global position
观察,
GestureDetector(
child: CustomPaint(painter: StudyPaint(points: _points)),
onPanEnd: (DragEndDetails details)=>_points.add(null),
onPanUpdate: (DragUpdateDetails details){
var a = details.globalPosition;
RenderBox referenceBox = context.findRenderObject();
Offset localPosition = referenceBox.globalToLocal(details.globalPosition);
print('a: $a, localposition: $localPosition');
setState(() {
_points = List.from(_points)..add(localPosition);
});
},
),
减了3个 h
import 'package:flutter/material.dart'; main() => runApp(MyApp()); class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
// TODO: implement build
return MaterialApp(
home: HomePage(),
);
}
} class HomePage extends StatefulWidget {
@override
State<StatefulWidget> createState() {
// TODO: implement createState
return HomePageState();
}
} class HomePageState extends State<HomePage> {
List<Offset> _points = <Offset>[]; @override
Widget build(BuildContext context) {
// print(_points);
var h = MediaQuery.of(context).padding.top;
var b = MediaQuery.of(context).padding.bottom;
// print('h: $h, b: $b'); return Scaffold(
appBar: AppBar(title: Text('Painter'),),
body: Container(
width: MediaQuery.of(context).size.width, height: MediaQuery.of(context).size.height-h,
child: Stack(
children: <Widget>[
GestureDetector(
// child:
onPanEnd: (DragEndDetails details)=>_points.add(null),
onPanUpdate: (DragUpdateDetails details){
var a = details.globalPosition;
var x = Offset(a.dx, a.dy-h-h-h);
RenderBox referenceBox = context.findRenderObject();
Offset localPosition = referenceBox.globalToLocal(details.globalPosition);
// print('a: $a, x: $x, localposition: $localPosition');
setState(() {
_points = List.from(_points)..add(x);
});
},
),
CustomPaint(painter: StudyPaint(points: _points)),
],
)
),
);
}
} class StudyPaint extends CustomPainter {
StudyPaint({this.points});
List<Offset> points; @override
void paint(Canvas canvas, Size size) {
print(points);
Paint paint = Paint()
..color = Colors.blue
..strokeCap = StrokeCap.round
..isAntiAlias = true
..strokeJoin = StrokeJoin.bevel
..strokeWidth = 12.0; for(int i=0; i<points.length; i++){
if(points[i]!=null && points[i+1]!=null)
canvas.drawLine(points[i], points[i+1], paint);
} } @override
bool shouldRepaint(StudyPaint other) => other.points!=points;
}
import 'package:flutter/material.dart'; main() => runApp(MyApp()); class MyApp extends StatelessWidget {
@override
Widget build(BuildContext context) {
// TODO: implement build
return MaterialApp(
home: HomePage(),
);
}
} class HomePage extends StatefulWidget {
@override
State<StatefulWidget> createState() {
// TODO: implement createState
return HomePageState();
}
} class HomePageState extends State<HomePage> {
List<Offset> _points = <Offset>[]; @override
Widget build(BuildContext context) {
// print(_points);
var h = MediaQuery.of(context).padding.top;
print('h: $h');
return Scaffold(
appBar: AppBar(title: Text('Painter'),),
body: Center(
child: Container(
width: double.infinity, height: double.infinity,
child: GestureDetector(
child: CustomPaint(painter: StudyPaint(points: _points)),
onPanEnd: (DragEndDetails details)=>_points.add(null),
onPanUpdate: (DragUpdateDetails details){
var a = details.globalPosition;
RenderBox referenceBox = context.findRenderObject();
Offset localPosition = referenceBox.globalToLocal(details.globalPosition);
print('a: $a, localposition: $localPosition');
setState(() {
_points = List.from(_points)..add(localPosition);
});
},
),
),
),
);
}
} class StudyPaint extends CustomPainter {
StudyPaint({this.points});
List<Offset> points; @override
void paint(Canvas canvas, Size size) {
Paint paint = Paint()
..color = Colors.blue
..strokeCap = StrokeCap.round
..isAntiAlias = true
..strokeWidth = 12.0
..strokeJoin = StrokeJoin.bevel; for(int i=0; i<points.length; i++){
if(points[i]!=null && points[i+1]!=null)
canvas.drawLine(points[i], points[i+1], paint);
} } @override
bool shouldRepaint(StudyPaint other) => other.points!=points;
}
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