A11y callback (#8005)

* implement callback for a11y readiness * use FlutterSemanticsUpdateNotification from header, move to VC header
flutter · Mar 7, 2019 · a93d99d · a93d99d
1 parent 3661d5e
commit a93d99d
Show file tree

Hide file tree

Showing 5 changed files with 40 additions and 5 deletions.
diff --git a/shell/platform/darwin/ios/framework/Headers/FlutterEngine.h b/shell/platform/darwin/ios/framework/Headers/FlutterEngine.h
@@ -133,6 +133,26 @@ FLUTTER_EXPORT
  */
 - (void)destroyContext;
 
+/**
+ * Ensures that Flutter will generate a semantics tree.
+ *
+ * This is enabled by default if certain accessibility services are turned on by
+ * the user, or when using a Simulator. This method allows a user to turn
+ * semantics on when they would not ordinarily be generated and the performance
+ * overhead is not a concern, e.g. for UI testing. Note that semantics should
+ * never be programatically turned off, as it would potentially disable
+ * accessibility services an end user has requested.
+ *
+ * This method must only be called after launching the engine via
+ * `-runWithEntrypoint:` or `-runWithEntryPoint:libraryURI`.
+ *
+ * You can subscribe to semantics updates via `NSNotificationCenter` by adding
+ * an observer for the name `FlutterSemanticsUpdateNotification`.  The `object`
+ * parameter will be the `FlutterViewController` associated with the semantics
+ * update.
+ */
+- (void)ensureSemanticsEnabled;
+
 /**
  * Sets the `FlutterViewController` for this instance.  The FlutterEngine must be
  * running (e.g. a successful call to `-runWithEntrypoint:` or `-runWithEntrypoint:libraryURI`)

diff --git a/shell/platform/darwin/ios/framework/Headers/FlutterViewController.h b/shell/platform/darwin/ios/framework/Headers/FlutterViewController.h
@@ -17,6 +17,14 @@
 
 @class FlutterEngine;
 
+/**
+ * The name used for semantic update nofications via `NSNotificationCenter`.
+ *
+ * The object passed as the sender is the `FlutterViewController` associated
+ * with the update.
+ */
+const NSNotificationName FlutterSemanticsUpdateNotification = @"FlutterSemanticsUpdate";
+
 /**
  * A `UIViewController` implementation for Flutter views.
  *

diff --git a/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm b/shell/platform/darwin/ios/framework/Source/FlutterEngine.mm
@@ -146,6 +146,10 @@ - (void)dispatchPointerDataPacket:(std::unique_ptr<blink::PointerDataPacket>)pac
   return _shell->GetTaskRunners().GetPlatformTaskRunner();
 }
 
+- (void)ensureSemanticsEnabled {
+  self.iosPlatformView->SetSemanticsEnabled(true);
+}
+
 - (void)setViewController:(FlutterViewController*)viewController {
   FML_DCHECK(self.iosPlatformView);
   _viewController = [viewController getWeakPtr];

diff --git a/shell/platform/darwin/ios/platform_view_ios.h b/shell/platform/darwin/ios/platform_view_ios.h
@@ -40,6 +40,9 @@ class PlatformViewIOS final : public PlatformView {
 
   void SetTextInputPlugin(fml::scoped_nsprotocol<FlutterTextInputPlugin*> plugin);
 
+  // |shell::PlatformView|
+  void SetSemanticsEnabled(bool enabled) override;
+
  private:
   fml::WeakPtr<FlutterViewController> owner_controller_;
   std::unique_ptr<IOSSurface> ios_surface_;
@@ -57,9 +60,6 @@ class PlatformViewIOS final : public PlatformView {
   // |shell::PlatformView|
   sk_sp<GrContext> CreateResourceContext() const override;
 
-  // |shell::PlatformView|
-  void SetSemanticsEnabled(bool enabled) override;
-
   // |shell::PlatformView|
   void SetAccessibilityFeatures(int32_t flags) override;
 

diff --git a/shell/platform/darwin/ios/platform_view_ios.mm b/shell/platform/darwin/ios/platform_view_ios.mm
@@ -90,8 +90,8 @@
 // |shell::PlatformView|
 void PlatformViewIOS::SetSemanticsEnabled(bool enabled) {
   if (!owner_controller_) {
-    FML_DLOG(WARNING) << "Could not set semantics to enabled, this "
-                         "PlatformViewIOS has no ViewController.";
+    FML_LOG(WARNING) << "Could not set semantics to enabled, this "
+                        "PlatformViewIOS has no ViewController.";
     return;
   }
   if (enabled && !accessibility_bridge_) {
@@ -111,8 +111,11 @@
 // |shell::PlatformView|
 void PlatformViewIOS::UpdateSemantics(blink::SemanticsNodeUpdates update,
                                       blink::CustomAccessibilityActionUpdates actions) {
+  FML_DCHECK(owner_controller_);
   if (accessibility_bridge_) {
     accessibility_bridge_->UpdateSemantics(std::move(update), std::move(actions));
+    [[NSNotificationCenter defaultCenter] postNotificationName:FlutterSemanticsUpdateNotification
+                                                        object:owner_controller_.get()];
   }
 }