flutter开发实战-ListWheelScrollView与自定义TimePicker
最近在使用时间选择器的时候，需要自定义一个TimePicker效果，当然这里就使用了ListWheelScrollView。ListWheelScrollView与ListView类似，但ListWheelScrollView渲染效果类似滚筒效果。
一、ListWheelScrollView
基本用法
ListWheelScrollView({
super.key,
this.controller,
this.physics,
this.diameterRatio = RenderListWheelViewport.defaultDiameterRatio,
this.perspective = RenderListWheelViewport.defaultPerspective,
this.offAxisFraction = 0.0,
this.useMagnifier = false,
this.magnification = 1.0,
this.overAndUnderCenterOpacity = 1.0,
required this.itemExtent,
this.squeeze = 1.0,
this.onSelectedItemChanged,
this.renderChildrenOutsideViewport = false,
this.clipBehavior = Clip.hardEdge,
this.restorationId,
this.scrollBehavior,
required List<Widget> children,
})
ListWheelScrollView的一些属性，如children是子控件
- children是子控件，
- itemExtent是每个item的高度
- magnification是圆筒直径和主轴渲染窗口的尺寸比，默认值是2
- perspective是圆柱投影试图，为0表示从无限远处看，1表示从无限近处看。默认值0.003
- offAxisFraction表示圆筒水平偏移中心的程度
- magnification与useMagnifier放大镜，分辨设置放大镜与放大倍率。
- squeeze表示圆筒上子控件数量与在同等大小的平面上的子控件的数量之比。
看下ListWheelScrollView基本用法
Container(
height: 250,
child: ListWheelScrollView(
itemExtent: 50,
children: [
Container(
color: Colors.red,
),
Container(
color: Colors.orangeAccent,
),
Container(
color: Colors.yellow,
),
Container(
color: Colors.green,
),
Container(
color: Colors.teal,
),
Container(
color: Colors.blue,
),
Container(
color: Colors.purple,
),
],
),
)
效果图如下
如果将diameterRatio调整为1的
效果图如下
其他属性的效果可以逐个尝试一下。
如果使用的数据比较多时候，可以使用userDelegate方式, 使用ListWheelChildBuilderDelegate来指定builder与childCount.
Container(
height: 350,
child: ListWheelScrollView.useDelegate(
itemExtent: 50,
diameterRatio: 2,
childDelegate:
ListWheelChildBuilderDelegate(builder: (context, index) {
return Container(
color: Colors.lightBlue,
alignment: Alignment.center,
child: Text("$index",
style: TextStyle(color: Colors.white, shadows: [
Shadow(
color: Colors.black,
offset: Offset(.5, .5),
blurRadius: 2)
])),
);
}, childCount: 100),
),
);
效果图如下
当然还有一个ListWheelChildLoopingListDelegate可以表现出来循环滚动的效果
final List dataList = [
"第1行",
"第2行",
"第3行",
"第4行",
"第5行",
"第6行",
"第7行",
"第8行",
"第9行",
"第10行",
];
Widget buildChildItem(String text) {
return Container(
color: Colors.lightBlue,
alignment: Alignment.center,
child: Text("$text",
style: TextStyle(color: Colors.white, shadows: [
Shadow(
color: Colors.black,
offset: Offset(.5, .5),
blurRadius: 2)
])),
);
}
void testListWheelScrollViewDelegate(BuildContext context) {
showModalBottomSheet(
context: context,
isScrollControlled: true,
builder: (ctx) {
return Container(
height: 350,
child: ListWheelScrollView.useDelegate(
itemExtent: 50,
diameterRatio: 2,
childDelegate: ListWheelChildLoopingListDelegate(children: dataList.map((e) => buildChildItem(e)).toList())),
);
},
);
}
效果图如下
二、自定义TimePicker
自定义TimePicker使用ListWheelScrollView
自定义TimePicker有小时和分钟，左边显示小时，右边显示分钟。点击确定确认选择的时间，时间格式为10:20
onSelectedItemChanged来确认选择的item
完整代码如下
class CustomTimePicker extends StatefulWidget {
const CustomTimePicker({
super.key,
this.width,
this.height,
});
final double? width;
final double? height;
@override
State<CustomTimePicker> createState() => _CustomTimePickerState();
}
class _CustomTimePickerState extends State<CustomTimePicker> {
List<String> hourData = [];
List<String> minuteData = [];
String selectedHour = "";
String selectedminute = "";
@override
void initState() {
// TODO: implement initState
super.initState();
for (int i = 0; i < 24; i++) {
String hour = i.toString();
if (i < 10) {
hour = "0" + i.toString();
}
hourData.add(hour);
}
for (int i = 0; i < 60; i++) {
String minute = i.toString();
if (i < 10) {
minute = "0" + i.toString();
}
minuteData.add(minute);
}
}
@override
void dispose() {
// TODO: implement dispose
super.dispose();
}
Widget buildItem(String text) {
return Text(
text,
textAlign: TextAlign.center,
softWrap: true,
style: TextStyle(
fontSize: 20,
fontWeight: FontWeight.w500,
fontStyle: FontStyle.normal,
color: Color(0xFF333333),
decoration: TextDecoration.none,
),
);
}
@override
Widget build(BuildContext context) {
return Container(
width: widget.width,
height: widget.height,
color: Colors.white,
child: Column(
mainAxisAlignment: MainAxisAlignment.center,
children: [
Container(
width: widget.width,
height: 50,
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
TextButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Container(
height: 36,
width: 100,
color: Colors.transparent,
alignment: Alignment.center,
child: Text(
'取消',
style: TextStyle(fontSize: 15, color: Colors.black87),
),
),
),
Expanded(
child: Text(
'${selectedHour}:${selectedminute}',
textAlign: TextAlign.center,
style: TextStyle(fontSize: 16, color: Colors.black87),
),
),
TextButton(
onPressed: () {
Navigator.of(context).pop();
},
child: Container(
height: 36,
width: 100,
alignment: Alignment.center,
child: Text(
'确定',
style: TextStyle(fontSize: 15, color: Colors.blue),
),
),
),
],
),
),
Expanded(
child: Row(
mainAxisAlignment: MainAxisAlignment.center,
crossAxisAlignment: CrossAxisAlignment.center,
children: [
Container(
width: 150,
height: widget.height,
child: Scrollable(
axisDirection: AxisDirection.down,
physics: BouncingScrollPhysics(),
dragStartBehavior: DragStartBehavior.start,
viewportBuilder: (ctx, position) =>
ListWheelScrollView.useDelegate(
itemExtent: 44,
squeeze: 1,
diameterRatio: 3,
useMagnifier: true,
overAndUnderCenterOpacity: 0.8,
magnification: 1.1,
onSelectedItemChanged: (index) {
String hour = hourData[index];
print("hour:${hour}");
setState(() {
selectedHour = hour;
});
},
childDelegate: ListWheelChildLoopingListDelegate(
children:
hourData.map((e) => buildItem(e)).toList()),
),
),
),
Container(
width: 150,
height: widget.height,
child: Scrollable(
axisDirection: AxisDirection.down,
physics: BouncingScrollPhysics(),
dragStartBehavior: DragStartBehavior.start,
viewportBuilder: (ctx, position) =>
ListWheelScrollView.useDelegate(
itemExtent: 44,
squeeze: 1,
diameterRatio: 3,
useMagnifier: true,
overAndUnderCenterOpacity: 0.8,
magnification: 1.1,
onSelectedItemChanged: (index) {
String minute = minuteData[index];
print("minute:${minute}");
setState(() {
selectedminute = minute;
});
},
childDelegate: ListWheelChildLoopingListDelegate(
children:
minuteData.map((e) => buildItem(e)).toList()),
),
),
),
],
),
),
],
));
}
}
效果图如下
三、小结
flutter开发实战-ListWheelScrollView与自定义TimePicker
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