Graphics.drawLine and Graphics.drawRect do not match

Question

Using a Graphics.scale (not == 1.0, but the value is insignificant) often Graphics.drawLine and Graphics.drawRect do not match (with same and x and y-Values), there are differences of one pixel in x- and y-direction when you use JDK 1.6_Update12 and later in about every third rectangle. The values in the code sample are not significant for getting the problem.
I am using Windows XP and can get the error with JDK 1.6 Update 12 until JDK 1.6 Update 16, but not with the earlier updates.
Could this be considered an Java error ?
public class LbCanvas extends Canvas
   Image scratchPad = null;
   Graphics scratchPadGraphics;
   double small = 0.99;
   public LbCanvas()
      setSize (new Dimension (1354, 1397));
   public void update(Graphics g)
      if (scratchPad==null)
         scratchPad = createImage (this.getSize().width, this.getSize().height);
      scratchPadGraphics = scratchPad.getGraphics();
      paint(scratchPadGraphics);
      g.drawImage (scratchPad, 0, 0, null);
   public void paint(Graphics g)
      super.paint(g);
      ((Graphics2D)g).scale (small, small);
      g.setColor(Color.black);
      for (int i=30; i<900; i+=31)
         g.drawRect (10, i, 150, 21);
         g.drawLine (10, i, 160, i);
}Edited by: Mausboesie on Oct 1, 2009 2:25 AM

Answer 1

I tried your code with various scalings--it seems some are better than others. It looks, without checking the implementation, that the problem is in how each andles the scaling and I would definetly consider this a "Java Error".