我正在使用颤动
我有一个容器,其形状为圆圈,使用此代码
new Container(
width: 50.0,
height: 50.0,
decoration: new BoxDecoration(
shape: BoxShape.circle)
我想让这个圈子像这样在屏幕上移动
我该怎么办?谢谢
答案 0 :(得分:3)
您要找的是Draggable
小部件。然后,您可以使用传递的onDraggableCanceled
和可用于更新展示位置的偏移来处理翻译
onDraggableCanceled :(velocity,offset){
//update the position here
}
<强>更新强>
检查图像后,您需要&#34;将我放在这里&#34; part为DragTarget,其方法为onAccept
,当你拖放Draggable
答案 1 :(得分:1)
您可以使用Draggable
类来拖动要拖动的项目并将其放置或粘贴到屏幕上的某个位置,您必须使用DragTarget
类包装该项目。在DragTarget
类onAccept
中,您可以在其中编写逻辑。您也可以在这里引用我的代码
import 'package:flutter/material.dart';
void main() => runApp(new MyApp());
class MyApp extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Flutter Demo',
theme: new ThemeData(
primarySwatch: Colors.indigo,
),
home: new MyHomePage(title: 'Flutter Demo Drag Box'),
);
}
}
class MyHomePage extends StatelessWidget {
MyHomePage({Key key, this.title}) : super(key: key);
final String title;
@override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text(title),
),
body:
new DragGame(), // This trailing comma makes auto-formatting nicer for build methods.
);
}
}
class DragGame extends StatefulWidget {
@override
_DragGameState createState() => new _DragGameState();
}
class _DragGameState extends State<DragGame> {
int boxNumberIsDragged;
@override
void initState() {
boxNumberIsDragged = null;
super.initState();
}
@override
Widget build(BuildContext context) {
return new Container(
constraints: BoxConstraints.expand(),
color: Colors.grey,
child: new Stack(
children: <Widget>[
buildDraggableBox(1, Colors.red, new Offset(30.0, 100.0)),
buildDraggableBox(2, Colors.yellow, new Offset(30.0, 200.0)),
buildDraggableBox(3, Colors.green, new Offset(30.0, 300.0)),
],
));
}
Widget buildDraggableBox(int boxNumber, Color color, Offset offset) {
return new Draggable(
maxSimultaneousDrags: boxNumberIsDragged == null || boxNumber == boxNumberIsDragged ? 1 : 0,
child: _buildBox(color, offset),
feedback: _buildBox(color, offset),
childWhenDragging: _buildBox(color, offset, onlyBorder: true),
onDragStarted: () {
setState((){
boxNumberIsDragged = boxNumber;
});
},
onDragCompleted: () {
setState((){
boxNumberIsDragged = null;
});
},
onDraggableCanceled: (_,__) {
setState((){
boxNumberIsDragged = null;
});
},
);
}
Widget _buildBox(Color color, Offset offset, {bool onlyBorder: false}) {
return new Container(
height: 50.0,
width: 50.0,
margin: EdgeInsets.only(left: offset.dx, top: offset.dy),
decoration: BoxDecoration(
color: !onlyBorder ? color : Colors.grey,
border: Border.all(color: color)),
);
}
}
答案 2 :(得分:1)
这里是:
import 'package:flutter/material.dart';
class SecondScreen extends StatelessWidget {
@override
Widget build(BuildContext context) {
return MaterialApp(
home: Scaffold(
appBar: AppBar(
title: Text("Drag app"),
),
body: HomePage(),
),
);
}
}
class HomePage extends StatefulWidget {
@override
State<StatefulWidget> createState() {
return _HomePageState();
}
}
class _HomePageState extends State<HomePage> {
double width = 100.0, height = 100.0;
Offset position ;
@override
void initState() {
super.initState();
position = Offset(0.0, height - 20);
}
@override
Widget build(BuildContext context) {
return Stack(
children: <Widget>[
Positioned(
left: position.dx,
//top: position.dy - height + 20,
child: Draggable(
child: Container(
width: width,
height: height,
color: Colors.blue,
child: Center(child: Text("Drag", style: Theme.of(context).textTheme.headline,),),
),
feedback: Container(
child: Center(
child: Text("Drag", style: Theme.of(context).textTheme.headline,),),
color: Colors.red[800],
width: width,
height: height,
),
onDraggableCanceled: (Velocity velocity, Offset offset){
setState(() => position = offset);
},
),
),
],
);
}
}
答案 3 :(得分:0)
这是执行此操作的整个过程
首先,我们构建骨架应用程序。然后,我们可以将多个框嵌入到此框架中,每个框都有一个Offset
,一个Color
和一个Label
string
。 Offset
确定框在给定时刻的位置,并具有初始状态和根据用户将框拖动到的位置来更新状态。
然后创建一个使用static UI element
的{{1}}。我们可以将DragTarget Class
拖到此Draggable Boxes
上,以将其颜色更改为DragTarget widget
的颜色。
完整示例:
Draggable Box
答案 4 :(得分:-1)
首先,用Container
将Stack
包裹在Positioned
内。
然后,使用Pan Gesture
在Pan
中实现Container
,并使用onPan...
方法来处理Pan Gesture
这是代码:
偏移位置;
@override
void initState() {
super.initState();
position = Offset(10, 10);
}
@override
Widget build(BuildContext context) {
double _width = MediaQuery.of(context).size.width;
double _height = _width * 9 / 16;
return GestureDetector(
onPanStart: (details) => _onPanStart(context, details),
onPanUpdate: (details) => _onPanUpdate(context, details, position),
onPanEnd: (details) => _onPanEnd(context, details),
onPanCancel: () => _onPanCancel(context),
child: SafeArea(
child: Stack(
children: <Widget>[
Positioned(
top: position.dy,
child: Container(
color: Colors.red,
width: _width,
height: _height,
),
),
],
),
),
);
}
void _onPanStart(BuildContext context, DragStartDetails details) {
print(details.globalPosition.dy);
}
void _onPanUpdate(BuildContext context, DragUpdateDetails details, Offset offset) {
setState(() {
position = details.globalPosition;
});
}
void _onPanEnd(BuildContext context, DragEndDetails details) {
print(details.velocity);
}
void _onPanCancel(BuildContext context) {
print("Pan canceled !!");
}
希望这会有所帮助!