Flutter组件基础——Button

Flutter中常用的Button有ElevatedButton、TextButton、OutlinedButton，之前可能还有RaisedButton、FlatButton、OutlineButton，但是已被废弃，参考RaisedButton vs ElevatedButton, FlatButton vs TextButton and OutlineButton vs OutlinedButton

TextButton

TextButton可简单理解为按钮，即可点击的Text。

常用属性如下：

• TextButton常用属性：
  • autofocus
  • child
  • clipBehavior
  • enabled
  • focusNode
  • onLongPress
  • onPressed
  • style

来看一下，定义三个按钮，分别对应，按钮不可点击，按钮可点击，按钮带有渐变背景，三种情况，效果如下：

使用代码如下：

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: _title,
        home: Scaffold(
          appBar: AppBar(
            title: const Text(_title),
          ),
          body: const MyStatelessWidget(),
        ));
  }
}

class MyStatelessWidget extends StatelessWidget {
  const MyStatelessWidget({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          TextButton(
            onPressed: null,
            child: const Text('Disabled'),
            style: TextButton.styleFrom(
              textStyle: const TextStyle(fontSize: 20),
            ),
          ),
          const SizedBox(
            height: 30,
          ),
          TextButton(
            onPressed: () {},
            child: const Text('Enabled'),
            style: TextButton.styleFrom(
              textStyle: const TextStyle(fontSize: 20),
            ),
          ),
          const SizedBox(
            height: 30,
          ),
          ClipRRect(
            borderRadius: BorderRadius.circular(4),
            child: Stack(
              children: [
                Positioned.fill(
                  child: Container(
                    decoration: const BoxDecoration(
                      gradient: LinearGradient(
                        colors: [
                          Color(0xFF0D47A1),
                          Color(0xFF1976D2),
                          Color(0xFF42A5F5),
                        ],
                      ),
                    ),
                  ),
                ),
                TextButton(
                  onPressed: () {},
                  child: const Text('Gradient'),
                  style: TextButton.styleFrom(
                    padding: const EdgeInsets.all(16.0),
                    primary: Colors.white,
                    textStyle: const TextStyle(fontSize: 20),
                  ),
                ),
              ],
            ),
          )
        ],
      ),
    );
  }
}

注意渐变按钮的实现，使用了Stack。

ElevatedButton

• ElevatedButton的属性：
  • autofocus
  • child
  • clipBehavior
  • enabled
  • focusNode
  • key
  • onLongPress
  • onPressed
  • style

代码如下：

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
        title: _title,
        home: Scaffold(
          appBar: AppBar(
            title: const Text(_title),
          ),
          body: const MyStatefulWidget(),
        ));
  }
}

class MyStatefulWidget extends StatefulWidget {
  const MyStatefulWidget({Key? key}) : super(key: key);

  @override
  State<MyStatefulWidget> createState() => _MyStatefulWidgetState();
}

class _MyStatefulWidgetState extends State<MyStatefulWidget> {
  @override
  Widget build(BuildContext context) {
    final ButtonStyle style =
        ElevatedButton.styleFrom(textStyle: const TextStyle(fontSize: 20));

    return Center(
      child: Column(
        mainAxisSize: MainAxisSize.min,
        children: [
          ElevatedButton(
              onPressed: null, 
              child: const Text('Disabled'), 
              style: style,
          ),
          const SizedBox(
            height: 30,
          ),
          ElevatedButton(
            onPressed: () {},
            child: const Text('Enabled'),
            style: style,
          )
        ],
      ),
    );
  }
}

效果如下：

OutlinedButton

• OutlinedButton的属性如下：
  • autofocus
  • child
  • clipBehavior
  • enabled
  • focusNode
  • key
  • onLongPress
  • onPressed
  • style

代码如下：

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code Sample';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(
          title: const Text(_title),
        ),
        body: const Center(
          child: MyStatelessWidget(),
        ),
      ),
    );
  }
}

class MyStatelessWidget extends StatelessWidget {
  const MyStatelessWidget({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return OutlinedButton(
        onPressed: () {
          print('Received Click');
        },
        child: const Text('Click Me'));
  }
}

样式如下：

Ps: 可以试一下点击效果！

各个Button样式的对比：

参考

Text Button Api Doc
ElevatedButton Api Doc
OutlinedButton Api Doc
RaisedButton vs ElevatedButton, FlatButton vs TextButton and OutlineButton vs OutlinedButton