Rename default views to implicit views (flutter#43364)

This PR renames a number of internal variables from "default view ID" to
"implicit view ID", as we have pretty much settled on naming this
mechanism. Some docs are also fixed accordingly.

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- [ ] I added new tests to check the change I am making or feature I am
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Author: dkwingsmt

runtime/runtime_controller.cc

@@ -20,7 +20,7 @@
 
 namespace flutter {
 
-const uint64_t kFlutterDefaultViewId = 0llu;
+const uint64_t kFlutterImplicitViewId = 0llu;
 
 RuntimeController::RuntimeController(RuntimeDelegate& p_client,
                                      const TaskRunners& task_runners)
@@ -320,7 +320,7 @@ void RuntimeController::ScheduleFrame() {
 // |PlatformConfigurationClient|
 void RuntimeController::Render(Scene* scene) {
   // TODO(dkwingsmt): Currently only supports a single window.
-  int64_t view_id = kFlutterDefaultViewId;
+  int64_t view_id = kFlutterImplicitViewId;
   auto window =
       UIDartState::Current()->platform_configuration()->get_window(view_id);
   if (window == nullptr) {

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

@@ -36,11 +36,13 @@ FLUTTER_DARWIN_EXPORT
 @property(nonnull, readonly) id<FlutterTextureRegistry> textures;
 
 /**
- * The default view displaying Flutter content.
+ * The view displaying Flutter content.
  *
- * This method may return |nil|, for instance in a headless environment.
+ * This property is provided for backwards compatibility for apps
+ * that assume a single view. This will eventually be replaced by
+ * a multi-view API variant.
  *
- * The default view is a special view operated by single-view APIs.
+ * This method may return |nil|, for instance in a headless environment.
  */
 @property(nullable, readonly) NSView* view;
 

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

@@ -22,7 +22,7 @@
   // TODO(dkwingsmt): This class only supports single-view for now. As more
   // classes are gradually converted to multi-view, it should get the view ID
   // from somewhere.
-  FlutterView* view = [view_provider_ viewForId:kFlutterDefaultViewId];
+  FlutterView* view = [view_provider_ viewForId:kFlutterImplicitViewId];
   if (!view) {
     return false;
   }

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

@@ -12,27 +12,27 @@
 #import "flutter/testing/testing.h"
 
 @interface FlutterViewMockProvider : NSObject <FlutterViewProvider> {
-  FlutterView* _defaultView;
+  FlutterView* _implicitView;
 }
 /**
- * Create a FlutterViewMockProvider with the provided view as the default view.
+ * Create a FlutterViewMockProvider with the provided view as the implicit view.
  */
-- (nonnull instancetype)initWithDefaultView:(nonnull FlutterView*)view;
+- (nonnull instancetype)initWithImplicitView:(nonnull FlutterView*)view;
 @end
 
 @implementation FlutterViewMockProvider
 
-- (nonnull instancetype)initWithDefaultView:(nonnull FlutterView*)view {
+- (nonnull instancetype)initWithImplicitView:(nonnull FlutterView*)view {
   self = [super init];
   if (self != nil) {
-    _defaultView = view;
+    _implicitView = view;
   }
   return self;
 }
 
 - (nullable FlutterView*)viewForId:(FlutterViewId)viewId {
-  if (viewId == kFlutterDefaultViewId) {
-    return _defaultView;
+  if (viewId == kFlutterImplicitViewId) {
+    return _implicitView;
   }
   return nil;
 }
@@ -81,7 +81,7 @@ - (nullable FlutterView*)viewForId:(FlutterViewId)viewId {
 
   OCMStub([surfaceMock asFlutterMetalTexture]).andReturn(texture);
 
-  return [[FlutterViewMockProvider alloc] initWithDefaultView:viewMock];
+  return [[FlutterViewMockProvider alloc] initWithImplicitView:viewMock];
 }
 }  // namespace
 
@@ -131,7 +131,7 @@ - (nullable FlutterView*)viewForId:(FlutterViewId)viewId {
   }};
   const FlutterLayer* layers_ptr = layers;
 
-  macos_compositor->Present(kFlutterDefaultViewId, &layers_ptr, 1);
+  macos_compositor->Present(kFlutterImplicitViewId, &layers_ptr, 1);
 
   ASSERT_EQ(presentedSurfaces.count, 1ul);
 }

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

@@ -95,7 +95,7 @@ - (nullable FlutterViewController*)viewControllerForId:(FlutterViewId)viewId;
  * An internal method that adds the view controller with the given ID.
  *
  * This method assigns the controller with the ID, puts the controller into the
- * map, and does assertions related to the default view ID.
+ * map, and does assertions related to the implicit view ID.
  */
 - (void)registerViewController:(FlutterViewController*)controller forId:(FlutterViewId)viewId;
 
@@ -296,7 +296,7 @@ - (instancetype)initWithPlugin:(NSString*)pluginKey flutterEngine:(FlutterEngine
 }
 
 - (NSView*)view {
-  return [self viewForId:kFlutterDefaultViewId];
+  return [self viewForId:kFlutterImplicitViewId];
 }
 
 - (NSView*)viewForId:(FlutterViewId)viewId {
@@ -422,9 +422,9 @@ - (instancetype)initWithName:(NSString*)labelPrefix
   [_isResponseValid addObject:@YES];
   _terminationHandler = [[FlutterEngineTerminationHandler alloc] initWithEngine:self
                                                                      terminator:nil];
-  // kFlutterDefaultViewId is reserved for the default view.
+  // kFlutterImplicitViewId is reserved for the implicit view.
   // All IDs above it are for regular views.
-  _nextViewId = kFlutterDefaultViewId + 1;
+  _nextViewId = kFlutterImplicitViewId + 1;
 
   _embedderAPI.struct_size = sizeof(FlutterEngineProcTable);
   FlutterEngineGetProcAddresses(&_embedderAPI);
@@ -506,10 +506,10 @@ - (BOOL)runWithEntrypoint:(NSString*)entrypoint {
   flutterArguments.update_semantics_callback2 = [](const FlutterSemanticsUpdate2* update,
                                                    void* user_data) {
     // TODO(dkwingsmt): This callback only supports single-view, therefore it
-    // only operates on the default view. To support multi-view, we need a
+    // only operates on the implicit view. To support multi-view, we need a
     // way to pass in the ID (probably through FlutterSemanticsUpdate).
     FlutterEngine* engine = (__bridge FlutterEngine*)user_data;
-    [[engine viewControllerForId:kFlutterDefaultViewId] updateSemantics:update];
+    [[engine viewControllerForId:kFlutterImplicitViewId] updateSemantics:update];
   };
   flutterArguments.custom_dart_entrypoint = entrypoint.UTF8String;
   flutterArguments.shutdown_dart_vm_when_done = true;
@@ -645,7 +645,7 @@ - (FlutterViewController*)viewControllerForId:(FlutterViewId)viewId {
 
 - (void)setViewController:(FlutterViewController*)controller {
   FlutterViewController* currentController =
-      [_viewControllers objectForKey:@(kFlutterDefaultViewId)];
+      [_viewControllers objectForKey:@(kFlutterImplicitViewId)];
   if (currentController == controller) {
     // From nil to nil, or from non-nil to the same controller.
     return;
@@ -658,26 +658,26 @@ - (void)setViewController:(FlutterViewController*)controller {
              @"If you wanted to create an FlutterViewController and set it to an existing engine, "
              @"you should use FlutterViewController#init(engine:, nibName, bundle:) instead.",
              controller.engine);
-    [self registerViewController:controller forId:kFlutterDefaultViewId];
+    [self registerViewController:controller forId:kFlutterImplicitViewId];
   } else if (currentController != nil && controller == nil) {
-    NSAssert(currentController.viewId == kFlutterDefaultViewId,
+    NSAssert(currentController.viewId == kFlutterImplicitViewId,
              @"The default controller has an unexpected ID %llu", currentController.viewId);
     // From non-nil to nil.
-    [self deregisterViewControllerForId:kFlutterDefaultViewId];
+    [self deregisterViewControllerForId:kFlutterImplicitViewId];
     [self shutDownIfNeeded];
   } else {
     // From non-nil to a different non-nil view controller.
     NSAssert(NO,
              @"Failed to set view controller to the engine: "
-             @"The engine already has a default view controller %@. "
-             @"If you wanted to make the default view render in a different window, "
+             @"The engine already has an implicit view controller %@. "
+             @"If you wanted to make the implicit view render in a different window, "
              @"you should attach the current view controller to the window instead.",
-             [_viewControllers objectForKey:@(kFlutterDefaultViewId)]);
+             [_viewControllers objectForKey:@(kFlutterImplicitViewId)]);
   }
 }
 
 - (FlutterViewController*)viewController {
-  return [self viewControllerForId:kFlutterDefaultViewId];
+  return [self viewControllerForId:kFlutterImplicitViewId];
 }
 
 - (FlutterCompositor*)createFlutterCompositor {
@@ -705,9 +705,9 @@ - (FlutterCompositor*)createFlutterCompositor {
                                            void* user_data               //
                                         ) {
     // TODO(dkwingsmt): This callback only supports single-view, therefore it
-    // only operates on the default view. To support multi-view, we need a new
+    // only operates on the implicit view. To support multi-view, we need a new
     // callback that also receives a view ID.
-    return reinterpret_cast<flutter::FlutterCompositor*>(user_data)->Present(kFlutterDefaultViewId,
+    return reinterpret_cast<flutter::FlutterCompositor*>(user_data)->Present(kFlutterImplicitViewId,
                                                                              layers, layers_count);
   };
 
@@ -725,7 +725,7 @@ - (FlutterCompositor*)createFlutterCompositor {
 #pragma mark - Framework-internal methods
 
 - (void)addViewController:(FlutterViewController*)controller {
-  [self registerViewController:controller forId:kFlutterDefaultViewId];
+  [self registerViewController:controller forId:kFlutterImplicitViewId];
 }
 
 - (void)removeViewController:(nonnull FlutterViewController*)viewController {
@@ -812,7 +812,7 @@ - (nonnull NSString*)executableName {
 }
 
 - (void)updateWindowMetricsForViewController:(FlutterViewController*)viewController {
-  if (viewController.viewId != kFlutterDefaultViewId) {
+  if (viewController.viewId != kFlutterImplicitViewId) {
     // TODO(dkwingsmt): The embedder API only supports single-view for now. As
     // embedder APIs are converted to multi-view, this method should support any
     // views.
@@ -1078,7 +1078,7 @@ - (void)handleAccessibilityEvent:(NSDictionary<NSString*, id>*)annotatedEvent {
 - (void)announceAccessibilityMessage:(NSString*)message
                         withPriority:(NSAccessibilityPriorityLevel)priority {
   NSAccessibilityPostNotificationWithUserInfo(
-      [self viewControllerForId:kFlutterDefaultViewId].flutterView,
+      [self viewControllerForId:kFlutterImplicitViewId].flutterView,
       NSAccessibilityAnnouncementRequestedNotification,
       @{NSAccessibilityAnnouncementKey : message, NSAccessibilityPriorityKey : @(priority)});
 }

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

@@ -25,7 +25,7 @@
 // CREATE_NATIVE_ENTRY and MOCK_ENGINE_PROC are leaky by design
 // NOLINTBEGIN(clang-analyzer-core.StackAddressEscape)
 
-constexpr int64_t kDefaultViewId = 0ll;
+constexpr int64_t kImplicitViewId = 0ll;
 
 @interface FlutterEngine (Test)
 /**
@@ -354,7 +354,7 @@ - (nonnull NSView*)createWithViewIdentifier:(int64_t)viewId arguments:(nullable
   FlutterSemanticsNode2* nodes[] = {&root, &child1};
   update.nodes = nodes;
   update.custom_action_count = 0;
-  // This call updates semantics for the default view, which does not exist,
+  // This call updates semantics for the implicit view, which does not exist,
   // and therefore this call is invalid. But the engine should not crash.
   update_semantics_callback(&update, (__bridge void*)engine);
 
@@ -632,7 +632,7 @@ - (nonnull NSView*)createWithViewIdentifier:(int64_t)viewId arguments:(nullable
   [threadSynchronizer shutdown];
 
   std::thread rasterThread([&threadSynchronizer] {
-    [threadSynchronizer performCommitForView:kDefaultViewId
+    [threadSynchronizer performCommitForView:kImplicitViewId
                                         size:CGSizeMake(100, 100)
                                       notify:^{
                                       }];

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

@@ -115,7 +115,7 @@ typedef NS_ENUM(NSInteger, FlutterAppExitResponse) {
  *
  * Practically, since FlutterEngine can only be attached with one controller,
  * the given controller, if successfully attached, will always have the default
- * view ID kFlutterDefaultViewId.
+ * view ID kFlutterImplicitViewId.
  *
  * The engine holds a weak reference to the attached view controller.
  *
@@ -127,11 +127,11 @@ typedef NS_ENUM(NSInteger, FlutterAppExitResponse) {
 /**
  * Dissociate the given view controller from this engine.
  *
- * Practically, since FlutterEngine can only be attached with one controller,
- * the given controller must be the default view controller.
- *
  * If the view controller is not associated with this engine, this call throws an
  * assertion.
+ *
+ * Practically, since FlutterEngine can only be attached with one controller for
+ * now, the given controller must be the current view controller.
  */
 - (void)removeViewController:(FlutterViewController*)viewController;
 

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

@@ -20,7 +20,7 @@ typedef int64_t FlutterViewId;
  * backward compatibility, single-view APIs will always operate on the view with
  * this ID. Also, the first view assigned to the engine will also have this ID.
  */
-constexpr FlutterViewId kFlutterDefaultViewId = 0ll;
+constexpr FlutterViewId kFlutterImplicitViewId = 0ll;
 
 /**
  * Listener for view resizing.

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

@@ -27,7 +27,7 @@
       .andDo(^(NSInvocation* invocation) {
         FlutterViewId viewId;
         [invocation getArgument:&viewId atIndex:2];
-        if (viewId == kFlutterDefaultViewId) {
+        if (viewId == kFlutterImplicitViewId) {
           if (mockFlutterViewController != nil) {
             [invocation setReturnValue:&mockFlutterViewController];
           }

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

@@ -8,7 +8,7 @@
 
 #import "flutter/testing/testing.h"
 
-constexpr int64_t kDefaultViewId = 0ll;
+constexpr int64_t kImplicitViewId = 0ll;
 
 @interface TestReshapeListener : NSObject <FlutterViewReshapeListener>
 
@@ -30,6 +30,6 @@ - (void)viewDidReshape:(nonnull NSView*)view {
                                                 commandQueue:queue
                                              reshapeListener:listener
                                           threadSynchronizer:threadSynchronizer
-                                                      viewId:kDefaultViewId];
+                                                      viewId:kImplicitViewId];
   EXPECT_EQ([view layer:view.layer shouldInheritContentsScale:3.0 fromWindow:view.window], YES);
 }