CODEWITHSUNDEEP
javaswinglayoutsplitgrid-layout
Martin Tuskevicius
Martin Tuskevicius

Reputation: 2630

Java: forcing a component to fill up the entire row in a GridLayout

I am writing a program that allows multiple users the share screenshots. Every time a user connects, everyone who is participating in the "room" (a bunch of users that are able to receive screen shots from one another) becomes able to see a screen shot that the user takes. To be able to see the screen shot, the frame needs to split itself up so that there is a dedicated space for that user's screen shots.

I decided to use a GridLayout because it splits components into equally-sized rectangles which is what I am looking for. The layout does exactly what I need it to, except there is one problem. If I my GridLayout configured that there are two rows and columns, the bottom-most row will still be split into two columns, even when there is only a single component. This is expected behavior, but is there a walk-around, preferably without using a different layout? I really like the simplicity of GridLayout. I have considered using a BorderLayout, but it is limited because there is a set amount of spaces where I can place items.

The format of the pictures wasn't supported, so I could not embed them into this question. Here is how the frame looks like it is full. I substituted the actual screen shots for buttons because I am just testing.

http://cl.ly/0N311g3w061P1B0W1T3s/Screen%20shot%202012-05-13%20at%204.23.25%20PM.png

Now here is how it looks when I remove a button from the bottom-most row: http://cl.ly/2j3Z0V1r3w1S3F160j05/Screen%20shot%202012-05-13%20at%204.23.41%20PM.png

Here is how I would want the bottom-most row to look: http://cl.ly/0J2R2y2L06151F0k0Y0i/Screen%20shot%202012-05-13%20at%204.24.11%20PM.png

How can I make the bottom-most row look like that? Keep in mind I still want the other rows to have two columns, but I only want the bottom-most one to have one column.

Thanks!

Upvotes: 1

Views: 6504

Answers (3)

Martin Tuskevicius
Martin Tuskevicius

Reputation: 2630

I decided to go with a slightly different approach. Since the separate screens are laid out really nicely using GridLayout when there are an even amount of screens, I decided to simply split up the screens into pages if there is an odd amount of screens.

Upvotes: 1

Guillaume Polet
Guillaume Polet

Reputation: 47617

To my knowledge, you can't. GridLayout is done this way.

But GridBagLayout will do a beautiful job for your program.

Take a look at this small demo that lays out buttons in rows and columns. (Click on a button to remove it).

import java.awt.Component;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;

import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.Timer;

public class Test4 {

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();

                final JPanel root = new JPanel(new GridBagLayout());
                frame.add(root);
                frame.setSize(600, 600);
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
                Timer t = new Timer(2000, new ActionListener() {

                    @Override
                    public void actionPerformed(ActionEvent e) {
                        final JButton b = new JButton("Hello" + root.getComponentCount());
                        b.addActionListener(new ActionListener() {

                            @Override
                            public void actionPerformed(ActionEvent e) {
                                root.remove(b);
                                updateConstraints(root);
                            }
                        });
                        root.add(b);
                        updateConstraints(root);
                    }
                });
                t.start();
            }
        });
    }

    protected static void updateConstraints(JPanel root) {
        if (!(root.getLayout() instanceof GridBagLayout)) {
            System.err.println("No a gridbaglayout");
            return;
        }
        GridBagLayout layout = (GridBagLayout) root.getLayout();
        int count = root.getComponentCount();
        int col = (int) Math.round(Math.sqrt(count));
        int row = (int) Math.ceil((double) count / col);
        GridBagConstraints gbc = new GridBagConstraints();
        gbc.fill = GridBagConstraints.BOTH;
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;
        int index = 0;
        for (int i = 0; i < row; i++) {
            for (int j = 0; j < col; j++) {
                gbc.gridx = j;
                gbc.gridy = i;
                boolean last = index + 1 == count;
                if (last) {
                    gbc.gridwidth = col - j;
                }
                Component c = root.getComponent(index);
                layout.setConstraints(c, gbc);
                if (last) {
                    break;
                }
                index++;
            }
        }
        root.doLayout();
    }
}

Upvotes: 2

amaidment
amaidment

Reputation: 7298

I think you want to use the GridBagLayout - check out the visual guide to layouts

In particular, with a GridBagLayout, you add components with a GridBagConstraints. This allows you to specify where each component should be put, but also what weight each component should have - e.g. see the GridBagLayout tutorial.

Upvotes: 0

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