我正在使用canvg lib将svg转换为png，但是当我的svg大小超过10000时，它无法在画布上绘制而数据URL只能获得＆＃34; data：;＆＃34;空的
这是我正在使用的代码
function getDiagramImage(isTrue,_callback){
var html = d3.select("svg")
//.attr("version", 1.1)
//.attr("xmlns", "http://www.w3.org/2000/svg")
.attr({
'xmlns': 'http://www.w3.org/2000/svg',
'xmlns:xmlns:xlink': 'http://www.w3.org/1999/xlink',
version: '1.1'
})
.node().parentNode.innerHTML;
d3.select('#hiddenCanvas').attr('width',_canvasWidth).attr('height',(parseFloat(_canvasHeight) + 300) );
var canvas = document.getElementById('hiddenCanvas');
var context = canvas.getContext("2d");
canvg(document.getElementById('hiddenCanvas'), html, {
renderCallback: function() {
var dataURL = canvas.toDataURL();
if(!isTrue){
var pngimg = '<img src="'+dataURL+'">';
d3.select("#pngdataurl").html(pngimg);
var a = document.createElement("a");
a.download = "export_"+Date.now()+".png";
a.href = dataURL;
document.body.appendChild(a);
a.click();
}
if(_callback){
_callback(dataURL);
}
}
});
}
关于此功能..有d3.js代码创建图表。一个保存和下载按钮是保存将获取数据URL到png并将其保存在服务器上，而下载将立即下载图像..相同的功能适用于两个参数。
问题来自＆＃34; renderCallback＆＃34;虽然svg很大，数据网址为空，但我也尝试过超时，但它没有得到我的结果和计时器继续运行
答案 0 :(得分：2)
我最终做了我的测试，实际上，它似乎运行良好，直到Firefox中大约23500 x 23500 px的大小。
但是只有你改变了
d3.select("svg")
.attr(foo:bar)
.node().parentNode.innerHTML
带
d3.select("svg")
.attr(foo:bar)
.node().outerHTML();
另外，canvg似乎将自己设置为渲染画布的大小，所以你的
d3.select('#hiddenCanvas').attr('width',_canvasWidth).attr('height',(parseFloat(_canvasHeight) + 300) );
没用，可能与您设置_canvasWidth和_canvasHeight的部分一样。
__小心这个片段，会有滞后__
function getDiagramImage(isTrue,_callback){
var html = d3.select("svg")
.attr({
'xmlns': 'http://www.w3.org/2000/svg',
'xmlns:xmlns:xlink': 'http://www.w3.org/1999/xlink',
version: '1.1'
})
.node().outerHTML;
var canvas = document.getElementById('hiddenCanvas');
var context = canvas.getContext("2d");
canvg(canvas, html, {renderCallback: function(){
var dataURL = canvas.toDataURL();
if(!isTrue){
var pngimg = '<img src="'+dataURL+'">';
d3.select("#pngdataurl").html(pngimg);
var a = document.createElement("a");
a.download = "export_"+Date.now()+".png";
a.href = dataURL;
document.body.appendChild(a);
// a.click();
}
if(_callback){
_callback(dataURL);
}
}});
}
getDiagramImage();svg{border:3px solid green;}
canvas{border:3px solid blue;}
img{border:3px solid red;}<script src="https://cdnjs.cloudflare.com/ajax/libs/d3/3.4.11/d3.min.js"></script>
<script src="https://cdnjs.cloudflare.com/ajax/libs/amcharts/3.13.0/exporting/canvg.js"></script>
<svg id="svg" xmlns="http://www.w3.org/2000/svg"
xmlns:xlink="http://www.w3.org/1999/xlink" width="15000" height="15000" viewBox="-0.5,0,500.5,500.5">
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,118 382,500.5 441,500.5 -0.5,59 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,295 205,500.5 264,500.5 -0.5,236 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,59 441,500.5 500,500.5 499.8,500.2 -0.5,0 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,354 146,500.5 205,500.5 -0.5,295 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,500.5 28,500.5 -0.5,472 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,472 28,500.5 87,500.5 -0.5,413 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,413 87,500.5 146,500.5 -0.5,354 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="-0.5,236 264,500.5 323,500.5 -0.5,177 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="499.5,0.5 448,0.5 499.5,52 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="499.5,52 448,0.5 392,0.5 499.5,108 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="0,0.5 499.5,500 499.5,444 56,0.5 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="392,0.5 336,0.5 499.5,164 499.5,108 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="280,0.5 499.5,220 499.5,164 336,0.5 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="56,0.5 499.5,444 499.5,388 112,0.5 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="112,0.5 499.5,388 499.5,332 168,0.5 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="168,0.5 499.5,332 499.5,276 224,0.5 "/>
<polygon fill="none" stroke="#000000" stroke-miterlimit="10" points="224,0.5 499.5,276 499.5,220 280,0.5 "/>
</svg>
<canvas id="hiddenCanvas"></canvas>
<div id="pngdataurl"></div>
<!--**__Be carefull with this snippet, there will be lags__**-->
答案 1 :(得分：0)
这是我尝试修复此问题的时间
function getDiagramImage(isTrue,_callback){
var html = d3.select("#nodePane svg#nodeEditor")
.attr({
'xmlns': 'http://www.w3.org/2000/svg',
'xmlns:xmlns:xlink': 'http://www.w3.org/1999/xlink',
version: '1.1'
})
.node().parentNode.innerHTML;
var _imageHeight = parseFloat(_canvasHeight);
var _imageWidth = parseFloat(_canvasWidth);
if(_imageHeight > 10000){
_imageHeight = 9700;
}
if(_imageWidth > 7000){
_imageWidth = 7000;
}
d3.select('#hiddenCanvas').attr('width',_imageWidth+"px").attr('height',( _imageHeight + 300+"px" ) );
var canvas = document.getElementById('hiddenCanvas');
var context = canvas.getContext("2d");
canvg('hiddenCanvas', html, {
ignoreMouse:true,
ignoreAnimation:true,
ignoreDimensions:true,
scaleWidth:_imageWidth,
scaleHeight:_imageHeight,
renderCallback: function() {
var dataURL = canvas.toDataURL();
if(!isTrue){
var pngimg = '<img src="'+dataURL+'">';
d3.select("#pngdataurl").html(pngimg);
var a = document.createElement("a");
a.download = "export_"+Date.now()+".png";
a.href = dataURL;
document.body.appendChild(a);
a.click();
}
if(_callback){
_callback(dataURL);
}
}
});
}