如何将jQuery FLOT图形保存为.png或其他图像格式？

我正在使用一个名为FLOT的Jquery插件http://code.google.com/p/flot/如何将jQuery FLOT图形保存为.png或其他图像格式？

一旦呈现图形，我希望客户端能够将图形保存到文件中以备后用。有关如何在不需要客户端下载某些工具或图像捕获设备的情况下完成这一任务的想法？

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 
<html lang="en"> 
    <head> 
     <!--[if IE]><script src="http://html5shiv.googlecode.com/svn/trunk/html5.js"></script><![endif]--> 
     <meta http-equiv="Content-Type" content="text/html; charset=utf-8"> 
     <title>Graph</title> 
     <link href="layout.css" rel="stylesheet" type="text/css"></link> 
     <!--[if IE]><script language="javascript" type="text/javascript" src="lib/flot/excanvas.min.js"></script><![endif]--> 
     <script language="javascript" type="text/javascript" src="lib/canvas2image/base64.js"></script> 
     <script language="javascript" type="text/javascript" src="lib/canvas2image/canvas2image.js"></script> 
     <script language="javascript" type="text/javascript" src="lib/flot/jquery.js"></script> 
     <script language="javascript" type="text/javascript" src="lib/gChart/jquery.gchart.js"></script> 
     <script language="javascript" type="text/javascript" src="lib/flot/jquery.flot.js"></script> 
     <script language="javascript" type="text/javascript" src="lib/flot/jquery.flot.selection.js"></script> 
     <script language="javascript" type="text/javascript" src="lib/flot/jquery.flot.crosshair.js"></script> 
     <script language="javascript" type="text/javascript" src="lib/flot/jquery.flot.navigate.js"></script> 
     <style> 
     </style> 
    </head> 
    <body> 

<div id="placeholder" style="width:1000px;height:400px;"></div> 
<div id="test" style="display: none; background: #ff0; padding: 5px; border: 1px solid #ddd; position: absolute;"></div> 

<script type="text/javascript"> 
    $(function() { 
     var options0 = { 
     xaxis: {mode: "time"}, 
     legend: {position: "nw"}, 
     lines: {show: true}, 
     grid: {hoverable: true}}; 
     var grid_data0 = [[new Date(1286172000 * 1000), 1219], [new Date(1286258400 * 1000), 1583], [new Date(1286344800 * 1000), 1566], [new Date(1286431200 * 1000), 2191], [new Date(1286517600 * 1000), 2471], [new Date(1286604000 * 1000), 3128], [new Date(1286690400 * 1000), 2713], [new Date(1286776800 * 1000), 2117], [new Date(1286863200 * 1000), 3174], [new Date(1286949600 * 1000), 3051], [new Date(1287036000 * 1000), 3582], [new Date(1287122400 * 1000), 3472], [new Date(1287208800 * 1000), 3928], [new Date(1287295200 * 1000), 3688], [new Date(1287381600 * 1000), 2547], [new Date(1287468000 * 1000), 1549], [new Date(1287554400 * 1000), 3008], [new Date(1287640800 * 1000), 2309], [new Date(1287727200 * 1000), 2973], [new Date(1287813600 * 1000), 3805], [new Date(1287900000 * 1000), 3643], [new Date(1287986400 * 1000), 2310], [new Date(1288072800 * 1000), 2323], [new Date(1288159200 * 1000), 2399], [new Date(1288245600 * 1000), 2305], [new Date(1288332000 * 1000), 2393], [new Date(1288418400 * 1000), 3212], [new Date(1288504800 * 1000), 3348], [new Date(1288591200 * 1000), 2391], [new Date(1288677600 * 1000), 2130], [new Date(1288764000 * 1000), 1896], [new Date(1288850400 * 1000), 1765], [new Date(1288936800 * 1000), 2191], [new Date(1289023200 * 1000), 3008], [new Date(1289109600 * 1000), 3085], [new Date(1289199600 * 1000), 2151], [new Date(1289286000 * 1000), 2011], [new Date(1289372400 * 1000), 2016], [new Date(1289458800 * 1000), 1914]]; 
     var plot = $.plot($("#placeholder"), [{data: grid_data0}, ], options0); 
    }); 

$("#placeholder").mouseout(function(e){ 
$("#test").hide(); 
}); 

function test() { 
//var oCanvas = $("#placeholder");//document.getElementById("placeholder"); 
//img=document.createElement("img"); 
//Save 
//img.src=oCanvas.toDataUrl(); 
//Restore 
//oCanvas.drawImage(img, 0, 0); 
//var oCanvas = $("#placeholder");//document.getElementById("placeholder"); 
//document.write(document.getElementById('placeholder').toDataUrl()); 
    Canvas2Image.saveAsPNG(document.getElementById('placeholder')); 
//Canvas2Image.saveAsPNG(oCanvas, true); 
} 
</script> 
<a onClick="JavaScript:test();">Click</a> 
    </body> 
</html>

来源

2010-11-16 Josh