波纹动画颤动

Posted 2023-02-23

【中文标题】波纹动画颤动

【英文标题】：Ripple animation flutter

【发布时间】：2019-08-31 20:56:10

【问题描述】：

我想使用颤振创建波纹动画。我已经知道涟漪效应，但这不是我想要的，我想要link

【参考方案1】：

输出

  AnimationController _controller;

  @override
  void initState() 
    super.initState();
    _controller = AnimationController(
      vsync: this,
      lowerBound: 0.5,
      duration: Duration(seconds: 3),
    )..repeat();
  

  @override
  Widget build(BuildContext context) 
    return Scaffold(
      appBar: AppBar(title: Text("Title")),
      body: _buildBody(),
    );
  

  Widget _buildBody() 
    return AnimatedBuilder(
      animation: CurvedAnimation(parent: _controller, curve: Curves.fastOutSlowIn),
      builder: (context, child) 
        return Stack(
          alignment: Alignment.center,
          children: <Widget>[
            _buildContainer(150 * _controller.value),
            _buildContainer(200 * _controller.value),
            _buildContainer(250 * _controller.value),
            _buildContainer(300 * _controller.value),
            _buildContainer(350 * _controller.value),
            Align(child: Icon(Icons.phone_android, size: 44,)),
          ],
        );
      ,
    );
  

  Widget _buildContainer(double radius) 
    return Container(
      width: radius,
      height: radius,
      decoration: BoxDecoration(
        shape: BoxShape.circle,
        color: Colors.blue.withOpacity(1 - _controller.value),
      ),
    );
  

【讨论】：

我需要更多帮助，我想将它与整个布局的底部中心对齐。我正在尝试但没有得到它

将AnimatedBuilder 包裹在Align 中并将alignment 更改为Alignment.bottomCenter

我做到了列小部件

这是一个非常好的答案。非常感谢！

with TickerProviderStateMixin 将此 mixin 添加到您的状态类中，如果您在 vsync 上遇到错误

【参考方案2】：

这是另一个使用CustomPaint的版本

import 'dart:math' as math show sin, pi, sqrt;

import 'package:flutter/animation.dart';
import 'package:flutter/material.dart';

class Ripples extends StatefulWidget 
  const Ripples(
    Key key,
    this.size = 80.0,
    this.color = Colors.pink,
    this.onPressed,
    @required this.child,
  ) : super(key: key);

  final double size;
  final Color color;
  final Widget child;
  final VoidCallback onPressed;

  @override
  _RipplesState createState() => _RipplesState();


class _CirclePainter extends CustomPainter 
  _CirclePainter(
    this._animation, 
    @required this.color,
  ) : super(repaint: _animation);

  final Color color;
  final Animation<double> _animation;

  void circle(Canvas canvas, Rect rect, double value) 
    final double opacity = (1.0 - (value / 4.0)).clamp(0.0, 1.0);
    final Color _color = color.withOpacity(opacity);

    final double size = rect.width / 2;
    final double area = size * size;
    final double radius = math.sqrt(area * value / 4);

    final Paint paint = Paint()..color = _color;
    canvas.drawCircle(rect.center, radius, paint);
  

  @override
  void paint(Canvas canvas, Size size) 
    final Rect rect = 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(_CirclePainter oldDelegate) => true;


class _RipplesState extends State<Ripples> with TickerProviderStateMixin 
  AnimationController _controller;

  @override
  void initState() 
    super.initState();
    _controller = AnimationController(
      duration: const Duration(milliseconds: 2000),
      vsync: this,
    )..repeat();
  

  @override
  void dispose() 
    _controller.dispose();
    super.dispose();
  

  Widget _button() 
    return Center(
      child: ClipRRect(
        borderRadius: BorderRadius.circular(widget.size),
        child: DecoratedBox(
          decoration: BoxDecoration(
            gradient: RadialGradient(
              colors: <Color>[
                widget.color,
                Color.lerp(widget.color, Colors.black, .05)
              ],
            ),
          ),
          child: ScaleTransition(
            scale: Tween(begin: 0.95, end: 1.0).animate(
              CurvedAnimation(
                parent: _controller,
                curve: const _PulsateCurve(),
              ),
            ),
            child: widget.child,
          ),
        ),
      ),
    );
  

  @override
  Widget build(BuildContext context) 
    return CustomPaint(
      painter: _CirclePainter(
        _controller,
        color: widget.color,
      ),
      child: SizedBox(
        width: widget.size * 2.125,
        height: widget.size * 2.125,
        child: _button(),
      ),
    );
  


class _PulsateCurve extends Curve 
  const _PulsateCurve();

  @override
  double transform(double t) 
    if (t == 0 || t == 1) 
      return 0.01;
    
    return math.sin(t * math.pi);
  

【讨论】：

老天...这么多样板对于一个简单的事情！

它并不像你想象的那么简单。这只是使用画家的替代实现。

信不信由你，这比公认的解决方案性能更高。 CustomPainter 是冗长的，但是是高性能的 AF，甚至这个块也比你应该只为此安装一个库的 java 解决方案更好

【参考方案3】：

你也可以使用这个源代码flutter_ripple_animation_demo来实现这个

只需将这些文件添加到您的项目中并像下面这样使用它们

例子在这里

import 'package:flutter/material.dart';
import 'package:flutter/animation.dart';
import 'package:rippledemo/circle_painter.dart';
import 'package:rippledemo/curve_wave.dart';


class RipplesAnimation extends StatefulWidget 
  const RipplesAnimation(Key key, this.size = 80.0, this.color = Colors.red,
    this.onPressed, @required this.child,) : super(key: key);
  final double size;
  final Color color;
  final Widget child;
  final VoidCallback onPressed;
  @override
  _RipplesAnimationState createState() => _RipplesAnimationState();


class _RipplesAnimationState extends State<RipplesAnimation> with TickerProviderStateMixin 
  AnimationController _controller;
  @override
  void initState() 
    super.initState();
    _controller = AnimationController(
      duration: const Duration(milliseconds: 2000),
      vsync: this,
    )..repeat();
  
  @override
  void dispose() 
    _controller.dispose();
    super.dispose();
  
  Widget _button() 
    return Center(
      child: ClipRRect(
        borderRadius: BorderRadius.circular(widget.size),
        child: DecoratedBox(
          decoration: BoxDecoration(
            gradient: RadialGradient(
              colors: <Color>[
                widget.color,
                Color.lerp(widget.color, Colors.black, .05)
              ],
            ),
          ),
          child: ScaleTransition(
              scale: Tween(begin: 0.95, end: 1.0).animate(
                CurvedAnimation(
                  parent: _controller,
                  curve: const CurveWave(),
                ),
              ),
              child: Icon(Icons.speaker_phone, size: 44,)
          ),
        ),
      ),
    );
  

  @override
  Widget build(BuildContext context) 
    return Scaffold(
      appBar: AppBar(
        title: Text("Flutter Ripple Demo"),
      ),
      body: Center(
        child: CustomPaint(
          painter: CirclePainter(
            _controller,
            color: widget.color,
          ),
          child: SizedBox(
            width: widget.size * 4.125,
            height: widget.size * 4.125,
            child: _button(),
          ),
        ),
      ),
    );