine* engine) {
@@ -229,7 +229,8 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
       .open_gl.make_current = (BoolCallback)OnMakeCurrent,
       .open_gl.clear_current = (BoolCallback)OnClearCurrent,
       .open_gl.present = (BoolCallback)OnPresent,
-      .open_gl.fbo_callback = (UIntCallback)OnFBO,
+      .open_gl.fbo_with_frame_info_callback = (UIntFrameInfoCallback)OnFBO,
+      .open_gl.fbo_reset_after_present = true,
       .open_gl.make_resource_current = (BoolCallback)OnMakeResourceCurrent,
       .open_gl.gl_external_texture_frame_callback = (TextureFrameCallback)OnAcquireExternalTexture,
   };
@@ -262,7 +263,6 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
   const FlutterCustomTaskRunners custom_task_runners = {
       .struct_size = sizeof(FlutterCustomTaskRunners),
       .platform_task_runner = &cocoa_task_runner_description,
-      .render_task_runner = &cocoa_task_runner_description,
   };
   flutterArguments.custom_task_runners = &custom_task_runners;
 
@@ -280,7 +280,8 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
   }
 
   [self sendUserLocales];
-  [self updateWindowMetrics];
+
+  [self.viewController.flutterView start];
   return YES;
 }
 
@@ -291,7 +292,9 @@ - (void)setViewController:(FlutterViewController*)controller {
     [self shutDownEngine];
     _resourceContext = nil;
   }
-  [self updateWindowMetrics];
+  if (_engine) {
+    [self.viewController.flutterView start];
+  }
 }
 
 - (id<FlutterBinaryMessenger>)binaryMessenger {
@@ -309,14 +312,15 @@ - (BOOL)running {
 - (NSOpenGLContext*)resourceContext {
   if (!_resourceContext) {
     NSOpenGLPixelFormatAttribute attributes[] = {
-        NSOpenGLPFAColorSize, 24, NSOpenGLPFAAlphaSize, 8, NSOpenGLPFADoubleBuffer, 0,
+        NSOpenGLPFAColorSize, 24, NSOpenGLPFAAlphaSize, 8, 0,
     };
     NSOpenGLPixelFormat* pixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:attributes];
     _resourceContext = [[NSOpenGLContext alloc] initWithFormat:pixelFormat shareContext:nil];
   }
   return _resourceContext;
 }
 
+// Must be driven by FlutterView (i.e. [FlutterView start])
 - (void)updateWindowMetrics {
   if (!_engine) {
     return;
@@ -334,6 +338,18 @@ - (void)updateWindowMetrics {
   FlutterEngineSendWindowMetricsEvent(_engine, &event);
 }
 
+- (void)scheduleOnRasterTread:(dispatch_block_t)block {
+  void* copy = Block_copy((__bridge void*)block);
+  FlutterEnginePostRenderThreadTask(
+      _engine,
+      [](void* callback) {
+        dispatch_block_t block = (__bridge dispatch_block_t)callback;
+        block();
+        Block_release(block);
+      },
+      copy);
+}
+
 - (void)sendPointerEvent:(const FlutterPointerEvent&)event {
   FlutterEngineSendPointerEvent(_engine, &event, 1);
 }
@@ -380,7 +396,7 @@ - (bool)engineCallbackOnPresent {
   if (!_mainOpenGLContext) {
     return false;
   }
-  [_mainOpenGLContext flushBuffer];
+  [self.viewController.flutterView present];
   return true;
 }
 

shell/platform/darwin/macos/framework/Source/FlutterEngine_Internal.h

@@ -26,6 +26,11 @@
  */
 - (void)updateWindowMetrics;
 
+/**
+ * Schedules the block on raster thread.
+ */
+- (void)scheduleOnRasterTread:(nonnull dispatch_block_t)block;
+
 /**
  * Dispatches the given pointer event data to engine.
  */

shell/platform/darwin/macos/framework/Source/FlutterView.h

@@ -4,35 +4,40 @@
 
 #import <Cocoa/Cocoa.h>
 
-/**
- * Listener for view resizing.
- */
-@protocol FlutterViewReshapeListener <NSObject>
+@protocol FlutterViewDelegate <NSObject>
 /**
  * Called when the view's backing store changes size.
  */
 - (void)viewDidReshape:(nonnull NSView*)view;
+
+- (void)scheduleOnRasterTread:(nonnull dispatch_block_t)block;
+
 @end
 
 /**
  * View capable of acting as a rendering target and input source for the Flutter
  * engine.
  */
-@interface FlutterView : NSOpenGLView
+@interface FlutterView : NSView
+
+@property(readwrite, nonatomic, nonnull) NSOpenGLContext* openGLContext;
 
 - (nullable instancetype)initWithFrame:(NSRect)frame
                           shareContext:(nonnull NSOpenGLContext*)shareContext
-                       reshapeListener:(nonnull id<FlutterViewReshapeListener>)reshapeListener
+                              delegate:(nonnull id<FlutterViewDelegate>)delegate
     NS_DESIGNATED_INITIALIZER;
 
 - (nullable instancetype)initWithShareContext:(nonnull NSOpenGLContext*)shareContext
-                              reshapeListener:
-                                  (nonnull id<FlutterViewReshapeListener>)reshapeListener;
+                                     delegate:(nonnull id<FlutterViewDelegate>)delegate;
 
 - (nullable instancetype)initWithFrame:(NSRect)frameRect
                            pixelFormat:(nullable NSOpenGLPixelFormat*)format NS_UNAVAILABLE;
 - (nonnull instancetype)initWithFrame:(NSRect)frameRect NS_UNAVAILABLE;
 - (nullable instancetype)initWithCoder:(nonnull NSCoder*)coder NS_UNAVAILABLE;
 - (nonnull instancetype)init NS_UNAVAILABLE;
 
+- (void)start;
+- (void)present;
+- (int)getFrameBufferIdForWidth:(int)width height:(int)height;
+
 @end