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return ElevatedButton(
onPressed: () {
developer.log('click');
},
child: const Text('Button'),
);
}<code_end>
If the Widget doesn’t support event detection,
wrap the widget in a GestureDetector and pass a function
to the onTap parameter.
<code_start>class SampleTapApp extends StatelessWidget {
const SampleTapApp({super.key});
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: GestureDetector(
onTap: () {
developer.log('tap');
},
child: const FlutterLogo(
size: 200,
),
),
),
);
}
}<code_end>
<topic_end>
<topic_start>
Handling other gestures
Using GestureDetector you can listen
to a wide range of gestures such as:TappingDouble tappingLong pressingVertical draggingHorizontal draggingThe following example shows a GestureDetector
that rotates the Flutter logo on a double tap:
<code_start>class SampleApp extends StatefulWidget {
const SampleApp({super.key});
@override
State<SampleApp> createState() => _SampleAppState();
}
class _SampleAppState extends State<SampleApp>
with SingleTickerProviderStateMixin {
late AnimationController controller;
late CurvedAnimation curve;
@override
void initState() {
super.initState();
controller = AnimationController(
vsync: this,
duration: const Duration(milliseconds: 2000),
);
curve = CurvedAnimation(
parent: controller,
curve: Curves.easeIn,
);
}
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: GestureDetector(
onDoubleTap: () {
if (controller.isCompleted) {
controller.reverse();
} else {
controller.forward();
}
},
child: RotationTransition(
turns: curve,
child: const FlutterLogo(
size: 200,
),
),
),
),
);
}
}<code_end>
<topic_end>
<topic_start>
Themes, styles, and media
Flutter applications are easy to style; you can switch
between light and dark themes,
change the style of your text and UI components,
and more. This section covers aspects of styling your Flutter apps
and compares how you might do the same in UIKit.<topic_end>
<topic_start>
Using a theme
Out of the box, Flutter comes with a beautiful implementation
of Material Design, which takes care of a lot of styling and
theming needs that you would typically do.To take full advantage of Material Components in your app,
declare a top-level widget, MaterialApp,
as the entry point to your application.
MaterialApp is a convenience widget that wraps a number
of widgets that are commonly required for applications
implementing Material Design.
It builds upon a WidgetsApp by adding Material specific functionality.But Flutter is flexible and expressive enough to implement
any design language. On iOS, you can use the
Cupertino library to produce an interface that adheres to the
Human Interface Guidelines.