add keyboardDismissBehavior into SingleChildScrollView (#76312)

packages/flutter/lib/src/widgets/single_child_scroll_view.dart

@@ -4,14 +4,19 @@
 
 import 'dart:math' as math;
 
-import 'package:flutter/rendering.dart';
 import 'package:flutter/gestures.dart' show DragStartBehavior;
+import 'package:flutter/rendering.dart';
 
 import 'basic.dart';
+import 'focus_manager.dart';
+import 'focus_scope.dart';
 import 'framework.dart';
+import 'notification_listener.dart';
 import 'primary_scroll_controller.dart';
 import 'scroll_controller.dart';
+import 'scroll_notification.dart';
 import 'scroll_physics.dart';
+import 'scroll_view.dart';
 import 'scrollable.dart';
 
 /// A box in which a single widget can be scrolled.
@@ -221,6 +226,7 @@ class SingleChildScrollView extends StatelessWidget {
     this.dragStartBehavior = DragStartBehavior.start,
     this.clipBehavior = Clip.hardEdge,
     this.restorationId,
+    this.keyboardDismissBehavior = ScrollViewKeyboardDismissBehavior.manual
   }) : assert(scrollDirection != null),
        assert(dragStartBehavior != null),
        assert(clipBehavior != null),
@@ -306,6 +312,9 @@ class SingleChildScrollView extends StatelessWidget {
   /// {@macro flutter.widgets.scrollable.restorationId}
   final String? restorationId;
 
+  /// {@macro flutter.widgets.scroll_view.keyboardDismissBehavior}
+  final ScrollViewKeyboardDismissBehavior keyboardDismissBehavior;
+
   AxisDirection _getDirection(BuildContext context) {
     return getAxisDirectionFromAxisReverseAndDirectionality(context, scrollDirection, reverse);
   }
@@ -319,7 +328,7 @@ class SingleChildScrollView extends StatelessWidget {
     final ScrollController? scrollController = primary
         ? PrimaryScrollController.of(context)
         : controller;
-    final Scrollable scrollable = Scrollable(
+    Widget scrollable = Scrollable(
       dragStartBehavior: dragStartBehavior,
       axisDirection: axisDirection,
       controller: scrollController,
@@ -334,6 +343,20 @@ class SingleChildScrollView extends StatelessWidget {
         );
       },
     );
+
+    if (keyboardDismissBehavior == ScrollViewKeyboardDismissBehavior.onDrag) {
+      scrollable = NotificationListener<ScrollUpdateNotification>(
+        child: scrollable,
+        onNotification: (ScrollUpdateNotification notification) {
+          final FocusScopeNode focusNode = FocusScope.of(context);
+          if (notification.dragDetails != null && focusNode.hasFocus) {
+            focusNode.unfocus();
+          }
+          return false;
+        },
+      );
+    }
+
     return primary && scrollController != null
       ? PrimaryScrollController.none(child: scrollable)
       : scrollable;

packages/flutter/test/widgets/single_child_scroll_view_test.dart

@@ -4,10 +4,9 @@
 
 import 'dart:ui';
 
+import 'package:flutter/material.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/rendering.dart';
-import 'package:flutter/widgets.dart';
-
 import '../rendering/rendering_tester.dart';
 import 'semantics_tester.dart';
 
@@ -922,4 +921,53 @@ void main() {
       expect(inner.offset, 0.0);
     });
   });
+
+  testWidgets('keyboardDismissBehavior tests', (WidgetTester tester) async {
+    final List<FocusNode> focusNodes = List<FocusNode>.generate(50, (int i) => FocusNode());
+
+    Future<void> boilerplate(ScrollViewKeyboardDismissBehavior behavior) {
+      return tester.pumpWidget(
+        MaterialApp(
+          home: Scaffold(
+            body: SingleChildScrollView(
+              padding: EdgeInsets.zero,
+              keyboardDismissBehavior: behavior,
+              child: Column(
+                children: focusNodes.map((FocusNode focusNode) {
+                  return Container(
+                    height: 50,
+                    child: TextField(focusNode: focusNode),
+                  );
+                }).toList(),
+              ),
+            ),
+          ),
+        ),
+      );
+    }
+
+    // ScrollViewKeyboardDismissBehavior.onDrag dismiss keyboard on drag
+    await boilerplate(ScrollViewKeyboardDismissBehavior.onDrag);
+
+    Finder finder = find.byType(TextField).first;
+    TextField textField = tester.widget(finder);
+    await tester.showKeyboard(finder);
+    expect(textField.focusNode!.hasFocus, isTrue);
+
+    await tester.drag(finder, const Offset(0.0, -40.0));
+    await tester.pumpAndSettle();
+    expect(textField.focusNode!.hasFocus, isFalse);
+
+    // ScrollViewKeyboardDismissBehavior.manual does no dismiss the keyboard
+    await boilerplate(ScrollViewKeyboardDismissBehavior.manual);
+
+    finder = find.byType(TextField).first;
+    textField = tester.widget(finder);
+    await tester.showKeyboard(finder);
+    expect(textField.focusNode!.hasFocus, isTrue);
+
+    await tester.drag(finder, const Offset(0.0, -40.0));
+    await tester.pumpAndSettle();
+    expect(textField.focusNode!.hasFocus, isTrue);
+  });
 }