title: How does animation at 60Hz works?
body: <p>I'm using a Thread to make a scrolling under Android.
  The thread run method is classic. I took it on Internet
  My view is a SurfaceView.</p>
  
  <pre><code>public void run() {
      Canvas canvas = null;
      while (_run) {
          canvas = _surfaceHolder.lockCanvas();
          if (canvas != null) {
              _surface.doDraw(canvas);
              _surfaceHolder.unlockCanvasAndPost(canvas);
          }
      }
  }
  </code></pre>
  
  <p>What I do not understand is:
  Why the doDraw (that will draw on screen) is called exactly 60 times per second ?
  And why there is no synchro problem ?</p>
  
  <p>I do not know how LCD works but on a screen, if you make a scrolling without waiting for the screen synchro, it is possible that the top of the screen display the previous image while the bottom display the correct image. I do not have the problem on Android.</p>
  
  <p>Is it the SurfaceView that handle a kind of double buffering ?
  And if it is the case, when the flip is done ?</p>
  
  <p>I do not find any information about that on Internet!</p>
  
  <p>Thank's
  Etienne</p>