Want to add a pulse animation in flutter? One way is with CustomPainter and an animation. Also look at SpriteWidget.
Example:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 | import 'dart:math'; import 'package:flutter/material.dart'; class SpritePainter extends CustomPainter { final Animation<double> _animation; SpritePainter(this._animation) : super(repaint: _animation); void circle(Canvas canvas, Rect rect, double value) { double opacity = (1.0 - (value / 4.0)).clamp(0.0, 1.0); Color color = new Color.fromRGBO(0, 117, 194, opacity); double size = rect.width / 2; double area = size * size; double radius = sqrt(area * value / 4); final Paint paint = new Paint()..color = color; canvas.drawCircle(rect.center, radius, paint); } @override void paint(Canvas canvas, Size size) { Rect rect = new Rect.fromLTRB(0.0, 0.0, size.width, size.height); for (int wave = 3; wave >= 0; wave--) { circle(canvas, rect, wave + _animation.value); } } @override bool shouldRepaint(SpritePainter oldDelegate) { return true; } } class SpriteDemo extends StatefulWidget { @override SpriteDemoState createState() => new SpriteDemoState(); } class SpriteDemoState extends State<SpriteDemo> with SingleTickerProviderStateMixin { AnimationController _controller; @override void initState() { super.initState(); _controller = new AnimationController( vsync: this, ); //_startAnimation(); } @override void dispose() { _controller.dispose(); super.dispose(); } void _startAnimation() { _controller.stop(); _controller.reset(); _controller.repeat( period: Duration(seconds: 1), ); } @override Widget build(BuildContext context) { return new Scaffold( appBar: new AppBar(title: const Text('Pulse')), body: new CustomPaint( painter: new SpritePainter(_controller), child: new SizedBox( width: 200.0, height: 200.0, ), ), floatingActionButton: new FloatingActionButton( onPressed: _startAnimation, child: new Icon(Icons.play_arrow), ), ); } } void main() { runApp( new MaterialApp( home: new SpriteDemo(), ), ); } |
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