JScrollPane Animation

Question

Can someone tell me the proper technique for writing code that will cause the viewport position in a JScrollPane component to scroll smoothly to a given set of coordinates rather than just jumping directly to the new coordinates?
Below is the code I have so far... it sort of works but the animation is not very smooth or consistent... sometimes it scrolls slowly, sometimes it scrolls quickly. I'm also very confused about when or if I should use SwingUtilities.invokeLater or if I should just use normal multi-thread technique or if I should multi-thread at all. The algorithm that calculates the coordinates in the animation is trivial to me; I'm more concerned with the smoothness of the animation which is probably swing or thread related.
public class GameCanvas extends JPanel
     public void panToPoint(final Point p)
          SwingUtilities.invokeLater(new Runnable()
               public void run()
                    Point p1 = getViewPosition(); //convienance method that gets center point of viewport (see below for definition)
                    Point p2 = p;
                    double m = (p2.y - p1.y) / (p2.x - p1.x); //calculate the slope
                    double b = p1.y - (m * p1.x); //calculate the y-intersect
                    for (int x = p1.x; x < p2.x; x++)
                         int y = (int)(m * x + b); //y = mx + b formula from gradeschool
                         setViewPosition(new Point(x, y)); //convienance method that sets center point of viewport (see below for definition)
                         try
                              Thread.sleep(1);
                         catch (Exception ex)
                              ex.printStackTrace();
     public Point getViewPosition()
          Point p = new Point();
          Rectangle r = getVisibleRect();
          p.x = r.x + r.width / 2;
          p.y = r.y + r.height / 2;
          return p;
     public void setViewPosition(final Point p)
          Rectangle r = getVisibleRect();
          r.x = p.x - r.width / 2;
          r.y = p.y - r.height / 2;
          scrollRectToVisible(r);
}Edited by: user6093557 on Feb 25, 2011 9:30 PM
Edited by: user6093557 on Feb 25, 2011 9:34 PM

Answer 1

You should never use Thread.sleep() on the Event Dispatch Thread. This will cause the GUI to freeze.
If you want animation then you should be using a Swing Timer to schedule the animation.