Add texture support for macOS shell.

shell/platform/darwin/macos/BUILD.gn

@@ -16,6 +16,7 @@ _flutter_framework_dir = "$root_out_dir/$_flutter_framework_filename"
 # the Flutter engine source root.
 _flutter_framework_headers = [
   "framework/Headers/FlutterMacOS.h",
+  "framework/Headers/FLETexture.h",
   "framework/Headers/FLEOpenGLContextHandling.h",
   "framework/Headers/FLEPlugin.h",
   "framework/Headers/FLEPluginRegistrar.h",
@@ -33,6 +34,8 @@ shared_library("create_flutter_framework_dylib") {
   output_name = "$_flutter_framework_name"
 
   sources = [
+    "framework/Source/FLEExternalTextureGL.h",
+    "framework/Source/FLEExternalTextureGL.mm",
     "framework/Source/FLETextInputModel.h",
     "framework/Source/FLETextInputModel.mm",
     "framework/Source/FLETextInputPlugin.h",

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

@@ -31,6 +31,11 @@ FLUTTER_EXPORT
  */
 @property(nonnull, readonly) id<FlutterBinaryMessenger> messenger;
 
+/**
+ * Returns a `FLETextureRegistry` for registering textures provided by the plugin.
+ */
+@property(nonnull, readonly) id<FLETextureRegistrar> textures;
+
 /**
  * The view displaying Flutter content.
  *

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

@@ -7,6 +7,7 @@
 #import "FLEOpenGLContextHandling.h"
 #import "FLEPluginRegistrar.h"
 #import "FLEReshapeListener.h"
+#import "FLETexture.h"
 
 #if defined(FLUTTER_FRAMEWORK)
 #import "flutter/shell/platform/darwin/ios/framework/Headers/FlutterBinaryMessenger.h"
@@ -35,8 +36,10 @@ typedef NS_ENUM(NSInteger, FlutterMouseTrackingMode) {
  * Flutter engine in non-interactive mode, or with a drawable Flutter canvas.
  */
 FLUTTER_EXPORT
-@interface FLEViewController
-    : NSViewController <FlutterBinaryMessenger, FLEPluginRegistrar, FLEReshapeListener>
+@interface FLEViewController : NSViewController <FlutterBinaryMessenger,
+                                                 FLEPluginRegistrar,
+                                                 FLEReshapeListener,
+                                                 FLETextureRegistrar>
 
 /**
  * The view this controller manages when launched in interactive mode (headless set to false). Must

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

@@ -6,6 +6,7 @@
 #import "FLEPlugin.h"
 #import "FLEPluginRegistrar.h"
 #import "FLEReshapeListener.h"
+#import "FLETexture.h"
 #import "FLEView.h"
 #import "FLEViewController.h"
 #import "FlutterBinaryMessenger.h"

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

@@ -0,0 +1,34 @@
+// 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 <Foundation/Foundation.h>
+
+#import "flutter/shell/platform/darwin/macos/framework/Headers/FLETexture.h"
+#import "flutter/shell/platform/embedder/embedder.h"
+
+/**
+ * Used to bridge external FLETexture objects,
+ * so the implementer only needs to return the CVPixelBufferRef object,
+ * which will make the interface consistent with the FlutterTexture.
+ */
+@interface FLEExternalTextureGL : NSObject
+
+/**
+ * Initializes a texture adapter with |fleTexture|.
+ */
+- (nonnull instancetype)initWithFLETexture:(nonnull id<FLETexture>)fleTexture;
+
+/**
+ * Accept texture rendering notifications from the flutter engine.
+ */
+- (BOOL)populateTextureWidth:(size_t)width
+                      height:(size_t)height
+                     texture:(nonnull FlutterOpenGLTexture*)texture;
+
+/**
+ * The texture id.
+ */
+- (int64_t)textureId;
+
+@end

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

@@ -0,0 +1,86 @@
+// 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 "flutter/shell/platform/darwin/macos/framework/Source/FLEExternalTextureGL.h"
+
+#import <AppKit/NSOpenGL.h>
+#import <CoreVideo/CVOpenGLBuffer.h>
+#import <CoreVideo/CVOpenGLTextureCache.h>
+#import <OpenGL/gl.h>
+
+@implementation FLEExternalTextureGL {
+  CVOpenGLTextureCacheRef _textureCache;
+  CVPixelBufferRef _pixelBuffer;
+  id<FLETexture> _fleTexture;
+}
+
+- (instancetype)initWithFLETexture:(id<FLETexture>)fleTexture {
+  self = [super init];
+
+  if (self) {
+    _fleTexture = fleTexture;
+  }
+
+  return self;
+}
+
+static void OnGLTextureRelease(CVPixelBufferRef pixelBuffer) {
+  CVPixelBufferRelease(pixelBuffer);
+}
+
+- (int64_t)textureId {
+  return (NSInteger)(self);
+}
+
+- (BOOL)populateTextureWidth:(size_t)width
+                      height:(size_t)height
+                     texture:(FlutterOpenGLTexture*)texture {
+  if (_fleTexture == NULL) {
+    return NO;
+  }
+
+  // Copy image buffer from external texture.
+  _pixelBuffer = [_fleTexture copyPixelBuffer:width height:height];
+
+  if (_pixelBuffer == NULL) {
+    return NO;
+  }
+
+  // Create the texture cache if necessary.
+  if (_textureCache == NULL) {
+    CGLContextObj context = [NSOpenGLContext currentContext].CGLContextObj;
+    CGLPixelFormatObj format = CGLGetPixelFormat(context);
+    if (CVOpenGLTextureCacheCreate(kCFAllocatorDefault, NULL, context, format, NULL,
+                                   &_textureCache) != kCVReturnSuccess) {
+      NSLog(@"Could not create texture cache.");
+      CVPixelBufferRelease(_pixelBuffer);
+      return NO;
+    }
+  }
+
+  // Try to clear the cache of OpenGL textures to save memory.
+  CVOpenGLTextureCacheFlush(_textureCache, 0);
+
+  CVOpenGLTextureRef openGLTexture = NULL;
+  if (CVOpenGLTextureCacheCreateTextureFromImage(kCFAllocatorDefault, _textureCache, _pixelBuffer,
+                                                 NULL, &openGLTexture) != kCVReturnSuccess) {
+    CVPixelBufferRelease(_pixelBuffer);
+    return NO;
+  }
+
+  texture->target = CVOpenGLTextureGetTarget(openGLTexture);
+  texture->name = CVOpenGLTextureGetName(openGLTexture);
+  texture->format = GL_RGBA8;
+  texture->destruction_callback = (VoidCallback)&OnGLTextureRelease;
+  texture->user_data = openGLTexture;
+
+  CVPixelBufferRelease(_pixelBuffer);
+  return YES;
+}
+
+- (void)dealloc {
+  CVOpenGLTextureCacheRelease(_textureCache);
+}
+
+@end

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

@@ -3,13 +3,13 @@
 // found in the LICENSE file.
 
 #import "flutter/shell/platform/darwin/macos/framework/Headers/FLEViewController.h"
-#import "flutter/shell/platform/darwin/macos/framework/Source/FLEViewController_Internal.h"
-
 #import "flutter/shell/platform/darwin/ios/framework/Headers/FlutterChannels.h"
 #import "flutter/shell/platform/darwin/ios/framework/Headers/FlutterCodecs.h"
 #import "flutter/shell/platform/darwin/macos/framework/Headers/FLEReshapeListener.h"
 #import "flutter/shell/platform/darwin/macos/framework/Headers/FLEView.h"
+#import "flutter/shell/platform/darwin/macos/framework/Source/FLEExternalTextureGL.h"
 #import "flutter/shell/platform/darwin/macos/framework/Source/FLETextInputPlugin.h"
+#import "flutter/shell/platform/darwin/macos/framework/Source/FLEViewController_Internal.h"
 #import "flutter/shell/platform/embedder/embedder.h"
 
 static NSString* const kICUBundlePath = @"icudtl.dat";
@@ -91,6 +91,10 @@ - (void)dispatchMouseEvent:(nonnull NSEvent*)event phase:(FlutterPointerPhase)ph
  */
 - (void)dispatchKeyEvent:(NSEvent*)event ofType:(NSString*)type;
 
+- (BOOL)populateTextureWithIdentifier:(int64_t)textureId
+                                width:(size_t)width
+                               height:(size_t)height
+                              texture:(FlutterOpenGLTexture*)texture;
 @end
 
 #pragma mark - Static methods provided to engine configuration
@@ -142,6 +146,17 @@ static bool OnMakeResourceCurrent(FLEViewController* controller) {
   return true;
 }
 
+static bool OnAcquireExternalTexture(FLEViewController* controller,
+                                     int64_t texture_identifier,
+                                     size_t width,
+                                     size_t height,
+                                     FlutterOpenGLTexture* texture) {
+  return [controller populateTextureWithIdentifier:texture_identifier
+                                             width:width
+                                            height:height
+                                           texture:texture];
+}
+
 #pragma mark Static methods provided for headless engine configuration
 
 static bool HeadlessOnMakeCurrent(FLEViewController* controller) {
@@ -181,6 +196,9 @@ @implementation FLEViewController {
   // A message channel for passing key events to the Flutter engine. This should be replaced with
   // an embedding API; see Issue #47.
   FlutterBasicMessageChannel* _keyEventChannel;
+
+  // A mapping of external textures.
+  NSMutableDictionary<NSNumber*, FLEExternalTextureGL*>* _textures;
 }
 
 @dynamic view;
@@ -191,6 +209,7 @@ @implementation FLEViewController {
 static void CommonInit(FLEViewController* controller) {
   controller->_messageHandlers = [[NSMutableDictionary alloc] init];
   controller->_additionalKeyResponders = [[NSMutableOrderedSet alloc] init];
+  controller->_textures = [[NSMutableDictionary alloc] init];
 }
 
 - (instancetype)initWithCoder:(NSCoder*)coder {
@@ -374,7 +393,9 @@ + (FlutterRendererConfig)createRenderConfigHeadless:(BOOL)headless {
         .open_gl.clear_current = (BoolCallback)OnClearCurrent,
         .open_gl.present = (BoolCallback)OnPresent,
         .open_gl.fbo_callback = (UIntCallback)OnFBO,
-        .open_gl.make_resource_current = (BoolCallback)OnMakeResourceCurrent};
+        .open_gl.make_resource_current = (BoolCallback)OnMakeResourceCurrent,
+        .open_gl.gl_external_texture_frame_callback =
+            (TextureFrameCallback)OnAcquireExternalTexture};
     return config;
   }
 }
@@ -389,6 +410,30 @@ - (void)makeResourceContextCurrent {
   [_resourceContext makeCurrentContext];
 }
 
+- (BOOL)populateTextureWithIdentifier:(int64_t)textureId
+                                width:(size_t)width
+                               height:(size_t)height
+                              texture:(FlutterOpenGLTexture*)texture {
+  return [_textures[@(textureId)] populateTextureWidth:width height:height texture:texture];
+}
+
+- (int64_t)registerTexture:(id<FLETexture>)texture {
+  FLEExternalTextureGL* fleTexture = [[FLEExternalTextureGL alloc] initWithFLETexture:texture];
+  int64_t textureId = [fleTexture textureId];
+  FlutterEngineRegisterExternalTexture(_engine, textureId);
+  _textures[@(textureId)] = fleTexture;
+  return textureId;
+}
+
+- (void)textureFrameAvailable:(int64_t)textureId {
+  FlutterEngineMarkExternalTextureFrameAvailable(_engine, textureId);
+}
+
+- (void)unregisterTexture:(int64_t)textureId {
+  FlutterEngineUnregisterExternalTexture(_engine, textureId);
+  [_textures removeObjectForKey:@(textureId)];
+}
+
 - (void)handlePlatformMessage:(const FlutterPlatformMessage*)message {
   NSData* messageData = [NSData dataWithBytesNoCopy:(void*)message->message
                                              length:message->message_size
@@ -522,6 +567,10 @@ - (void)setMessageHandlerOnChannel:(nonnull NSString*)channel
   return self;
 }
 
+- (id<FLETextureRegistrar>)textures {
+  return self;
+}
+
 - (void)addMethodCallDelegate:(nonnull id<FLEPlugin>)delegate
                       channel:(nonnull FlutterMethodChannel*)channel {
   [channel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {