docs: 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();
  	}