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="https://cdn.bootcss.com/jquery/2.2.0/jquery.min.js" type="text/javascript"></script> <link href="https://www.jb51.net/img.css" type="text/css" /> <meta 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> <img src="https://www.jb51.net/images/1.jpg"> <canvas> </canvas> <a href="javascript:reset()"> 重置 </a> <a href="javascript:show()"> 显示 </a> </div> <script type="text/javascript" src="https://www.jb51.net/article/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.innerWidth var canvasHeight = window.innerHeight var canvas = document.getElementById("canvas") var context = canvas.getContext("2d") canvas.width=canvasWidth canvas.height=canvasHeight var radius = 50 var image = new Image() var clippingRegion = {x:-1,y:-1,r:radius} var leftMargin = 0, topMargin=0 var a; image.src = "https://www.jb51.net/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) / 2 topMargin = (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 += 20 if(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() });*/