Restrict window size reduction up to a certain size

Question

Hi,
I didn't know how to search for this, hence sorry if it has been answered before.
My question is not about window resizing which is easy via
setResizable() method.
I 've noticed that some complex dialog boxes do not allow to descrease their size after a specified value. See e.g., JBuilder's Project Properties dialog box; you can increase its size as much as you want, but when you try to reduce its size, after a certain size it isn't reducing any more.
How can you do that? Is it something that has to do with JWindow or with the layout it's using (GridBagLayout I guess)?
Thanks in advance.
John.

Answer 1

I was very fustrated with that problem so I came up with a "solution". I never actually needed that kind of feature but the very idea that it wasn't available in the api bothered me.
I probably shoud be shot for that but here goes :import javax.swing.*;
import javax.swing.event.MouseInputListener;
import java.awt.*;
import java.awt.event.*;
* <dl>
* <dt><b> Creation date :</b></dt>
* <dd> 22 nov. 2004 </dd>
* </dl>
* @author Pierre LE LANNIC
public class MinimumSizedDialog {
     private Dimension theMinimumSize;
     private JDialog theDialog;
     private class ResizePanel extends JPanel implements MouseInputListener {
          private int theDirection;
          private Point theFirstPoint;
          private Dimension theStartDragDimension;
          private Cursor thePreviousCursor;
          private Cursor theResizeCursor;
          public ResizePanel(int direction) {
               super();
               theDirection = direction;
               // for debug purposes only
               setOpaque(true);
               setBackground(Color.RED);
               addMouseListener(this);
               addMouseMotionListener(this);
               switch(theDirection) {
                    case SwingConstants.EAST :
                         theResizeCursor = Cursor.getPredefinedCursor(Cursor.E_RESIZE_CURSOR);
                         break;
                    case SwingConstants.SOUTH :
                         theResizeCursor = Cursor.getPredefinedCursor(Cursor.S_RESIZE_CURSOR);
                         break;
          public Dimension getPreferredSize() {
               Dimension dim = super.getPreferredSize();
               Dimension pref = dim;
               // width / height should be 2 . 10 is just to make the panel more obvious.
               switch(theDirection) {
                    case SwingConstants.EAST :
                         pref = new Dimension(10, dim.height);
                         break;
                    case SwingConstants.SOUTH :
                         pref = new Dimension(dim.width, 10);
                         break;
               return pref;
          public void mouseClicked(MouseEvent e) {}
          public void mouseEntered(MouseEvent e) {
               thePreviousCursor = getCursor();
               setCursor(theResizeCursor);
          public void mouseExited(MouseEvent e) {
               if (thePreviousCursor != null) {
                    setCursor(thePreviousCursor);
                    thePreviousCursor = null;
          public void mousePressed(MouseEvent e) {
               theFirstPoint = getPointOnScreen(e.getPoint());
               theStartDragDimension = theDialog.getSize();
          public void mouseReleased(MouseEvent e) {}
          public void mouseDragged(MouseEvent e) {
               Point current = getPointOnScreen(e.getPoint());
               switch(theDirection) {
                    case SwingConstants.EAST :
                         horizontalResize(current);
                         break;
                    case SwingConstants.SOUTH :
                         verticalResize(current);
                         break;
          public void mouseMoved(MouseEvent e) {}
          private void horizontalResize(Point aNewPoint) {
               int diff = aNewPoint.x - theFirstPoint.x;
               final Dimension newDim = new Dimension(theStartDragDimension.width + diff,
                                                               theStartDragDimension.height);
               if (validateDimension(newDim)) {
                    theDialog.setSize(newDim);
                    theDialog.validate();
          private void verticalResize(Point aNewPoint) {
               int diff = aNewPoint.y - theFirstPoint.y;
               Dimension newDim = new Dimension(theStartDragDimension.width,
                                                        theStartDragDimension.height + diff);
               if (validateDimension(newDim)) {
                    theDialog.setSize(newDim);
                    theDialog.validate();
          private Point getPointOnScreen(Point aPoint) {
               Point p = new Point(aPoint);
               SwingUtilities.convertPointToScreen(p, ResizePanel.this);
               return p;
     public MinimumSizedDialog(Frame anOwner, Container aUserContentPane, Dimension aMinimumSize) {
          theDialog = new JDialog(anOwner, MinimumSizedDialog.class.getName(), true);
          theDialog.setResizable(false);
          final JPanel parentContentPane = new JPanel(new BorderLayout());
          parentContentPane.add(new ResizePanel(SwingConstants.EAST), BorderLayout.EAST);
          parentContentPane.add(new ResizePanel(SwingConstants.SOUTH), BorderLayout.SOUTH);
          parentContentPane.add(aUserContentPane, BorderLayout.CENTER);
          theDialog.setContentPane(parentContentPane);
          theMinimumSize = aMinimumSize;
     public JDialog getDialog() {
          return theDialog;
     private boolean validateDimension(Dimension aDimension) {
          if (aDimension.width < theMinimumSize.width) return false;
          if (aDimension.height < theMinimumSize.height) return false;
          return true;
     private static void test() {
          final JFrame frame = new JFrame(MinimumSizedDialog.class.getName());
          frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
          JButton launchButton = new JButton("showDialog");
          frame.setContentPane(launchButton);
          JPanel panel = new JPanel();
          panel.setPreferredSize(new Dimension(500, 500));
          final JDialog testDialog = new MinimumSizedDialog(frame, panel, new Dimension(300, 300)).getDialog();
          launchButton.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent e) {
                    testDialog.pack();
                    testDialog.setVisible(true);
          SwingUtilities.invokeLater(new Runnable() {
               public void run() {
                    frame.pack();
                    frame.show();
     public static void main(String[] args) {
          test();
}As you can see, there is still a LOT of room for improvement. I just hope it might help somebody out there.