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the 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.
for the full set of these widgets,
see the cupertino widgets gallery.
you can also use a WidgetsApp as your app widget,
which provides some of the same functionality,
but is not as rich as MaterialApp.
to customize the colors and styles of any child components,
pass a ThemeData object to the MaterialApp widget.
for example, in the code below,
the color scheme from seed is set to deepPurple and divider color is grey.
<code_start>
import 'package:flutter/material.dart';
class SampleApp extends StatelessWidget {
const SampleApp({super.key});
@override
widget build(BuildContext context) {
return MaterialApp(
title: 'sample app',
theme: ThemeData(
colorScheme: ColorScheme.fromSeed(seedColor: Colors.deepPurple),
dividerColor: colors.grey,
),
home: const SampleAppPage(),
);
}
}
<code_end>
<topic_end>