Develop Reference

Brightness implementation for JPanel in Swing

I want to create brightness functionality in Swing. JPanel and its component's brightness level will be adjust in this functionality.
To achieve this I used JLayeredPane and added JPanel as BrightNessPanel on the top of my JPanel called MainPanel. I am giving brightness effect by changing the opacity of BrightNessPanel. This will simulate Brightness effect for my MainPanel.
Now problem is that, I am not able to click the buttons present on MainPanel because of layer of BrightNessPanel.
How do I pass through clicks from BrightNessPanel to the buttons present on MainPanel??

You might be able to make use the JLayer API which allows you to perform painting operations ontop of other components.
import java.awt.AlphaComposite;
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLayer;
import javax.swing.JPanel;
import javax.swing.JSlider;
import javax.swing.JTextField;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
import javax.swing.plaf.LayerUI;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
TestPane testPane = new TestPane();
BrightnessLayerUI layerUI = new BrightnessLayerUI();
JLayer<JComponent> layer = new JLayer<>(testPane, layerUI);
JSlider slider = new JSlider(0, 100);
slider.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
int value = slider.getValue();
float brightness = (100 - value) / 100f;
layerUI.setBrightness(brightness);
testPane.repaint();
}
});
slider.setValue(100);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(layer);
frame.add(slider, BorderLayout.SOUTH);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridwidth = GridBagConstraints.REMAINDER;
add(new JTextField(10), gbc);
add(new JButton("Hello"), gbc);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
g2d.dispose();
}
}
public class BrightnessLayerUI extends LayerUI<JComponent> {
private float brightness = 0f;
public void setBrightness(float brightness) {
this.brightness = brightness;
}
public float getBrightness() {
return brightness;
}
#Override
public void paint(Graphics g, JComponent c) {
super.paint(g, c);
Graphics2D g2d = (Graphics2D) g.create();
g2d.setColor(c.getBackground());
g2d.setComposite(AlphaComposite.SrcOver.derive(getBrightness()));
g2d.fillRect(0, 0, c.getWidth(), c.getHeight());
g2d.dispose();
}
}
}
One of the advantages of this is you could actually introduce a "brightness" algorithm, rather than faking it, by using a backing buffer, which is demonstrated the link above (this use to to blur the UI)

JPanel fills entire JScrollPane

I'm making a level editor for a project of mine so I added a JPanel to a JScrollPane in order to view the level being worked on. The idea was that if the level was too big the scroll pane would handle that. The issue is when the level is to small, when I try to size the panel to a size smaller than the scrollpane it gets stretched to fill the whole scrollpane instead of the size I set. I can't seem to find a solution to the problem.
EDIT: I added a some sample code, When the window is enlarged the panel stretches to fit the scrollpane instead of staying at the set 500 by 500 in the example.
Setting up the JScrollPane:
public class Example {
public static void main(String[] args) {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(600, 600);
LevelView levelView = new LevelView();
JScrollPane pane = new JScrollPane(levelView);
frame.add(pane, BorderLayout.CENTER);
frame.setVisible(true);
}
}
JPanel:
public class LevelView extends JPanel {
private static final long serialVersionUID = 1L;
public LevelView() {
Dimension dim = new Dimension(500, 500);
setPreferredSize(dim);
setMaximumSize(dim);
setMinimumSize(dim);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
System.out.println(getWidth() + " " + getHeight());
g.setColor(Color.BLACK);
g.fillRect(0, 0, getWidth(), getHeight());
// Draw grid
g.setColor(Color.WHITE);
for (int x = 0; x < getWidth(); x += 50) {
g.drawLine(x, 0, x, getHeight());
}
for (int y = 0; y < getHeight(); y += 50) {
g.drawLine(0, y, getWidth(), y);
}
}
}
Thanks in advance!

First of all, remember, the preferredSize of the component is providing both the size of the viewport AND the size hints for the JScrollPane
Now, before you run screaming from the room, Swing provides the Scrollable interface to allow you to provide more information to the JScrollPane and JViewport, including the preferred view port size (which allows the JScrollPane to be smaller than the preferred size of the view been displayed when it's been laid out) and, which is what you're interested in, how the view should be sized when it is smaller than the view area
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Rectangle;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JSlider;
import javax.swing.Scrollable;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.event.ChangeEvent;
import javax.swing.event.ChangeListener;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
TestPane tp = new TestPane();
JSlider slider = new JSlider(50, 1024);
slider.setValue(200);
slider.addChangeListener(new ChangeListener() {
#Override
public void stateChanged(ChangeEvent e) {
int value = slider.getValue();
tp.apply(new Dimension(value, value));
tp.revalidate();
}
});
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(slider, BorderLayout.NORTH);
frame.add(new JScrollPane(tp));
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel implements Scrollable {
private Dimension preferredSize = new Dimension(200, 200);
public TestPane() {
setBackground(Color.RED);
}
#Override
public Dimension getPreferredSize() {
return preferredSize;
}
public void apply(Dimension size) {
preferredSize = size;
revalidate();
}
#Override
public Dimension getPreferredScrollableViewportSize() {
return new Dimension(200, 200);
}
#Override
public int getScrollableUnitIncrement(Rectangle visibleRect, int orientation, int direction) {
return 128;
}
#Override
public int getScrollableBlockIncrement(Rectangle visibleRect, int orientation, int direction) {
return 128;
}
#Override
public boolean getScrollableTracksViewportWidth() {
return false;
}
#Override
public boolean getScrollableTracksViewportHeight() {
return false;
}
}
}

Try drawing whatever it is you're drawing to a different object and add that object to a JPanel with a layout manager. Check out:
http://docs.oracle.com/javase/tutorial/uiswing/layout/visual.html
for more information about layout managers.

JFrame, JPanel, paintComponent how to

Hi I have following classes, I want display content
(paintComponentor that panel with this rectangle from paint class)
inside my JFrame. I try already find out how to achieve this by
looking at different examples posted on this forum however this
doesn't help me I need simple example like panel inside frame with
paint component or something similar to understand how should work!
ps. don't hang me on tree because I am newbie jut ask question!!!
[I want something like this][1]
package scp;
import java.awt.*;
import javax.swing.*;
public class Panel extends JPanel {
public Panel() {
//this.setPreferredSize(new Dimension(200,200));
//panel = new Panel();
setVisible(true);
setLayout(new FlowLayout());
setSize(200, 300);
getRootPane();
}
#Override
public void paintComponent(Graphics g){
g.drawString("HEY",20,20);
g.drawRect(200, 200, 200, 200);
}
}
and
package scp;
import javax.swing.JFrame;
import javax.swing.JButton;
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import java.beans.EventHandler;
public class Frame extends JFrame {
JButton redButton;
JButton blueButton;
public Frame()
{
super("EventHandling");
setLayout(new FlowLayout());
redButton = new JButton("Red");
add(redButton);
blueButton = new JButton("Blue");
add(blueButton);
EventHandler h = new EventHandler();
redButton.addActionListener(h);
blueButton.addActionListener(h);
}
private class EventHandler implements ActionListener
{
public void actionPerformed(ActionEvent e)
{
if (e.getSource()==redButton)
getContentPane().setBackground(Color.RED);
else if(e.getSource()==blueButton)
getContentPane().setBackground(Color.BLUE);
}
}
}
and
package scp;
import javax.swing.JFrame;
public class EventHandling {
public static void main(String[] args) {
Frame f = new Frame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setSize(800,600);
f.setVisible(true);
f.getContentPane().add(new Panel());
}
}
[1]: http://i.stack.imgur.com/OJTrq.png

Start by taking a look at:
Painting in AWT and Swing
Performing Custom Painting
2D Graphics
This is probably the simplest I can make it...
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int width = getWidth() - 100;
int height = getHeight() - 100;
int x = (getWidth() - width) / 2;
int y = (getHeight() - height) / 2;
g2d.setColor(Color.RED);
g2d.drawRect(x, y, width, height);
g2d.dispose();
}
}
}
Compound Example
This example uses an outer panel, which has an empty border applied to it, this pushes the content of the edges of the outer panel.
The inner panel (which is unchanged from the last example), as a light gray border applied to it so you can see it, the red rectangle is still been painted by the panels paintComponent method.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.EmptyBorder;
import javax.swing.border.LineBorder;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
ex.printStackTrace();
}
JPanel outer = new JPanel(new BorderLayout()) {
#Override
public Dimension getPreferredSize() {
return new Dimension(400, 400);
}
};
outer.setBorder(new EmptyBorder(50, 50, 50, 50));
TestPane tp = new TestPane();
tp.setBorder(new LineBorder(Color.LIGHT_GRAY));
outter.add(tp);
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(outer);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Graphics2D g2d = (Graphics2D) g.create();
int width = getWidth() - 100;
int height = getHeight() - 100;
int x = (getWidth() - width) / 2;
int y = (getHeight() - height) / 2;
g2d.setColor(Color.RED);
g2d.drawRect(x, y, width, height);
g2d.dispose();
}
}
}

Painting issue in custom layered container?

So I am working on a project here that requires a custom JLayeredPane - like class.
It has two members 'ground' and 'foreground' that are JPanel and an background (Image) member.
The way it was supposed to show was that the background Image should have been drawn and then all the components of the ground on top of it and then foreground's components at the apex. So foreground covers up ground which covers up background. Background should be shown only at places that do not have a Component in ground and foreground or where there is transparency in the JPanels.
It's paint function goes like this:
#Override
public void paint(Graphics g){
g.drawImage(background, 0, 0, null);
ground.paint(g.create());
foreground.paint(g.create());
g.dispose();
}
But nothing like that happens. Just the background image gets painted and nothing else shows.
I have used System.out.println() function to check that ground and foreground actually hold components and they do. But they just don't show.
Can anyone help me here?

The most significant issue is you're not calling super.paint, which is preventing what ever was previously painted to the Graphics context from been cleared or any child components from been painted.
For painting the background, you should be using paintComponent, which is used to paint the background of the component.
If you need to paint under the child components, but above the background, you should still use paintComponent, but paint the background first and then the next layer. The components will be painted after paintComponent.
Painting over components is actually more complex
Take a closer look at Custom Painting and Painting in Swing and AWT
Updated based on code snippets
In Screen which extends from Container, you are doing...
#Override
public void paint(Graphics g) {
super.paint(g);
GraphicsUtilities.drawPictureTiled(background, g);
paintComponents(g);
g.dispose();
}
Don't call paintComponents, super.paint has already done this.
Don't call dispose on a Graphics context you don't create
Based on the rest of the example code I have, you should be extending from JPanel and overriding paintComponent instead. This will allow you to put under the component layer
Because GroundPanel and ForeGroundPanel are both JPanels, there's no need to ever paint them yourself. In fact, you could simply use OverlayLayout or even a GridBagLayout and add them directly to the NestedScreen which is itself a container...
So, I stripped down you example code so I could get it working with the missing code as an example. I got a little more fancy and simply made a JPanel to act as the pause screen
This is all done by simply overlaying the components on top of each other using a GridBagLayout
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
public class Test1001 {
public static void main(String[] args) {
new Test1001();
}
public Test1001() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
try {
NestedScreen screen = new NestedScreen();
screen.setBackgroundLayer(ImageIO.read(getClass().getResource("/Sky.png")));
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(screen);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
} catch (IOException exp) {
exp.printStackTrace();
}
}
});
}
public interface GraphicsEngineComponents {
}
public class NestedScreen extends Screen implements GraphicsEngineComponents {
GroundPanel ground;
ForeGroundPanel foreground;
private PausePane pausePane;
public NestedScreen() {
ground = new GroundPanel();
foreground = new ForeGroundPanel();
pausePane = new PausePane();
setLayout(new GridBagLayout());
GridBagConstraints gbc = new GridBagConstraints();
gbc.gridx = 0;
gbc.gridy = 0;
gbc.weightx = 1;
gbc.weighty = 1;
gbc.fill = GridBagConstraints.BOTH;
add(pausePane, gbc);
add(foreground, gbc);
add(ground, gbc);
MouseAdapter handler = new MouseAdapter() {
#Override
public void mouseClicked(MouseEvent e) {
pausePane.setVisible(!pausePane.isVisible());
}
};
addMouseListener(handler);
foreground.addMouseListener(handler);
ground.addMouseListener(handler);
}
public GroundPanel getGroundLayer() {
return ground;
}
public ForeGroundPanel getForegroundLayer() {
return foreground;
}
public void setBackgroundLayer(BufferedImage background) {
super.setBackgroundLayer(background);
}
public class GroundPanel extends JPanel {
public GroundPanel() {
setOpaque(false);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(Color.GREEN);
g.fillRect(0, getHeight() - 200, getWidth(), 200);
}
}
public class PausePane extends JPanel {
private JLabel label;
public PausePane() {
setVisible(false);
setOpaque(false);
setBackground(new Color(0, 0, 0, 128));
setLayout(new GridBagLayout());
label = new JLabel("Paused");
label.setHorizontalAlignment(JLabel.CENTER);
label.setVerticalAlignment(JLabel.CENTER);
Font font = label.getFont();
font = font.deriveFont(Font.BOLD, 48f);
label.setFont(font);
label.setForeground(Color.WHITE);
add(label);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
}
public class ForeGroundPanel extends JPanel {
private BufferedImage pony;
public ForeGroundPanel() {
setOpaque(false);
try {
pony = ImageIO.read(getClass().getResource("/Pony.png"));
} catch (IOException ex) {
ex.printStackTrace();
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (pony != null) {
int x = (getWidth() - pony.getWidth()) / 2;
int y = getHeight() - 200 - (pony.getHeight() / 2);
g.drawImage(pony, x, y, this);
}
}
}
}
public class Screen extends JPanel implements GraphicsEngineComponents {
private BufferedImage background;
public Screen() {
}
#Override
public String toString() {
return "Screen{" + "background=" + background + '}';
}
public BufferedImage getBackgroundPicture() {
return background;
}
#Override
public Dimension getPreferredSize() {
return background == null ? super.getPreferredSize() : new Dimension(background.getWidth(), background.getHeight());
}
protected void setBackgroundLayer(BufferedImage background) {
if (background != null && background.getHeight() != 0 && background.getWidth() != 0) {
this.background = background;
}
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (background != null) {
g.drawImage(background, 0, 0, this);
}
}
}
}
Take a look at Painting in AWT and Swing and Performing Custom Painting to understand how painting works in Swing.
A basic idea would be to avoid using all these compound or nested components and instead, create an engine that can paint the layers directly onto a Graphics context, maybe even painting to a BufferedImage which you can the paint onto a single component...

There are a few ways you go about doing this. I'll just introduce one way.
Create a background panel where you paint the background image (in the example below, it is BackgroundPanel with the image only being the forresty background). Set that panel as the content pane to the frame.
Create another ground panel where you can also paint something (in the example below if it the GroundPanel with only the image of bugs bunny painted.
Create your foreground panel and add it to the ground panel. You can add your foreground components to it. (in the example below the foreground image is the grassy hill, and I also add a button to it
All the panels' opaque property should be set to false, as to allow the panel behind it to be shown under any transparency.
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
public class ThreeTier {
public static final int DIM_WIDTH = 600;
public static final int DIM_HEIGHT = 400;
private BufferedImage backgroundImage;
private BufferedImage groundImage;
private BufferedImage foregroundImage;
public ThreeTier() {
initImages();
JFrame frame = new JFrame();
frame.setContentPane(new BackgroundPanel());
frame.add(new GroundPanel());
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private void initImages() {
try {
backgroundImage = ImageIO.read(getClass().getResource("/resources/background.png"));
foregroundImage = ImageIO.read(getClass().getResource("/resources/foreground.png"));
groundImage = ImageIO.read(getClass().getResource("/resources/bugsBunny.png"));
} catch (IOException ex) {
Logger.getLogger(ThreeTier.class.getName()).log(Level.SEVERE, null, ex);
}
}
class BackgroundPanel extends JPanel {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(backgroundImage, 0, 0, DIM_WIDTH, DIM_HEIGHT, this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(ThreeTier.DIM_WIDTH, ThreeTier.DIM_HEIGHT);
}
}
class GroundPanel extends JPanel {
private static final String RIGHT_ACTION = "rightAction";
private int imageX = 50;
private int imageY = 140;
public GroundPanel() {
setOpaque(false);
add(new ForegroundPanel());
InputMap im = getInputMap(JComponent.WHEN_IN_FOCUSED_WINDOW);
im.put(KeyStroke.getKeyStroke("RIGHT"), RIGHT_ACTION);
getActionMap().put(RIGHT_ACTION, new AbstractAction() {
public void actionPerformed(ActionEvent e) {
if (imageX >= DIM_WIDTH) {
imageX = 0 - groundImage.getWidth();
repaint();
} else {
imageX += 10;
repaint();
}
}
});
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(groundImage, imageX, imageY, groundImage.getWidth(), groundImage.getHeight(), this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(ThreeTier.DIM_WIDTH, ThreeTier.DIM_HEIGHT);
}
}
class ForegroundPanel extends JPanel {
public ForegroundPanel() {
setOpaque(false);
setLayout(new FlowLayout(FlowLayout.TRAILING, 10, 0));
JButton button = new JButton("I'm in the Foreground!");
add(button);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(foregroundImage, 0, 0, DIM_WIDTH, DIM_HEIGHT, this);
}
#Override
public Dimension getPreferredSize() {
return new Dimension(ThreeTier.DIM_WIDTH, ThreeTier.DIM_HEIGHT);
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new ThreeTier();
}
});
}
}
UPDATE
Of course you could always just use the JLayeredPane. That's what it's for. See this example
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Font;
import java.awt.Graphics;
import java.awt.GridBagLayout;
import java.awt.GridLayout;
import java.awt.Image;
import java.io.IOException;
import java.util.logging.Level;
import java.util.logging.Logger;
import javax.imageio.ImageIO;
import javax.swing.ImageIcon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JLayeredPane;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;
import javax.swing.border.LineBorder;
public class LayeredPaneDemo {
public static final int DIM_WIDTH = 600;
public static final int DIM_HEIGHT = 400;
public LayeredPaneDemo() {
ContainerPanel container = new ContainerPanel();
JLabel title = new JLabel("Lame Google Map");
title.setFont(new Font("verdana", Font.BOLD, 36));
title.setHorizontalAlignment(JLabel.CENTER);
JPanel panel = new JPanel(new GridBagLayout());
panel.add(container);
JFrame frame = new JFrame();
frame.add(panel);
frame.add(title, BorderLayout.NORTH);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
new LayeredPaneDemo();
}
});
}
public class ContainerPanel extends JPanel {
public ContainerPanel() {
JLayeredPane layeredPane = new JLayeredPane();
layeredPane.setPreferredSize(new Dimension(DIM_WIDTH, DIM_HEIGHT));
BackgroundPanel bg = new BackgroundPanel();
GroundPanel gg = new GroundPanel();
ForegroundPanel fg = new ForegroundPanel();
bg.setBounds(0, 0, DIM_WIDTH, DIM_HEIGHT);
layeredPane.add(bg, new Integer(1));
gg.setBounds(0, 0, DIM_WIDTH, DIM_HEIGHT);
layeredPane.add(gg, new Integer(2));
fg.setBounds(0, 0, DIM_WIDTH, DIM_HEIGHT);
layeredPane.add(fg, new Integer(3));
setLayout(new GridBagLayout());
add(layeredPane);
setBorder(new LineBorder(Color.BLUE, 10));
}
}
public class ForegroundPanel extends JPanel {
public ForegroundPanel() {
JPanel buttonPanel = new JPanel(new GridLayout(3, 3));
buttonPanel.setOpaque(false);
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("UP"));
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("Left"));
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("Right"));
buttonPanel.add(new JLabel());
buttonPanel.add(new JButton("Down"));
buttonPanel.add(new JLabel());
FlowLayout flow = (FlowLayout) getLayout();
flow.setAlignment(FlowLayout.TRAILING);
flow.setHgap(0);
flow.setVgap(0);
add(buttonPanel);
setOpaque(false);
}
}
public class GroundPanel extends JPanel {
Image image = null;
public GroundPanel() {
try {
image = ImageIO.read(getClass().getResource("/resources/california.png"));
} catch (IOException ex) {
Logger.getLogger(LayeredPaneDemo.class.getName()).log(Level.SEVERE, null, ex);
}
setOpaque(false);
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.drawImage(image, 0, 0, DIM_WIDTH, DIM_HEIGHT, this);
}
}
public class BackgroundPanel extends JPanel {
public BackgroundPanel() {
setLayout(new GridBagLayout());
setBackground(Color.WHITE);
try {
Image img = ImageIO.read(getClass().getResource("/resources/google.jpg"));
add(new JLabel(new ImageIcon(img)));
} catch (IOException ex) {
Logger.getLogger(LayeredPaneDemo.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}

Making a JPanel square

If I have a JPanel with multiple subcomponents, how would I make it so that JPanel remains a square despite how its parent is resized? I have tried variations on the following code, but it does not result in the subcomponents also being square.
public void paint(Graphics g){
if(this.isSquare()){
Dimension d = this.getSize();
if(d.height > d.width){
this.setSize(d.width, d.width);
} else {
this.setSize(d.height, d.height);
}
super.paint(g);
}
Here is an SSCCE.
The containing parent:
import javax.swing.JFrame;
public class TestFrame extends JFrame{
public TestFrame(){
this.add(new TestPanel());
}
public static void main(String[] args){
TestFrame tf = new TestFrame();
tf.setSize(500, 500);
tf.setVisible(true);
}
}
What should be a square JPanel:
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.border.LineBorder;
public class TestPanel extends JPanel{
private boolean isSquare;
public TestPanel(){
this.setSquare(true);
this.setLayout(new BorderLayout());
JLabel panel1 = new JLabel();
panel1.setBorder(new LineBorder(Color.RED, 4));
panel1.setBackground(Color.CYAN);
JLabel panel2 = new JLabel();
panel2.setBorder(new LineBorder(Color.BLUE, 4));
panel2.setBackground(Color.CYAN);
this.setBorder(new LineBorder(Color.GREEN, 4));
this.setBackground(Color.CYAN);
this.add(panel1, BorderLayout.WEST);
this.add(panel2, BorderLayout.EAST);
}
public void paint(Graphics g){
if(this.isSquare()){
Dimension d = this.getSize();
if(d.height > d.width){
this.setSize(d.width, d.width);
} else {
this.setSize(d.height, d.height);
}
super.paint(g);
}
}
private boolean isSquare() {
return isSquare;
}
private void setSquare(boolean isSquare) {
this.isSquare = isSquare;
}
}

import java.awt.*;
import javax.swing.*;
import javax.swing.border.EmptyBorder;
public class SoSquare {
public static void main(String[] args) {
Runnable r = new Runnable() {
#Override
public void run() {
// the GUI as seen by the user (without frame)
// A single component added to a GBL with no constraint
// will be centered.
JPanel gui = new JPanel(new GridBagLayout());
gui.setBackground(Color.WHITE);
SquarePanel p = new SquarePanel();
p.setBackground(Color.red);
gui.add(p);
JFrame f = new JFrame("Demo");
f.add(gui);
// Ensures JVM closes after frame(s) closed and
// all non-daemon threads are finished
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
// See http://stackoverflow.com/a/7143398/418556 for demo.
f.setLocationByPlatform(true);
// ensures the frame is the minimum size it needs to be
// in order display the components within it
f.pack();
f.setSize(400,100);
// should be done last, to avoid flickering, moving,
// resizing artifacts.
f.setVisible(true);
}
};
// Swing GUIs should be created and updated on the EDT
// http://docs.oracle.com/javase/tutorial/uiswing/concurrency/initial.html
SwingUtilities.invokeLater(r);
}
}
/**
* A square panel for rendering. NOTE: To work correctly, this must be the only
* component in a parent with a layout that allows the child to decide the size.
*/
class SquarePanel extends JPanel {
#Override
public Dimension getPreferredSize() {
Dimension d = super.getPreferredSize();
Container c = getParent();
if (c != null) {
d = c.getSize();
} else {
return new Dimension(10, 10);
}
int w = (int) d.getWidth();
int h = (int) d.getHeight();
int s = (w < h ? w : h);
return new Dimension(s, s);
}
}

Take advantage of a layout manager that respect the preferred/min/max size of a component. Override the getPreferred/Minimum/MaximumSize methods to return the size you want.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;
import javax.swing.border.LineBorder;
public class SqaurePaneTest {
public static void main(String[] args) {
new SqaurePaneTest();
}
public SqaurePaneTest() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (ClassNotFoundException | InstantiationException | IllegalAccessException | UnsupportedLookAndFeelException ex) {
}
JFrame frame = new JFrame("Testing");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridBagLayout());
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new BorderLayout());
add(new JLabel("Look ma, I'm a square", JLabel.CENTER));
setBorder(new LineBorder(Color.GRAY));
}
#Override
public Dimension getMinimumSize() {
return getPreferredSize();
}
#Override
public Dimension getMaximumSize() {
return getPreferredSize();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}
Alternatively, create your own layout manager that does the same thing (makes all the components square)