Add ToggleButtons.textStyle property (#38813)

* Add ToggleButtons.textStyle property

packages/flutter/lib/src/material/toggle_buttons.dart

@@ -165,6 +165,7 @@ class ToggleButtons extends StatelessWidget {
     @required this.children,
     @required this.isSelected,
     this.onPressed,
+    this.textStyle,
     this.color,
     this.selectedColor,
     this.disabledColor,
@@ -215,6 +216,13 @@ class ToggleButtons extends StatelessWidget {
   /// When the callback is null, all toggle buttons will be disabled.
   final void Function(int index) onPressed;
 
+  /// The [TextStyle] to apply to any text in these toggle buttons.
+  ///
+  /// [TextStyle.color] will be ignored and substituted by [color],
+  /// [selectedColor] or [disabledColor] depending on whether the buttons
+  /// are active, selected, or disabled.
+  final TextStyle textStyle;
+
   /// The color for descendant [Text] and [Icon] widgets if the button is
   /// enabled and not selected.
   ///
@@ -569,6 +577,7 @@ class ToggleButtons extends StatelessWidget {
 
           return _ToggleButton(
             selected: isSelected[index],
+            textStyle: textStyle,
             color: color,
             selectedColor: selectedColor,
             disabledColor: disabledColor,
@@ -603,6 +612,7 @@ class ToggleButtons extends StatelessWidget {
       ifTrue: 'Buttons are disabled',
       ifFalse: 'Buttons are enabled',
     ));
+    textStyle?.debugFillProperties(properties, prefix: 'textStyle.');
     properties.add(ColorProperty('color', color, defaultValue: null));
     properties.add(ColorProperty('selectedColor', selectedColor, defaultValue: null));
     properties.add(ColorProperty('disabledColor', disabledColor, defaultValue: null));
@@ -634,6 +644,7 @@ class _ToggleButton extends StatelessWidget {
   const _ToggleButton({
     Key key,
     this.selected = false,
+    this.textStyle,
     this.color,
     this.selectedColor,
     this.disabledColor,
@@ -657,6 +668,9 @@ class _ToggleButton extends StatelessWidget {
   /// Determines if the button is displayed as active/selected or enabled.
   final bool selected;
 
+  /// The [TextStyle] to apply to any text that appears in this button.
+  final TextStyle textStyle;
+
   /// The color for [Text] and [Icon] widgets if the button is enabled.
   ///
   /// If [selected] is false and [onPressed] is not null, this color will be used.
@@ -769,10 +783,12 @@ class _ToggleButton extends StatelessWidget {
       currentFillColor = theme.colorScheme.surface.withOpacity(0.0);
     }
 
+    final TextStyle currentTextStyle = textStyle ?? toggleButtonsTheme.textStyle ?? theme.textTheme.body1;
+
     final Widget result = ClipRRect(
       borderRadius: clipRadius,
       child: RawMaterialButton(
-        textStyle: TextStyle(
+        textStyle: currentTextStyle.copyWith(
           color: currentColor,
         ),
         elevation: 0.0,

packages/flutter/lib/src/material/toggle_buttons_theme.dart

@@ -28,6 +28,7 @@ class ToggleButtonsThemeData extends Diagnosticable {
   /// Creates the set of color and border properties used to configure
   /// [ToggleButtons].
   const ToggleButtonsThemeData({
+    this.textStyle,
     this.color,
     this.selectedColor,
     this.disabledColor,
@@ -43,6 +44,13 @@ class ToggleButtonsThemeData extends Diagnosticable {
     this.borderWidth,
   });
 
+  /// The default text style for [ToggleButtons.children].
+  ///
+  /// [TextStyle.color] will be ignored and substituted by [color],
+  /// [selectedColor] or [disabledColor] depending on whether the buttons
+  /// are active, selected, or disabled.
+  final TextStyle textStyle;
+
   /// The color for descendant [Text] and [Icon] widgets if the toggle button
   /// is enabled.
   final Color color;
@@ -95,6 +103,7 @@ class ToggleButtonsThemeData extends Diagnosticable {
   /// Creates a copy of this object but with the given fields replaced with the
   /// new values.
   ToggleButtonsThemeData copyWith({
+    TextStyle textStyle,
     Color color,
     Color selectedColor,
     Color disabledColor,
@@ -110,6 +119,7 @@ class ToggleButtonsThemeData extends Diagnosticable {
     double borderWidth,
   }) {
     return ToggleButtonsThemeData(
+      textStyle: textStyle ?? this.textStyle,
       color: color ?? this.color,
       selectedColor: selectedColor ?? this.selectedColor,
       disabledColor: disabledColor ?? this.disabledColor,
@@ -132,6 +142,7 @@ class ToggleButtonsThemeData extends Diagnosticable {
     if (a == null && b == null)
       return null;
     return ToggleButtonsThemeData(
+      textStyle: TextStyle.lerp(a?.textStyle, b?.textStyle, t),
       color: Color.lerp(a?.color, b?.color, t),
       selectedColor: Color.lerp(a?.selectedColor, b?.selectedColor, t),
       disabledColor: Color.lerp(a?.disabledColor, b?.disabledColor, t),
@@ -151,6 +162,7 @@ class ToggleButtonsThemeData extends Diagnosticable {
   @override
   int get hashCode {
     return hashValues(
+      textStyle,
       color,
       selectedColor,
       disabledColor,
@@ -174,7 +186,8 @@ class ToggleButtonsThemeData extends Diagnosticable {
     if (other.runtimeType != runtimeType)
       return false;
     final ToggleButtonsThemeData typedOther = other;
-    return typedOther.color == color
+    return typedOther.textStyle == textStyle
+        && typedOther.color == color
         && typedOther.selectedColor == selectedColor
         && typedOther.disabledColor == disabledColor
         && typedOther.fillColor == fillColor
@@ -192,6 +205,7 @@ class ToggleButtonsThemeData extends Diagnosticable {
   @override
   void debugFillProperties(DiagnosticPropertiesBuilder properties) {
     super.debugFillProperties(properties);
+    textStyle?.debugFillProperties(properties, prefix: 'textStyle.');
     properties.add(ColorProperty('color', color, defaultValue: null));
     properties.add(ColorProperty('selectedColor', selectedColor, defaultValue: null));
     properties.add(ColorProperty('disabledColor', disabledColor, defaultValue: null));

packages/flutter/test/material/toggle_buttons_test.dart

@@ -250,6 +250,78 @@ void main() {
     },
   );
 
+  testWidgets('Default text style is applied', (WidgetTester tester) async {
+    final ThemeData theme = ThemeData();
+    await tester.pumpWidget(
+      Material(
+        child: boilerplate(
+          child: ToggleButtons(
+            isSelected: const <bool>[false, true],
+            onPressed: (int index) {},
+            children: const <Widget>[
+              Text('First child'),
+              Text('Second child'),
+            ],
+          ),
+        ),
+      ),
+    );
+
+    TextStyle textStyle;
+    textStyle = tester.widget<DefaultTextStyle>(find.descendant(
+        of: find.widgetWithText(RawMaterialButton, 'First child'),
+        matching: find.byType(DefaultTextStyle),
+    )).style;
+    expect(textStyle.fontFamily, theme.textTheme.body1.fontFamily);
+    expect(textStyle.decoration, theme.textTheme.body1.decoration);
+
+    textStyle = tester.widget<DefaultTextStyle>(find.descendant(
+        of: find.widgetWithText(RawMaterialButton, 'Second child'),
+        matching: find.byType(DefaultTextStyle),
+    )).style;
+    expect(textStyle.fontFamily, theme.textTheme.body1.fontFamily);
+    expect(textStyle.decoration, theme.textTheme.body1.decoration);
+  });
+
+  testWidgets('Custom text style except color is applied', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      Material(
+        child: boilerplate(
+          child: ToggleButtons(
+            isSelected: const <bool>[false, true],
+            onPressed: (int index) {},
+            textStyle: const TextStyle(
+              textBaseline: TextBaseline.ideographic,
+              fontSize: 20.0,
+              color: Colors.orange,
+            ),
+            children: const <Widget>[
+              Text('First child'),
+              Text('Second child'),
+            ],
+          ),
+        ),
+      ),
+    );
+
+    TextStyle textStyle;
+    textStyle = tester.widget<DefaultTextStyle>(find.descendant(
+        of: find.widgetWithText(RawMaterialButton, 'First child'),
+        matching: find.byType(DefaultTextStyle),
+    )).style;
+    expect(textStyle.textBaseline, TextBaseline.ideographic);
+    expect(textStyle.fontSize, 20.0);
+    expect(textStyle.color, isNot(Colors.orange));
+
+    textStyle = tester.widget<DefaultTextStyle>(find.descendant(
+        of: find.widgetWithText(RawMaterialButton, 'Second child'),
+        matching: find.byType(DefaultTextStyle),
+    )).style;
+    expect(textStyle.textBaseline, TextBaseline.ideographic);
+    expect(textStyle.fontSize, 20.0);
+    expect(textStyle.color, isNot(Colors.orange));
+  });
+
   testWidgets(
     'Default text/icon colors for enabled, selected and disabled states',
     (WidgetTester tester) async {

packages/flutter/test/material/toggle_buttons_theme_test.dart

@@ -24,6 +24,7 @@ void main() {
 
   test('ToggleButtonsThemeData defaults', () {
     const ToggleButtonsThemeData themeData = ToggleButtonsThemeData();
+    expect(themeData.textStyle, null);
     expect(themeData.color, null);
     expect(themeData.selectedColor, null);
     expect(themeData.disabledColor, null);
@@ -39,6 +40,7 @@ void main() {
     expect(themeData.borderWidth, null);
 
     const ToggleButtonsTheme theme = ToggleButtonsTheme(data: ToggleButtonsThemeData());
+    expect(theme.data.textStyle, null);
     expect(theme.data.color, null);
     expect(theme.data.selectedColor, null);
     expect(theme.data.disabledColor, null);
@@ -69,6 +71,7 @@ void main() {
   testWidgets('ToggleButtonsThemeData implements debugFillProperties', (WidgetTester tester) async {
     final DiagnosticPropertiesBuilder builder = DiagnosticPropertiesBuilder();
     const ToggleButtonsThemeData(
+      textStyle: TextStyle(fontSize: 10),
       color: Color(0xfffffff0),
       selectedColor: Color(0xfffffff1),
       disabledColor: Color(0xfffffff2),
@@ -90,6 +93,8 @@ void main() {
         .toList();
 
      expect(description, <String>[
+      'textStyle.inherit: true',
+      'textStyle.size: 10.0',
       'color: Color(0xfffffff0)',
       'selectedColor: Color(0xfffffff1)',
       'disabledColor: Color(0xfffffff2)',
@@ -106,6 +111,49 @@ void main() {
     ]);
   });
 
+  testWidgets('Theme text style, except color, is applied', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      Material(
+        child: boilerplate(
+          child: ToggleButtonsTheme(
+            data: const ToggleButtonsThemeData(
+              textStyle: TextStyle(
+                color: Colors.orange,
+                textBaseline: TextBaseline.ideographic,
+                fontSize: 20.0,
+              ),
+            ),
+            child: ToggleButtons(
+              isSelected: const <bool>[false, true],
+              onPressed: (int index) {},
+              children: const <Widget>[
+                Text('First child'),
+                Text('Second child'),
+              ],
+            ),
+          ),
+        ),
+      ),
+    );
+
+    TextStyle textStyle;
+    textStyle = tester.widget<DefaultTextStyle>(find.descendant(
+        of: find.widgetWithText(RawMaterialButton, 'First child'),
+        matching: find.byType(DefaultTextStyle),
+    )).style;
+    expect(textStyle.textBaseline, TextBaseline.ideographic);
+    expect(textStyle.fontSize, 20.0);
+    expect(textStyle.color, isNot(Colors.orange));
+
+    textStyle = tester.widget<DefaultTextStyle>(find.descendant(
+        of: find.widgetWithText(RawMaterialButton, 'Second child'),
+        matching: find.byType(DefaultTextStyle),
+    )).style;
+    expect(textStyle.textBaseline, TextBaseline.ideographic);
+    expect(textStyle.fontSize, 20.0);
+    expect(textStyle.color, isNot(Colors.orange));
+  });
+
   testWidgets(
     'Theme text/icon colors for enabled, selected and disabled states',
     (WidgetTester tester) async {