使用canvas做出红包照片的效果

来源：互联网发布：美国黑人矛盾知乎编辑：程序博客网时间：2024/05/08 22:42

今天跟着学习了一个制作红包照片类似功能的demo，很有意思，所以在这里分享代码给大家，可以直接使用。

先贴出效果图大家看一下：

点击重置后会以随机一个点为圆心生成半径为50px的圆，然后显示清晰的图像；

点击显示后会全部显示清晰的图像；

功能虽然很少，但是很有意思不是吗，而且做好了适配可以在不同分辨率大小的设备上都可以玩。

只需要js+css+html就可以实现，不过需要引入jquery

下面po出完整代码：

demo.html:

<!DOCTYPE HTML><html><head lang="en"><meta http-equiv="Content-Type" content="text/html; charset=utf-8"><title>Canvas玩儿转红包照片</title><script src="http://cdn.bootcss.com/jquery/2.2.0/jquery.min.js" type="text/javascript"></script><link href="img.css" rel="stylesheet" type="text/css" /><meta name="viewport"content=" height = device-height,  width = device-width,  initial-scale = 1.0,  minimum-scale = 1.0,  maximum-scale = 1.0,  user-scalable = no"/></head><body><div id="blur-div"><img src="images/1.jpg" id="blur-image"><canvas id="canvas"></canvas><a href="javascript:reset()" class="button" id="reset-button">  重置  </a><a href="javascript:show()" class="button" id="show-button">  显示  </a></div><script type="text/javascript" src="img.js"></script></body></html>

img.css:

*{margin: 0 0;padding: 0 0;}#blur-div{/*width: 800px;height: 500px;*/margin: 0 auto;position: relative;/*超过部分隐藏*/overflow: hidden;}#blur-image {display: block;/*width: 800px;height: 500px;*/margin: 0 auto;/*滤镜 模糊 括号内值越大，就越模糊*/filter: blur(20px);-webkit-filter:blur(20px);-moz-filter:blur(20px);-ms-filter:blur(20px);-o-filter:blur(20px);position: absolute;left: 0px;top: 0px;/*表示在z轴上的值*/z-index: 0;}#canvas{display: block;margin: 0 auto;position: absolute;left: 0px;top: 0px;z-index: 100;} .button{display: block;position: absolute;z-index: 200;width: 100px;height: 30px;color: white;text-decoration: none;text-align: center;line-height: 30px;border-radius: 5px;}#reset-button{left: 50px;bottom: 20px;background-color: #058;}#reset-button:hover{background-color: #047;}#show-button{right: 50px;bottom: 20px;background-color: #085;}#show-button:hover{background-color: #074;}

img.js:

var canvasWidth = window.innerWidthvar canvasHeight = window.innerHeightvar canvas = document.getElementById("canvas")var context = canvas.getContext("2d")canvas.width=canvasWidthcanvas.height=canvasHeightvar radius = 50var image = new Image()var clippingRegion = {x:-1,y:-1,r:radius}var leftMargin = 0, topMargin=0var a;image.src = "images/1.jpg"image.onload = function(e){$("#blur-div").css("width", canvasWidth + "px")$("#blur-div").css("height", canvasHeight + "px")$("#blur-image").css("width", image.width + "px")$("#blur-image").css("height", image.height + "px")leftMargin = (image.width - canvas.width) / 2topMargin = (image.height - canvas.height) / 2$("#blur-image").css("top", "-" + topMargin + "px")$("#blur-image").css("left", "-" + leftMargin + "px")initCanvas()}function initCanvas(){clearInterval(a)clippingRegion = {x:Math.random()*(canvas.width-2*radius)+radius,y:Math.random()*(canvas.height-2*radius)+radius,r:radius}console.log(canvas.width);console.log(canvas.height);clippingRegion.r = 0;var id = setInterval(function(){clippingRegion.r += 2;if(clippingRegion.r > 50){clearInterval(id)}draw(image,clippingRegion)},30)}function setClippingRegion(clippingRegion){/*创建剪辑区域的路径*/context.beginPath()/*第六个参数表示是顺时针还是逆时针绘制*/context.arc(clippingRegion.x, clippingRegion.y, clippingRegion.r, 0, Math.PI*2, false)/*希望路径是个剪辑区域调用此方法*/context.clip()}function draw(image ,clippingRegion){/*每次绘制之前，对canvas的内容进行清空*/context.clearRect(0,0,canvas.width,canvas.height)/*存储canvas的当前状态*/context.save()/*剪辑出一个圆形的区域*/setClippingRegion(clippingRegion)/*开始画*///context.drawImage(image, 0 , 0)/*leftMargin, topMargin, canvas.width, canvas.height表示image剪出这么大0, 0, canvas.width, canvas.height 表示canvas的大小*/context.drawImage(image, leftMargin, topMargin, canvas.width, canvas.height,0, 0, canvas.width, canvas.height)/*canvas的状态恢复*/context.restore()}function reset(){initCanvas();}function show(){/*此函数是内置函数，表示每隔多少秒就执行前面的函数 所以第一个参数是函数，后面是间隔时间*/var id = setInterval(function(){a = id;clippingRegion.r += 20if(clippingRegion.r > 2*Math.max(canvas.width,canvas.height)){/*用来关闭函数执行的*/clearInterval(id);}draw(image ,clippingRegion)},30)}/*阻止滑动操作*//*canvas.addEventListener("touchstart",function(e){e.preventDefault()});*/

0 0