Assign implicitViewEnabled from C++

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/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

@@ -118,6 +118,9 @@ class PlatformDispatcher {
   /// these. Use [instance] to access the singleton.
   PlatformDispatcher._() {
     _setNeedsReportTimings = _nativeSetNeedsReportTimings;
+    if (_implicitViewEnabled) {
+      _doAddView(_kImplicitViewId);
+    }
   }
 
   /// The [PlatformDispatcher] singleton.
@@ -225,18 +228,8 @@ class PlatformDispatcher {
   /// * [PlatformDispatcher.views] for a list of all [FlutterView]s provided
   ///   by the platform.
   FlutterView? get implicitView {
-    if (_implicitViewEnabled()) {
-      if (_implicitView == null) {
-        _addView(_kImplicitViewId);
-      }
-      return _implicitView!;
-    }
-    return null;
+    return _views[_kImplicitViewId];
   }
-  FlutterView? _implicitView;
-
-  @Native<Handle Function()>(symbol: 'PlatformConfigurationNativeApi::ImplicitViewEnabled')
-  external static bool _implicitViewEnabled();
 
   /// A callback that is invoked whenever the [ViewConfiguration] of any of the
   /// [views] changes.
@@ -265,22 +258,23 @@ class PlatformDispatcher {
   }
 
   FlutterView _createView(int id) {
-    if (id == _kImplicitViewId) {
-      assert(_implicitViewEnabled());
-      return _implicitView ??= FlutterView._(id, this);
-    }
     return FlutterView._(id, this);
   }
 
   void _addView(int id) {
-    assert(!_views.containsKey(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(!_views.containsKey(id));
-    // TODO(dkwingsmt): Reset _implicitView?
+    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);
   }

lib/ui/window/platform_configuration.cc

@@ -36,7 +36,7 @@ PlatformConfiguration::PlatformConfiguration(
     PlatformConfigurationClient* client)
     : client_(client) {
   if (client_->ImplicitViewEnabled()) {
-    AddView(kFlutterDefaultViewId);
+    DoAddView(kFlutterDefaultViewId);
   }
 }
 
@@ -89,11 +89,17 @@ void PlatformConfiguration::DidCreateIsolate() {
 }
 
 void PlatformConfiguration::AddView(int64_t view_id) {
-  // TODO(dkwingsmt): How do I access the current dart state after
-  // DidCreateIsolate?
+  FML_DCHECK(view_id != kFlutterDefaultViewId);
+  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 == kFlutterDefaultViewId) {
+    return;
+  }
   std::shared_ptr<tonic::DartState> dart_state = add_view_.dart_state().lock();
   if (!dart_state) {
     return;
@@ -106,6 +112,7 @@ void PlatformConfiguration::AddView(int64_t view_id) {
 }
 
 void PlatformConfiguration::RemoveView(int64_t view_id) {
+  FML_DCHECK(view_id != kFlutterDefaultViewId);
   windows_.erase(view_id);
   std::shared_ptr<tonic::DartState> dart_state =
       remove_view_.dart_state().lock();
@@ -527,16 +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

@@ -480,6 +480,8 @@ class PlatformConfiguration final {
   int next_response_id_ = 1;
   std::unordered_map<int, fml::RefPtr<PlatformMessageResponse>>
       pending_responses_;
+
+  void DoAddView(int64_t view_id);
 };
 
 //----------------------------------------------------------------------------
@@ -508,8 +510,6 @@ class PlatformMessageHandlerStorage {
 //----------------------------------------------------------------------------
 class PlatformConfigurationNativeApi {
  public:
-  static Dart_Handle ImplicitViewEnabled();
-
   static std::string DefaultRouteName();
 
   static void ScheduleFrame();

shell/platform/embedder/embedder.cc

@@ -1813,6 +1813,8 @@ FlutterEngineResult FlutterEngineInitialize(size_t version,
   settings.assets_path = args->assets_path;
   settings.leak_vm = !SAFE_ACCESS(args, shutdown_dart_vm_when_done, false);
   settings.old_gen_heap_size = SAFE_ACCESS(args, dart_old_gen_heap_size, -1);
+  settings.enable_implicit_view =
+      !SAFE_ACCESS(args, implicit_view_disabled, false);
 
   if (!flutter::DartVM::IsRunningPrecompiledCode()) {
     // Verify the assets path contains Dart 2 kernel assets.

shell/platform/embedder/embedder.h

@@ -2113,6 +2113,8 @@ typedef struct {
   /// and `update_semantics_callback2` may be provided; the others must be set
   /// to null.
   FlutterUpdateSemanticsCallback2 update_semantics_callback2;
+
+  bool implicit_view_disabled;
 } FlutterProjectArgs;
 
 #ifndef FLUTTER_ENGINE_NO_PROTOTYPES