将HTML5 Canvas的内容保存为图片建议收藏

全栈程序员-站长 • 2021年12月21日上午6:00 • 未分类 • 阅读 40

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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：

 1 <html>
 2 <meta http-equiv="X-UA-Compatible" content="chrome=1">
 3 <head>
 4 <script>
 5         window.onload = function() {
 6             draw();
 7             var saveButton = document.getElementById("saveImageBtn");
 8             bindButtonEvent(saveButton, "click", saveImageInfo);
 9             var dlButton = document.getElementById("downloadImageBtn");
10             bindButtonEvent(dlButton, "click", saveAsLocalImage);
11         };
12             function draw(){
13                 var canvas = document.getElementById("thecanvas");
14                 var ctx = canvas.getContext("2d");
15                 ctx.fillStyle = "rgba(125, 46, 138, 0.5)";
16                 ctx.fillRect(25,25,100,100); 
17                 ctx.fillStyle = "rgba( 0, 146, 38, 0.5)";
18                 ctx.fillRect(58, 74, 125, 100);
19                 ctx.fillStyle = "rgba( 0, 0, 0, 1)"; // black color
20                 ctx.fillText("Gloomyfish - Demo", 50, 50);
21             }
22             
23             function bindButtonEvent(element, type, handler)
24             {
25                    if(element.addEventListener) {
26                       element.addEventListener(type, handler, false);
27                    } else {
28                       element.attachEvent('on'+type, handler);
29                    }
30             }
31             
32             function saveImageInfo () 
33             {
34                 var mycanvas = document.getElementById("thecanvas");
35                 var image    = mycanvas.toDataURL("image/png");
36                 var w=window.open('about:blank','image from canvas');
37                 w.document.write("<img src='"+image+"' alt='from canvas'/>");
38             }
39 
40             function saveAsLocalImage () {
41                 var myCanvas = document.getElementById("thecanvas");
42                 // here is the most important part because if you dont replace you will get a DOM 18 exception.
43                 // var image = myCanvas.toDataURL("image/png").replace("image/png", "image/octet-stream;Content-Disposition: attachment;filename=foobar.png");
44                 var image = myCanvas.toDataURL("image/png").replace("image/png", "image/octet-stream"); 
45                 window.location.href=image; // it will save locally
46             }
47         </script>
48 </head>
49 <body bgcolor="#E6E6FA">
50     <div>
51         <canvas width=200 height=200 id="thecanvas"></canvas>
52         <button id="saveImageBtn">Save Image</button>
53         <button id="downloadImageBtn">Download Image</button>
54     </div><a href=http://www.cnblogs.com/roucheng/">柔城</a>
55 </body>
56 </html>