Fix done button click not blur in iOS keyboard

lib/web_ui/lib/src/engine/text_editing/text_editing.dart

@@ -1389,6 +1389,16 @@ class IOSTextEditingStrategy extends GloballyPositionedTextEditingStrategy {
   Timer? _positionInputElementTimer;
   static const Duration _delayBeforePlacement = Duration(milliseconds: 100);
 
+  /// The interval is considered as fast between blur subscription and callback.
+  ///
+  /// This is only used for iOS. The blur callback may trigger as soon as
+  /// the creation of the subscription. In that case, the virtual keyboard will
+  /// show and hide again occasionally.
+  ///
+  /// Lesser than the interval allows the virtual keyboard to keep showing up
+  /// instead of hiding rapidly.
+  static const Duration _blurFastCallbackInterval = Duration(milliseconds: 200);
+
   /// Whether or not the input element can be positioned at this point in time.
   ///
   /// This is currently only used in iOS. It's set to false before focusing the
@@ -1453,6 +1463,9 @@ class IOSTextEditingStrategy extends GloballyPositionedTextEditingStrategy {
 
     _addTapListener();
 
+    // Record start time of blur subscription.
+    final DateTime blurSubscriptionStart = DateTime.now();
+
     // On iOS, blur is trigerred in the following cases:
     //
     // 1. The browser app is sent to the background (or the tab is changed). In
@@ -1465,7 +1478,7 @@ class IOSTextEditingStrategy extends GloballyPositionedTextEditingStrategy {
     //    okay because the virtual keyboard will hide, and as soon as the user
     //    taps the text field again, the virtual keyboard will come up.
     subscriptions.add(activeDomElement.onBlur.listen((_) {
-      if (windowHasFocus) {
+      if (DateTime.now().difference(blurSubscriptionStart) < _blurFastCallbackInterval) {
         activeDomElement.focus();
       } else {
         owner.sendTextConnectionClosedToFrameworkIfAny();

lib/web_ui/test/text_editing_test.dart

@@ -675,6 +675,56 @@ void testMain() {
         // TODO(mdebbar): https://github.com/flutter/flutter/issues/50769
         skip: browserEngine == BrowserEngine.edge);
 
+    test('focus and disconnection with delaying blur in iOS', () async {
+      // Test on ios-safari only.
+      if (browserEngine == BrowserEngine.webkit &&
+          operatingSystem == OperatingSystem.iOs) {
+        final MethodCall setClient = MethodCall(
+            'TextInput.setClient', <dynamic>[123, flutterSinglelineConfig]);
+        sendFrameworkMessage(codec.encodeMethodCall(setClient));
+
+        const MethodCall setEditingState =
+        MethodCall('TextInput.setEditingState', <String, dynamic>{
+          'text': 'abcd',
+          'selectionBase': 2,
+          'selectionExtent': 3,
+        });
+        sendFrameworkMessage(codec.encodeMethodCall(setEditingState));
+
+        // Editing shouldn't have started yet.
+        expect(defaultTextEditingRoot.activeElement, null);
+
+        const MethodCall show = MethodCall('TextInput.show');
+        sendFrameworkMessage(codec.encodeMethodCall(show));
+
+        // The "setSizeAndTransform" message has to be here before we call
+        // checkInputEditingState, since on some platforms (e.g. Desktop Safari)
+        // we don't put the input element into the DOM until we get its correct
+        // dimensions from the framework.
+        final MethodCall setSizeAndTransform =
+        configureSetSizeAndTransformMethodCall(150, 50,
+            Matrix4.translationValues(10.0, 20.0, 30.0).storage.toList());
+        sendFrameworkMessage(codec.encodeMethodCall(setSizeAndTransform));
+
+        checkInputEditingState(
+            textEditing!.strategy.domElement, 'abcd', 2, 3);
+        expect(textEditing!.isEditing, isTrue);
+
+        // Delay for not to be a fast callback with blur.
+        await Future<void>.delayed(const Duration(milliseconds: 200));
+        // DOM element is blurred.
+        textEditing!.strategy.domElement!.blur();
+
+        expect(spy.messages, hasLength(1));
+        expect(spy.messages[0].channel, 'flutter/textinput');
+        expect(
+            spy.messages[0].methodName, 'TextInputClient.onConnectionClosed');
+        await Future<void>.delayed(Duration.zero);
+        // DOM element loses the focus.
+        expect(defaultTextEditingRoot.activeElement, null);
+      }
+    });
+
     test('finishAutofillContext closes connection no autofill element',
         () async {
       final MethodCall setClient = MethodCall(