大型SVG以固定分辨率轉換為png

Question

我正在使用canvg lib將svg轉換為png，但是有些方法在我的svg大小大於10000時卻無法在畫布上繪制，並且data-URL僅獲得“ data :;” 空的

這是我正在使用的代碼

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);
         }
        }
    });
}

關於此功能..有d3.js代碼可創建圖表。 並帶有一個保存和下載按鈕，保存將獲取數據URL到png，並將其保存在服務器上，而下載將立即下載圖像。

問題伴隨着“ renderCallback”出現，而svg很大，數據URL為空，我也嘗試了超時，但是沒有得到結果並且計時器繼續運行

Answer 1

最后，我進行了測試，實際上，在Firefox中大約23500 x 23500 px的大小之前，它似乎運行良好。

但只有當您更改

d3.select("svg")
.attr(foo:bar)
.node().parentNode.innerHTML

與

d3.select("svg")
.attr(foo:bar)
.node().outerHTML();

另外，canvg似乎可以自行設置渲染畫布的大小，因此您的

d3.select('#hiddenCanvas').attr('width',_canvasWidth).attr('height',(parseFloat(_canvasHeight) + 300) );

是沒有用的，可能與設置_canvasWidth和_canvasHeight的部分_canvasHeight 。

__請謹慎處理此代碼段，否則會出現滯后現象__

 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__**--> 

Answer 2

這是我嘗試修復此問題的方法

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);
        }
    }
  });
}