html2canvas/src/svgcontainer.js

function SVGContainer(src) {
    this.src = src;
    this.image = null;
    var self = this;

    this.promise = this.hasFabric().then(function() {
        return (self.isInline(src) ? Promise.resolve(self.inlineFormatting(src)) : XHR(src));
    }).then(function(svg) {
        return new Promise(function(resolve) {
            html2canvas.fabric.loadSVGFromString(svg, self.createCanvas.call(self, resolve));
        });
    });
}

SVGContainer.prototype.hasFabric = function() {
    return !html2canvas.fabric ? Promise.reject(new Error("html2canvas.svg.js is not loaded, cannot render svg")) : Promise.resolve();
};

SVGContainer.prototype.inlineFormatting = function(src) {
    return (/^data:image\/svg\+xml;base64,/.test(src)) ? this.decode64(this.removeContentType(src)) : this.removeContentType(src);
};

SVGContainer.prototype.removeContentType = function(src) {
    return src.replace(/^data:image\/svg\+xml(;base64)?,/,'');
};

SVGContainer.prototype.isInline = function(src) {
    return (/^data:image\/svg\+xml/i.test(src));
};

SVGContainer.prototype.createCanvas = function(resolve) {
    var self = this;
    return function (objects, options) {
        var canvas = new html2canvas.fabric.StaticCanvas('c');
        self.image = canvas.lowerCanvasEl;
        canvas
            .setWidth(options.width)
            .setHeight(options.height)
            .add(html2canvas.fabric.util.groupSVGElements(objects, options))
            .renderAll();
        resolve(canvas.lowerCanvasEl);
    };
};

SVGContainer.prototype.decode64 = function(str) {
    return (typeof(window.atob) === "function") ? window.atob(str) : decode64(str);
};

/*
 * base64-arraybuffer
 * https://github.com/niklasvh/base64-arraybuffer
 *
 * Copyright (c) 2012 Niklas von Hertzen
 * Licensed under the MIT license.
 */

function decode64(base64) {
    var chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
    var len = base64.length, i, encoded1, encoded2, encoded3, encoded4, byte1, byte2, byte3;

    var output = "";

    for (i = 0; i < len; i+=4) {
        encoded1 = chars.indexOf(base64[i]);
        encoded2 = chars.indexOf(base64[i+1]);
        encoded3 = chars.indexOf(base64[i+2]);
        encoded4 = chars.indexOf(base64[i+3]);

        byte1 = (encoded1 << 2) | (encoded2 >> 4);
        byte2 = ((encoded2 & 15) << 4) | (encoded3 >> 2);
        byte3 = ((encoded3 & 3) << 6) | encoded4;
        if (encoded3 === 64) {
            output += String.fromCharCode(byte1);
        } else if (encoded4 === 64 || encoded4 === -1) {
            output += String.fromCharCode(byte1, byte2);
        } else{
            output += String.fromCharCode(byte1, byte2, byte3);
        }
    }

    return output;
}