title: canvas.toDataURL results in solid black image?
body: <p>I have a canvas element with some doodling in it.</p>
  
  <p>I am using the following to convert the canvas to a jpeg:</p>
  
  <pre><code>var data = canvas.toDataURL( "image/jpeg", 0.5 );
  var img = new Image();
  img.src = data;
  $( "body" ).append( img );
  </code></pre>
  
  <p>However instead of my doodle, I get a solid black jpeg.</p>
  
  <p>Can anyone tell me what I'm doing wrong?</p>
  
  <p>Thanks!</p>