I want to achieve this effect using GridBagLayout:
|-----------|
| Button1 |
|-----------|
|-----------|
| Button2 |
|-----------|
I initially just placed the buttons, but GridBagLayout is ignoring the empty cells. Now, I am trying to use Box.createHorizontalStrut(10) as spacers, but GridBagLayout is stretching the spaces to give me a 2x2 grid. I also tried JLabels and JPanels as the spacers, but I still get a 2x2 grid. Here is my code:
import java.awt.*;
import javax.swing.*;
public class GridBagLayoutDemo extends JFrame
{
// class level references
GridBagLayout layout;
JButton button1, button2;
// constructor
public GridBagLayoutDemo()
{
super("GridBagLayout Demo");
layout = new GridBagLayout();
setLayout( layout );
// create components
button1 = new JButton("Button 1");
button2 = new JButton("Button 2");
// components should be resized vertically AND horizontally (BOTH) to fill given area
int fill = GridBagConstraints.BOTH;
// if you do not fill the area, where should the component go?
int anchor = GridBagConstraints.CENTER;
// place components on the frame using a method
placeComponent( button1, 0, 0, 2, 2, 0.5, 0.5, fill, 0, 0, 0, 0, anchor );
placeComponent( Box.createHorizontalStrut(5), 2, 0, 1, 2, 0.5, 0.5, fill, 0, 0, 0, 0, anchor );
placeComponent( Box.createHorizontalStrut(5), 0, 2, 1, 2, 0.5, 0.5, fill, 0, 0, 0, 0, anchor );
placeComponent( button2, 1, 2, 2, 2, 0.5, 0.5, fill, 0, 0, 0, 0, anchor );
}
/// Place the component on the GridBag with appropriate parameters
private void placeComponent( Component comp, int column, int row, int width, int height, double weightX, double weightY,
int fill, int marginTop, int marginLeft, int marginBottom, int marginRight, int anchor )
{
GridBagConstraints constraints = new GridBagConstraints();
constraints.gridx = column; // column to start
constraints.gridy = row; // row to start
constraints.gridwidth = width; // number of cells wide
constraints.gridheight = height; // number of cells tall
constraints.weightx = weightX; // when size is changed, grow in x direction
constraints.weighty = weightY; // when size is changed, grow in y direction
constraints.fill = fill; // should the component fill the given area? GridBagConstraints.NONE, GridBagConstraints.BOTH, GridBagConstraints.CENTER, etc
constraints.insets = new Insets( marginTop, marginLeft, marginBottom, marginRight );
constraints.anchor = anchor;
layout.setConstraints(comp, constraints);
add(comp); // place component on the frame with these parameters
}
/// launches the application
public static void main(String[] args)
{
GridBagLayoutDemo app = new GridBagLayoutDemo();
app.setSize(400, 300);
app.setLocationRelativeTo(null);
app.setVisible(true);
}
}
Any ideas? Thanks!
GridBagLayout works off of what the first word entails; a grid. In order to achieve the effect you desire above, you actually need a 2x3 grid:
c1 | c2 | c3
| |
v v
|------------|
r1 | B1 | <S1>
|------------|
---->
|------------|
r2 <S2> | B2 |
|------------|
A 2x1 or 2x2 grid cannot realize the desired offset effect (if you want overlap on the buttons). We need the third column in order to get that overlapping of buttons.
In this paradigm, you have the following:
comp | x | y | w | h
------------------------------------
B1 | 0 | 0 | 2 | 1
S1 | 2 | 0 | 1 | 1
S2 | 0 | 1 | 1 | 1
B2 | 1 | 1 | 2 | 1
Basically, we're saying that B1 occupies [r1, c1-c2], S1 occupies [r1, c3], S2 occupies [r2, c1], and B2 occupies [r2, c2-c3]. Hope that is clear.
Here's a MCVE that illustrates how to achieve this. You can apply it to your code fairly painlessly:
public class StaggerTest {
public static void main(String[] args) {
JFrame frame = new JFrame("Stagger Test");
frame.setSize(600, 600);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JPanel panel = new JPanel(new GridBagLayout());
placeComp(new JButton("1"), panel, 0, 0, 2, 1);
placeComp(Box.createHorizontalStrut(10), panel, 2, 0, 1, 1);
placeComp(Box.createHorizontalStrut(10), panel, 0, 1, 1, 1);
placeComp(new JButton("2"), panel, 1, 1, 2, 1);
frame.setContentPane(panel);
frame.setVisible(true);
}
public static void placeComp(Component comp, JPanel panel, int x, int y, int w, int h) {
GridBagConstraints cons = new GridBagConstraints();
cons.gridx = x;
cons.gridy = y;
cons.gridwidth = w;
cons.gridheight = h;
panel.add(comp, cons);
}
}
Using insets, as mentioned in the other answer could also be applicable, depending on your use case.
One thing I would caution is that, if the layout of the panel is intended to be dynamic in nature, you might want to cascade panels and layouts within panels. For example, to extend the given example to:
|-----------|
| Button1 |
|-----------|
|-----------|
| Button2 |
|-----------|
|-----------|
| Button3 |
|-----------|
And etc., it becomes a little messier to tackle with a single panel (especially if needing to handle dynamically; IE: add button 4 when event X occurs). The insets approach would manage this better; you could simply iterate the inset value.
A better approach, IMO, would instead cascade your panels so that each row is managed by its own panel (and layout manager).
+-------MAIN PANEL----------+
| +------c1-----R1 PANEL---+|
| ||-----------| ||
r1|| Button1 | ||
| ||-----------| ||
| +------------------------+|
| +---c1--------c2-R2 PANEL+|
| | |-----------| ||
r2|<STRUT>| Button1 | ||
| | |-----------| ||
| +------------------------+|
| etc... |
+---------------------------+
Hope that helps!