阅读 2804

小程序抛物线动画

前言

由于最近小程序项目需要用到加入购物车的动画,自己结合小程序官方文档写了一下加入购物车动画demo, 有需要改进的地方还请指出;

先来看一下demo的效果图:

分析

要实现抛物线动画,我当时想到的是用插件的方式,网上有很多,但是要兼容小程序还是有点困难,况且小程序的主包有2M限制;

那么如何在小程序中实现这种效果呢?

  • 小程序提供API wx.createAnimation
  • css3 transition

实现方式有了,我们再来看一下什么是抛物线,数学上定义抛物线的种类有很多,但就上图的效果而言,需要水平方向匀速运动&垂直方向加速运动; wx.createAnimation提供timingFunction, 即水平方向linear, 垂直方向 ease-in

实现

一. 小程序实现

本次实现基于wepy框架(非小程序原生),所以$apply ---> setData就好了~

html

<view class="box">
	<view>
        <button bindtap="handleClick">点击</button>
    </view>
    <view animation="{{animationY}}" style="position:fixed;top:{{ballY}}px;" hidden="{{!showBall}}">
        <view class="ball" animation="{{animationX}}" style="position:fixed;left:{{ballX}}px;"></view>
    </view>
</view>

复制代码

JS

// 设置延迟时间
    methods = {
		handleClick: (e) => {
			// x, y表示手指点击横纵坐标, 即小球的起始坐标
			let ballX = e.detail.x,
			    ballY = e.detail.y;
			this.isLoading = true;
			this.$apply();
			this.createAnimation(ballX, ballY);
		}
    }
	setDelayTime(sec) {
		return new Promise((resolve, reject) => {
			setTimeout(() => {resolve()}, sec)
		});
	}
	// 创建动画
	createAnimation(ballX, ballY) {
		let that = this,
		bottomX = that.$parent.globalData.windowWidth,
		bottomY = that.$parent.globalData.windowHeight-50,
		animationX = that.flyX(bottomX, ballX),      // 创建小球水平动画
		animationY = that.flyY(bottomY, ballY);			 // 创建小球垂直动画

		that.ballX = ballX;
		that.ballY = ballY;
		that.showBall = true;
		that.$apply();
		that.setDelayTime(100).then(() => {
			// 100ms延时,  确保小球已经显示
			that.animationX = animationX.export();
			that.animationY = animationY.export();
			that.$apply();
			// 400ms延时, 即小球的抛物线时长
			return that.setDelayTime(400);
		}).then(() => {
			that.animationX = this.flyX(0, 0, 0).export();
			that.animationY = this.flyY(0, 0, 0).export();
			that.showBall = false;
			that.isLoading = false;
			that.$apply();
		})
	}
	// 水平动画
	flyX(bottomX, ballX, duration) {
		let animation = wx.createAnimation({
			duration: duration || 400,
			timingFunction: 'linear',
		})
		animation.translateX(bottomX-ballX).step();
		return animation;
	}
	// 垂直动画
	flyY(bottomY, ballY, duration) {
		let animation = wx.createAnimation({
			duration: duration || 400,
			timingFunction: 'ease-in',
		})
		animation.translateY(bottomY-ballY).step();
		return animation;
	}
	

复制代码

二. H5实现

除了小程序以外, 前端日常开发更多的还是H5,下面用css3 transition来实现;

<!DOCTYPE html>
<html lang="en" style="width:100%;height:100%;">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width">
    <style>
        * {
            padding: 0;
            margin: 0;
        }
        .ball {
            width:12px;
            height:12px;
            background: #5EA345;
            border-radius: 50%;
            position: fixed;
        }
    </style>
    <title>CSS3 水平抛物线动画</title>
</head>
<body>
</body>
<script>
	let body = document.documentElement;
	body.addEventListener('click', (evt) => {
		let ball = document.createElement('div');
		let left = evt.pageX;
		let top = evt.pageY;
		ball.classList.add('ball');
		ball.style.left = left+'px';
		ball.style.top = top+'px';
		body.append(ball);
		setTimeout(() => {
			ball.style.left = 0;
			ball.style.top = window.innerHeight+'px';
			ball.style.transition = 'left 200ms linear, top 200ms ease-in';
		}, 20)
	})
</script>
</html>

复制代码

体验链接请点我

至此,js抛物线动画的实现就介绍的差不多了~哈哈

文章分类
前端
文章标签