2
我相信我的问题的答案可以在Is there an equivalent of canvas's toDataURL method for SVG?中找到。有人可以确认或给我一个正确的方向指针。toDataURL不适用于具有SVG图像的html5画布
如果画布包含Chrome和/或Safari上的SVG,我无法获取canvas.toDataURL()以生成正确的图像。下面的代码说明了这个问题。
<!DOCTYPE html>
<html>
<head>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(document).ready(function() {
var __readLocalXml = function(file)
{
xmlHttp = new XMLHttpRequest();
xmlHttp.open("GET",file,false);
xmlHttp.send();
return xmlHttp.responseXML;
};
var __drawSVG = function(context, sourceSVG, x, y){
var svg_xml = (new XMLSerializer()).serializeToString(sourceSVG);
var img = new Image();
img.src="";
var myFunction = function() {
context.drawImage(img, x, y);
}
img.addEventListener('load', myFunction, false);
img.src = "data:image/svg+xml;base64,"+btoa(svg_xml);
};
var settings = {
//White King
//Chess_klt45.svg
//<http://en.wikipedia.org/wiki/File:Chess_klt45.svg>
'whiteKingSVG' : function() { return __readLocalXml("svg/Chess_klt45.svg") }
}
var canvas = document.createElement('canvas');
var cw = canvas.width = 45;
var ch = canvas.height = 45;
var context = canvas.getContext('2d');
context.fillStyle = '#FFFFCC';
context.fillRect(0,
0,
ch,
cw);
__drawSVG(context, settings.whiteKingSVG(),0,0);
$('#withCanvas').after(canvas);
$('#withToDataUrl').after('<img src="' + canvas.toDataURL() + '" />');
});
</script>
</head>
<body>
<h1>Works</h1>
<div id="withCanvas"></div>
<hr>
<h1>Does not Work</h1>
<div id="withToDataUrl"></div>
</body>
</html>
我甚至写了使用节点0.4.2和节点用帆布开罗库等效的程序,我和SVG图像使用canvas.toDataURL()时,得到了同样的结果。当使用node-canvas时,由于某种原因img.onload事件没有被触发,如果我试图在不等待onload事件的情况下绘制图像,那么我得到一个错误,说图像没有完成加载。节点程序也可以在下面找到。
var Canvas = require('canvas');
var __readFileNodeSync=function(file){
var fs = require('fs');
try {
return fs.readFileSync(file, 'ascii');
} catch (err) {
console.error("There was an error opening the file:");
console.log(err);
}
}
var __loadXml_xmldom=function(file){
var DOMParser = require("xmldom").DOMParser;
var xml=__readFileNodeSync(file)
return new DOMParser().parseFromString(xml)
}
var __drawSVG = function(context, sourceSVG, x, y){
var btoa = require('btoa');
var XMLSerializer = require("xmldom").XMLSerializer;
var svg_xml = new XMLSerializer().serializeToString(sourceSVG);
var img = new Canvas.Image;
img.onload = function(){
context.drawImage(img, x, y);
}
img.src = "data:image/svg+xml;base64,"+btoa(svg_xml);
};
var settings = {
//White King
//Chess_klt45.svg
//<http://en.wikipedia.org/wiki/File:Chess_klt45.svg>
'whiteKingSVG' : function() { return __loadXml_xmldom("../svg/Chess_klt45.svg") }
}
var canvas = new Canvas();
var cw = canvas.width = 45;
var ch = canvas.height = 45;
var context = canvas.getContext('2d');
context.fillStyle = '#FFFFCC';
context.fillRect(0,
0,
ch,
cw);
__drawSVG(context, settings.whiteKingSVG(),0,0);
console.log("<html>");
console.log("<head>");
console.log("</head>");
console.log("<body>");
console.log('<img src="'+canvas.toDataURL() + '" />');
console.log("</body>");
console.log("</html>");
编辑我能解决我的问题,感谢@ Phrogz的评论
下面是有问题的代码解决
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="http://canvg.googlecode.com/svn/trunk/rgbcolor.js"></script>
<script type="text/javascript" src="http://canvg.googlecode.com/svn/trunk/canvg.js"></script>
<script src="http://code.jquery.com/jquery-latest.js"></script>
<script>
$(document).ready(function() {
var settings = {
//White King
//Chess_klt45.svg
//<http://en.wikipedia.org/wiki/File:Chess_klt45.svg>
'whiteKingSVG' : "svg/Chess_klt45.svg"
}
var canvas = document.createElement('canvas');
var cw = canvas.width = 45;
var ch = canvas.height = 45;
var context = canvas.getContext('2d');
context.fillStyle = '#FFFFCC';
context.fillRect(0,
0,
ch,
cw);
canvg(canvas, settings.whiteKingSVG, {
ignoreMouse: true,
ignoreAnimation: true,
ignoreDimensions: true,
ignoreClear: true,
offsetX: 0,
offsetY: 0
});
$('#withCanvas').after(canvas);
$('#withToDataUrl').after('<img alt="whiteKing.png" src="' + canvas.toDataURL("image/png") + '" />');
});
</script>
</head>
<body>
<h1>Works</h1>
<div id="withCanvas"></div>
<hr>
<h1>Works! (using canvg)</h1>
<div id="withToDataUrl"></div>
</body>
</html>
的[栅格化的在文档的SVG画布]可能重复(http://stackoverflow.com/questions/8158312/rasterizing-an-in-document-svg-to-canvas) – Phrogz 2012-04-25 14:43:32
的Webkit目前玷污的当你画一个SVG的时候画布(由于难以跟踪的安全问题)。在FF v12之前,Firefox也是如此,但现在已经修复。如果您需要数据URL,您现在需要使用像CanVG这样的SVG解析器。 – Phrogz 2012-04-25 14:54:01
谢谢@Phrogz。你的评论是我需要的。 – 2012-04-26 10:04:22