How to create a button in AlloyEditor?

I'm using alloyeditor and I have conveyed the following toolbar:

          toolbars: {
            add: {
              buttons: ['image', 'hline', 'table', 'camera'],
            },
            styles: {
              selections: [{
                name: 'text',
                buttons: [
                  'h1',
                  'h2',
                  'bold',
                  'italic',
                  'underline',
                  'ul',
                  'ol',
                  'quote',
                  'link',
                  'removeFormat'
                ],
                test: AlloyEditor.SelectionTest.text
              },
              {
                name: 'image',
                buttons: ['imageLeft', 'imageCenter', 'imageRight'],
                test: AlloyEditor.SelectionTest.image
              }],
            }
          }

My image button is adding images normally, however I want to add an image button that will only change a class to the css. In the case I configured to add image the following function:

alloyEditorGet.on('imageAdd', function(event) {
          var file = Image.base64ToFile($(event.data.el.$).attr('src')),
              imageTag = $(event.data.el.$);
          Image.uploadImage(file).then(function(response) {
            var imageLink = '.image({uidImage: "' + response.uid + '"';

            imageLink += '})';

            imageTag.attr({
              'data-uid': response.uid,
              'ui-sref': imageLink,
              'width': imageTag.width(),
              'height': imageTag.height(),
            });

            imageTag.wrap('<span>');

            imageTag.after($('<span>').attr({
              'data-uid': response.uid,
              'class': 'image-caption'
            }));
          }, function() {
            imageTag.remove();
          });
        });

This function will make all the changes I need, but in this new button I will add the class in the image: class:'expanded' . I know where I should change to add the class. But what I want to know is how will I add a new button with the same default button properties image and add some details as I did above?