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。
<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> </body> </html>
运行效果如下：
