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 header_end = dataURI.indexOf(","),
          data = dataURI.substring(header_end + 1),
          isBase64 = BASE64_REGEX.test(dataURI.substring(0, header_end)),
          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);
    }
  };
})();