How to resize window keeping relative width and hieght

Question

Ok as usual I do not want this done for me but I could use a pointer. Simply put I wish to set a JFrame so that when it is resized by the user it holds its relative width and height.
Could somebody point me to where it is at in the API or a generic sample of code that I can rework? I have read for it but am not finding it so far. Thank you for your patience and any help offered. If it matters I'm doing a fairly simple app in NetBeans not an applet or anything.
Edited by: Donalds on Apr 8, 2010 5:10 PM

Answer 1

This was the best I could think of off the top of my head.
You may want to request this thread be moved to the swing forums for better contributions.
import javax.swing.*;
import java.awt.*;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
public class SampleFrame {
    public Dimension lastSize = new Dimension(400,300);
    public JFrame frame;
    public SampleFrame() {
        frame = new JFrame("Sample Frame");
        frame.setSize(lastSize);
        frame.setLocationRelativeTo(null);
        frame.addComponentListener(new ComponentListener() {
            public void componentResized(ComponentEvent e) {
                Dimension currentFrameSize = frame.getSize();
                int widthDelta = Math.abs(lastSize.width - currentFrameSize.width);
                int heightDelta = Math.abs(lastSize.height - currentFrameSize.height);
                if(heightDelta > widthDelta) {
                    double scaleRatio = currentFrameSize.getHeight() / lastSize.height;
                    currentFrameSize.width = (int) (lastSize.width * scaleRatio);
                } else {
                    double scaleRatio = currentFrameSize.getWidth() / lastSize.width;
                    currentFrameSize.height = (int) (lastSize.height * scaleRatio);
                frame.setSize(currentFrameSize);
                lastSize = currentFrameSize;
                frame.setLocationRelativeTo(null);
            public void componentMoved(ComponentEvent e) {
            public void componentShown(ComponentEvent e) {
            public void componentHidden(ComponentEvent e) {
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    public static void main(String[] args) {
        new SampleFrame();
}