[MacOS] Add support for creating and presenting platform views.

ci/licenses_golden/licenses_flutter

@@ -1094,6 +1094,13 @@ FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterMouse
 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/FlutterOpenGLRendererTest.mm
+FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterPlatformViewController.h
+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/FlutterRenderer.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterResizableBackingStoreProvider.h
 FILE: ../../../flutter/shell/platform/darwin/macos/framework/Source/FlutterResizableBackingStoreProvider.mm

shell/platform/darwin/macos/BUILD.gn

@@ -77,6 +77,9 @@ source_set("flutter_framework_source") {
     "framework/Source/FlutterMouseCursorPlugin.mm",
     "framework/Source/FlutterOpenGLRenderer.h",
     "framework/Source/FlutterOpenGLRenderer.mm",
+    "framework/Source/FlutterPlatformViewController.mm",
+    "framework/Source/FlutterPlatformViewController_Internal.h",
+    "framework/Source/FlutterPlatformViews.h",
     "framework/Source/FlutterRenderer.h",
     "framework/Source/FlutterResizableBackingStoreProvider.h",
     "framework/Source/FlutterResizableBackingStoreProvider.mm",
@@ -147,6 +150,9 @@ 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/FlutterEngine.mm

@@ -14,6 +14,7 @@
 #import "flutter/shell/platform/darwin/macos/framework/Source/FlutterMetalRenderer.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/darwin/macos/framework/Source/FlutterPlatformViewController_Internal.h"
 #import "flutter/shell/platform/embedder/embedder.h"
 
 /**
@@ -57,6 +58,16 @@ - (void)postMainThreadTask:(FlutterTask)task targetTimeInNanoseconds:(uint64_t)t
  */
 - (void)loadAOTData:(NSString*)assetsDir;
 
+/**
+ * Creates and returns a FlutterCompositor* to be used by the embedder.
+ */
+- (FlutterCompositor*)createFlutterCompositor;
+
+/**
+ * Create a platform view channel and setup a method call handler.
+ */
+- (void)setupPlatformViewChannel;
+
 @end
 
 #pragma mark -
@@ -141,6 +152,13 @@ @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 {
@@ -248,6 +266,9 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
     flutterArguments.aot_data = _aotData;
   }
 
+  [self setupPlatformViewChannel];
+  _platformViewController = [[FlutterPlatformViewController alloc] init];
+
   flutterArguments.compositor = [self createFlutterCompositor];
 
   FlutterRendererConfig rendererConfig = [_renderer createRendererConfig];
@@ -428,6 +449,10 @@ - (void)sendPointerEvent:(const FlutterPointerEvent&)event {
   _embedderAPI.SendPointerEvent(_engine, &event, 1);
 }
 
+- (FlutterPlatformViewController*)platformViewController {
+  return _platformViewController;
+}
+
 #pragma mark - Private methods
 
 - (void)sendUserLocales {
@@ -504,6 +529,67 @@ - (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* weakSelf = self;
+  _macOSGLCompositor->SetPresentCallback(
+      [weakSelf]() { return [weakSelf engineCallbackOnPresent]; });
+
+  _compositor.avoid_backing_store_cache = true;
+
+  return &_compositor;
+}
+
+- (void)setupPlatformViewChannel {
+  _platformViewsChannel =
+      [FlutterMethodChannel methodChannelWithName:@"flutter/platform_views"
+                                  binaryMessenger:self.binaryMessenger
+                                            codec:[FlutterStandardMethodCodec sharedInstance]];
+
+  __weak FlutterEngine* weakSelf = self;
+  [_platformViewsChannel setMethodCallHandler:^(FlutterMethodCall* call, FlutterResult result) {
+    [[weakSelf platformViewController] handleMethodCall:call result:result];
+  }];
+}
+
 #pragma mark - FlutterBinaryMessenger
 
 - (void)sendOnChannel:(nonnull NSString*)channel message:(nullable NSData*)message {
@@ -610,11 +696,11 @@ - (BOOL)unregisterTextureWithID:(int64_t)textureID {
 - (void)postMainThreadTask:(FlutterTask)task targetTimeInNanoseconds:(uint64_t)targetTime {
   const auto engine_time = _embedderAPI.GetCurrentTime();
 
-  __weak FlutterEngine* weak_self = self;
+  __weak FlutterEngine* weakSelf = self;
   auto worker = ^{
-    FlutterEngine* strong_self = weak_self;
-    if (strong_self && strong_self->_engine) {
-      auto result = _embedderAPI.RunTask(strong_self->_engine, &task);
+    FlutterEngine* strongSelf = weakSelf;
+    if (strongSelf && strongSelf->_engine) {
+      auto result = _embedderAPI.RunTask(strongSelf->_engine, &task);
       if (result != kSuccess) {
         NSLog(@"Could not post a task to the Flutter engine.");
       }

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"
@@ -50,6 +52,7 @@ class FlutterGLCompositor {
 
  private:
   const FlutterViewController* view_controller_;
+  const FlutterPlatformViewController* platform_view_controller_;
   const NSOpenGLContext* open_gl_context_;
   PresentCallback present_callback_;
 
@@ -67,6 +70,15 @@ 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);
+
+  // Add the Platform View's content to the FlutterView at depth
+  // layer_position.
+  void PresentPlatformView(const FlutterLayer* layer, size_t layer_position);
+
   // Set frame_started_ to true and reset all layer state.
   void StartFrame();
 

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

@@ -23,7 +23,11 @@
                                          NSOpenGLContext* opengl_context)
     : open_gl_context_(opengl_context) {
   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,
@@ -75,35 +79,21 @@
 }
 
 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";
+        PresentPlatformView(layer, i);
         break;
     };
   }
@@ -113,6 +103,48 @@
   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::PresentPlatformView(const FlutterLayer* layer, size_t layer_position) {
+  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 = layer_position;
+  }
+}
+
 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, nullptr);
+      std::make_unique<FlutterGLCompositor>(mockViewController, platformViewController);
 
   bool flag = false;
   macos_compositor->SetPresentCallback([f = &flag]() {