【Flutter 专题】62 图解基本 Button 按钮小结 (二)

和尚继续尝试 Flutter 的基本按钮;今天和尚学习 MaterialButton 系列相关 Button;该系列以 MaterialButton 为父类,衍生出 RaisedButton 凸起按钮,FlatButton 扁平按钮和 OutlineButton 边框按钮;可根据不同场景灵活运用;

MaterialButton

源码分析
const MaterialButton({
    Key key,
    @required this.onPressed,
    this.onHighlightChanged,        // 高亮变化的回调
    this.textTheme,                 // 文字主题
    this.textColor,                 // 文字颜色
    this.disabledTextColor,         // 不可点击时文字颜色
    this.color,                     // 背景色
    this.disabledColor,             // 不可点击时背景色
    this.highlightColor,            // 点击高亮时背景色
    this.splashColor,               // 水波纹颜色
    this.colorBrightness,
    this.elevation,                 // 阴影高度
    this.highlightElevation,        // 高亮时阴影高度
    this.disabledElevation,         // 不可点击时阴影高度
    this.padding,                   // 内容周围边距
    this.shape,                     // 按钮样式
    this.clipBehavior = Clip.none,  // 抗锯齿剪切效果
    this.materialTapTargetSize,     // 点击目标的最小尺寸
    this.animationDuration,         // 动画效果持续时长
    this.minWidth,                  // 最小宽度
    this.height,                    // 按钮高度
    this.child,
 })

分析源码可知,MaterialButton 作为其他 Button 父类,各属性比较清晰明了,有 hight 属性可设置 Button 高度,其子类 Button 只可通过 padding 或其他方式调整高度;

案例尝试

和尚测试发现 hight 可以设置 MaterialButton 高度,但 shape 按钮形状却不适用;其父类 RawMaterialButton 却正常;和尚尝试网上大神的处理方式是外层依赖 Material 并需要 clip 裁切成 shape 样式;有待进一步学习;

Material(
    shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(30.0)),
    clipBehavior: Clip.antiAlias,
    child: MaterialButton(
        color: Colors.teal.withOpacity(0.4),
        height: 60.0,
        child: Text('MaterialButton'),
        onPressed: () {}))

RaisedButton / FlatButton

源码分析
const RaisedButton({
    Key key,
    @required VoidCallback onPressed,
    ValueChanged<bool> onHighlightChanged,
    ButtonTextTheme textTheme,          // 按钮文字主题
    Color textColor,                    // 子元素颜色
    Color disabledTextColor,            // 不可点击时子元素颜色
    Color color,                        // 按钮背景色
    Color disabledColor,                // 不可点击时按钮背景色
    Color highlightColor,               // 点击高亮时按钮背景色
    Color splashColor,                  // 水波纹颜色
    Brightness colorBrightness,         // 颜色对比度
    double elevation,                   // 阴影高度
    double highlightElevation,          // 高亮时阴影高度
    double disabledElevation,           // 不可点击时阴影高度
    EdgeInsetsGeometry padding,         // 子元素周围边距
    ShapeBorder shape,                  // 按钮样式
    Clip clipBehavior = Clip.none,      // 抗锯齿剪切效果
    MaterialTapTargetSize materialTapTargetSize,
    Duration animationDuration,         // 动画时长
    Widget child,
})

const FlatButton({
    Key key,
    @required VoidCallback onPressed,
    ValueChanged<bool> onHighlightChanged,
    ButtonTextTheme textTheme,          // 按钮文字主题
    Color textColor,                    // 子元素颜色
    Color disabledTextColor,            // 不可点击时子元素颜色
    Color color,                        // 按钮背景色
    Color disabledColor,                // 不可点击时按钮背景色
    Color highlightColor,               // 点击高亮时按钮背景色
    Color splashColor,                  // 水波纹颜色
    Brightness colorBrightness,         // 颜色对比度
    EdgeInsetsGeometry padding,         // 子元素周围边距
    ShapeBorder shape,                  // 按钮样式
    Clip clipBehavior = Clip.none,      // 抗锯齿剪切效果
    MaterialTapTargetSize materialTapTargetSize,
    @required Widget child,
  })

分析源码可知,RaisedButtonFlatButton 基本完全相同,只是 RaisedButton 多了一些阴影高度的特有属性,和尚准备同时对两类 Button 进行尝试,比较两者的不同;

案例尝试
  1. 和尚首先尝试最基本的 RaisedButton / FlatButton 可点击和不可点击样式;
// 可点击
RaisedButton(child: Text('RaisedButton'), onPressed: () => Toast.show('RaisedButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
FlatButton(child: Text('FlatButton'), onPressed: () => Toast.show('FlatButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))

// 不可点击
RaisedButton(child: Text('RaisedButton'), onPressed: null)
FlatButton(child: Text('FlatButton'), onPressed: null)
  1. ButtonTextTheme 为默认子元素主题,可以设置基本的三种主题样式:nomal 对应 [ThemeData.brightness]primary 对应 [ThemeData.primaryColor]accent 对应 [ThemeData.accentColor];展示效果比较明显;
RaisedButton(child: Text('R.nomal'), textTheme: ButtonTextTheme.normal, onPressed: () => Toast.show('RaisedButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
RaisedButton(child: Text('R.primary'), textTheme: ButtonTextTheme.primary, onPressed: () => Toast.show('RaisedButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
RaisedButton(child: Text('R.accent'), textTheme: ButtonTextTheme.accent, onPressed: () => Toast.show('RaisedButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))

FlatButton(child: Text('F.nomal'), textTheme: ButtonTextTheme.normal, onPressed: () => Toast.show('FlatButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
FlatButton(child: Text('F.primary'), textTheme: ButtonTextTheme.primary, onPressed: () => Toast.show('FlatButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
FlatButton(child: Text('F.accent'), textTheme: ButtonTextTheme.accent, onPressed: () => Toast.show('FlatButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))

OutlineButton(child: Text('O.nomal'), textTheme: ButtonTextTheme.normal, onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
OutlineButton(child: Text('O.primary'), textTheme: ButtonTextTheme.primary, onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
OutlineButton(child: Text('O.accent'), textTheme: ButtonTextTheme.accent, onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
  1. textColor 为子 Widget 中元素颜色,不仅为文字颜色;disabledTextColor 为不可点击时子 Widget 元素颜色;splashColor 为点击时水波纹颜色;
// 可点击
RaisedButton(child: Row(mainAxisSize: MainAxisSize.min,
        children: <Widget>[ Padding(child: Icon(Icons.ac_unit), padding: EdgeInsets.only(right: 10.0)), Text('RaisedButton') ]),
    textColor: Colors.deepPurple, onPressed: () => {})
FlatButton(child: Row(mainAxisSize: MainAxisSize.min,
        children: <Widget>[ Padding(child: Icon(Icons.ac_unit), padding: EdgeInsets.only(right: 10.0)), Text('FlatButton') ]),
    textColor: Colors.deepPurple, onPressed: () => {})

// 不可点击
RaisedButton(child: Row(mainAxisSize: MainAxisSize.min,
        children: <Widget>[ Padding(child: Icon(Icons.ac_unit), padding: EdgeInsets.only(right: 10.0)), Text('RaisedButton') ]),
    textColor: Colors.deepPurple, onPressed: null)
FlatButton(child: Row(mainAxisSize: MainAxisSize.min,
        children: <Widget>[ Padding(child: Icon(Icons.ac_unit), padding: EdgeInsets.only(right: 10.0)), Text('FlatButton') ]),
    textColor: Colors.deepPurple, onPressed: null)
  1. colorButton 背景色;highlightColor 为点击时高亮背景色;disabledColor 为不可点击时背景色;
// 可点击
RaisedButton(child: Text('RaisedButton'), onPressed: () => {},
    color: Colors.green.withOpacity(0.4), highlightColor: Colors.purple.withOpacity(0.4),
    splashColor: Colors.yellow.withOpacity(0.7))
FlatButton(child: Text('FlatButton'), onPressed: () => {},
    color: Colors.green.withOpacity(0.4), highlightColor: Colors.purple.withOpacity(0.4),
    splashColor: Colors.yellow.withOpacity(0.7))

// 不可点击
RaisedButton(child: Text('RaisedButton'), onPressed: null, disabledColor: Colors.red.withOpacity(0.4))
FlatButton(child: Text('FlatButton'), onPressed: null, disabledColor: Colors.red.withOpacity(0.4),)
  1. shapeButton 形状;因按钮没有 Materialhight 属性,需要采用 padding 或外层依赖其他 Widget 调整按钮大小;
RaisedButton(child: Text('RaisedButton'), onPressed: () => {}
    padding: EdgeInsets.all(16.0),
    shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(30.0))))
FlatButton(child: Text('FlatButton'), onPressed: () => {}
    padding: EdgeInsets.all(16.0),
    shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(30.0))))
  1. colorBrightness 代表颜色对比度,一般分为 light / dark 两种;一般时深色的背景需要浅色的文字对比,浅色的背景需要深色的文字对比;
// 可点击
RaisedButton(child: Text('R.light'), colorBrightness: Brightness.light, onPressed: () => {})
RaisedButton(child: Text('R.dark'), colorBrightness: Brightness.dark, onPressed: () => {})
FlatButton(child: Text('F.light'), colorBrightness: Brightness.light, onPressed: () => {})
FlatButton(child: Text('F.dark'), colorBrightness: Brightness.dark, onPressed: () => {})

// 不可点击
RaisedButton(child: Text('R.light'), colorBrightness: Brightness.light, onPressed: null)
RaisedButton(child: Text('R.dark'), colorBrightness: Brightness.dark, onPressed: null)
FlatButton(child: Text('F.light'), colorBrightness: Brightness.light, onPressed: null)
FlatButton(child: Text('F.dark'), colorBrightness: Brightness.dark, onPressed: null)
  1. RaisedButton / FlatButton 均提供了 .icon 带图标的简单方式,icon / label 两个属性是必须属性;注意,.icon 方式中 RaisedButton 没有 padding 属性;
RaisedButton.icon(icon: Icon(Icons.ac_unit), label: Text('RaisedButton'),
    shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(30.0))), onPressed: () => {})
FlatButton.icon(icon: Icon(Icons.ac_unit), label: Text('FlatButton'),
    padding: EdgeInsets.all(16.0),
    shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(30.0))), onPressed: () => {})
  1. elevationRaisedButton 所特有的阴影高度;highlightElevation 为高亮时阴影高度;disabledColor 为不可点击时阴影高度;
RaisedButton(child: Text('阴影'), elevation: 20.0, onPressed: () => {})
RaisedButton(child: Text('阴影'), elevation: 0.0, highlightElevation: 20.0, onPressed: () => {})
RaisedButton(child: Text('阴影'), disabledElevation: 20.0, onPressed: null)

OutlineButton

源码分析
const OutlineButton({
    Key key,
    @required VoidCallback onPressed,
    ButtonTextTheme textTheme,          // 按钮文字主题
    Color textColor,                    // 文字颜色
    Color disabledTextColor,            // 不可点击时文字颜色
    Color color,                        // 按钮背景色
    Color highlightColor,               // 高亮时颜色
    Color splashColor,                  // 水波纹颜色
    double highlightElevation,          // 高亮时阴影高度
    this.borderSide,                    // 边框样式
    this.disabledBorderColor,           // 不可点击时边框颜色
    this.highlightedBorderColor,        // 高亮时边框颜色
    EdgeInsetsGeometry padding,         // 内容周围边距
    ShapeBorder shape,                  // 按钮样式
    Clip clipBehavior = Clip.none,      // 抗锯齿剪切效果
    Widget child,
})

分析源码可知,OutlineButton 与其他两种按钮略有不同,强调边框的样式属性且无长按的 tooltip 属性;

案例尝试
  1. 和尚首先尝试一个最基本的 OutlineButton;长按无提醒;
OutlineButton(child: Text('OutlineButton'), onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
  1. 和尚尝试与其他按钮相同的几类按钮属性,使用方式相同;
OutlineButton(
    child: Row(mainAxisSize: MainAxisSize.min, children: <Widget>[
      Padding(child: Icon(Icons.ac_unit), padding: EdgeInsets.only(right: 10.0)),
      Text('OutlineButton')
    ]),
    textColor: Colors.pink,
    disabledTextColor: Colors.green,
    padding: EdgeInsets.all(20.0),
    color: Colors.blueAccent.withOpacity(0.2),
    highlightColor: Colors.amber,
    borderSide: BorderSide(width: 4.0),
    highlightedBorderColor: Colors.brown,
    disabledBorderColor: Colors.greenAccent,
    shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(50.0))),
    clipBehavior: Clip.none,
    onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
  1. 以下为 OutlineButton 特有属性:borderSide 代表边框样式;disabledBorderColor 代表不可点击时边框颜色;highlightedBorderColor 代表高亮时边框颜色;其中 borderSide 可以设置边框颜色宽度及样式(solid / none);
OutlineButton(child: Text('OutlineButton'),
    borderSide: BorderSide(width: 4.0, color: Colors.deepPurple, style: BorderStyle.solid),
    highlightedBorderColor: Colors.teal,
    onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))

OutlineButton(child: Text('OutlineButton'),
    borderSide: BorderSide(width: 4.0, color: Colors.deepPurple, style: BorderStyle.solid),
    disabledBorderColor: Colors.redAccent,
    onPressed: null)
  1. OutlineButton 还提供了 .icon 带图标的简单方式,icon / label 两个属性是必须属性;
OutlineButton.icon(
    icon: Icon(Icons.ac_unit),
    label: Text('OutlineButton'),
    textColor: Colors.pink,
    disabledTextColor: Colors.green,
    padding: EdgeInsets.all(20.0),
    color: Colors.blueAccent.withOpacity(0.2),
    highlightColor: Colors.amber,
    borderSide: BorderSide(width: 4.0),
    highlightedBorderColor: Colors.brown,
    disabledBorderColor: Colors.greenAccent,
    shape: RoundedRectangleBorder(borderRadius: BorderRadius.all(Radius.circular(50.0))),
    clipBehavior: Clip.none,
    onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))

扩展

1. textColor 的作用?

和尚原来以为按钮的子元素是 Widget,可自由设置各类效果,单独的 textColor 是否会略显多余;可实际并非如此,子元素设置颜色等之后 textColor 不生效;但 textColor 与主题相关;和尚以 OutlineButton 为例,一目了然;

// Text 设置颜色
OutlineButton(
    child: Text('OutlineButton', style: TextStyle(color: Colors.deepPurple)),
    onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))
// textColor 设置颜色 
OutlineButton(
    child: Text('OutlineButton'), textColor: Colors.deepPurple,
    onPressed: () => Toast.show('OutlineButton', context, duration: Toast.LENGTH_SHORT, gravity: Toast.BOTTOM))

2. 阴影如何改颜色?

使用 RaisedButton 时会自带阴影效果,阴影的高度和高亮时的阴影高度均可自由设置;但是阴影的颜色应该如何处理呢,官方暂未提供阴影效果属性;和尚尝试了网上大神的方式,RaisedButton 外层依赖带模糊阴影效果的 Container;和尚借鉴并稍微调整一下,解决方案并非最佳,仅作尝试;

初始时定义一个默认的高度 height 作为阴影高度,监听按钮的 onHighlightChanged 方法更改 height 高度作为高亮时阴影高度;

建议: a. 使用高亮颜色时 highlightElevation 建议设置为 0.0; b. 若按钮有样式设置,依赖的 Container 也要设置相同的 shape 样式;

var height = 5.0;
Container(
    decoration: BoxDecoration(
        borderRadius: BorderRadius.circular(30.0),
        boxShadow: <BoxShadow>[
          BoxShadow(
              color: Colors.red.withOpacity(0.2),
              blurRadius: hight,
              offset: Offset(0, hight))
        ]),
    child: RaisedButton(
        child: Text('RaisedButton'),
        padding: EdgeInsets.symmetric(vertical: 15.0),
        highlightElevation: 0.0,
        onHighlightChanged: (state) {
          setState(() {
            hight = (state) ? 20.0 : 5.0;
          });
        },
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(30.0)),
        onPressed: () => {}))

原文发布于微信公众号 - 阿策小和尚(gh_8297e718c166)

原文发表时间:2019-09-23

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