Created
March 14, 2018 18:25
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This gist shows the GestureDetector usage on latest dart 2 preview version
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import 'package:flutter/material.dart'; | |
class SignaturePainter extends CustomPainter { | |
SignaturePainter(this.points); | |
final List<Offset> points; | |
void paint(Canvas canvas, Size size) { | |
Paint paint = new Paint() | |
..color = Colors.black | |
..strokeCap = StrokeCap.round | |
..strokeWidth = 5.0; | |
for (int i = 0; i < points.length - 1; i++) { | |
if (points[i] != null && points[i + 1] != null) | |
canvas.drawLine(points[i], points[i + 1], paint); | |
} | |
} | |
bool shouldRepaint(SignaturePainter other) => other.points != points; | |
} | |
class Signature extends StatefulWidget { | |
SignatureState createState() => new SignatureState(); | |
} | |
class SignatureState extends State<Signature> { | |
List<Offset> _points = <Offset>[]; | |
Widget build(BuildContext context) { | |
return new Stack( | |
children: [ | |
GestureDetector( | |
onPanUpdate: (DragUpdateDetails details) { | |
RenderBox referenceBox = context.findRenderObject(); | |
Offset localPosition = | |
referenceBox.globalToLocal(details.globalPosition); | |
setState(() { | |
_points = new List.from(_points)..add(localPosition); | |
}); | |
}, | |
onPanEnd: (DragEndDetails details) => _points.add(null), | |
), | |
CustomPaint(painter: new SignaturePainter(_points)) | |
], | |
); | |
} | |
} | |
class DemoApp extends StatelessWidget { | |
Widget build(BuildContext context) => new Scaffold(body: new Signature()); | |
} | |
void main() => runApp(new MaterialApp(home: new DemoApp())); |
what about performance issue while drawing more points?
line 19 other.points != points; allways false.
thanks for a delightful piece of code. One doubt, I am showing appBar and body in my app.
But after using appBar, my touch position gets shifted down.
If I remove appBar, then no problems, but I need the appBar.
It's working fine on Full screen Container. But how to set bound within a Container?
@Amir-OffsureIt do you find the answer?
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How to get the signature that I need to send on my server?