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Asked: 2026-05-11T04:11:18+00:00

I’m trying to create a generic graphics export tool which works by implementing the

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I’m trying to create a generic graphics export tool which works by implementing the Graphics interface and intercepts and interprets the calls to its various methods. However although I can do this successfully for a single component my Graphics class is being replaced when I use it on a component which contains other components. Strangely this only happens on Windows and Linux. On OSX it works fine.

Can anyone suggest how I can ensure that it’s my original Graphics class which is passed to all subcomponents?

I’ve got a short script which demonstrates the fundamental problem. When I explicitly call paint using an instance of MyGraphics I don’t see MyGraphics in the JPanel – just sun.java2d.SunGraphics2D.

import java.awt.*; import java.awt.image.*; import java.text.AttributedCharacterIterator; import javax.swing.*;  public class GraphicsTest {  public static void main(String[] args) {     new GraphicsTest(); }  public GraphicsTest () {     JFrame frame = new JFrame();     frame.getContentPane().add(new MyPanel());     frame.setSize(500,500);     frame.setVisible(true);     try {         Thread.sleep(2000);     } catch (InterruptedException e) {}     System.out.println('Using my graphics - expect to see 'MyGraphics' next');     frame.paint(new MyGraphics());  }  class MyPanel extends JPanel {     public void paint (Graphics g) {         super.paint(g);         System.out.println('Graphics is '+g);          g.fillRect(10, 10, 20, 20);     } }  class MyGraphics extends Graphics {      public String toString () {         return 'MyGraphics';     }      public Graphics create() {         return this;     }      // I've left out the huge list of abstract methods from the original script     // since they're unchanged from the defaults and don't really matter here. }

On my windows system the output is:

 Graphics is sun.java2d.SunGraphics2D[font=javax.swing.plaf.FontUIResource[family=Dialog,name=Dialog,style=plain,size=12],color=sun.swing.PrintColorUIResource[r=51,g=51,b=51]] Using my graphics - expect to see 'MyGraphics' next Graphics is sun.java2d.SunGraphics2D[font=javax.swing.plaf.FontUIResource[family=Dialog,name=Dialog,style=plain,size=12],color=sun.swing.PrintColorUIResource[r=51,g=51,b=51]]

whereas under OSX I get what I expected, which is:

 Graphics is sun.java2d.SunGraphics2D[font=apple.laf.CUIAquaFonts$DerivedUIResourceFont[family=LucidaGrande,name=LucidaGrande,style=plain,size=13],color=javax.swing.plaf.ColorUIResource[r=0,g=0,b=0]] Using my graphics - expect to see 'MyGraphics' next  Graphics is MyGraphics

So what I can I do to ensure that in all cases I get ‘MyGraphics’ passed to the appropriate subcomponents?

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  1. I don’t know for sure, but I suspect that as swing is double-buffered by Java on Windows (rather than by the window manager on OS X), you won’t draw to your graphics, but to the Graphics2D provided by the off-screen buffer, then blt to your graphics.

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