JavaScript 下载svg图片为png格式

var doctype = '<?xml version="1.0" standalone="no"?><!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd" [<!ENTITY nbsp " ">]>'; function convertToPng(src, w, h) {       var canvas = document.createElement('canvas');       var context = canvas.getContext('2d');       canvas.width = w;       canvas.height = h;       context.drawImage(src, 0, 0);       var png;       try {         png = canvas.toDataURL("image/png");       } catch (e) {         if ((typeof SecurityError !== 'undefined' && e instanceof SecurityError) || e.name == "SecurityError") {           console.error("Rendered SVG images cannot be downloaded in this browser.");           return;         } else {           throw e;         }       }       return png;     }     function isElement(obj) {       return obj instanceof HTMLElement || obj instanceof SVGElement;     }     function reEncode(data) {       data = encodeURIComponent(data);       data = data.replace(/%([0-9A-F]{2})/g, function (match, p1) {         var c = String.fromCharCode('0x' + p1);         return c === '%' ? '%25' : c;       });       return decodeURIComponent(data);     }     function uriToBlob(uri) {       var byteString = window.atob(uri.split(',')[1]);       var mimeString = uri.split(',')[0].split(':')[1].split(';')[0]       var buffer = new ArrayBuffer(byteString.length);       var intArray = new Uint8Array(buffer);       for (var i = 0; i < byteString.length; i++) {         intArray[i] = byteString.charCodeAt(i);       }       return new Blob([buffer], {type: mimeString});     }     function downLoad(el, name) {       if (!isElement(el)) {         throw new Error('an HTMLElement or SVGElement is required; got ' + el);       }       if (!name) {         console.error("文件名为空!");         return;       }       var xmlns = "http://www.w3.org/2000/xmlns/";       var clone = el.cloneNode(true);       clone.setAttribute("version", "1.1");       if (!clone.getAttribute('xmlns')) {         clone.setAttributeNS(xmlns, "xmlns", "http://www.w3.org/2000/svg");       }       if (!clone.getAttribute('xmlns:xlink')) {         clone.setAttributeNS(xmlns, "xmlns:xlink", "http://www.w3.org/1999/xlink");       }       var svg = clone.outerHTML;       var uri = 'data:image/svg+xml;base64,' + window.btoa(reEncode(doctype + svg));       var image = new Image();       image.onload = function () {         var png = convertToPng(image, image.width, image.height);         var saveLink = document.createElement('a');         var downloadSupported = 'download' in saveLink;         if (downloadSupported) {           saveLink.download = name + ".png";           saveLink.style.display = 'none';           document.body.appendChild(saveLink);           try {             var blob = uriToBlob(png);             var url = URL.createObjectURL(blob);             saveLink.href = url;             saveLink.onclick = function () {               requestAnimationFrame(function () {                 URL.revokeObjectURL(url);               })             };           } catch (e) {             saveLink.href = uri;           }           saveLink.click();           document.body.removeChild(saveLink);         }       };       image.src = uri;     } 

<div id="svg-parent-div"><svg>...</svg></div> 

var el = d3.select("#svg-parent-div").node().children[0]; download(el,"下载图片"); 

el.setAttributeNS(xmlns, "xmlns", "http://www.w3.org/2000/svg"); el.setAttributeNS(xmlns, "xmlns:xlink", "http://www.w3.org/1999/xlink");