title: Setting pattern-fill to a rectangle after pattern-image has been loaded
body: <p>I want to set a fill to my rectangle in Fabric.js like this:</p>
  
  <pre><code>myRect.fill = new fabric.Pattern({
    source: myImg //myImg was loaded previously in another
                  //fabric.util.loadImage block
  });
  </code></pre>
  
  <p>My image is being loaded correctly before this code block is run. I've looked up the demos for patterns at Fabric.js website. There the pattern is set within a <code>fabric.util.loadImage</code> block.</p>
  
  <p>So the following code works fine for me:</p>
  
  <pre><code>fabric.util.loadImage('myImg.png', function(img) {
    myRect.fill = new fabric.Pattern({
      source: img
    });
  });
  </code></pre>
  
  <p>I want to understand why I can't set the source afterwards without using <code>fabric.util.loadImage</code>. Is there an option with setting the fill using an already loaded image?</p>