Slider（每日Flutter 小部件）

const Slider({
  Key key,
  @required this.value,   //当前值
  @required this.onChanged,  //改变回调
  this.onChangeStart,
  this.onChangeEnd,
  this.min = 0.0,
  this.max = 1.0,
  this.divisions, //多少个刻度
  this.label,  //滑块上显示的文案
  this.activeColor,  //活动区域颜色
  this.inactiveColor, //非活动区域颜色
  this.semanticFormatterCallback, // 用于根据滑块值创建语义值的回调。例：semanticFormatterCallback: (double newValue) {return '${newValue.round()} dollars}';},

class SliderWidget extends StatefulWidget {
  SliderWidget({Key key}) : super(key: key);

  _SliderWidgetState createState() => _SliderWidgetState();
}

class _SliderWidgetState extends State<SliderWidget> {
  double _sliderValue = 0;

  @override
  Widget build(BuildContext context) {
    return Center(
      child: Slider(
          value: _sliderValue,
          onChanged: (double value) {
            setState(() {
              this._sliderValue = value;
            });
          },
          min: 0,
          max: 100,
          divisions: 100,
          label: '进度：$_sliderValue',
          activeColor: Colors.red,
          inactiveColor: Colors.purple,
          semanticFormatterCallback: (double value) {
            return '进度：$_sliderValue';
          }),
    );
  }
}