Flutter-使用Flutter创建自定义控件 [英] Flutter - Creating a custom control with Flutter
问题描述
我需要创建一个自定义控件,该控件允许用户在有界矩形内拖动指针。非常类似于此操纵杆控件:
import'package:flutter / material.dart';
导入的 package:flutter / gestures.dart;
导入的 package:flutter / rendering.dart;
void main(){
runApp(new TouchTest());
}
类TouchTest扩展了StatelessWidget {
//此小部件是应用程序的根。
@override
小部件构建(BuildContext上下文){
返回新的MaterialApp(
标题:触摸测试,
主题:新的ThemeData(
primarySwatch :Colors.blue,
),
主页:new Scaffold(
appBar:new AppBar(
title:const Text('Test'),
),
正文:新Container(
装饰:new BoxDecoration(
颜色:Colors.white,
边框:new Border.all(
颜色:Colors。黑色,
宽度:2.0,
),
),
子级:new Center(
子级:new TouchControl()
),
),
)
);
}
}
类TouchControl扩展了StatefulWidget {
final double xPos;
最终双倍yPos;
final ValueChanged< Offset> onChanged;
const TouchControl({Key key,
this.onChanged,
this.xPos:0.0,
this.yPos:0.0}):超级(key:key );
@override
TouchControlState createState()=>新的TouchControlState();
}
/ **
*在提供的位置绘制一个圆圈。
*
* /
类TouchControlState扩展了State< TouchControl> {
double xPos = 0.0;
double yPos = 0.0;
GlobalKey _painterKey = new GlobalKey();
void onChanged(Offset offset){
final RenderBox referenceBox = context.findRenderObject();
偏移位置= referenceBox.globalToLocal(offset);
if(widget.onChanged!= null)
widget.onChanged(position);
setState((){
xPos = position.dx;
yPos = position.dy;
});
}
@override
bool hitTestSelf(Offset position)=>真正;
@override
void handleEvent(PointerEvent event,BoxHitTestEntry entry){
if(event is PointerDownEvent){
// ??
}
}
void _handlePanStart(DragStartDetails details){
onChanged(details.globalPosition);
}
void _handlePanEnd(DragEndDetails details){
print(’end’);
// TODO
}
void _handlePanUpdate(DragUpdateDetails details){
onChanged(details.globalPosition);
}
@override
小部件构建(BuildContext上下文){
返回new ConstrainedBox(
约束:new BoxConstraints.expand(),
子:new GestureDetector(
行为:HitTestBehavior.opaque,
onPanStart:_handlePanStart,
onPanEnd:_handlePanEnd,
onPanUpdate:_handlePanUpdate,
子级:new CustomPaint(
size:new Size(xPos,yPos),
画家:new TouchControlPainter(xPos,yPos),
),
),
);
}
}
类TouchControlPainter扩展了CustomPainter {
静态const markerRadius = 10.0;
最终双倍xPos;
最终双倍yPos;
TouchControlPainter(this.xPos,this.yPos);
@override
无效绘画(画布画布,大小大小){
最终绘画= new Paint()
..color = Colors.blue [400]
..style = PaintingStyle.fill;
canvas.drawCircle(new Offset(xPos,yPos),markerRadius,paint);
}
@override
bool shouldRepaint(TouchControlPainter old)=> xPos!= old.xPos& yPos!= old.yPos;
}
I need to create a custom control which allows a user to drag a pointer within a bounded rectangle. Very like this joystick control here :https://github.com/zerokol/JoystickView
I have managed to cobble something together using a CustomPainter to draw the control point and a GestureDetector to track where the user drags the pointer on the view. However, I can't get this to capture the panning input. I can't get it to capture any input at all. I don't know if what I am doing is the best approach. I could be on the totally wrong track. Here is the code.
import 'package:flutter/material.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/rendering.dart';
void main() {
runApp(new TouchTest());
}
class TouchTest extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Touch Test',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new Scaffold(
appBar: new AppBar(
title: const Text('Test'),
),
body: new Container(
decoration: new BoxDecoration(
color: Colors.white,
border: new Border.all(
color: Colors.black,
width: 2.0,
),
),
child: new Center(
child: new TouchControl()
),
),
)
);
}
}
class TouchControl extends StatefulWidget {
final double xPos;
final double yPos;
final ValueChanged<Offset> onChanged;
const TouchControl({Key key,
this.onChanged,
this.xPos:0.0,
this.yPos:0.0}) : super(key: key);
@override
TouchControlState createState() => new TouchControlState();
}
/**
* Draws a circle at supplied position.
*
*/
class TouchControlState extends State<TouchControl> {
double xPos = 0.0;
double yPos = 0.0;
GestureDetector _gestureDetector;
TouchControl() {
_gestureDetector = new GestureDetector(
onPanStart:_handlePanStart,
onPanEnd: _handlePanEnd,
onPanUpdate: _handlePanUpdate);
}
void onChanged(Offset offset) {
setState(() {
widget.onChanged(offset);
xPos = offset.dx;
yPos = offset.dy;
});
}
@override
bool hitTestSelf(Offset position) => true;
@override
void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
if (event is PointerDownEvent ) {
// ??
}
}
void _handlePanStart(DragStartDetails details) {
onChanged(details.globalPosition);
}
void _handlePanEnd(DragEndDetails details) {
// TODO
}
void _handlePanUpdate(DragUpdateDetails details) {
onChanged(details.globalPosition);
}
@override
Widget build(BuildContext context) {
return new Center(
child: new CustomPaint(
size: new Size(xPos, yPos),
painter: new TouchControlPainter(xPos, yPos),
),
);
}
}
class TouchControlPainter extends CustomPainter {
static const markerRadius = 10.0;
final double xPos;
final double yPos;
TouchControlPainter(this.xPos, this.yPos);
@override
void paint(Canvas canvas, Size size) {
final paint = new Paint()
..color = Colors.blue[400]
..style = PaintingStyle.fill;
canvas.drawCircle(new Offset(xPos, yPos), markerRadius, paint);
}
@override
bool shouldRepaint(TouchControlPainter old) => xPos != old.xPos && yPos !=old.yPos;
}
Your code isn't using the GestureDetector
anywhere.
You should use it to wrap the CustomPaint
the build()
function of TouchControlState
.
import 'package:flutter/material.dart';
import 'package:flutter/gestures.dart';
import 'package:flutter/rendering.dart';
void main() {
runApp(new TouchTest());
}
class TouchTest extends StatelessWidget {
// This widget is the root of your application.
@override
Widget build(BuildContext context) {
return new MaterialApp(
title: 'Touch Test',
theme: new ThemeData(
primarySwatch: Colors.blue,
),
home: new Scaffold(
appBar: new AppBar(
title: const Text('Test'),
),
body: new Container(
decoration: new BoxDecoration(
color: Colors.white,
border: new Border.all(
color: Colors.black,
width: 2.0,
),
),
child: new Center(
child: new TouchControl()
),
),
)
);
}
}
class TouchControl extends StatefulWidget {
final double xPos;
final double yPos;
final ValueChanged<Offset> onChanged;
const TouchControl({Key key,
this.onChanged,
this.xPos:0.0,
this.yPos:0.0}) : super(key: key);
@override
TouchControlState createState() => new TouchControlState();
}
/**
* Draws a circle at supplied position.
*
*/
class TouchControlState extends State<TouchControl> {
double xPos = 0.0;
double yPos = 0.0;
GlobalKey _painterKey = new GlobalKey();
void onChanged(Offset offset) {
final RenderBox referenceBox = context.findRenderObject();
Offset position = referenceBox.globalToLocal(offset);
if (widget.onChanged != null)
widget.onChanged(position);
setState(() {
xPos = position.dx;
yPos = position.dy;
});
}
@override
bool hitTestSelf(Offset position) => true;
@override
void handleEvent(PointerEvent event, BoxHitTestEntry entry) {
if (event is PointerDownEvent ) {
// ??
}
}
void _handlePanStart(DragStartDetails details) {
onChanged(details.globalPosition);
}
void _handlePanEnd(DragEndDetails details) {
print('end');
// TODO
}
void _handlePanUpdate(DragUpdateDetails details) {
onChanged(details.globalPosition);
}
@override
Widget build(BuildContext context) {
return new ConstrainedBox(
constraints: new BoxConstraints.expand(),
child: new GestureDetector(
behavior: HitTestBehavior.opaque,
onPanStart:_handlePanStart,
onPanEnd: _handlePanEnd,
onPanUpdate: _handlePanUpdate,
child: new CustomPaint(
size: new Size(xPos, yPos),
painter: new TouchControlPainter(xPos, yPos),
),
),
);
}
}
class TouchControlPainter extends CustomPainter {
static const markerRadius = 10.0;
final double xPos;
final double yPos;
TouchControlPainter(this.xPos, this.yPos);
@override
void paint(Canvas canvas, Size size) {
final paint = new Paint()
..color = Colors.blue[400]
..style = PaintingStyle.fill;
canvas.drawCircle(new Offset(xPos, yPos), markerRadius, paint);
}
@override
bool shouldRepaint(TouchControlPainter old) => xPos != old.xPos && yPos !=old.yPos;
}
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