code: function (file, callback) {
  
                  var self = this,
                      reader = new FileReader();
  
                  var uploadDesign = this.$.imageUploadService.upload(file, function (err) {
                      if (!err) {
                          self.trigger("uploadComplete", {
                              uploadDesign: uploadDesign
                          });
                      } else {
                          self.trigger("uploadError", {
                              error: err,
                              uploadDesign: uploadDesign
                          });
                      }
  
                      callback && callback(err, uploadDesign);
                  });
  
                  reader.onload = function(evt) {
  
                      var img = new Image();
                      img.onload = function() {
                          uploadDesign.set({
                              previewImage: evt.target.result,
                              localImage: evt.target.result
                          });
                      };
                      img.src = evt.target.result;
                  };
  
                  reader.readAsDataURL(file);
  
  
                  return uploadDesign;
              }
docs: Upload image to Spreadshirt platform.
  
  @param {File} file
  @param {Function} [callback]
  @returns {sprd.type.UploadDesign}