FocusNode.requestFocus should show the keyboard (#9558)

This patch introduces the notion of a keyboard token, which generalizes the
logic in EditableText for distinguishing between gaining focus by default and
gaining focus because of an explicit use action.

Fixes #7985

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

@@ -225,7 +225,6 @@ class EditableTextState extends State<EditableText> implements TextInputClient {
   void didChangeDependencies() {
     super.didChangeDependencies();
     if (!_didAutoFocus && widget.autofocus) {
-      _didRequestKeyboard = true;
       FocusScope.of(context).autofocus(widget.focusNode);
       _didAutoFocus = true;
     }
@@ -311,17 +310,16 @@ class EditableTextState extends State<EditableText> implements TextInputClient {
     return scrollOffset;
   }
 
-  bool _didRequestKeyboard = false;
   bool get _hasInputConnection => _textInputConnection != null && _textInputConnection.attached;
 
-  void _openInputConnectionIfNeeded() {
+  void _openInputConnection() {
     if (!_hasInputConnection) {
       final TextEditingValue localValue = _value;
       _lastKnownRemoteTextEditingValue = localValue;
       _textInputConnection = TextInput.attach(this, new TextInputConfiguration(inputType: widget.keyboardType))
-        ..setEditingState(localValue)
-        ..show();
+        ..setEditingState(localValue);
     }
+    _textInputConnection.show();
   }
 
   void _closeInputConnectionIfNeeded() {
@@ -333,13 +331,12 @@ class EditableTextState extends State<EditableText> implements TextInputClient {
   }
 
   void _openOrCloseInputConnectionIfNeeded() {
-    if (_hasFocus && _didRequestKeyboard) {
-      _openInputConnectionIfNeeded();
+    if (_hasFocus && widget.focusNode.consumeKeyboardToken()) {
+      _openInputConnection();
     } else if (!_hasFocus) {
       _closeInputConnectionIfNeeded();
       widget.controller.clearComposing();
     }
-    _didRequestKeyboard = false;
   }
 
   /// Express interest in interacting with the keyboard.
@@ -350,17 +347,11 @@ class EditableTextState extends State<EditableText> implements TextInputClient {
   /// focus, the control will then attach to the keyboard and request that the
   /// keyboard become visible.
   void requestKeyboard() {
-    if (_hasInputConnection) {
-      _textInputConnection.show();
-    } else {
-      if (_hasFocus) {
-        _openInputConnectionIfNeeded();
-      } else {
-        _didRequestKeyboard = true;
+    if (_hasFocus)
+      _openInputConnection();
+    else
       FocusScope.of(context).requestFocus(widget.focusNode);
   }
-    }
-  }
 
   void _hideSelectionOverlayIfNeeded() {
     _selectionOverlay?.hide();

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

@@ -31,6 +31,7 @@ import 'package:flutter/foundation.dart';
 class FocusNode extends ChangeNotifier {
   FocusScopeNode _parent;
   FocusManager _manager;
+  bool _hasKeyboardToken = false;
 
   /// Whether this node has the overall focus.
   ///
@@ -48,6 +49,27 @@ class FocusNode extends ChangeNotifier {
   /// This object notifies its listeners whenever this value changes.
   bool get hasFocus => _manager?._currentFocus == this;
 
+  /// Removes the keyboard token from this focus node if it has one.
+  ///
+  /// This mechanism helps distinguish between an input control gaining focus by
+  /// default and gaining focus as a result of an explicit user action.
+  ///
+  /// When a focus node requests the focus (either via
+  /// [FocusScopeNode.requestFocus] or [FocusScopeNode.autofocus]), the focus
+  /// node receives a keyboard token if it does not already have one. Later,
+  /// when the focus node becomes focused, the widget that manages the
+  /// [TextInputConnection] should show the keyboard (i.e., call
+  /// [TextInputConnection.show]) only if it successfully consumes the keyboard
+  /// token from the focus node.
+  ///
+  /// Returns whether this function successfully consumes a keyboard token.
+  bool consumeKeyboardToken() {
+    if (!_hasKeyboardToken)
+      return false;
+    _hasKeyboardToken = false;
+    return true;
+  }
+
   /// Cancels any outstanding requests for focus.
   ///
   /// This method is safe to call regardless of whether this node has ever
@@ -216,13 +238,9 @@ class FocusScopeNode extends Object with TreeDiagnosticsMixin {
     assert(node != null);
     if (_focus == node)
       return;
-    assert(node._parent == null);
     _focus?.unfocus();
-    assert(_focus == null);
-    _focus = node;
-    _focus._parent = this;
-    _focus._manager = _manager;
-    _didChangeFocusChain();
+    node._hasKeyboardToken = true;
+    _setFocus(node);
   }
 
   /// If this scope lacks a focus, request that the given node becomes the
@@ -235,8 +253,10 @@ class FocusScopeNode extends Object with TreeDiagnosticsMixin {
   /// microtask.
   void autofocus(FocusNode node) {
     assert(node != null);
-    if (_focus == null)
-      requestFocus(node);
+    if (_focus == null) {
+      node._hasKeyboardToken = true;
+      _setFocus(node);
+    }
   }
 
   /// Adopts the given node if it is focused in another scope.
@@ -250,7 +270,19 @@ class FocusScopeNode extends Object with TreeDiagnosticsMixin {
       return;
     node.unfocus();
     assert(node._parent == null);
-    autofocus(node);
+    if (_focus == null)
+      _setFocus(node);
+  }
+
+  void _setFocus(FocusNode node) {
+    assert(node != null);
+    assert(node._parent == null);
+    assert(_focus == null);
+    _focus = node;
+    _focus._parent = this;
+    _focus._manager = _manager;
+    _focus._hasKeyboardToken = true;
+    _didChangeFocusChain();
   }
 
   void _resignFocus(FocusNode node) {

packages/flutter/test/material/text_field_focus_test.dart

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:flutter/material.dart';
+
+void main() {
+  testWidgets('Request focus shows keyboard', (WidgetTester tester) async {
+    final FocusNode focusNode = new FocusNode();
+
+    await tester.pumpWidget(
+      new MaterialApp(
+        home: new Material(
+          child: new Center(
+            child: new TextField(
+              focusNode: focusNode,
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    FocusScope.of(tester.element(find.byType(TextField))).requestFocus(focusNode);
+    await tester.idle();
+
+    expect(tester.testTextInput.isVisible, isTrue);
+
+    await tester.pumpWidget(new Container());
+
+    expect(tester.testTextInput.isVisible, isFalse);
+  });
+
+  testWidgets('Autofocus shows keyboard', (WidgetTester tester) async {
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    await tester.pumpWidget(
+      new MaterialApp(
+        home: const Material(
+          child: const Center(
+            child: const TextField(
+              autofocus: true,
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(tester.testTextInput.isVisible, isTrue);
+
+    await tester.pumpWidget(new Container());
+
+    expect(tester.testTextInput.isVisible, isFalse);
+  });
+
+  testWidgets('Tap shows keyboard', (WidgetTester tester) async {
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    await tester.pumpWidget(
+      new MaterialApp(
+        home: const Material(
+          child: const Center(
+            child: const TextField(),
+          ),
+        ),
+      ),
+    );
+
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    await tester.tap(find.byType(TextField));
+    await tester.idle();
+
+    expect(tester.testTextInput.isVisible, isTrue);
+
+    tester.testTextInput.hide();
+
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    await tester.tap(find.byType(TextField));
+    await tester.idle();
+
+    expect(tester.testTextInput.isVisible, isTrue);
+
+    await tester.pumpWidget(new Container());
+
+    expect(tester.testTextInput.isVisible, isFalse);
+  });
+
+  testWidgets('Dialog interaction', (WidgetTester tester) async {
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    await tester.pumpWidget(
+      new MaterialApp(
+        home: const Material(
+          child: const Center(
+            child: const TextField(
+              autofocus: true,
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(tester.testTextInput.isVisible, isTrue);
+
+    final BuildContext context = tester.element(find.byType(TextField));
+
+    showDialog<Null>(
+      context: context,
+      child: const SimpleDialog(title: const Text('Dialog')),
+    );
+
+    await tester.pump();
+
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    Navigator.of(tester.element(find.text('Dialog'))).pop();
+    await tester.pump();
+
+    expect(tester.testTextInput.isVisible, isFalse);
+
+    await tester.tap(find.byType(TextField));
+    await tester.idle();
+
+    expect(tester.testTextInput.isVisible, isTrue);
+
+    await tester.pumpWidget(new Container());
+
+    expect(tester.testTextInput.isVisible, isFalse);
+  });
+
+}

packages/flutter_test/lib/src/test_text_input.dart

@@ -21,24 +21,40 @@ const String _kTextInputClientChannel = 'flutter/textinputclient';
 /// * [WidgetTester.showKeyboard], which uses this class to simulate showing the
 ///   popup keyboard and initializing its text.
 class TestTextInput {
+  /// Installs this object as a mock handler for [SystemChannels.textInput].
   void register() {
-    SystemChannels.textInput.setMockMethodCallHandler(handleTextInputCall);
+    SystemChannels.textInput.setMockMethodCallHandler(_handleTextInputCall);
   }
 
   int _client = 0;
   Map<String, dynamic> editingState;
 
-  Future<dynamic> handleTextInputCall(MethodCall methodCall) async {
+  Future<dynamic> _handleTextInputCall(MethodCall methodCall) async {
     switch (methodCall.method) {
       case 'TextInput.setClient':
         _client = methodCall.arguments[0];
         break;
+      case 'TextInput.clearClient':
+        _client = 0;
+        _isVisible = false;
+        break;
       case 'TextInput.setEditingState':
         editingState = methodCall.arguments;
         break;
+      case 'TextInput.show':
+        _isVisible = true;
+        break;
+      case 'TextInput.hide':
+        _isVisible = false;
+        break;
     }
   }
 
+  /// Whether the onscreen keyboard is visible to the user.
+  bool get isVisible => _isVisible;
+  bool _isVisible = false;
+
+  /// Simulates the user changing the [TextEditingValue] to the given value.
   void updateEditingValue(TextEditingValue value) {
     expect(_client, isNonZero);
     BinaryMessages.handlePlatformMessage(
@@ -53,10 +69,16 @@ class TestTextInput {
     );
   }
 
+  /// Simulates the user typing the given text.
   void enterText(String text) {
     updateEditingValue(new TextEditingValue(
       text: text,
       composing: new TextRange(start: 0, end: text.length),
     ));
   }
+
+  /// Simulates the user hiding the onscreen keyboard.
+  void hide() {
+    _isVisible = false;
+  }
 }