Rebase

Author: dkwingsmt

common/settings.h

@@ -224,6 +224,10 @@ struct Settings {
   // must be available to the application.
   bool enable_vulkan_validation = false;
 
+  // Enable the implicit view, so that the shell should create a view with
+  // kFlutterImplicitViewId without the platform calling FlutterEngineAddView.
+  bool enable_implicit_view = true;
+
   // Data set by platform-specific embedders for use in font initialization.
   uint32_t font_initialization_data = 0;
 

lib/ui/dart_ui.cc

@@ -96,7 +96,6 @@ typedef CanvasPath Path;
   V(IsolateNameServerNatives::RemovePortNameMapping, 1)               \
   V(NativeStringAttribute::initLocaleStringAttribute, 4)              \
   V(NativeStringAttribute::initSpellOutStringAttribute, 3)            \
-  V(PlatformConfigurationNativeApi::ImplicitViewEnabled, 0)           \
   V(PlatformConfigurationNativeApi::DefaultRouteName, 0)              \
   V(PlatformConfigurationNativeApi::ScheduleFrame, 0)                 \
   V(PlatformConfigurationNativeApi::Render, 1)                        \
@@ -381,6 +380,14 @@ void DartUI::InitForIsolate(const Settings& settings) {
       Dart_PropagateError(result);
     }
   }
+
+  if (settings.enable_implicit_view) {
+    result =
+        Dart_SetField(dart_ui, ToDart("_implicitViewEnabled"), Dart_True());
+    if (Dart_IsError(result)) {
+      Dart_PropagateError(result);
+    }
+  }
 }
 
 }  // namespace flutter

lib/ui/hooks.dart

@@ -4,6 +4,20 @@
 
 part of dart.ui;
 
+@pragma('vm:entry-point')
+void _addView(
+  int id,
+) {
+  PlatformDispatcher.instance._addView(id);
+}
+
+@pragma('vm:entry-point')
+void _removeView(
+  int id,
+) {
+  PlatformDispatcher.instance._removeView(id);
+}
+
 @pragma('vm:entry-point')
 void _updateDisplays(
   List<int> ids,

lib/ui/natives.dart

@@ -135,3 +135,7 @@ _ScheduleImmediateClosure _getScheduleMicrotaskClosure() => _scheduleMicrotask;
 // rendering.
 @pragma('vm:entry-point')
 bool _impellerEnabled = false;
+
+// Used internally to indicate whether the platform uses the implicit view.
+@pragma('vm:entry-point')
+bool _implicitViewEnabled = false;

lib/ui/platform_dispatcher.dart

@@ -66,6 +66,8 @@ typedef ErrorCallback = bool Function(Object exception, StackTrace stackTrace);
 // A gesture setting value that indicates it has not been set by the engine.
 const double _kUnsetGestureSetting = -1.0;
 
+const int _kImplicitViewId = 0;
+
 // A message channel to receive KeyData from the platform.
 //
 // See embedder.cc::kFlutterKeyDataChannel for more information.
@@ -116,6 +118,9 @@ class PlatformDispatcher {
   /// these. Use [instance] to access the singleton.
   PlatformDispatcher._() {
     _setNeedsReportTimings = _nativeSetNeedsReportTimings;
+    if (_implicitViewEnabled) {
+      _doAddView(_kImplicitViewId);
+    }
   }
 
   /// The [PlatformDispatcher] singleton.
@@ -213,10 +218,9 @@ class PlatformDispatcher {
   /// * [View.of], for accessing the current view.
   /// * [PlatformDispatcher.views] for a list of all [FlutterView]s provided
   ///   by the platform.
-  FlutterView? get implicitView => _implicitViewEnabled() ? _views[0] : null;
-
-  @Native<Handle Function()>(symbol: 'PlatformConfigurationNativeApi::ImplicitViewEnabled')
-  external static bool _implicitViewEnabled();
+  FlutterView? get implicitView {
+    return _views[_kImplicitViewId];
+  }
 
   /// A callback that is invoked whenever the [ViewConfiguration] of any of the
   /// [views] changes.
@@ -244,6 +248,28 @@ class PlatformDispatcher {
     _onMetricsChangedZone = Zone.current;
   }
 
+  FlutterView _createView(int id) {
+    return FlutterView._(id, this);
+  }
+
+  void _addView(int id) {
+    assert(id != _kImplicitViewId, 'The implicit view #$id can not be added.');
+    _doAddView(id);
+  }
+
+  void _doAddView(int id) {
+    assert(!_views.containsKey(id), 'View ID $id already exists.');
+    _views[id] = _createView(id);
+    _viewConfigurations[id] = const _ViewConfiguration();
+  }
+
+  void _removeView(int id) {
+    assert(id != _kImplicitViewId, 'The implicit view #$id can not be removed.');
+    assert(_views.containsKey(id), 'View ID $id does not exist.');
+    _views.remove(id);
+    _viewConfigurations.remove(id);
+  }
+
   // Called from the engine, via hooks.dart.
   //
   // Updates the available displays.
@@ -283,9 +309,7 @@ class PlatformDispatcher {
   ) {
     final _ViewConfiguration previousConfiguration =
         _viewConfigurations[id] ?? const _ViewConfiguration();
-    if (!_views.containsKey(id)) {
-      _views[id] = FlutterView._(id, this);
-    }
+    _views.putIfAbsent(id, () => _createView(id));
     _viewConfigurations[id] = previousConfiguration.copyWith(
       view: _views[id],
       devicePixelRatio: devicePixelRatio,

lib/ui/window/platform_configuration.cc

@@ -22,7 +22,7 @@
 namespace flutter {
 namespace {
 
-constexpr int kImplicitViewId = 0;
+static constexpr int64_t kFlutterImplicitViewId = 0ll;
 
 Dart_Handle ToByteData(const fml::Mapping& buffer) {
   return tonic::DartByteData::Create(buffer.GetMapping(), buffer.GetSize());
@@ -34,7 +34,11 @@ PlatformConfigurationClient::~PlatformConfigurationClient() {}
 
 PlatformConfiguration::PlatformConfiguration(
     PlatformConfigurationClient* client)
-    : client_(client) {}
+    : client_(client) {
+  if (client_->ImplicitViewEnabled()) {
+    DoAddView(kFlutterImplicitViewId);
+  }
+}
 
 PlatformConfiguration::~PlatformConfiguration() {}
 
@@ -43,6 +47,10 @@ void PlatformConfiguration::DidCreateIsolate() {
 
   on_error_.Set(tonic::DartState::Current(),
                 Dart_GetField(library, tonic::ToDart("_onError")));
+  add_view_.Set(tonic::DartState::Current(),
+                Dart_GetField(library, tonic::ToDart("_addView")));
+  remove_view_.Set(tonic::DartState::Current(),
+                   Dart_GetField(library, tonic::ToDart("_removeView")));
   update_displays_.Set(
       tonic::DartState::Current(),
       Dart_GetField(library, tonic::ToDart("_updateDisplays")));
@@ -76,12 +84,46 @@ void PlatformConfiguration::DidCreateIsolate() {
   report_timings_.Set(tonic::DartState::Current(),
                       Dart_GetField(library, tonic::ToDart("_reportTimings")));
 
-  // TODO(loicsharma): This should only be created if the embedder enables the
-  // implicit view.
-  // See: https://github.com/flutter/flutter/issues/120306
-  windows_.emplace(kImplicitViewId,
-                   std::make_unique<Window>(
-                       kImplicitViewId, ViewportMetrics{1.0, 0.0, 0.0, -1, 0}));
+  library_.Set(tonic::DartState::Current(),
+               Dart_LookupLibrary(tonic::ToDart("dart:ui")));
+}
+
+void PlatformConfiguration::AddView(int64_t view_id) {
+  FML_DCHECK(view_id != kFlutterImplicitViewId);
+  DoAddView(view_id);
+}
+
+void PlatformConfiguration::DoAddView(int64_t view_id) {
+  windows_.emplace(
+      view_id, std::make_unique<Window>(library_, view_id,
+                                        ViewportMetrics{1.0, 0.0, 0.0, -1, 0}));
+  if (view_id == kFlutterImplicitViewId) {
+    return;
+  }
+  std::shared_ptr<tonic::DartState> dart_state = add_view_.dart_state().lock();
+  if (!dart_state) {
+    return;
+  }
+  tonic::DartState::Scope scope(dart_state);
+  tonic::CheckAndHandleError(
+      tonic::DartInvoke(add_view_.Get(), {
+                                             tonic::ToDart(view_id),
+                                         }));
+}
+
+void PlatformConfiguration::RemoveView(int64_t view_id) {
+  FML_DCHECK(view_id != kFlutterImplicitViewId);
+  windows_.erase(view_id);
+  std::shared_ptr<tonic::DartState> dart_state =
+      remove_view_.dart_state().lock();
+  if (!dart_state) {
+    return;
+  }
+  tonic::DartState::Scope scope(dart_state);
+  tonic::CheckAndHandleError(
+      tonic::DartInvoke(remove_view_.Get(), {
+                                                tonic::ToDart(view_id),
+                                            }));
 }
 
 void PlatformConfiguration::UpdateDisplays(
@@ -492,16 +534,6 @@ Dart_Handle PlatformConfigurationNativeApi::ComputePlatformResolvedLocale(
   return tonic::DartConverter<std::vector<std::string>>::ToDart(results);
 }
 
-Dart_Handle PlatformConfigurationNativeApi::ImplicitViewEnabled() {
-  UIDartState::ThrowIfUIOperationsProhibited();
-  bool enabled = UIDartState::Current()
-                     ->platform_configuration()
-                     ->client()
-                     ->ImplicitViewEnabled();
-
-  return Dart_NewBoolean(enabled);
-}
-
 std::string PlatformConfigurationNativeApi::DefaultRouteName() {
   UIDartState::ThrowIfUIOperationsProhibited();
   return UIDartState::Current()

lib/ui/window/platform_configuration.h

@@ -268,6 +268,10 @@ class PlatformConfiguration final {
   ///
   void DidCreateIsolate();
 
+  void AddView(int64_t view_id);
+
+  void RemoveView(int64_t view_id);
+
   //----------------------------------------------------------------------------
   /// @brief      Update the specified display data in the framework.
   ///
@@ -415,7 +419,14 @@ class PlatformConfiguration final {
   ///
   /// @return     a pointer to the Window.
   ///
-  Window* get_window(int window_id) { return windows_[window_id].get(); }
+  Window* get_window(int window_id) {
+    auto found = windows_.find(window_id);
+    if (found != windows_.end()) {
+      return found->second.get();
+    } else {
+      return nullptr;
+    }
+  }
 
   //----------------------------------------------------------------------------
   /// @brief      Responds to a previous platform message to the engine from the
@@ -442,6 +453,8 @@ class PlatformConfiguration final {
  private:
   PlatformConfigurationClient* client_;
   tonic::DartPersistentValue on_error_;
+  tonic::DartPersistentValue add_view_;
+  tonic::DartPersistentValue remove_view_;
   tonic::DartPersistentValue update_displays_;
   tonic::DartPersistentValue update_locales_;
   tonic::DartPersistentValue update_user_settings_data_;
@@ -455,12 +468,20 @@ class PlatformConfiguration final {
   tonic::DartPersistentValue draw_frame_;
   tonic::DartPersistentValue report_timings_;
 
+  tonic::DartPersistentValue library_;
+
+  // All *actual* views that the app has.
+  //
+  // This means that, if implicit view is enabled but the implicit view is
+  // currently closed, `windows_` will not have an entry for ID 0.
   std::unordered_map<int64_t, std::unique_ptr<Window>> windows_;
 
   // ID starts at 1 because an ID of 0 indicates that no response is expected.
   int next_response_id_ = 1;
   std::unordered_map<int, fml::RefPtr<PlatformMessageResponse>>
       pending_responses_;
+
+  void DoAddView(int64_t view_id);
 };
 
 //----------------------------------------------------------------------------
@@ -489,8 +510,6 @@ class PlatformMessageHandlerStorage {
 //----------------------------------------------------------------------------
 class PlatformConfigurationNativeApi {
  public:
-  static Dart_Handle ImplicitViewEnabled();
-
   static std::string DefaultRouteName();
 
   static void ScheduleFrame();

lib/ui/window/window.cc

@@ -13,11 +13,12 @@
 
 namespace flutter {
 
-Window::Window(int64_t window_id, ViewportMetrics metrics)
-    : window_id_(window_id), viewport_metrics_(std::move(metrics)) {
-  library_.Set(tonic::DartState::Current(),
-               Dart_LookupLibrary(tonic::ToDart("dart:ui")));
-}
+Window::Window(tonic::DartPersistentValue& library,
+               int64_t window_id,
+               ViewportMetrics metrics)
+    : library_(library),
+      window_id_(window_id),
+      viewport_metrics_(std::move(metrics)) {}
 
 Window::~Window() {}
 

lib/ui/window/window.h

@@ -20,7 +20,9 @@
 namespace flutter {
 class Window final {
  public:
-  Window(int64_t window_id, ViewportMetrics metrics);
+  Window(tonic::DartPersistentValue& library,
+         int64_t window_id,
+         ViewportMetrics metrics);
 
   ~Window();
 
@@ -31,7 +33,7 @@ class Window final {
   void UpdateWindowMetrics(const ViewportMetrics& metrics);
 
  private:
-  tonic::DartPersistentValue library_;
+  tonic::DartPersistentValue& library_;
   int64_t window_id_;
   ViewportMetrics viewport_metrics_;
 };