Convert SVG to image (JPEG, PNG, etc.) in the browser

Question

I want to convert SVG into bitmap images (like JPEG, PNG, etc.) through JavaScript.

Answer 1

change svg to match your element

function svg2img(){
    var svg = document.querySelector('svg');
    var xml = new XMLSerializer().serializeToString(svg);
    var svg64 = btoa(xml); //for utf8: btoa(unescape(encodeURIComponent(xml)))
    var b64start = 'data:image/svg+xml;base64,';
    var image64 = b64start + svg64;
    return image64;
};svg2img()

Answer 2

Here a function that works without libraries and returns a Promise:

/**
 * converts a base64 encoded data url SVG image to a PNG image
 * @param originalBase64 data url of svg image
 * @param width target width in pixel of PNG image
 * @return {Promise<String>} resolves to png data url of the image
 */
function base64SvgToBase64Png (originalBase64, width) {
    return new Promise(resolve => {
        let img = document.createElement('img');
        img.onload = function () {
            document.body.appendChild(img);
            let canvas = document.createElement("canvas");
            let ratio = (img.clientWidth / img.clientHeight) || 1;
            document.body.removeChild(img);
            canvas.width = width;
            canvas.height = width / ratio;
            let ctx = canvas.getContext("2d");
            ctx.drawImage(img, 0, 0, canvas.width, canvas.height);
            try {
                let data = canvas.toDataURL('image/png');
                resolve(data);
            } catch (e) {
                resolve(null);
            }
        };
        img.src = originalBase64;
    });
}

On Firefox there is an issue for SVGs without set width / height.

See this working example including a fix for the Firefox issue.

Answer 3

This seems to work in most browsers:

function copyStylesInline(destinationNode, sourceNode) {
   var containerElements = ["svg","g"];
   for (var cd = 0; cd < destinationNode.childNodes.length; cd++) {
       var child = destinationNode.childNodes[cd];
       if (containerElements.indexOf(child.tagName) != -1) {
            copyStylesInline(child, sourceNode.childNodes[cd]);
            continue;
       }
       var style = sourceNode.childNodes[cd].currentStyle || window.getComputedStyle(sourceNode.childNodes[cd]);
       if (style == "undefined" || style == null) continue;
       for (var st = 0; st < style.length; st++){
            child.style.setProperty(style[st], style.getPropertyValue(style[st]));
       }
   }
}

function triggerDownload (imgURI, fileName) {
  var evt = new MouseEvent("click", {
    view: window,
    bubbles: false,
    cancelable: true
  });
  var a = document.createElement("a");
  a.setAttribute("download", fileName);
  a.setAttribute("href", imgURI);
  a.setAttribute("target", '_blank');
  a.dispatchEvent(evt);
}

function downloadSvg(svg, fileName) {
  var copy = svg.cloneNode(true);
  copyStylesInline(copy, svg);
  var canvas = document.createElement("canvas");
  var bbox = svg.getBBox();
  canvas.width = bbox.width;
  canvas.height = bbox.height;
  var ctx = canvas.getContext("2d");
  ctx.clearRect(0, 0, bbox.width, bbox.height);
  var data = (new XMLSerializer()).serializeToString(copy);
  var DOMURL = window.URL || window.webkitURL || window;
  var img = new Image();
  var svgBlob = new Blob([data], {type: "image/svg+xml;charset=utf-8"});
  var url = DOMURL.createObjectURL(svgBlob);
  img.onload = function () {
    ctx.drawImage(img, 0, 0);
    DOMURL.revokeObjectURL(url);
    if (typeof navigator !== "undefined" && navigator.msSaveOrOpenBlob)
    {
        var blob = canvas.msToBlob();         
        navigator.msSaveOrOpenBlob(blob, fileName);
    } 
    else {
        var imgURI = canvas
            .toDataURL("image/png")
            .replace("image/png", "image/octet-stream");
        triggerDownload(imgURI, fileName);
    }
    document.removeChild(canvas);
  };
  img.src = url;
}