title: Emulate mouse scroll event
body: <p>I'm using Jack Moore's <a href="http://www.jacklmoore.com/wheelzoom/" rel="nofollow">Wheelzoom</a> jQuery plugin to zoom and drag an SVG image.</p>
  
  <p>However, I also need to implement manual zoom in and out buttons.</p>
  
  <p>The two options I can think of are to trigger a mouse wheel event on the image when a button is clicked or add a button click handler to the plugin. As far as I'm aware, you can't specify a direction when triggering a mouse wheel event and I'm really not sure how to go about adding a button click handler to the plugin.</p>
  
  <p>Any help with either of those options would be greatly appreciated.</p>
  
  <p>I did try this, but doesn't seem to do anything:</p>
  
  <pre><code>$('#site-viewer img').wheelzoom();
  
  var mouseWheelUp = $.Event('DOMMouseScroll', {delta: 1});
  var mouseWheelDown = $.Event('DOMMouseScroll', {delta: -1});
  
  $('#zoom-in').click(function() {
      $('#site-viewer img').trigger(mouseWheelUp);
  });
  
  $('#zoom-out').click(function() {
      $('#site-viewer img').trigger(mouseWheelDown);
  });
  </code></pre>
  
  <p>EDIT: If I replace 'DOMMouseScroll' with 'mousewheel', since I'm using Chrome, it is able to zoom out on click, but it does that for the zoom in button as well. Am I specifying the delta correctly? Is there a different way of specifying direction?</p>