Re: Graphics and JVMs

"Knute Johnson" <knute.johnson@THRWHITE.remove-dii-this>
Wed, 27 Apr 2011 15:40:46 GMT
  To: wrote:

Thank you guys for guidances. It works well for this example but it
doesn't fit into my final code. Not because of the technique used but
the component used to displayed the message. If I used JFrame,as
mentioned by Knute, the message will "eat into" the scroll bars when I
resize the frame to smaller. At the same time, I would like to scale
the "drawing" in JPanel without scaling my message. My best guess is
to override JViewport's paint(...) method to do this. I didn't
success. I overrode the paint(Graphics g) or paintComponents(...)
method in JViewport but it doesn't work. Any pointers here?

Please forgive me for not mentioning this earlier.


I don't quite get what you commentede,

// Except for Swing root components, use 'paint()'.
// but then, it is unwise to be rendering
// to root components. Better to render to a
// JPanel and add it to the root component.

I suppose JFrame is the root or the lowest component of all the
components it contains. If so, why do you override paint(...) instead
of paintComponents(...) in the sample code above?



I'm not clear what you want to do with your message. It is very easy
however to scale the box drawings. Assume a standard size, in this case
400x300, and transform your Graphics component accordingly.

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.util.*;
import javax.swing.*;

public class test9 extends JComponent implements Runnable {
     private final Random random;
     private final int prefX=400, prefY=300;

     public test9() {
         random = new Random(new Date().getTime());
         setPreferredSize(new Dimension(prefX,prefY));

     public void paintComponent(Graphics g2D) {
         Graphics2D g = (Graphics2D)g2D;
         double scaleX = getWidth() / (double)prefX;
         double scaleY = getHeight() / (double)prefY;
         int x = random.nextInt(prefX - 40);
         int y = random.nextInt(prefY - 40);
         AffineTransform at = g.getTransform();
         g.scale(scaleX,scaleY); // adjust for scale
         g.setTransform(at); // return to original

     public void run() {
         while (true) {
             try {
             } catch (InterruptedException ie) { }

     public static void main(String[] args) {
         Runnable r = new Runnable() {
             public void run() {
                 JFrame f = new JFrame();
                 test9 t9 = new test9();
                 new Thread(t9).start();


Knute Johnson
email s/nospam/knute/

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