piskel/src/js/utils/BlobUtils.js

(function () {
  var ns = $.namespace('pskl.utils');

  var BASE64_REGEX = /\s*;\s*base64\s*(?:;|$)/i;

  ns.BlobUtils = {
    dataToBlob : function(dataURI, type, callback) {
      var headerEnd = dataURI.indexOf(',');
      var data = dataURI.substring(headerEnd + 1);
      var isBase64 = BASE64_REGEX.test(dataURI.substring(0, headerEnd));
      var blob;

      if (Blob.fake) {
        // no reason to decode a data: URI that's just going to become a data URI again
        blob = new Blob();
        blob.encoding = isBase64 ? 'base64' : 'URI';
        blob.data = data;
        blob.size = data.length;
      } else if (Uint8Array) {
        var blobData = isBase64 ? pskl.utils.Base64.decode(data) : decodeURIComponent(data);
        blob = new Blob([blobData], {type: type});
      }
      callback(blob);
    },

    canvasToBlob : function (canvas, callback, type /*, ...args*/) {
      type = type || 'image/png';

      if (canvas.mozGetAsFile) {
        callback(canvas.mozGetAsFile('canvas', type));
      } else {
        var args = Array.prototype.slice.call(arguments, 2);
        var dataURI = canvas.toDataURL.apply(canvas, args);
        pskl.utils.BlobUtils.dataToBlob(dataURI, type, callback);
      }
    },

    stringToBlob : function (string, callback, type) {
      type = type || 'text/plain';
      pskl.utils.BlobUtils.dataToBlob('data:' + type + ',' + string, type, callback);
    }
  };
})();