[macOS] Isolate openGL rendering to FlutterOpenGLRenderer

This is in preparation for having an equivalent FlutterMetalRenderer

Author: iskakaushik

ci/licenses_golden/licenses_flutter

@@ -1054,6 +1054,8 @@ FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterExter
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterExternalTextureGL.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterMouseCursorPlugin.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterMouseCursorPlugin.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterOpenGLRenderer.h
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterOpenGLRenderer.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterResizeSynchronizer.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterResizeSynchronizer.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterSurfaceManager.h

shell/platform/darwin/common/framework/Headers/FlutterTexture.h

@@ -39,7 +39,7 @@ FLUTTER_EXPORT
 /**
  * Registers a `FlutterTexture` for usage in Flutter and returns an id that can be used to reference
  * that texture when calling into Flutter with channels. Textures must be registered on the
- * platform thread.
+ * platform thread. On success returns the pointer to the registered texture, else returns 0.
  */
 - (int64_t)registerTexture:(NSObject<FlutterTexture>*)texture;
 /**

shell/platform/darwin/macos/BUILD.gn

@@ -54,6 +54,8 @@ source_set("flutter_framework_source") {
     "framework/Source/FlutterExternalTextureGL.mm",
     "framework/Source/FlutterMouseCursorPlugin.h",
     "framework/Source/FlutterMouseCursorPlugin.mm",
+    "framework/Source/FlutterOpenGLRenderer.h",
+    "framework/Source/FlutterOpenGLRenderer.mm",
     "framework/Source/FlutterResizeSynchronizer.h",
     "framework/Source/FlutterResizeSynchronizer.mm",
     "framework/Source/FlutterSurfaceManager.h",

shell/platform/darwin/macos/framework/Headers/FlutterEngine.h

@@ -21,7 +21,7 @@
  * Coordinates a single instance of execution of a Flutter engine.
  */
 FLUTTER_EXPORT
-@interface FlutterEngine : NSObject <FlutterTextureRegistry, FlutterPluginRegistry>
+@interface FlutterEngine : NSObject <FlutterPluginRegistry>
 
 /**
  * Initializes an engine with the given viewController.

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

@@ -10,6 +10,7 @@
 
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterDartProject_Internal.h"
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterExternalTextureGL.h"
+#import "flutter/shell/platform/darwin/macos/framework/Source/FlutterOpenGLRenderer.h"
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController_Internal.h"
 #import "flutter/shell/platform/embedder/embedder.h"
 
@@ -37,42 +38,11 @@ @interface FlutterEngine () <FlutterBinaryMessenger>
  */
 - (void)sendUserLocales;
 
-/**
- * Called by the engine to make the context the engine should draw into current.
- */
-- (bool)engineCallbackOnMakeCurrent;
-
-/**
- * Called by the engine to clear the context the engine should draw into.
- */
-- (bool)engineCallbackOnClearCurrent;
-
-/**
- * Called by the engine when the context's buffers should be swapped.
- */
-- (bool)engineCallbackOnPresent;
-
-/**
- * Called by the engine when framebuffer object ID is requested.
- */
-- (uint32_t)engineCallbackOnFBO:(const FlutterFrameInfo*)info;
-
-/**
- * Makes the resource context the current context.
- */
-- (bool)engineCallbackOnMakeResourceCurrent;
-
 /**
  * Handles a platform message from the engine.
  */
 - (void)engineCallbackOnPlatformMessage:(const FlutterPlatformMessage*)message;
 
-/**
- * Forwards texture copy request to the corresponding texture via |textureID|.
- */
-- (BOOL)populateTextureWithIdentifier:(int64_t)textureID
-                        openGLTexture:(FlutterOpenGLTexture*)openGLTexture;
-
 /**
  * Requests that the task be posted back the to the Flutter engine at the target time. The target
  * time is in the clock used by the Flutter engine.
@@ -119,7 +89,7 @@ - (instancetype)initWithPlugin:(NSString*)pluginKey flutterEngine:(FlutterEngine
 }
 
 - (id<FlutterTextureRegistry>)textures {
-  return _flutterEngine;
+  return _flutterEngine.openGLRenderer;
 }
 
 - (NSView*)view {
@@ -138,38 +108,10 @@ - (void)addMethodCallDelegate:(nonnull id<FlutterPlugin>)delegate
 // Callbacks provided to the engine. See the called methods for documentation.
 #pragma mark - Static methods provided to engine configuration
 
-static bool OnMakeCurrent(FlutterEngine* engine) {
-  return [engine engineCallbackOnMakeCurrent];
-}
-
-static bool OnClearCurrent(FlutterEngine* engine) {
-  return [engine engineCallbackOnClearCurrent];
-}
-
-static bool OnPresent(FlutterEngine* engine) {
-  return [engine engineCallbackOnPresent];
-}
-
-static uint32_t OnFBO(FlutterEngine* engine, const FlutterFrameInfo* info) {
-  return [engine engineCallbackOnFBO:info];
-}
-
-static bool OnMakeResourceCurrent(FlutterEngine* engine) {
-  return [engine engineCallbackOnMakeResourceCurrent];
-}
-
 static void OnPlatformMessage(const FlutterPlatformMessage* message, FlutterEngine* engine) {
   [engine engineCallbackOnPlatformMessage:message];
 }
 
-static bool OnAcquireExternalTexture(FlutterEngine* engine,
-                                     int64_t texture_identifier,
-                                     size_t width,
-                                     size_t height,
-                                     FlutterOpenGLTexture* open_gl_texture) {
-  return [engine populateTextureWithIdentifier:texture_identifier openGLTexture:open_gl_texture];
-}
-
 #pragma mark -
 
 @implementation FlutterEngine {
@@ -179,22 +121,12 @@ @implementation FlutterEngine {
   // The project being run by this engine.
   FlutterDartProject* _project;
 
-  // The context provided to the Flutter engine for resource loading.
-  NSOpenGLContext* _resourceContext;
-
-  // The context that is owned by the currently displayed FlutterView. This is stashed in the engine
-  // so that the view doesn't need to be accessed from a background thread.
-  NSOpenGLContext* _mainOpenGLContext;
-
   // A mapping of channel names to the registered handlers for those channels.
   NSMutableDictionary<NSString*, FlutterBinaryMessageHandler>* _messageHandlers;
 
   // Whether the engine can continue running after the view controller is removed.
   BOOL _allowHeadlessExecution;
 
-  // A mapping of textureID to internal FlutterExternalTextureGL adapter.
-  NSMutableDictionary<NSNumber*, FlutterExternalTextureGL*>* _textures;
-
   // Pointer to the Dart AOT snapshot and instruction data.
   _FlutterEngineAOTData* _aotData;
 }
@@ -211,10 +143,10 @@ - (instancetype)initWithName:(NSString*)labelPrefix
 
   _project = project ?: [[FlutterDartProject alloc] init];
   _messageHandlers = [[NSMutableDictionary alloc] init];
-  _textures = [[NSMutableDictionary alloc] init];
   _allowHeadlessExecution = allowHeadlessExecution;
   _embedderAPI.struct_size = sizeof(FlutterEngineProcTable);
   FlutterEngineGetProcAddresses(&_embedderAPI);
+  _openGLRenderer = [[FlutterOpenGLRenderer alloc] initWithFlutterEngine:_engine];
 
   NSNotificationCenter* notificationCenter = [NSNotificationCenter defaultCenter];
   [notificationCenter addObserver:self
@@ -242,17 +174,8 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
     return NO;
   }
 
-  const FlutterRendererConfig rendererConfig = {
-      .type = kOpenGL,
-      .open_gl.struct_size = sizeof(FlutterOpenGLRendererConfig),
-      .open_gl.make_current = (BoolCallback)OnMakeCurrent,
-      .open_gl.clear_current = (BoolCallback)OnClearCurrent,
-      .open_gl.present = (BoolCallback)OnPresent,
-      .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,
-  };
+  [_openGLRenderer attachToFlutterView:_viewController.flutterView];
+  const FlutterRendererConfig rendererConfig = [_openGLRenderer createRendererConfig];
 
   // TODO(stuartmorgan): Move internal channel registration from FlutterViewController to here.
 
@@ -351,15 +274,6 @@ - (void)loadAOTData:(NSString*)assetsDir {
   }
 }
 
-- (void)setViewController:(FlutterViewController*)controller {
-  _viewController = controller;
-  _mainOpenGLContext = controller.flutterView.openGLContext;
-  if (!controller && !_allowHeadlessExecution) {
-    [self shutDownEngine];
-    _resourceContext = nil;
-  }
-}
-
 - (id<FlutterBinaryMessenger>)binaryMessenger {
   // TODO(stuartmorgan): Switch to FlutterBinaryMessengerRelay to avoid plugins
   // keeping the engine alive.
@@ -372,17 +286,6 @@ - (BOOL)running {
   return _engine != nullptr;
 }
 
-- (NSOpenGLContext*)resourceContext {
-  if (!_resourceContext) {
-    NSOpenGLPixelFormatAttribute attributes[] = {
-        NSOpenGLPFAColorSize, 24, NSOpenGLPFAAlphaSize, 8, 0,
-    };
-    NSOpenGLPixelFormat* pixelFormat = [[NSOpenGLPixelFormat alloc] initWithAttributes:attributes];
-    _resourceContext = [[NSOpenGLContext alloc] initWithFormat:pixelFormat shareContext:nil];
-  }
-  return _resourceContext;
-}
-
 - (void)updateDisplayConfig {
   if (!_engine) {
     return;
@@ -461,37 +364,6 @@ - (void)sendUserLocales {
   _embedderAPI.UpdateLocales(_engine, flutterLocaleList.data(), flutterLocaleList.size());
 }
 
-- (bool)engineCallbackOnMakeCurrent {
-  if (!_mainOpenGLContext) {
-    return false;
-  }
-  [_mainOpenGLContext makeCurrentContext];
-  return true;
-}
-
-- (uint32_t)engineCallbackOnFBO:(const FlutterFrameInfo*)info {
-  CGSize size = CGSizeMake(info->size.width, info->size.height);
-  return [_viewController.flutterView frameBufferIDForSize:size];
-}
-
-- (bool)engineCallbackOnClearCurrent {
-  [NSOpenGLContext clearCurrentContext];
-  return true;
-}
-
-- (bool)engineCallbackOnPresent {
-  if (!_mainOpenGLContext) {
-    return false;
-  }
-  [self.viewController.flutterView present];
-  return true;
-}
-
-- (bool)engineCallbackOnMakeResourceCurrent {
-  [self.resourceContext makeCurrentContext];
-  return true;
-}
-
 - (void)engineCallbackOnPlatformMessage:(const FlutterPlatformMessage*)message {
   NSData* messageData = [NSData dataWithBytesNoCopy:(void*)message->message
                                              length:message->message_size
@@ -618,31 +490,6 @@ - (void)cleanupConnection:(FlutterBinaryMessengerConnection)connection {
   return [[FlutterEngineRegistrar alloc] initWithPlugin:pluginName flutterEngine:self];
 }
 
-#pragma mark - FlutterTextureRegistrar
-
-- (BOOL)populateTextureWithIdentifier:(int64_t)textureID
-                        openGLTexture:(FlutterOpenGLTexture*)openGLTexture {
-  return [_textures[@(textureID)] populateTexture:openGLTexture];
-}
-
-- (int64_t)registerTexture:(id<FlutterTexture>)texture {
-  FlutterExternalTextureGL* FlutterTexture =
-      [[FlutterExternalTextureGL alloc] initWithFlutterTexture:texture];
-  int64_t textureID = [FlutterTexture textureID];
-  _embedderAPI.RegisterExternalTexture(_engine, textureID);
-  _textures[@(textureID)] = FlutterTexture;
-  return textureID;
-}
-
-- (void)textureFrameAvailable:(int64_t)textureID {
-  _embedderAPI.MarkExternalTextureFrameAvailable(_engine, textureID);
-}
-
-- (void)unregisterTexture:(int64_t)textureID {
-  _embedderAPI.UnregisterExternalTexture(_engine, textureID);
-  [_textures removeObjectForKey:@(textureID)];
-}
-
 #pragma mark - Task runner integration
 
 - (void)postMainThreadTask:(FlutterTask)task targetTimeInNanoseconds:(uint64_t)targetTime {

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

@@ -6,6 +6,7 @@
 
 #import <Cocoa/Cocoa.h>
 
+#import "flutter/shell/platform/darwin/macos/framework/Source/FlutterOpenGLRenderer.h"
 #include "flutter/shell/platform/embedder/embedder.h"
 
 @interface FlutterEngine ()
@@ -16,10 +17,10 @@
 @property(nonatomic, readonly) BOOL running;
 
 /**
- * The resource context used by the engine for texture uploads. FlutterViews associated with this
- * engine should be created to share with this context.
+ * Provides the renderer config needed to initialize the engine and also handles external texture
+ * management.
  */
-@property(nonatomic, readonly, nullable) NSOpenGLContext* resourceContext;
+@property(nonatomic, readonly, nonnull) FlutterOpenGLRenderer* openGLRenderer;
 
 /**
  * Function pointers for interacting with the embedder.h API.

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

@@ -0,0 +1,80 @@
+// 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 <Cocoa/Cocoa.h>
+
+#import "flutter/shell/platform/darwin/macos/framework/Headers/FlutterEngine.h"
+#import "flutter/shell/platform/darwin/macos/framework/Source/FlutterView.h"
+#import "flutter/shell/platform/embedder/embedder.h"
+
+NS_ASSUME_NONNULL_BEGIN
+
+/**
+ * Provides the renderer config needed to initialize the embedder engine and also handles external
+ * texture management. This is initialized during FlutterEngine creation and then attached to the
+ * FlutterView once the FlutterViewController is initializer.
+ */
+@interface FlutterOpenGLRenderer : NSObject <FlutterTextureRegistry>
+
+/**
+ * The resource context used by the engine for texture uploads. FlutterViews associated with this
+ * engine should be created to share with this context.
+ */
+@property(nonatomic, readonly, nullable) NSOpenGLContext* resourceContext;
+
+/**
+ * Intializes the renderer with the given FlutterEngine.
+ */
+- (instancetype)initWithFlutterEngine:(FLUTTER_API_SYMBOL(FlutterEngine))engine;
+
+/**
+ * Attaches to the FlutterView and sets up the renderers main OpenGL context.
+ */
+- (void)attachToFlutterView:(FlutterView*)view;
+
+/**
+ * Called by the engine to make the context the engine should draw into current.
+ */
+- (bool)makeCurrent;
+
+/**
+ * Called by the engine to clear the context the engine should draw into.
+ */
+- (bool)clearCurrent;
+
+/**
+ * Called by the engine when the context's buffers should be swapped.
+ */
+- (bool)present;
+
+/**
+ * Called by the engine when framebuffer object ID is requested.
+ */
+- (uint32_t)getFBO:(const FlutterFrameInfo*)info;
+
+/**
+ * Makes the resource context the current context.
+ */
+- (bool)makeResourceCurrent;
+
+/**
+ * Called by the engine to unset the resource context.
+ */
+- (void)clearResourceContext;
+
+/**
+ * Populates the texture registry with the provided openGLTexture.
+ */
+- (BOOL)populateTextureWithIdentifier:(int64_t)textureID
+                        openGLTexture:(FlutterOpenGLTexture*)openGLTexture;
+
+/**
+ * Creates a FlutterRendererConfig that renders using OpenGL context(s) held
+ * by this class.
+ */
+- (FlutterRendererConfig)createRendererConfig;
+
+@end
+
+NS_ASSUME_NONNULL_END