将HTML5 Canvas的内容保存为图片

主要思想是借助Canvas自己的API - toDataURL()来实现，整个实现
HTML + JavaScript的代码很简单。
代码如下：
 <html>

 <meta http-equiv="X-UA-Compatible" content="chrome=1">

 <head>

 <script>

         window.onload = function() {

             draw();

             var saveButton = document.getElementById("saveImageBtn");

             bindButtonEvent(saveButton, "click", saveImageInfo);

             var dlButton = document.getElementById("downloadImageBtn");

             bindButtonEvent(dlButton, "click", saveAsLocalImage);

         };

             function draw(){

                 var canvas = document.getElementById("thecanvas");

                 var ctx = canvas.getContext("2d");

                 ctx.fillStyle = "rgba(125, 46, 138, 0.5)";

                 ctx.fillRect(25,25,100,100);

                 ctx.fillStyle = "rgba( 0, 146, 38, 0.5)";

                 ctx.fillRect(58, 74, 125, 100);

                 ctx.fillStyle = "rgba( 0, 0, 0, 1)"; // black color

                 ctx.fillText("Gloomyfish - Demo", 50, 50);

             }

             function bindButtonEvent(element, type, handler)

             {

                    if(element.addEventListener) {

                       element.addEventListener(type, handler, false);

                    } else {

                       element.attachEvent('on'+type, handler);

                    }

             }

             function saveImageInfo ()

             {

                 var mycanvas = document.getElementById("thecanvas");

                 var image    = mycanvas.toDataURL("image/png");

                 var w=window.open('about:blank','image from canvas');

                 w.document.write("<img src='"+image+"' alt='from canvas'/>");

             }

             function saveAsLocalImage () {

                 var myCanvas = document.getElementById("thecanvas");

                 // here is the most important part because if you dont replace you will get a DOM 18 exception.

                 // var image = myCanvas.toDataURL("image/png").replace("image/png", "image/octet-stream;Content-Disposition: attachment;filename=foobar.png");

                 var image = myCanvas.toDataURL("image/png").replace("image/png", "image/octet-stream");

                 window.location.href=image; // it will save locally

             }

         </script>

 </head>

 <body bgcolor="#E6E6FA">

     <div>

         <canvas width=200 height=200 id="thecanvas"></canvas>

         <button id="saveImageBtn">Save Image</button>

         <button id="downloadImageBtn">Download Image</button>

     </div><a href=http://www.cnblogs.com/roucheng/">柔城</a>

 </body>

 </html>
http://www.cnblogs.com/roucheng/