效果

简介

仿抖音点赞手势，单击暂停，双击点赞，可连续点击添加多个爱心，特点如下

全部效果为代码绘制(爱心图标来自Material Icon的图标)

套上在目标Widget外即可使用

提供单击与点赞的回调

建议复制代码使用，动画可按需修改

没有flutter之外的依赖项，可复制使用(懒得发pub)

基本原理

一个罩在child上的stack层，双击后根据坐标添加目标爱心Widget，爱心Widget在出现时会播放动画，用坐标作为key，动画结束后移除已经消失的爱心。

全部代码

什么都不依赖，可以直接复制使用。

import 'dart:async';

import 'dart:math';

import 'package:flutter/material.dart';

/// 视频手势封装

/// 单击：暂停

/// 双击：点赞，双击后再次单击也是增加点赞爱心

class TikTokVideoGesture extends StatefulWidget {

const TikTokVideoGesture({

Key key,

@required this.child,

this.onAddFavorite,

this.onSingleTap,

}) : super(key: key);

final Function onAddFavorite;

final Function onSingleTap;

final Widget child;

@override

_TikTokVideoGestureState createState() => _TikTokVideoGestureState();

}

class _TikTokVideoGestureState extends State {

GlobalKey _key = GlobalKey();

// 内部转换坐标点

Offset _p(Offset p) {

RenderBox getBox = _key.currentContext.findRenderObject();

return getBox.globalToLocal(p);

}

List icons = [];

bool canAddFavorite = false;

bool justAddFavorite = false;

Timer timer;

@override

Widget build(BuildContext context) {

var iconStack = Stack(

children: icons

.map(

(p) => TikTokFavoriteAnimationIcon(

key: Key(p.toString()),

position: p,

onAnimationComplete: () {

icons.remove(p);

},

),

)

.toList(),

);

return GestureDetector(

key: _key,

onTapDown: (detail) {

setState(() {

if (canAddFavorite) {

print('添加爱心，当前爱心数量:${icons.length}');

icons.add(_p(detail.globalPosition));

widget.onAddFavorite?.call();

justAddFavorite = true;

} else {

justAddFavorite = false;

}

});

},

onTapUp: (detail) {

timer?.cancel();

var delay = canAddFavorite ? 1200 : 600;

timer = Timer(Duration(milliseconds: delay), () {

canAddFavorite = false;

timer = null;

if (!justAddFavorite) {

widget.onSingleTap?.call();

}

});

canAddFavorite = true;

},

onTapCancel: () {

print('onTapCancel');

},

child: Stack(

children: [

widget.child,

iconStack,

],

),

);

}

}

class TikTokFavoriteAnimationIcon extends StatefulWidget {

final Offset position;

final double size;

final Function onAnimationComplete;

const TikTokFavoriteAnimationIcon({

Key key,

this.onAnimationComplete,

this.position,

this.size: 100,

}) : super(key: key);

@override

_TikTokFavoriteAnimationIconState createState() =>

_TikTokFavoriteAnimationIconState();

}

class _TikTokFavoriteAnimationIconState

extends State with TickerProviderStateMixin {

AnimationController _animationController;

@override

void dispose() {

_animationController?.dispose();

super.dispose();

}

@override

void didChangeDependencies() {

print('didChangeDependencies');

super.didChangeDependencies();

}

@override

void initState() {

_animationController = AnimationController(

lowerBound: 0,

upperBound: 1,

duration: Duration(milliseconds: 1600),

vsync: this,

);

_animationController.addListener(() {

setState(() {});

});

startAnimation();

super.initState();

}

startAnimation() async {

await _animationController.forward();

widget.onAnimationComplete?.call();

}

double rotate = pi / 10.0 * (2 * Random().nextDouble() - 1);

double get value => _animationController?.value;

double appearDuration = 0.1;

double dismissDuration = 0.8;

double get opa {

if (value < appearDuration) {

return 0.99 / appearDuration * value;

}

if (value < dismissDuration) {

return 0.99;

}

var res = 0.99 - (value - dismissDuration) / (1 - dismissDuration);

return res < 0 ? 0 : res;

}

double get scale {

if (value < appearDuration) {

return 1 + appearDuration - value;

}

if (value < dismissDuration) {

return 1;

}

return (value - dismissDuration) / (1 - dismissDuration) + 1;

}

@override

Widget build(BuildContext context) {

Widget content = Icon(

Icons.favorite,

size: widget.size,

color: Colors.redAccent,

);

content = ShaderMask(

child: content,

blendMode: BlendMode.srcATop,

shaderCallback: (Rect bounds) => RadialGradient(

center: Alignment.topLeft.add(Alignment(0.66, 0.66)),

colors: [

Color(0xffEF6F6F),

Color(0xffF03E3E),

],

).createShader(bounds),

);

Widget body = Transform.rotate(

angle: rotate,

child: Opacity(

opacity: opa,

child: Transform.scale(

alignment: Alignment.bottomCenter,

scale: scale,

child: content,

),

),

);

return widget.position == null

? Container()

: Positioned(

left: widget.position.dx - widget.size / 2,

top: widget.position.dy - widget.size / 2,

child: body,

);

}

}

结语

作者：马嘉伦

日期：2020/01/31

平台：Segmentfault独家，勿转载