BufferedImage/translate/drawString

[Bob Stafford]

Can anyone tell me why the following two programs (test.java and
test1.java) produce different results.

I feel that they should display a list of y co-ordinates down the center
of the window. The only difference is that one uses a BufferedImage to
create the display and then copies it to the screen and the other writes
directly to the screen. I feel that the one that writes directly to the
screen is correct. It also seems that if I remove the call to
translate() and do the co-oridinate translation myself that the
BufferedImage version works.

Am I missing something or is this a bug in the JDK.

Thanks

Bob Stafford
[EMAIL PROTECTED]

test.java

import java.awt.*;
import java.awt.geom.*;
import java.lang.*;
import java.awt.image.BufferedImage;
import javax.swing.*;

public class test extends JApplet

 public void init()
 {
  // just set up some color stuff

  setBackground(Color.white);
  setForeground(Color.black);
 }

 public void paint(Graphics g)
 {
  // get size of JApplet

  Dimension d = getSize();

  // covert g to a Graphics2D
  Graphics2D g2 = (Graphics2D) g;

  // Translate co-oridnate system so that y=0 is aligned with
  // the vertical center of the JApplet

  g2.translate(0.0,d.height/2.0);

  // Plot a list of y co-ordinates down the center of the JApplet
  for (int y=-d.height/2;y<d.height/2;y+=10)
  {
   g2.drawString(String.valueOf(y),d.width/2,y);
  }

 }
 public static void main(String[] args)
 {
  JFrame f=new JFrame("test");

  JApplet applet= new test();

  f.getContentPane().add(applet,"Center");
  applet.init();

  f.pack();

  f.setSize(new Dimension(300,300));
  f.show();
 }


test1.java::
import java.awt.*;
import java.awt.geom.*;
import java.lang.*;
import java.awt.image.BufferedImage;
import javax.swing.*;

public class test1 extends JApplet

 public void init()
 {
  setBackground(Color.white);
  setForeground(Color.black);
 }

 public void paint(Graphics g)
 {
  Dimension d = getSize();

  // Get a buffered image the same size as the JApplet
  BufferedImage bimg=(BufferedImage) createImage(d.width,d.height)
  // Get the graphics and convert it to a Graphics2D
  Graphics2D g2 = (Graphics2D) bimg.createGraphics();

  // Same as test.java
  g2.translate(0.0,d.height/2.0);

  for (int y=-d.height/2;y<d.height/2;y+=10)
  {
   g2.drawString(String.valueOf(y),d.width/2,y);
  }

  // Copy BufferedImage to JApplet
  g.drawImage(bimg,0,0,this);

 }
 public static void main(String[] args)
 {
  JFrame f=new JFrame("test1");

  JApplet applet= new test1();

  f.getContentPane().add(applet,"Center");

  applet.init();
  f.pack();

  f.setSize(new Dimension(300,300));
  f.show();
 }









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