大佬教程收集整理的这篇文章主要介绍了【Flutter 实战】自定义动画-涟漪和雷达扫描,大佬教程大佬觉得挺不错的,现在分享给大家,也给大家做个参考。
实现涟漪动画效果如下:
此动画通过 CustomPainter 绘制配合 AnimationController 动画控制实现,定义动画控制部分:
class WaterRipple extends StatefulWidget {
final int count;
final Color color;
const WaterRipple({Key key,this.count = 3,this.color = const color(0xFF0080ff)}) : super(key: key);
@override
_WaterRippleState createState() => _WaterRippleState();
}
class _WaterRippleState extends State<WaterRipple>
with SingleTickerProviderStatemixin {
AnimationController _controller;
@override
void initState() {
_controller =
AnimationController(vsync: this,duration: Duration(milliseconds: 2000))
..repeat();
super.initState();
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return AnimatedBuilder(
animation: _controller,builder: (context,child) {
return CustomPaint(
painter: WaterRipplePainter(_controller.value,count: widget.count,color: widget.color),);
},);
}
}
count 和 color 分别代表水波纹的数量和颜色。
WaterRipplePainter 定义如下:
class WaterRipplePainter extends CustomPainter {
final double progress;
final int count;
final Color color;
Paint _paint = Paint()..style = PainTingStyle.fill;
WaterRipplePainter(this.progress,{this.count = 3,this.color = const color(0xFF0080ff)});
@override
void paint(Canvas canvas,Size sizE) {
double radius = min(size.width / 2,size.height / 2);
for (int i = count; i >= 0; i--) {
final double opacity = (1.0 - ((i + progress) / (count + 1)));
final Color _color = color.withOpacity(opacity);
_paint..color = _color;
double _radius = radius * ((i + progress) / (count + 1));
canvas.drawCircle(
Offset(size.width / 2,size.height / 2),_radius,_paint);
}
}
@override
bool shouldRepaint(CustomPainter oldDelegatE) {
return true;
}
}
重点是 paint 方法,根据动画进度计算颜色的透明度和半径。
使用如下:
class WaterRipplePage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
body: Center(
child: Container(height: 200,width: 200,child: WaterRipple())),);
}
}
实现雷达扫描效果:
中间的 logo 图片边缘有阴影效果,像是太阳发光一样,实现:
Container(
height: 70.0,width: 70.0,decoration: BoxDecoration(
color: Colors.grey,image: DecorationImage(
image: AssetImage('assets/images/logo.png')),shape: BoxShape.circle,BoxShadow: [
BoxShadow(
color: Colors.white.withOpacity(.5),blurRadius: 5.0,spreadRadius: 3.0,),]),)
定义雷达扫描的动画控制器:
class RadarView extends StatefulWidget {
@override
_RadarViewState createState() => _RadarViewState();
}
class _RadarViewState extends State<RadarView>
with SingleTickerProviderStatemixin {
AnimationController _controller;
Animation<double> _animation;
@override
void initState() {
_controller =
AnimationController(vsync: this,duration: Duration(seconds: 5));
_animation = Tween(begin: .0,end: pi * 2).animate(_controller);
_controller.repeat();
super.initState();
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
return AnimatedBuilder(
animation: _animation,child) {
return CustomPaint(
painter: RadarPainter(_animation.value),);
}
}
RadarPainter 定义如下:
class RadarPainter extends CustomPainter {
final double angle;
Paint _bgPaint = Paint()
..color = Colors.white
..strokeWidth = 1
..style = PainTingStyle.stroke;
Paint _paint = Paint()..style = PainTingStyle.fill;
int circleCount = 3;
RadarPainter(this.anglE);
@override
void paint(Canvas canvas,Size sizE) {
var radius = min(size.width / 2,size.height / 2);
canvas.drawLine(Offset(size.width / 2,size.height / 2 - radius),Offset(size.width / 2,size.height / 2 + radius),_bgPaint);
canvas.drawLine(Offset(size.width / 2 - radius,Offset(size.width / 2 + radius,_bgPaint);
for (var i = 1; i <= circleCount; ++i) {
canvas.drawCircle(Offset(size.width / 2,radius * i / circleCount,_bgPaint);
}
_paint.shader = ui.Gradient.sweep(
Offset(size.width / 2,[Colors.white.withOpacity(.01),Colors.white.withOpacity(.5)],[.0,1.0],TileMode.clamp,.0,pi / 12);
canvas.save();
double r = sqrt(pow(size.width,2) + pow(size.height,2));
double startAngle = atan(size.height / size.width);
Point p0 = Point(r * cos(startAnglE),r * sin(startAnglE));
Point px = Point(r * cos(angle + startAnglE),r * sin(angle + startAnglE));
canvas.translate((p0.x - px.X) / 2,(p0.y - px.y) / 2);
canvas.rotate(anglE);
canvas.drawArc(
Rect.fromCircle(
center: Offset(size.width / 2,radius: radius),pi / 12,true,_paint);
canvas.restore();
}
@override
bool shouldRepaint(CustomPainter oldDelegatE) {
return true;
}
}
将两者结合在一起:
class RadarPage extends StatelessWidget {
@override
Widget build(BuildContext context) {
return Scaffold(
BACkgroundColor: Color(0xFF0F1532),body: Stack(
children: [
Positioned.fill(
left: 10,right: 10,child: Center(
child: Stack(children: [
Positioned.fill(
child: RadarView(),Positioned(
child: Center(
child: Container(
height: 70.0,decoration: BoxDecoration(
color: Colors.grey,image: DecorationImage(
image: AssetImage('assets/images/logo.png')),BoxShadow: [
BoxShadow(
color: Colors.white.withOpacity(.5),)
],));
}
}
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