Segmented control fixes (#20202)

Segment width now determined by width of widest child + children widgets now centered within segments

bin/internal/goldens.version

-64b7a3a7aef2fea9c7529d4834bf9eb3d85602d8
-
+46cf554baf4840c326bbceaa51b11534069bb557
\ No newline at end of file

packages/flutter/lib/src/cupertino/segmented_control.dart

@@ -46,10 +46,11 @@ const Duration _kFadeDuration = Duration(milliseconds: 165);
 /// The [children] will be displayed in the order of the keys in the [Map].
 /// The height of the segmented control is determined by the height of the
 /// tallest widget provided as a value in the [Map] of [children].
-/// The width of the segmented control is determined by the horizontal
-/// constraints on its parent. The available horizontal space is divided by
-/// the number of provided [children] to determine the width of each widget.
-/// The selection area for each of the widgets in the [Map] of
+/// The width of each child in the segmented control will be equal to the width
+/// of widest child, unless the combined width of the children is wider than
+/// the available horizontal space. In this case, the available horizontal space
+/// is divided by the number of provided [children] to determine the width of
+/// each widget. The selection area for each of the widgets in the [Map] of
 /// [children] will then be expanded to fill the calculated space, so each
 /// widget will appear to have the same dimensions.
 ///
@@ -75,10 +76,10 @@ class SegmentedControl<T> extends StatefulWidget {
   /// in the [onValueChanged] callback when a new value from the [children] map
   /// is selected.
   ///
-  /// The [groupValue] must be one of the keys in the [children] map.
   /// The [groupValue] is the currently selected value for the segmented control.
   /// If no [groupValue] is provided, or the [groupValue] is null, no widget will
-  /// appear as selected.
+  /// appear as selected. The [groupValue] must be either null or one of the keys
+  /// in the [children] map.
   SegmentedControl({
     Key key,
     @required this.children,
@@ -91,7 +92,8 @@ class SegmentedControl<T> extends StatefulWidget {
   })  : assert(children != null),
         assert(children.length >= 2),
         assert(onValueChanged != null),
-        assert(groupValue == null || children.keys.any((T child) => child == groupValue)),
+        assert(groupValue == null || children.keys.any((T child) => child == groupValue),
+        'The groupValue must be either null or one of the keys in the children map.'),
         assert(unselectedColor != null),
         assert(selectedColor != null),
         assert(borderColor != null),
@@ -189,7 +191,7 @@ class SegmentedControl<T> extends StatefulWidget {
   /// This attribute must not be null.
   ///
   /// If this attribute is unspecified, this color will default to
-  /// 'Color(0x33007AFF)', a light, partially-transparent blue color.
+  /// `Color(0x33007AFF)`, a light, partially-transparent blue color.
   final Color pressedColor;
 
   @override
@@ -346,7 +348,10 @@ class _SegmentedControlState<T> extends State<SegmentedControl<T>>
         color: getTextColor(index, currentKey),
       );
 
-      Widget child = widget.children[currentKey];
+      Widget child = new Center(
+        child: widget.children[currentKey],
+      );
+
       child = new GestureDetector(
         onTapDown: (TapDownDetails event) {
           _onTapDown(currentKey);
@@ -599,15 +604,11 @@ class _RenderSegmentedControl<T> extends RenderBox
   void performLayout() {
     double maxHeight = _kMinSegmentedControlHeight;
 
-    double childWidth;
-    if (constraints.maxWidth.isFinite) {
-      childWidth = constraints.maxWidth / childCount;
-    } else {
-      childWidth = constraints.minWidth / childCount;
-      for (RenderBox child in getChildrenAsList()) {
-        childWidth = math.max(childWidth, child.getMaxIntrinsicWidth(double.infinity));
-      }
+    double childWidth = constraints.minWidth / childCount;
+    for (RenderBox child in getChildrenAsList()) {
+      childWidth = math.max(childWidth, child.getMaxIntrinsicWidth(double.infinity));
     }
+    childWidth = math.min(childWidth, constraints.maxWidth / childCount);
 
     RenderBox child = firstChild;
     while (child != null) {

packages/flutter/test/cupertino/segmented_control_test.dart

@@ -218,8 +218,6 @@ void main() {
       ),
     );
 
-    await tester.pumpAndSettle();
-
     DefaultTextStyle textStyle = tester.widget(find.widgetWithText(DefaultTextStyle, 'Child 1'));
     IconTheme iconTheme = tester.widget(find.widgetWithIcon(IconTheme, const IconData(1)));
 
@@ -238,63 +236,88 @@ void main() {
 
   testWidgets('SegmentedControl is correct when user provides custom colors',
           (WidgetTester tester) async {
-        final Map<int, Widget> children = <int, Widget>{};
-        children[0] = const Text('Child 1');
-        children[1] = const Icon(IconData(1));
+    final Map<int, Widget> children = <int, Widget>{};
+    children[0] = const Text('Child 1');
+    children[1] = const Icon(IconData(1));
 
-        int sharedValue = 0;
+    int sharedValue = 0;
 
-        await tester.pumpWidget(
-          new StatefulBuilder(
-            builder: (BuildContext context, StateSetter setState) {
-              return boilerplate(
-                child: new SegmentedControl<int>(
-                  children: children,
-                  onValueChanged: (int newValue) {
-                    setState(() {
-                      sharedValue = newValue;
-                    });
-                  },
-                  groupValue: sharedValue,
-                  unselectedColor: CupertinoColors.lightBackgroundGray,
-                  selectedColor: CupertinoColors.activeGreen,
-                  borderColor: CupertinoColors.black,
-                  pressedColor: const Color(0x638CFC7B),
-                ),
-              );
-            },
-          ),
-        );
+    await tester.pumpWidget(
+      new StatefulBuilder(
+        builder: (BuildContext context, StateSetter setState) {
+          return boilerplate(
+            child: new SegmentedControl<int>(
+              children: children,
+              onValueChanged: (int newValue) {
+                setState(() {
+                  sharedValue = newValue;
+                });
+              },
+              groupValue: sharedValue,
+              unselectedColor: CupertinoColors.lightBackgroundGray,
+              selectedColor: CupertinoColors.activeGreen,
+              borderColor: CupertinoColors.black,
+              pressedColor: const Color(0x638CFC7B),
+            ),
+          );
+        },
+      ),
+    );
 
-        await tester.pumpAndSettle();
+    DefaultTextStyle textStyle = tester.widget(find.widgetWithText(DefaultTextStyle, 'Child 1'));
+    IconTheme iconTheme = tester.widget(find.widgetWithIcon(IconTheme, const IconData(1)));
 
-        DefaultTextStyle textStyle = tester.widget(find.widgetWithText(DefaultTextStyle, 'Child 1'));
-        IconTheme iconTheme = tester.widget(find.widgetWithIcon(IconTheme, const IconData(1)));
+    expect(getRenderSegmentedControl(tester).borderColor, CupertinoColors.black);
+    expect(textStyle.style.color, CupertinoColors.lightBackgroundGray);
+    expect(iconTheme.data.color, CupertinoColors.activeGreen);
+    expect(getBackgroundColor(tester, 0), CupertinoColors.activeGreen);
+    expect(getBackgroundColor(tester, 1), CupertinoColors.lightBackgroundGray);
 
-        expect(getRenderSegmentedControl(tester).borderColor, CupertinoColors.black);
-        expect(textStyle.style.color, CupertinoColors.lightBackgroundGray);
-        expect(iconTheme.data.color, CupertinoColors.activeGreen);
-        expect(getBackgroundColor(tester, 0), CupertinoColors.activeGreen);
-        expect(getBackgroundColor(tester, 1), CupertinoColors.lightBackgroundGray);
+    await tester.tap(find.widgetWithIcon(IconTheme, const IconData(1)));
+    await tester.pumpAndSettle();
 
-        await tester.tap(find.widgetWithIcon(IconTheme, const IconData(1)));
-        await tester.pumpAndSettle();
+    textStyle = tester.widget(find.widgetWithText(DefaultTextStyle, 'Child 1'));
+    iconTheme = tester.widget(find.widgetWithIcon(IconTheme, const IconData(1)));
 
-        textStyle = tester.widget(find.widgetWithText(DefaultTextStyle, 'Child 1'));
-        iconTheme = tester.widget(find.widgetWithIcon(IconTheme, const IconData(1)));
+    expect(textStyle.style.color, CupertinoColors.activeGreen);
+    expect(iconTheme.data.color, CupertinoColors.lightBackgroundGray);
+    expect(getBackgroundColor(tester, 0), CupertinoColors.lightBackgroundGray);
+    expect(getBackgroundColor(tester, 1), CupertinoColors.activeGreen);
 
-        expect(textStyle.style.color, CupertinoColors.activeGreen);
-        expect(iconTheme.data.color, CupertinoColors.lightBackgroundGray);
-        expect(getBackgroundColor(tester, 0), CupertinoColors.lightBackgroundGray);
-        expect(getBackgroundColor(tester, 1), CupertinoColors.activeGreen);
+    final Offset center = tester.getCenter(find.text('Child 1'));
+    await tester.startGesture(center);
+    await tester.pumpAndSettle();
 
-        final Offset center = tester.getCenter(find.text('Child 1'));
-        await tester.startGesture(center);
-        await tester.pumpAndSettle();
+    expect(getBackgroundColor(tester, 0), const Color(0x638CFC7B));
+    expect(getBackgroundColor(tester, 1), CupertinoColors.activeGreen);
+  });
 
-        expect(getBackgroundColor(tester, 0), const Color(0x638CFC7B));
-        expect(getBackgroundColor(tester, 1), CupertinoColors.activeGreen);
-      });
+  testWidgets('Widgets are centered within segments', (WidgetTester tester) async {
+    final Map<int, Widget> children = <int, Widget>{};
+    children[0] = const Text('Child 1');
+    children[1] = const Text('Child 2');
+
+    await tester.pumpWidget(
+      new Directionality(
+        textDirection: TextDirection.ltr,
+        child: new Align(
+          alignment: Alignment.topLeft,
+          child: new SizedBox(
+            width: 200.0,
+            height: 200.0,
+            child: new SegmentedControl<int>(
+              children: children,
+              onValueChanged: (int newValue) {},
+            ),
+          ),
+        ),
+      ),
+    );
+
+    // Widgets are centered taking into account 16px of horizontal padding
+    expect(tester.getCenter(find.text('Child 1')), const Offset(58.0, 100.0));
+    expect(tester.getCenter(find.text('Child 2')), const Offset(142.0, 100.0));
+  });
 
   testWidgets('Tap calls onValueChanged', (WidgetTester tester) async {
     final Map<int, Widget> children = <int, Widget>{};
@@ -510,16 +533,21 @@ void main() {
     final RenderBox buttonBox = tester.renderObject(
         find.byKey(const ValueKey<String>('Segmented Control')));
 
-    // Default height of Placeholder is 400.0px, which is greater than heights
-    // of other child widgets.
     expect(buttonBox.size.height, 400.0);
   });
 
-  testWidgets('Width of each child widget is the same', (WidgetTester tester) async {
+  testWidgets('Width of each segmented control segment is determined by widest widget',
+          (WidgetTester tester) async {
     final Map<int, Widget> children = <int, Widget>{};
-    children[0] = new Container();
-    children[1] = const Placeholder();
-    children[2] = new Container();
+    children[0] = new Container(
+      constraints: const BoxConstraints.tightFor(width: 50.0),
+    );
+    children[1] = new Container(
+      constraints: const BoxConstraints.tightFor(width: 100.0),
+    );
+    children[2] = new Container(
+      constraints: const BoxConstraints.tightFor(width: 200.0),
+    );
 
     await tester.pumpWidget(
       new StatefulBuilder(
@@ -542,6 +570,8 @@ void main() {
     // to each child equally.
     final double childWidth = (segmentedControl.size.width - 32.0) / 3;
 
+    expect(childWidth, 200.0);
+
     expect(childWidth,
         getRenderSegmentedControl(tester).getChildrenAsList()[0].parentData.surroundingRect.width);
     expect(childWidth,
@@ -748,8 +778,8 @@ void main() {
 
   testWidgets('Non-centered taps work on smaller widgets', (WidgetTester tester) async {
     final Map<int, Widget> children = <int, Widget>{};
-    children[0] = const Text('A');
-    children[1] = const Text('B');
+    children[0] = const Text('Child 1');
+    children[1] = const Text('Child 2');
 
     int sharedValue = 1;
 
@@ -775,10 +805,15 @@ void main() {
     expect(sharedValue, 1);
 
     final double childWidth = getRenderSegmentedControl(tester).firstChild.size.width;
-    final Offset centerOfSegmentedControl = tester.getCenter(find.text('A'));
+    final Offset centerOfSegmentedControl = tester.getCenter(find.text('Child 1'));
 
     // Tap just inside segment bounds
-    await tester.tapAt(new Offset(childWidth - 10.0, centerOfSegmentedControl.dy));
+    await tester.tapAt(
+      new Offset(
+        centerOfSegmentedControl.dx + (childWidth / 2) - 10.0,
+        centerOfSegmentedControl.dy,
+      ),
+    );
 
     expect(sharedValue, 0);
   });
@@ -1257,11 +1292,14 @@ void main() {
         child: new StatefulBuilder(
           builder: (BuildContext context, StateSetter setState) {
             return boilerplate(
-              child: new SegmentedControl<int>(
-                key: const ValueKey<String>('Segmented Control'),
-                children: children,
-                onValueChanged: (int newValue) {},
-                groupValue: currentValue,
+              child: new SizedBox(
+                width: 800.0,
+                child: new SegmentedControl<int>(
+                  key: const ValueKey<String>('Segmented Control'),
+                  children: children,
+                  onValueChanged: (int newValue) {},
+                  groupValue: currentValue,
+                ),
               ),
             );
           },
@@ -1273,7 +1311,7 @@ void main() {
       find.byType(RepaintBoundary),
       matchesGoldenFile('segmented_control_test.0.0.png'),
     );
-  }, skip: !Platform.isLinux);
+  }, skip: !Platform.isMacOS);
 
   testWidgets('Golden Test Pressed State', (WidgetTester tester) async {
     final Map<int, Widget> children = <int, Widget>{};
@@ -1288,11 +1326,14 @@ void main() {
         child: new StatefulBuilder(
           builder: (BuildContext context, StateSetter setState) {
             return boilerplate(
-              child: new SegmentedControl<int>(
-                key: const ValueKey<String>('Segmented Control'),
-                children: children,
-                onValueChanged: (int newValue) {},
-                groupValue: currentValue,
+              child: new SizedBox(
+                width: 800.0,
+                child: new SegmentedControl<int>(
+                  key: const ValueKey<String>('Segmented Control'),
+                  children: children,
+                  onValueChanged: (int newValue) {},
+                  groupValue: currentValue,
+                ),
               ),
             );
           },
@@ -1308,5 +1349,5 @@ void main() {
       find.byType(RepaintBoundary),
       matchesGoldenFile('segmented_control_test.1.0.png'),
     );
-  }, skip: !Platform.isLinux);
+  }, skip: !Platform.isMacOS);
 }