Re: A few questions about

"John B. Matthews" <john.b..matthews@THRWHITE.remove-dii-this>
Wed, 27 Apr 2011 15:50:09 GMT
In article
 "Qu0ll" <> wrote:

"John B. Matthews" <nospam@nospam.invalid> wrote in message

Hi John,

Thanks for the reply.

I ran the code and see no problems. I am running jdk1.6.0_03 on Suse
Linux 10.2

Looks right on Mac OS X 10.4.11, Java 1.5.0_16. Also, you can use the
AffineTransform to do the translate followed by the scale:

I am using Java 6 Update 10 RC2 on Windows Vista. Thanks for the tip on
combining the transforms - that's really useful. However, it still has the
same problems on my setup.

I am intrigued by the questions you raised up-thread about rendering
errors while scaling. I have seen a few such anomalies on Windows XP.
They tend to be small, off-by-one-pixel errors that are magnified by
scaling: lines that don't meet, circles that aren't circular.

I know that Java2D and Mac OS Quartz (and Linux GDK?) model graphics
devices using "Coordinates [that] are infinitely thin and lie between
the pixels of the output device." I have been told that Windows uses a
slightly different model, but I was using older systems (Java 1.4.2 &
Windows XP).

If you get a chance to run the example on a Mac, use accessibility
magnification or the Pixie tool to see the difference:

/Developer/Applications/Graphics Tools/

I was able to produce some artifact on Mac OS by adding diagonal lines
having CAP_SQUARE ends. Using CAP_ROUND precludes the problem. This
example lines up perfectly on my implementation at all sizes, weights,
aspects and magnifications I tried:

import java.awt.BasicStroke;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.geom.AffineTransform;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class TransTest extends JFrame {

    private class MyPanel extends JPanel {

        public void paintComponent(final Graphics g) {
            final Graphics2D g2d = (Graphics2D)g;
            final double scaleX = this.getWidth() / 100.0;
            final double scaleY = this.getHeight() / 100.0;
            final BasicStroke stroke = new BasicStroke(4f,
                BasicStroke.CAP_ROUND , BasicStroke.JOIN_ROUND);
            final AffineTransform at = new AffineTransform(
                AffineTransform.getScaleInstance(scaleX, scaleY));
            at.translate(10, 10);
            g2d.drawRect(0, 0, 80, 80);
            g2d.drawLine(0, 40, 80, 40);
            g2d.drawLine(40, 0, 40, 80);
            g2d.drawLine(0, 0, 80, 80);
            g2d.drawLine(80, 0, 0, 80);

    private void fade(Graphics2D g2d) {
        Color color = g2d.getColor();

    public TransTest() {
        this.setLayout(new BorderLayout());
        final MyPanel panel = new MyPanel();
        this.add(panel, BorderLayout.CENTER);
        this.setSize(543, 567);

    public static void main(final String[] args) {
        EventQueue.invokeLater(new Runnable() {

            public void run() {
                new TransTest().setVisible(true);

John B. Matthews
trashgod at gmail dot com
home dot woh dot rr dot com slash jbmatthews

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