Re: [handling data](1)how to go handle panel objects for edition inside a panel container

From:
Daniel Moyne <daniel.moyne@neuf.fr>
Newsgroups:
comp.lang.java.help
Date:
Mon, 22 Dec 2008 11:55:35 +0100
Message-ID:
<494f7227$5$28668$7a628cd7@news.club-internet.fr>
John B. Matthews wrote:

In article <494e4d00$0$28668$7a628cd7@news.club-internet.fr>,
 Daniel Moyne <daniel.moyne@neuf.fr> wrote:

[...] for the time being I am thinking of using absolute layout with
the need to calculate position of each marriage objects taking into
account their widths and heights.


I am wary of absolute layouts; I tend to prefer a layout that "breathes"
appropriately when the container is resized. One approach is a nested
BoxLayout in a vertical layout, which adjusts to the preferred height
and maximum width of each component. It's a way to accommodate the
slightly different font metrics extant among implementations. The
example uses vertical glue, but struts are an alternative:

<code>
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.GridLayout;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.util.Random;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;

/**
  * @author John B. Matthews
  */
public class BoxTest {

     public static final Random random = new Random();

     public static void main(String[] args) {

         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 (new BoxTest()).create();
             }
         });
     }

     void create() {
         JPanel panel = new JPanel();
         panel.setLayout(new BoxLayout(panel, BoxLayout.Y_AXIS));
         panel.add(Box.createVerticalGlue());
         for (int i = 0; i < 4; i++) {
             panel.add(new SizePanel());
             panel.add(Box.createVerticalGlue());
         }
         
         JFrame f = new JFrame("BoxTest");
         f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         f.add(panel);
         f.pack();
         f.setLocationRelativeTo(null);
         f.setVisible(true);
     }
}

/**
 * A SizePanel has a label showing its current size,
 * as well as a variable number of text items.
 */
class SizePanel extends JPanel {

     private static final String text =
         "Sed ut perspiciatis unde omnis iste natus error sit.";
    private final JLabel sizeLabel = new JLabel("Size:");

    public SizePanel() {
        this.setLayout(new GridLayout(0, 1));
        this.add(sizeLabel);
        int count = BoxTest.random.nextInt(4) + 1;
        for (int i = 0; i < count; i++) {
            this.add(new JLabel(text));
        }
        this.setBorder(BorderFactory.createCompoundBorder(
            new LineBorder(Color.blue), new EmptyBorder(3,3,3,3)));
        this.addComponentListener(new ComponentAdapter() {
            @Override
            public void componentResized(ComponentEvent e) {
                int w = e.getComponent().getWidth();
                int h = e.getComponent().getHeight();
                sizeLabel.setText("Size: " + w + "\u00d7" + h);
            }
        });
    }
}
</code>

John what do you mean by adjust for :
.. width if for example an object inside the container becomes wider ?,
.. height if I have to add an extra object vertically ?.

Daniel

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