saveSvgAsPng.js

(function() {
  var out$ = typeof exports != 'undefined' && exports || typeof define != 'undefined' && {} || this;

  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 "&#160;">]>';

  function isElement(obj) {
    return obj instanceof HTMLElement || obj instanceof SVGElement;
  }

  function requireDomNode(el) {
    if (!isElement(el)) {
      throw new Error('an HTMLElement or SVGElement is required; got ' + el);
    }
  }

  function isExternal(url) {
    return url && url.lastIndexOf('http',0) == 0 && url.lastIndexOf(window.location.host) == -1;
  }

  function inlineImages(el, callback) {
    requireDomNode(el);

    var images = el.querySelectorAll('image'),
        left = images.length,
        checkDone = function() {
          if (left === 0) {
            callback();
          }
        };

    checkDone();
    for (var i = 0; i < images.length; i++) {
      (function(image) {
        var href = image.getAttributeNS("http://www.w3.org/1999/xlink", "href");
        if (href) {
          if (isExternal(href.value)) {
            console.warn("Cannot render embedded images linking to external hosts: "+href.value);
            return;
          }
        }
        var canvas = document.createElement('canvas');
        var ctx = canvas.getContext('2d');
        var img = new Image();
        img.crossOrigin="anonymous";
        href = href || image.getAttribute('href');
        if (href) {
          img.src = href;
          img.onload = function() {
            canvas.width = img.width;
            canvas.height = img.height;
            ctx.drawImage(img, 0, 0);
            image.setAttributeNS("http://www.w3.org/1999/xlink", "href", canvas.toDataURL('image/png'));
            left--;
            checkDone();
          }
          img.onerror = function() {
            console.log("Could not load "+href);
            left--;
            checkDone();
          }
        } else {
          left--;
          checkDone();
        }
      })(images[i]);
    }
  }

  function styles(el, options, cssLoadedCallback) {
    var selectorRemap = options.selectorRemap;
    var modifyStyle = options.modifyStyle;
    var css = "";
    // each font that has extranl link is saved into queue, and processed
    // asynchronously
    var fontsQueue = [];
    var sheets = document.styleSheets;
    for (var i = 0; i < sheets.length; i++) {
      try {
        var rules = sheets[i].cssRules;
      } catch (e) {
        console.warn("Stylesheet could not be loaded: "+sheets[i].href);
        continue;
      }

      if (rules != null) {
        for (var j = 0, match; j < rules.length; j++, match = null) {
          var rule = rules[j];
          if (typeof(rule.style) != "undefined") {
            var selectorText;

            try {
              selectorText = rule.selectorText;
            } catch(err) {
              console.warn('The following CSS rule has an invalid selector: "' + rule + '"', err);
            }

            try {
              if (selectorText) {
                match = el.querySelector(selectorText) || el.parentNode.querySelector(selectorText);
              }
            } catch(err) {
              console.warn('Invalid CSS selector "' + selectorText + '"', err);
            }

            if (match) {
              var selector = selectorRemap ? selectorRemap(rule.selectorText) : rule.selectorText;
              var cssText = modifyStyle ? modifyStyle(rule.style.cssText) : rule.style.cssText;
              css += selector + " { " + cssText + " }\n";
            } else if(rule.cssText.match(/^@font-face/)) {
              // below we are trying to find matches to external link. E.g.
              // @font-face {
              //   // ...
              //   src: local('Abel'), url(https://fonts.gstatic.com/s/abel/v6/UzN-iejR1VoXU2Oc-7LsbvesZW2xOQ-xsNqO47m55DA.woff2);
              // }
              //
              // This regex will save extrnal link into first capture group
              var fontUrlRegexp = /url\(["']?(.+?)["']?\)/;
              // TODO: This needs to be changed to support multiple url declarations per font.
              var fontUrlMatch = rule.cssText.match(fontUrlRegexp);

              var externalFontUrl = (fontUrlMatch && fontUrlMatch[1]) || '';
              var fontUrlIsDataURI = externalFontUrl.match(/^data:/);
              if (fontUrlIsDataURI) {
                // We should ignore data uri - they are already embedded
                externalFontUrl = '';
              }

              if (externalFontUrl === 'about:blank') {
                // no point trying to load this
                externalFontUrl = '';
              }

              if (externalFontUrl) {
                // okay, we are lucky. We can fetch this font later

                //handle url if relative
                if (externalFontUrl.startsWith('../')) {
                  externalFontUrl = sheets[i].href + '/../' + externalFontUrl
                } else if (externalFontUrl.startsWith('./')) {
                  externalFontUrl = sheets[i].href + '/.' + externalFontUrl
                }

                fontsQueue.push({
                  text: rule.cssText,
                  // Pass url regex, so that once font is downladed, we can run `replace()` on it
                  fontUrlRegexp: fontUrlRegexp,
                  format: getFontMimeTypeFromUrl(externalFontUrl),
                  url: externalFontUrl
                });
              } else {
                // otherwise, use previous logic
                css += rule.cssText + '\n';
              }
            }
          }
        }
      }
    }

    // Now all css is processed, it's time to handle scheduled fonts
    processFontQueue(fontsQueue);

    function getFontMimeTypeFromUrl(fontUrl) {
      var supportedFormats = {
        'woff2': 'font/woff2',
        'woff': 'font/woff',
        'otf': 'application/x-font-opentype',
        'ttf': 'application/x-font-ttf',
        'eot': 'application/vnd.ms-fontobject',
        'sfnt': 'application/font-sfnt',
        'svg': 'image/svg+xml'
      };
      var extensions = Object.keys(supportedFormats);
      for (var i = 0; i < extensions.length; ++i) {
        var extension = extensions[i];
        // TODO: This is not bullet proof, it needs to handle edge cases...
        if (fontUrl.indexOf('.' + extension) > 0) {
          return supportedFormats[extension];
        }
      }

      // If you see this error message, you probably need to update code above.
      console.error('Unknown font format for ' + fontUrl+ '; Fonts may not be working correctly');
      return 'application/octet-stream';
    }

    function processFontQueue(queue) {
      if (queue.length > 0) {
        // load fonts one by one until we have anything in the queue:
        var font = queue.pop();
        processNext(font);
      } else {
        // no more fonts to load.
        cssLoadedCallback(css);
      }

      function processNext(font) {
        // TODO: This could benefit from caching.
        var oReq = new XMLHttpRequest();
        oReq.addEventListener('load', fontLoaded);
        oReq.addEventListener('error', transferFailed);
        oReq.addEventListener('abort', transferFailed);
        oReq.open('GET', font.url);
        oReq.responseType = 'arraybuffer';
        oReq.send();

        function fontLoaded() {
          // TODO: it may be also worth to wait until fonts are fully loaded before
          // attempting to rasterize them. (e.g. use https://developer.mozilla.org/en-US/docs/Web/API/FontFaceSet )
          var fontBits = oReq.response;
          var fontInBase64 = arrayBufferToBase64(fontBits);
          updateFontStyle(font, fontInBase64);
        }

        function transferFailed(e) {
          console.warn('Failed to load font from: ' + font.url);
          console.warn(e)
          css += font.text + '\n';
          processFontQueue(queue);
        }

        function updateFontStyle(font, fontInBase64) {
          var dataUrl = 'url("data:' + font.format + ';base64,' + fontInBase64 + '")';
          css += font.text.replace(font.fontUrlRegexp, dataUrl) + '\n';

          // schedule next font download on next tick.
          setTimeout(function() {
            processFontQueue(queue)
          }, 0);
        }

      }
    }

    function arrayBufferToBase64(buffer) {
      var binary = '';
      var bytes = new Uint8Array(buffer);
      var len = bytes.byteLength;

      for (var i = 0; i < len; i++) {
          binary += String.fromCharCode(bytes[i]);
      }

      return window.btoa(binary);
    }
  }

  function getDimension(el, clone, dim) {
    var v = (el.viewBox && el.viewBox.baseVal && el.viewBox.baseVal[dim]) ||
      (clone.getAttribute(dim) !== null && !clone.getAttribute(dim).match(/%$/) && parseInt(clone.getAttribute(dim))) ||
      el.getBoundingClientRect()[dim] ||
      parseInt(clone.style[dim]) ||
      parseInt(window.getComputedStyle(el).getPropertyValue(dim));
    return (typeof v === 'undefined' || v === null || isNaN(parseFloat(v))) ? 0 : v;
  }

  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);
  }

  out$.prepareSvg = function(el, options, cb) {
    requireDomNode(el);

    options = options || {};
    options.scale = options.scale || 1;
    options.responsive = options.responsive || false;
    var xmlns = "http://www.w3.org/2000/xmlns/";

    inlineImages(el, function() {
      var outer = document.createElement("div");
      var clone = el.cloneNode(true);
      var width, height;
      if(el.tagName == 'svg') {
        width = options.width || getDimension(el, clone, 'width');
        height = options.height || getDimension(el, clone, 'height');
      } else if(el.getBBox) {
        var box = el.getBBox();
        width = box.x + box.width;
        height = box.y + box.height;
        clone.setAttribute('transform', clone.getAttribute('transform').replace(/translate\(.*?\)/, ''));

        var svg = document.createElementNS('http://www.w3.org/2000/svg','svg')
        svg.appendChild(clone)
        clone = svg;
      } else {
        console.error('Attempted to render non-SVG element', el);
        return;
      }

      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");
      }

      if (options.responsive) {
        clone.removeAttribute('width');
        clone.removeAttribute('height');
        clone.setAttribute('preserveAspectRatio', 'xMinYMin meet');
      } else {
        clone.setAttribute("width", width * options.scale);
        clone.setAttribute("height", height * options.scale);
      }

      clone.setAttribute("viewBox", [
        options.left || 0,
        options.top || 0,
        width,
        height
      ].join(" "));

      var fos = clone.querySelectorAll('foreignObject > *');
      for (var i = 0; i < fos.length; i++) {
        if (!fos[i].getAttribute('xmlns')) {
          fos[i].setAttributeNS(xmlns, "xmlns", "http://www.w3.org/1999/xhtml");
        }
      }

      outer.appendChild(clone);

      // In case of custom fonts we need to fetch font first, and then inline
      // its url into data-uri format (encode as base64). That's why style
      // processing is done asynchonously. Once all inlining is finshed
      // cssLoadedCallback() is called.
      styles(el, options, cssLoadedCallback);

      function cssLoadedCallback(css) {
        // here all fonts are inlined, so that we can render them properly.
        var s = document.createElement('style');
        s.setAttribute('type', 'text/css');
        s.innerHTML = "<![CDATA[\n" + css + "\n]]>";
        var defs = document.createElement('defs');
        defs.appendChild(s);
        clone.insertBefore(defs, clone.firstChild);

        if (cb) {
          var outHtml = outer.innerHTML;
          outHtml = outHtml.replace(/NS\d+:href/gi, 'xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href');
          cb(outHtml, width, height);
        }
      }
    });
  }

  out$.svgAsDataUri = function(el, options, cb) {
    out$.prepareSvg(el, options, function(svg) {
      var uri = 'data:image/svg+xml;base64,' + window.btoa(reEncode(doctype + svg));
      if (cb) {
        cb(uri);
      }
    });
  }

  out$.svgAsPngUri = function(el, options, cb) {
    requireDomNode(el);

    options = options || {};
    options.encoderType = options.encoderType || 'image/png';
    options.encoderOptions = options.encoderOptions || 0.8;

    var convertToPng = function(src, w, h) {
      var canvas = document.createElement('canvas');
      var context = canvas.getContext('2d');
      canvas.width = w;
      canvas.height = h;

      if(options.canvg) {
        options.canvg(canvas, src);
      } else {
        context.drawImage(src, 0, 0);
      }

      if(options.backgroundColor){
        context.globalCompositeOperation = 'destination-over';
        context.fillStyle = options.backgroundColor;
        context.fillRect(0, 0, canvas.width, canvas.height);
      }

      var png;
      try {
        png = canvas.toDataURL(options.encoderType, options.encoderOptions);
      } 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;
        }
      }
      cb(png);
    }

    if(options.canvg) {
      out$.prepareSvg(el, options, convertToPng);
    } else {
      out$.svgAsDataUri(el, options, function(uri) {
        var image = new Image();

        image.onload = function() {
          convertToPng(image, image.width, image.height);
        }

        image.onerror = function() {
          console.error(
            'There was an error loading the data URI as an image on the following SVG\n',
            window.atob(uri.slice(26)), '\n',
            "Open the following link to see browser's diagnosis\n",
            uri);
        }

        image.src = uri;
      });
    }
  }

  out$.download = function(name, uri) {
    if (navigator.msSaveOrOpenBlob) {
      navigator.msSaveOrOpenBlob(uriToBlob(uri), name);
    } else {
      var saveLink = document.createElement('a');
      var downloadSupported = 'download' in saveLink;
      if (downloadSupported) {
        saveLink.download = name;
        saveLink.style.display = 'none';
        document.body.appendChild(saveLink);
        try {
          var blob = uriToBlob(uri);
          var url = URL.createObjectURL(blob);
          saveLink.href = url;
          saveLink.onclick = function() {
            requestAnimationFrame(function() {
              URL.revokeObjectURL(url);
            })
          };
        } catch (e) {
          console.warn('This browser does not support object URLs. Falling back to string URL.');
          saveLink.href = uri;
        }
        saveLink.click();
        document.body.removeChild(saveLink);
      }
      else {
        window.open(uri, '_temp', 'menubar=no,toolbar=no,status=no');
      }
    }
  }

  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});
  }

  out$.saveSvg = function(el, name, options) {
    requireDomNode(el);

    options = options || {};
    out$.svgAsDataUri(el, options, function(uri) {
      out$.download(name, uri);
    });
  }

  out$.saveSvgAsPng = function(el, name, options) {
    requireDomNode(el);

    options = options || {};
    out$.svgAsPngUri(el, options, function(uri) {
      out$.download(name, uri);
    });
  }

  // if define is defined create as an AMD module
  if (typeof define !== 'undefined') {
    define(function() {
      return out$;
    });
  }

})();