js canvas实现红包照片效果

时间：2021-05-26

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="external nofollow" 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()" rel="external nofollow" class="button" id="reset-button"> 重置 </a> <a href="javascript:show()" rel="external nofollow" 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{ margin: 0 auto; position: relative; overflow: hidden;} #blur-image { display: block; margin: 0 auto; 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; 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.innerHeight var canvas = document.getElementById("canvas")var context = canvas.getContext("2d") canvas.width=canvasWidthcanvas.height=canvasHeightvar radius = 50 var image = new Image()var clippingRegion = {x:-1,y:-1,r:radius} var leftMargin = 0, topMargin=0 var 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) / 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){ context.beginPath() context.arc(clippingRegion.x, clippingRegion.y, clippingRegion.r, 0, Math.PI*2, false) context.clip()} function draw(image ,clippingRegion){ context.clearRect(0,0,canvas.width,canvas.height) context.save() setClippingRegion(clippingRegion) //context.drawImage(image, 0 , 0) context.drawImage(image, leftMargin, topMargin, canvas.width, canvas.height, 0, 0, canvas.width, canvas.height) context.restore()} function reset(){ initCanvas();} function show(){ var id = setInterval( function(){ a = id; clippingRegion.r += 20 if(clippingRegion.r > 2*Math.max(canvas.width,canvas.height)){ clearInterval(id); } draw(image ,clippingRegion) }, 30 )}


以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。

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