Add an Info.plist flag to enable MacOS platform views preview support

ci/licenses_golden/licenses_flutter

@@ -1056,6 +1056,7 @@ FILE: ../../../flutter/shell/platform/darwin/macos/framework/Info.plist
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterAppDelegate.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterBackingStoreData.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterBackingStoreData.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterConstants.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterDartProject.mm
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterDartProject_Internal.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterEngine.mm
@@ -1072,6 +1073,12 @@ FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterIOSur
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterIOSurfaceHolder.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/FlutterPlatformViewController.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewControllerTest.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewController_Internal.h
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewMock.h
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewMock.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViews.h
 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/macos/BUILD.gn

@@ -62,6 +62,9 @@ source_set("flutter_framework_source") {
     "framework/Source/FlutterIOSurfaceHolder.mm",
     "framework/Source/FlutterMouseCursorPlugin.h",
     "framework/Source/FlutterMouseCursorPlugin.mm",
+    "framework/Source/FlutterPlatformViewController.mm",
+    "framework/Source/FlutterPlatformViewController_Internal.h",
+    "framework/Source/FlutterPlatformViews.h",
     "framework/Source/FlutterResizeSynchronizer.h",
     "framework/Source/FlutterResizeSynchronizer.mm",
     "framework/Source/FlutterSurfaceManager.h",
@@ -127,6 +130,9 @@ executable("flutter_desktop_darwin_unittests") {
   sources = [
     "framework/Source/FlutterEngineTest.mm",
     "framework/Source/FlutterGLCompositorUnittests.mm",
+    "framework/Source/FlutterPlatformViewControllerTest.mm",
+    "framework/Source/FlutterPlatformViewMock.h",
+    "framework/Source/FlutterPlatformViewMock.mm",
     "framework/Source/FlutterViewControllerTest.mm",
     "framework/Source/FlutterViewControllerTestUtils.h",
     "framework/Source/FlutterViewControllerTestUtils.mm",

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

@@ -0,0 +1,6 @@
+// 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.
+
+// The name of the Info.plist flag to enable the embedded MacOS views preview.
+const char* const kEmbeddedViewsPreview = "io.flutter_embedded_views_preview";

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

@@ -11,6 +11,7 @@
 #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/FlutterGLCompositor.h"
+#import "flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewController_Internal.h"
 #import "flutter/shell/platform/embedder/embedder.h"
 
 /**
@@ -204,6 +205,13 @@ @implementation FlutterEngine {
 
   // FlutterCompositor is copied and used in embedder.cc.
   FlutterCompositor _compositor;
+
+  // A method channel for platform view functionality.
+  FlutterMethodChannel* _platformViewsChannel;
+
+  // Used to support creation and deletion of platform views and
+  // registering platform view factories.
+  FlutterPlatformViewController* _platformViewController;
 }
 
 - (instancetype)initWithName:(NSString*)labelPrefix project:(FlutterDartProject*)project {
@@ -302,17 +310,27 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
       },
       .identifier = ++sTaskRunnerIdentifiers,
   };
+
+  bool embedded_views_preview_enabled = [FlutterPlatformViewController embeddedViewsEnabled];
+
   const FlutterCustomTaskRunners custom_task_runners = {
       .struct_size = sizeof(FlutterCustomTaskRunners),
       .platform_task_runner = &cocoa_task_runner_description,
-  };
+      // If platform views are enabled, set the render thread to the platform thread.
+      // Otherwise the render thread is created separately in embedder_thread_host.cc.
+      .render_task_runner =
+          embedded_views_preview_enabled ? &cocoa_task_runner_description : nullptr};
+
   flutterArguments.custom_task_runners = &custom_task_runners;
 
   [self loadAOTData:_project.assetsPath];
   if (_aotData) {
     flutterArguments.aot_data = _aotData;
   }
 
+  [self setupPlatformViewChannel];
+  [self createPlatformViewController];
+
   flutterArguments.compositor = [self createFlutterCompositor];
 
   FlutterEngineResult result = _embedderAPI.Initialize(
@@ -369,54 +387,6 @@ - (void)setViewController:(FlutterViewController*)controller {
   }
 }
 
-- (FlutterCompositor*)createFlutterCompositor {
-  // TODO(richardjcai): Add support for creating a FlutterGLCompositor
-  // with a nil _viewController for headless engines.
-  // https://github.com/flutter/flutter/issues/71606
-  if (_viewController == nullptr) {
-    return nullptr;
-  }
-
-  [_mainOpenGLContext makeCurrentContext];
-
-  _macOSGLCompositor = std::make_unique<flutter::FlutterGLCompositor>(_viewController);
-
-  _compositor = {};
-  _compositor.struct_size = sizeof(FlutterCompositor);
-  _compositor.user_data = _macOSGLCompositor.get();
-
-  _compositor.create_backing_store_callback = [](const FlutterBackingStoreConfig* config,  //
-                                                 FlutterBackingStore* backing_store_out,   //
-                                                 void* user_data                           //
-                                              ) {
-    return reinterpret_cast<flutter::FlutterGLCompositor*>(user_data)->CreateBackingStore(
-        config, backing_store_out);
-  };
-
-  _compositor.collect_backing_store_callback = [](const FlutterBackingStore* backing_store,  //
-                                                  void* user_data                            //
-                                               ) {
-    return reinterpret_cast<flutter::FlutterGLCompositor*>(user_data)->CollectBackingStore(
-        backing_store);
-  };
-
-  _compositor.present_layers_callback = [](const FlutterLayer** layers,  //
-                                           size_t layers_count,          //
-                                           void* user_data               //
-                                        ) {
-    return reinterpret_cast<flutter::FlutterGLCompositor*>(user_data)->Present(layers,
-                                                                               layers_count);
-  };
-
-  __weak FlutterEngine* weak_self = self;
-  _macOSGLCompositor->SetPresentCallback(
-      [weak_self]() { return [weak_self engineCallbackOnPresent]; });
-
-  _compositor.avoid_backing_store_cache = true;
-
-  return &_compositor;
-}
-
 - (id<FlutterBinaryMessenger>)binaryMessenger {
   // TODO(stuartmorgan): Switch to FlutterBinaryMessengerRelay to avoid plugins
   // keeping the engine alive.
@@ -493,6 +463,10 @@ - (void)sendPointerEvent:(const FlutterPointerEvent&)event {
   _embedderAPI.SendPointerEvent(_engine, &event, 1);
 }
 
+- (FlutterPlatformViewController*)platformViewController {
+  return _platformViewController;
+}
+
 #pragma mark - Private methods
 
 - (void)sendUserLocales {
@@ -600,6 +574,71 @@ - (void)shutDownEngine {
   _engine = nullptr;
 }
 
+- (FlutterCompositor*)createFlutterCompositor {
+  // TODO(richardjcai): Add support for creating a FlutterGLCompositor
+  // with a nil _viewController for headless engines.
+  // https://github.com/flutter/flutter/issues/71606
+  if (_viewController == nullptr) {
+    return nullptr;
+  }
+
+  [_mainOpenGLContext makeCurrentContext];
+
+  _macOSGLCompositor =
+      std::make_unique<flutter::FlutterGLCompositor>(_viewController, _platformViewController);
+
+  _compositor = {};
+  _compositor.struct_size = sizeof(FlutterCompositor);
+  _compositor.user_data = _macOSGLCompositor.get();
+
+  _compositor.create_backing_store_callback = [](const FlutterBackingStoreConfig* config,  //
+                                                 FlutterBackingStore* backing_store_out,   //
+                                                 void* user_data                           //
+                                              ) {
+    return reinterpret_cast<flutter::FlutterGLCompositor*>(user_data)->CreateBackingStore(
+        config, backing_store_out);
+  };
+
+  _compositor.collect_backing_store_callback = [](const FlutterBackingStore* backing_store,  //
+                                                  void* user_data                            //
+                                               ) {
+    return reinterpret_cast<flutter::FlutterGLCompositor*>(user_data)->CollectBackingStore(
+        backing_store);
+  };
+
+  _compositor.present_layers_callback = [](const FlutterLayer** layers,  //
+                                           size_t layers_count,          //
+                                           void* user_data               //
+                                        ) {
+    return reinterpret_cast<flutter::FlutterGLCompositor*>(user_data)->Present(layers,
+                                                                               layers_count);
+  };
+
+  __weak FlutterEngine* weak_self = self;
+  _macOSGLCompositor->SetPresentCallback(
+      [weak_self]() { return [weak_self engineCallbackOnPresent]; });
+
+  _compositor.avoid_backing_store_cache = true;
+
+  return &_compositor;
+}
+
+- (void)createPlatformViewController {
+  _platformViewController = [[FlutterPlatformViewController alloc] init];
+}
+
+- (void)setupPlatformViewChannel {
+  _platformViewsChannel =
+      [FlutterMethodChannel methodChannelWithName:@"flutter/platform_views"
+                                  binaryMessenger:self.binaryMessenger
+                                            codec:[FlutterStandardMethodCodec sharedInstance]];
+
+  __weak FlutterEngine* weak_self = self;
+  [_platformViewsChannel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
+    [[weak_self platformViewController] handleMethodCall:call result:result];
+  }];
+}
+
 #pragma mark - FlutterBinaryMessenger
 
 - (void)sendOnChannel:(nonnull NSString*)channel message:(nullable NSData*)message {

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

@@ -5,6 +5,8 @@
 #include <map>
 
 #include "flutter/fml/macros.h"
+#include "flutter/shell/platform/darwin/macos/framework/Source/FlutterBackingStoreData.h"
+#include "flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewController_Internal.h"
 #include "flutter/shell/platform/darwin/macos/framework/Source/FlutterSurfaceManager.h"
 #include "flutter/shell/platform/darwin/macos/framework/Source/FlutterViewController_Internal.h"
 #include "flutter/shell/platform/embedder/embedder.h"
@@ -18,7 +20,8 @@ namespace flutter {
 // FlutterGLCompositor is created and destroyed by FlutterEngine.
 class FlutterGLCompositor {
  public:
-  FlutterGLCompositor(FlutterViewController* view_controller);
+  FlutterGLCompositor(FlutterViewController* view_controller,
+                      FlutterPlatformViewController* platform_view_controller);
 
   // Creates a BackingStore and saves updates the backing_store_out
   // data with the new BackingStore data.
@@ -49,6 +52,7 @@ class FlutterGLCompositor {
 
  private:
   const FlutterViewController* view_controller_;
+  const FlutterPlatformViewController* platform_view_controller_;
   const NSOpenGLContext* open_gl_context_;
   PresentCallback present_callback_;
 
@@ -66,6 +70,11 @@ class FlutterGLCompositor {
   // created for the frame.
   bool frame_started_ = false;
 
+  // Update the backing CALayer using the backing store's specifications.
+  void PresentBackingStoreContent(
+      FlutterBackingStoreData* flutter_backing_store_data,
+      size_t layer_position);
+
   // Set frame_started_ to true and reset all layer state.
   void StartFrame();
 

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

@@ -18,10 +18,15 @@
 
 namespace flutter {
 
-FlutterGLCompositor::FlutterGLCompositor(FlutterViewController* view_controller)
+FlutterGLCompositor::FlutterGLCompositor(FlutterViewController* view_controller,
+                                         FlutterPlatformViewController* platform_view_controller)
     : open_gl_context_(view_controller.flutterView.openGLContext) {
   FML_CHECK(view_controller != nullptr) << "FlutterViewController* cannot be nullptr";
+  FML_CHECK(platform_view_controller != nullptr)
+      << "FlutterPlatformViewController* cannot be nullptr";
+
   view_controller_ = view_controller;
+  platform_view_controller_ = platform_view_controller;
 }
 
 bool FlutterGLCompositor::CreateBackingStore(const FlutterBackingStoreConfig* config,
@@ -71,35 +76,37 @@
 }
 
 bool FlutterGLCompositor::Present(const FlutterLayer** layers, size_t layers_count) {
+  [platform_view_controller_ disposePlatformViews];
   for (size_t i = 0; i < layers_count; ++i) {
     const auto* layer = layers[i];
     FlutterBackingStore* backing_store = const_cast<FlutterBackingStore*>(layer->backing_store);
     switch (layer->type) {
       case kFlutterLayerContentTypeBackingStore: {
         if (backing_store->open_gl.framebuffer.user_data) {
-          FlutterBackingStoreData* backing_store_data =
+          FlutterBackingStoreData* flutter_backing_store_data =
               (__bridge FlutterBackingStoreData*)backing_store->open_gl.framebuffer.user_data;
-
-          FlutterIOSurfaceHolder* io_surface_holder = [backing_store_data ioSurfaceHolder];
-          size_t layer_id = [backing_store_data layerId];
-
-          CALayer* content_layer = ca_layer_map_[layer_id];
-
-          FML_CHECK(content_layer) << "Unable to find a content layer with layer id " << layer_id;
-
-          content_layer.frame = content_layer.superlayer.bounds;
-
-          // The surface is an OpenGL texture, which means it has origin in bottom left corner
-          // and needs to be flipped vertically
-          content_layer.transform = CATransform3DMakeScale(1, -1, 1);
-          IOSurfaceRef io_surface_contents = [io_surface_holder ioSurface];
-          [content_layer setContents:(__bridge id)io_surface_contents];
+          PresentBackingStoreContent(flutter_backing_store_data, i);
         }
         break;
       }
       case kFlutterLayerContentTypePlatformView:
-        // Add functionality in follow up PR.
-        FML_LOG(WARNING) << "Presenting PlatformViews not yet supported";
+        FML_DCHECK([[NSThread currentThread] isMainThread])
+            << "Must be on the main thread to handle presenting platform views";
+
+        FML_DCHECK(platform_view_controller_.platformViews.count(layer->platform_view->identifier))
+            << "Platform view not found for id: " << layer->platform_view->identifier;
+
+        NSView* platform_view =
+            platform_view_controller_.platformViews[layer->platform_view->identifier];
+
+        CGFloat scale = [[NSScreen mainScreen] backingScaleFactor];
+        platform_view.frame = CGRectMake(layer->offset.x / scale, layer->offset.y / scale,
+                                         layer->size.width / scale, layer->size.height / scale);
+        if (platform_view.superview == nil) {
+          [view_controller_.flutterView addSubview:platform_view];
+        } else {
+          platform_view.layer.zPosition = i;
+        }
         break;
     };
   }
@@ -109,6 +116,29 @@
   return present_callback_();
 }
 
+void FlutterGLCompositor::PresentBackingStoreContent(
+    FlutterBackingStoreData* flutter_backing_store_data,
+    size_t layer_position) {
+  FML_DCHECK([[NSThread currentThread] isMainThread])
+      << "Must be on the main thread to update CALayer contents";
+
+  FlutterIOSurfaceHolder* io_surface_holder = [flutter_backing_store_data ioSurfaceHolder];
+  size_t layer_id = [flutter_backing_store_data layerId];
+
+  CALayer* content_layer = ca_layer_map_[layer_id];
+
+  FML_DCHECK(content_layer) << "Unable to find a content layer with layer id " << layer_id;
+
+  content_layer.frame = content_layer.superlayer.bounds;
+  content_layer.zPosition = layer_position;
+
+  // The surface is an OpenGL texture, which means it has origin in bottom left corner
+  // and needs to be flipped vertically
+  content_layer.transform = CATransform3DMakeScale(1, -1, 1);
+  IOSurfaceRef io_surface_contents = [io_surface_holder ioSurface];
+  [content_layer setContents:(__bridge id)io_surface_contents];
+}
+
 void FlutterGLCompositor::SetPresentCallback(
     const FlutterGLCompositor::PresentCallback& present_callback) {
   present_callback_ = present_callback;

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

@@ -5,16 +5,19 @@
 #import <Foundation/Foundation.h>
 
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterGLCompositor.h"
+#import "flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewController_Internal.h"
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterViewControllerTestUtils.h"
 #import "flutter/testing/testing.h"
 
 namespace flutter::testing {
 
 TEST(FlutterGLCompositorTest, TestPresent) {
   id mockViewController = CreateMockViewController(nil);
+  FlutterPlatformViewController* platformViewController =
+      [[FlutterPlatformViewController alloc] init];
 
   std::unique_ptr<flutter::FlutterGLCompositor> macos_compositor =
-      std::make_unique<FlutterGLCompositor>(mockViewController);
+      std::make_unique<FlutterGLCompositor>(mockViewController, platformViewController);
 
   bool flag = false;
   macos_compositor->SetPresentCallback([f = &flag]() {