canvas红包照片实例分享

时间:2020-05-15 ywhluck 人气:0

效果:

点击RESET：随机显示剪辑区域；

点击SHOW：显示完整清晰图片；

图（1）点击RESET

图（2）点击SHOW

代码如下：

<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>canvas红包照片</title>
<script type="text/javascript" src="https://code.jquery.com/jquery-3.1.1.min.js"></script>
<style type="text/css">
 #blur_div{
 width: 500px;
 height: 334px;
 margin: 0 auto;
 position: relative;
 margin-top:100px;
 }
 #blur_img{
 display: block;
 width: 500px;
 height: 334px;
 margin: 0 auto;
 filter: blur(15px);/*CSS3模糊*/
 -webkit-filter: blur(15px);
 -moz-filter: blur(15px);
 -ms-filter: blur(15px);
 -o-filter: blur(15px);
 position:absolute;
 left: 0px;
 top: 0px;
 z-index: 0;
 }
 #canvas{
 display: block;
 margin: 0 auto;
 position:absolute;
 left: 0px;
 top: 0px;
 z-index: 100;
/* background-color:red;*/
 }
 .button{
 display:block;
 position:absolute;
 z-index:200;
 width:80px;
 height:30px;
 color:white;
 text-decoration:none;
 text-align:center;
 line-height:30px;
 border-radius:5px;
 }
 #reset_button{
 left:100px;
 bottom:20px;
 background-color:#058;
 }
 #reset_button:hover{
 background-color:#047;
 }
 #show_button{
 right:100px;
 bottom:20px;
 background-color:#085;
 }
 #show_button:hover{
 background-color:#074;
 }
</style>
</head>
<body>
 <div id="blur_div">
 <img id="blur_img" src="http://cdn.attach.qdfuns.com/notes/pics/201702/27/221935e35ugwllljg10912.jpg" />
  <canvas id="canvas"></canvas>
  <a href="javascript:reset()" rel="external nofollow" class="button" id="reset_button">RESET</a>
  <a href="javascript:show()" rel="external nofollow" class="button" id="show_button">SHOW</a>
  </div>
 <script>
   var canvasWidth = 500;
 var canvasHeight = 334;
 var canvas = document.getElementById("canvas");
 var context = canvas.getContext("2d");
 canvas.width = canvasWidth;
 canvas.height = canvasHeight;
 /*在canvas上绘制清晰的图片*/
 var image = new Image();
 var radius = 40;
 var clippingRegion = {x:-1,y:-1,r:radius};/*初始化剪辑区域*/
 image.src = "http://cdn.attach.qdfuns.com/notes/pics/201702/27/221935e35ugwllljg10912.jpg";
 image.onload = function(e){
  initCanvas();
 }
 function initCanvas(){
  clippingRegion = {x:Math.random()*(canvas.width-2*radius)+radius,
     y:Math.random()*(canvas.height-2*radius)+radius,
     r:radius};/*随机剪辑区域*/
  draw(image,clippingRegion);
 }
 function setClippingRegion(clippingRegion){
  context.beginPath();
  context.arc(clippingRegion.x,clippingRegion.y,clippingRegion.r,0,2*Math.PI,false);/*绘制剪辑区域的路径*/
  context.clip();
 }
 function draw(image,clippingRegion){
  context.clearRect(0,0,canvas.width,canvas.height);/*清除画布*/
  context.save();
  setClippingRegion(clippingRegion);/*重新设置剪辑区域*/
  context.drawImage(image,0,0);
  context.restore();
 }
 /*重置显示剪辑区域*/
 function reset(){
  initCanvas();
 }
 /*显示整个清晰图片*/
 function show(){
  var theAnimation = setInterval( 
  function(){
   clippingRegion.r += 20; 
   if(clippingRegion.r>2*Math.max(canvas.width,canvas.height)){
   clearInterval(theAnimation);
   }
   draw(image,clippingRegion);
  },20)
 }  
  </script>
</body>
</html>

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