title: Canvas rotation - JavaScript
body: <p>If someone has the answer could you help me, please?
  I have 2 images - background similar to arc and arrow. And i need to move arrow image over background image like this is a clock ticker arrow. So i need :</p>
  
  <ol>
  <li>Rotate arrow to make it parallel to current tick on the arc</li>
  <li>Move arrow to the next point</li>
  </ol>
  
  <p>For this i need to use Canvas object in JavaScript and its method transform - this will allow to move arrow and rotate it. </p>
  
  <p>The question is : how to use canvas.transform method to rotate (and desirable move) arrow around the arc? And which values and what relation between them should be in this case :</p>
  
  <pre><code>contextData.clearRect (0, 0, contextData.canvas.width, contextData.canvas.height);
  contextData.save ();
  contextData.translate(indicatorData.width () / 2, indicatorData.height () / 2);
  contextData.transform(1, 0, 0, 1, x, y);  // the question is HERE
  contextData.drawImage(rotationArrow, -rotationArrow.width / 2, -rotationArrow.height / 2);
  contextData.restore ();
  </code></pre>
  
  <p>Thanks in advance.</p>