code: public void setTrackerLocation( int x0 , int y0 , int x1 , int y1 ) {
  
  		int width = x1-x0;
  		int height = y1-y0;
  
  		// change change in scale
  		double scale = (width/targetRegion.getWidth() + height/targetRegion.getHeight())/2.0;
  
  		// new center location
  		double centerX = (x0+x1)/2.0;
  		double centerY = (y0+y1)/2.0;
  
  		targetRegion.p0.x = centerX-scale*targetRegion.getWidth()/2.0;
  		targetRegion.p1.x = targetRegion.p0.x + scale*targetRegion.getWidth();
  		targetRegion.p0.y = centerY-scale*targetRegion.getHeight()/2.0;
  		targetRegion.p1.y = targetRegion.p0.y + scale*targetRegion.getHeight();
  	}
docs: Used to set the location of the track without changing any appearance history.
  
  Move the track region but keep the same aspect ratio as it had before
  So scale the region and re-center it