[ html drawImage 图片预加载 ] canvas绘制图片 drawImage 属性实例演示之三--使用New Image,进行图片预加载

 1 <!DOCTYPE html>
 2 <html >
 3 <head>
 4 <title>Insert you title</title>
 5 <meta name='description' content='this is my page'>
 6 <meta name='keywords' content='keyword1,keyword2,keyword3'>
 7 <meta http-equiv='Content-Type' content='text/html; charset=utf-8'>
 8 <link rel='stylesheet' type='text/css' href='./css/index.css' />
 9 <script type='text/javascript' src='./js/jquery-1.12.1.min.js'></script>
10 <style type='text/css'>
11 html,body {
12     margin: 0; padding: 0;
13 }
14 
15 html {
16     height: 100%;
17 }
18 
19 body {
20     background: #000;
21 }
22 
23 #can {
24     background: #FFF; display: block; margin: 25px auto; border-radius: 2px;
25 }
26 </style>
27 <script type='text/javascript'>
28     var oCan = null , oImg = null;
29     $( function(){
30         oCan = $( '#can' ).get( 0 ).getContext( '2d' );
31         var oImg = new Image();
32         oImg.src = './images/demoImg.jpg';
33         oImg.onload = function(){
34             oCan.drawImage( oImg , 0 , 0 , oImg.width / 2 , oImg.height / 2 );
35         };
36     } );
37 </script>
38 </head>
39 <body>
40     <canvas  width='500' height='450'>检测到您的浏览器版本过低请升级您的浏览器以获取更好的使用体验...</canvas>
41 </body>
42 </html>