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Unable to create a button on top of a rectangle

Here is a piece of code :
import java.awt.Color;
import java.awt.Component;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.util.Random;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
#SuppressWarnings("serial")
public class QuitButton extends JPanel implements ActionListener
{
static JButton button = new JButton("Panic");
Color[] colors = new Color[9];
boolean pressed = false;
public QuitButton()
{
button.addActionListener(this);
colors[0] = Color.RED;
colors[1] = Color.BLUE;
colors[2] = Color.GREEN;
colors[3] = Color.YELLOW;
colors[4] = Color.BLACK;
colors[5] = Color.PINK;
colors[6] = Color.MAGENTA;
colors[7] = Color.ORANGE;
colors[8] = Color.CYAN;
}
#Override
public void actionPerformed(ActionEvent e)
{
pressed = true;
}
public static void main(String args[])
{
JFrame frame = new JFrame("Do NOT Panic!!");
QuitButton qb = new QuitButton();
frame.add(qb);
frame.add(button);
frame.setLayout(new FlowLayout());
frame.setSize(400, 400);
frame.setVisible(true);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLocationRelativeTo(null);
//frame.pack();
button.requestFocus();
qb.gameLoop();
}
public void gameLoop()
{
while (true)
{
repaint();
try
{
Thread.sleep(200);
} catch (Exception e)
{
}
}
}
public void paint(Graphics g)
{
Graphics2D g2d = (Graphics2D) g;
if (pressed == false)
{
super.paint(g2d);
g2d.setColor(Color.GRAY);
g2d.fillRect(0, 0, 400, 400);
} else
{
super.paint(g2d);
Random r = new Random();
int min = 0;
int max = 8;
int index = r.nextInt(max - min) + min;
g2d.setColor(colors[index]);
g2d.fillRect(0, 0, 400, 400);
}
}
The purpose of this program: The rectangle should be grey before but when I click the panic button colours should start changing.
Please don't get confused with the name of the class which is QuitButton.
But my rectangle is not occupying the entire window. Instead I am getting a teeny tiny rectangle like this : http://g.recordit.co/xJAMiQu6fM.gif
I think it is because of the layout I am using and I haven't specified anywhere that the button will be on top. Probably that's why they are coming side by side. I am new to GUI creation and thank you for your help.

You seem to be making some guesses on how to do this, which is not a good way to learn to use a library. Your first step should be to check the relevant tutorials on this, most of which will be found here: Swing Info Since this appears to be homework, I'm not going to give you a code solution but rather suggestions on how to improve:
Override paintComponent, not paint since the latter gives double buffering and is less risky (less painting of borders and child component problems)
In your paintComponent override, be sure to call the super's paintComponent method first to clear "dirty" pixels.
Use a Swing Timer, not a while loop for your game loop. This will prevent your while loop from freezing the Swing event thread, a problem that can freeze your program. Google the tutorial as it is quite helpful.
Do your randomization within the ActionListener's code (here likely the ActionListener for your Swing Timer), not within the painting code. The painting code should not change the state of the object but rather should only display the object's state.
FlowLayout will respect a component's preferredSize, and your component's preferred size is 0,0 or close to it. Change this. Best to override public Dimension getPreferredSize() and return a Dimension that matches your Rectangle's size.
Avoid using "magic" numbers, such as for your rectangle's size, and instead use constants or fields.
Call repaint() within your Timer's ActionListener so the JVM knows to paint the component.

Why does theBufferedImage output look different than on screen in the JFrame window on Linux platform?

I am working on one project that requires to capture image data of on-screen GUI (e.g. JFrame). Somehow, my application is working for windows and Mac OS, but for Linux it's not giving same Image output as on-screen GUI.
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.image.BufferedImage;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.imageio.ImageIO;
import java.io.File;
class jframeExample {
public static BufferedImage getImageData(
Component component) {
BufferedImage image = new BufferedImage(
component.getWidth(),
component.getHeight(),
BufferedImage.TYPE_INT_RGB
);
component.printAll( image.createGraphics() );
return image;
}
public static void main(String[] args){
Runnable r = new Runnable() {
public void run() {
final JFrame f = new JFrame("JFrame Border");
f.setLayout(new BorderLayout());
f.setLocation(500,300);
f.setSize(560, 420);
f.getContentPane().setBackground(Color.BLUE);
JMenuItem screenshot =
new JMenuItem("TakeSnapshot");
screenshot.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent ae) {
BufferedImage imageOutput = getImageData(f);
try {
// write the image as a PNG
ImageIO.write(
imageOutput,
"png",
new File("CapturedImage.png"));
} catch(Exception e) {
e.printStackTrace();
}
}
} );
JMenu menu = new JMenu("Menu");
menu.add(screenshot);
JMenuBar menuBar = new JMenuBar();
menuBar.add(menu);
f.setJMenuBar(menuBar);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}
Above code will give GUI with Menu option to capture it as an image output. You can see on-screen GUI and image output of it as attached files.Generated image is little different than on-screen GUI. See left/right edge of JFrame border, it overlap with contentPane blue color.
How to get exact same image as on-screen GUI OR tweak left/right border so that it don't overlap with contentPane area? I tried couple of options using LookAndFeel class but not getting any success yet. Any help/suggestion would be appreciated.
On-Screen GUI
CapturedImage

Swing doesn't paint the entire frame. The frame is a widget of the OS.
Try using Screen Image.
It will use the Robot class to take an image when a frame is specified as the component. Otherwise is will use the Swing painting.

Quick Fix
Try changing...
BufferedImage imageOutput = getImageData(f);
to
BufferedImage imageOutput = getImageData(f.getContentPane());
This might work on Linux too (I can't test it at the moment) and would be an easy fix to your problem.
Solution
Alternatively you can use the Robot class. Robot has a more compatible screen capture capability, but this means serious alterations to your code. You can find the code at the very bottom of my answer. Let me explain the reasons for all the changes...
Robot is the class needed to perform screen captures. It can capture either the full desktop or a part of the screen. In this case, we will let it capture the blue part of your application by finding out the respective XY coordinates on the desktop. Robot needs to be static in this case because you are trying to access it through the main() method. Therefore the Robot variable needs to be outside of the main() method so that the JMenuItem's ActionListener can access it.
If you perform the screen capture through the menu, the menu will appear in the screen capture because you haven't given the menu time to disappear. As a result, a delay needs to be added. Simultaneously, this delay needs to occur in a separate thread, otherwise your menu will just freeze... The way I created the new thread is called a Lambda expression. It's just an easy way to easily create a new thread that starts immediately, that's all. It works like this: new Thread(() -> { /* Do something */ }.start();
Next is to find the coordinates of the blue part of the screen. This is a simple getLocationOnScreen() on the context pane of the frame (or which-ever component you wish to capture).
Now the screen capture can be created by Robot and saved to file using your previous code.
That's all! If you have any questions just place a comment and I'll check back later.
Code
import java.awt.AWTException;
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.image.BufferedImage;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.imageio.ImageIO;
import java.io.File;
class jframeExample {
public static BufferedImage getImageData(
Component component) {
BufferedImage image = new BufferedImage(
component.getWidth(),
component.getHeight(),
BufferedImage.TYPE_INT_RGB
);
component.printAll( image.createGraphics() );
return image;
}
static Robot robot = null;
public static void main(String[] args){
Runnable r = new Runnable() {
public void run() {
try {
if(robot == null) robot = new Robot();
} catch (AWTException e1) {
e1.printStackTrace();
}
final JFrame f = new JFrame("JFrame Border");
f.setLayout(new BorderLayout());
f.setLocation(500,300);
f.setSize(560, 420);
f.getContentPane().setBackground(Color.BLUE);
JMenuItem screenshot =
new JMenuItem("TakeSnapshot");
screenshot.addActionListener(
new ActionListener(){
public void actionPerformed(ActionEvent ae) {
new Thread(() -> {
try {
Thread.sleep(100);
} catch (InterruptedException e1) {
e1.printStackTrace();
}
int screenshotX = f.getContentPane().getLocationOnScreen().x;
int screenshotY = f.getContentPane().getLocationOnScreen().y;
int screenshotWidth = f.getContentPane().getWidth();
int screenshotHeight = f.getContentPane().getHeight();
BufferedImage imageOutput = robot.createScreenCapture(new Rectangle(screenshotX, screenshotY, screenshotWidth, screenshotHeight));
try {
// write the image as a PNG
ImageIO.write(
imageOutput,
"png",
new File("CapturedImage.png"));
} catch(Exception e) {
e.printStackTrace();
}
}).start();
}
} );
JMenu menu = new JMenu("Menu");
menu.add(screenshot);
JMenuBar menuBar = new JMenuBar();
menuBar.add(menu);
f.setJMenuBar(menuBar);
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setVisible(true);
}
};
SwingUtilities.invokeLater(r);
}
}

JFrame getLocation and setLocation deal with system border differently

I am creating a multi-user Swing GUI application, and want the user's window location and size settings to persist when they log out and back in. I am currently getting the window location and size using the getLocation() and getSize() methods on my parent JFrame when the user logs out and saving them to a file, and then when the user logs back in I read those values back in and set the window size and location using setLocation() and setSize().
The problem that I am having is that getLocation() and getSize() appear to be subtracting off the system border (e.g. if I put the window in the upper left corner getLocation returns (1,54) instead of (0,0)), but setLocation() and setSize() don't. The result is that every time I logout and log back in, the window appears slightly offset and slightly smaller than it did when I closed it.
Does anybody know why this might be happening or how I can get around it? Is there some other method I should be using to get and set the window location and size?
I'm running java 1.7.0_45 on Ubuntu 12.04, if that helps.
Thanks!
EDIT:
The following example replicates the issue I am seeing:
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.WindowConstants;
public class JFrameTest
{
private JFrame frame;
private JButton button;
private Point lastLocation;
private Dimension lastSize;
private void run()
{
button = new JButton("Test");
button.addActionListener(listener);
lastLocation = new Point(0, 0);
lastSize = new Dimension(200, 200);
initFrame();
}
private void initFrame()
{
frame = new JFrame();
frame.setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
frame.getContentPane().add(button);
frame.setLocation(lastLocation);
frame.setPreferredSize(lastSize);
frame.pack();
frame.setVisible(true);
}
private ActionListener listener = new ActionListener()
{
#Override
public void actionPerformed(ActionEvent e)
{
if (e.getSource() == button)
{
lastLocation = frame.getLocationOnScreen();
lastSize = frame.getSize();
frame.dispose();
initFrame();
}
}
};
public static void main(String[] args)
{
EventQueue.invokeLater(new Runnable() {
public void run()
{
new JFrameTest().run();
}
});
}
}
Also, I see the same issue when I use getLocationOnScreen() instead of getLocation().

You can use getLocationOnScreen()
Gets the location of this component in the form of a point specifying
the component's top-left corner in the screen's coordinate space.

How to get the painted size of a Swing component?

When I add Swing component (like a JButton) to a JPanel, it renders with it's 'preferred size'.
However, the preferred size is actually larger than the painted button. There appears to be an invisible border around it.
Here's a simple frame with my test panel:
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
TestPanel pnl = new TestPanel();
frame.getContentPane().add(pnl);
frame.pack();
frame.setVisible(true);
Here's my test panel ...
public class TestPanel extends JPanel {
JButton btn1 = new JButton("Test1");
JButton btn2 = new JButton("Test2");
public TestPanel() {
this.add(btn1);
this.add(btn2);
}
public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.RED);
Dimension dim = btn1.getPreferredSize();
g.drawRect(btn1.getX(), btn1.getY(), (int)(dim.getWidth()), (int)(dim.getHeight()));
}
}
Notice I painted btn1's "PreferredSize" in RED to demonstrate that the preferredSize is actually larger than the button itself.
My question is, how can I determine the width and height of the painted button, not the JButton's preferredSize?
Any help is greatly appreciated, thanks!
UPDATE
Because I actually need this to work for all Swing components, here's a screen shot with the more components.
Unfortunately, I need to figure this out, determining the "real" size of the visible widget is crucial to my application.

I don't think this is particular or practically achievable.
The problem is, the button is using the "unpainted" area to paint other elements, like the focus highlight.
You could try look at the AbstractButton#set/getMargin

If nothing better comes along, note that the authors "recommend that you put the component in a JPanel and set the border on the JPanel."
Addendum: Based on your comments below, it's clear that your question is not about rendering borders but about establishing a component's boundary. What you perceive as unused space is actually reserved by the UI delegate for any number of uses, e.g. selection highlighting or esthetic coherence. You can get an idea of how this varies by selecting different Look & Feel themes in the examples here and here.
Using getbounds():
Using setBorder():
import component.Laf;
import java.awt.Color;
import java.awt.EventQueue;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.Rectangle;
import javax.swing.JButton;
import javax.swing.JCheckBox;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextArea;
import javax.swing.JTextField;
/**
* #see https://stackoverflow.com/a/15490187/230513
*/
public class Test {
private void display() {
JFrame f = new JFrame("Test");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLayout(new FlowLayout());
// https://stackoverflow.com/a/11949899/230513
f.add(Laf.createToolBar(f));
f.add(decorate(new JButton("Test")));
f.add(decorate(new JTextField("Test")));
f.add(decorate(new JTextArea(3, 8)));
f.add(decorate(new JCheckBox("Test")));
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
private JPanel decorate(final JComponent c) {
JPanel p = new JPanel() {
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
Rectangle r = c.getBounds();
g.setColor(Color.red);
// NB pen hangs down and to the right
g.drawRect(r.x - 1, r.y - 1, r.width + 1, r.height + 1);
}
};
p.add(c);
return p;
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
new Test().display();
}
});
}
}

Get a components location on its current monitor

I want to set the location of a JPopupMenu depending of the y location of the button that opens the menu. My code works fine on my first monitor, but fails on my second monitor, wich has a different height.
The problem is getLocationOnScreen() delivers the location relative to the main screen, not the actual screen on which the component is shown.
My code:
// screenSize represents the size of the screen where the button is
// currently showing
final Rectangle screenSize = dateButton.getGraphicsConfiguration().getBounds();
final int yScreen = screenSize.height;
int preferredY;
// getLocationOnScreen does always give the relative position to the main screen
if (getLocationOnScreen().y + dateButton.getHeight() + datePopup.getPreferredSize().height > yScreen) {
preferredY = -datePopup.getPreferredSize().height;
} else {
preferredY = getPreferredSize().height;
}
datePopup.show(DateSpinner.this, 0, preferredY);
How can I get the location of a component on its actual monitor?

I got a solution for this using the bounds of the second screen, it's quite simple:
public static Point getLocationOnCurrentScreen(final Component c) {
final Point relativeLocation = c.getLocationOnScreen();
final Rectangle currentScreenBounds = c.getGraphicsConfiguration().getBounds();
relativeLocation.x -= currentScreenBounds.x;
relativeLocation.y -= currentScreenBounds.y;
return relativeLocation;
}
Thanks for your answers!

Usually when you call "getLocationOnScreen()" it gets the location of the component "this" (from the code I don't quite understand who "this" is).
Maybe you can try to get location of the button by using "button.getLocationOnScreen()".

Here is a small snippet that shows how to position elements relatively to another one. It displays a popup menu below the button, and a JDialog to its left. I tested it on a multi-screen environment where secondary screen is on the right of the main one.
Also, use getSize(), getWidth() and getHeight() instead of getPreferredSize(). getSize(), getWidth and getHeight return the actual dimensions of the component, while getPreferredSize() is only an indicator to the LayoutManager to what the component wishes to have.
If you use the method JPopupMenu.show() make sure to use coordinates and sizes relative to the invoker component.
import java.awt.Dimension;
import java.awt.Point;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.ComponentEvent;
import java.awt.event.ComponentListener;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JFrame;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
public class Test2 {
public static void main(String[] args) {
final JFrame frame = new JFrame();
final JButton button = new JButton("Hello");
button.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JPopupMenu popupMenu = new JPopupMenu();
popupMenu.add(new JMenuItem("Some test"));
System.err.println(button.getLocationOnScreen());
popupMenu.show(button, 0, button.getHeight());
JDialog dialog = new JDialog(frame);
dialog.setSize(100, 30);
Point locationOnScreen = button.getLocationOnScreen();
locationOnScreen.x += button.getWidth();
dialog.setLocation(locationOnScreen);
dialog.setVisible(true);
}
});
frame.addComponentListener(new ComponentListener() {
#Override
public void componentShown(ComponentEvent e) {
}
#Override
public void componentResized(ComponentEvent e) {
info(button);
}
private void info(final JButton button) {
if (button.isShowing()) {
System.err.println(button.getLocationOnScreen());
System.err.println(button.getGraphicsConfiguration().getBounds());
}
}
#Override
public void componentMoved(ComponentEvent e) {
info(button);
}
#Override
public void componentHidden(ComponentEvent e) {
}
});
button.setPreferredSize(new Dimension(200, 60));
frame.add(button);
frame.pack();
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.setVisible(true);
}
}