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What prevents java swing components from being painted when added to a JComponent?

JTextField, JSlider, JComboBox, etc added to a JComponent are not displayed in the JFrame containing the JComponent. It seems only drawing by the Graphics parameter allows painting. The included test program compares using JPanel to JComponent in my efforts to discover how to display components added to a JComponent. Is there any way to get such components displayed?
public class TestPaints {
public static void main(String[] args) {
new TestPaints();
}
JTextField _text1;
JLabel _label1 = new JLabel("Text1");
JTextField _text2;
JLabel _label2 = new JLabel("Text2");
TestPaints() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame("Paint a Widget");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout(3, 2));
GridBagConstraints grid = new GridBagConstraints();
frame.add(new JLabel("TextField in JComponent "));
grid.gridx = 2;
frame.add(new JLabel("TextField in JPanel"), grid);
grid.gridy = 2;
grid.gridx = 1;
frame.add(new TestJComponent(), grid);
grid.gridx = 2;
frame.add(new TestJPanel(), grid);
grid.gridy = 3;
grid.gridx = 1;
/* tabbing between the two TextFields shows that keystrokes are seen */
frame.add(_label1, grid);
grid.gridx = 2;
frame.add(_label2, grid);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestJComponent extends JComponent {
public TestJComponent() {
setPreferredSize(new Dimension(100, 30));
_text1 = new JTextField(6);
_text1.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
_label1.setText(_text1.getText());
_label1.repaint();
}
});
_text1.setOpaque(true);
_text1.setVisible(true);
add(_text1);
/* This doesn't work
JPanel panel = new JPanel();
panel.add(_text1);
add(panel); */
setOpaque(true);
setVisible(true);
setBackground(Color.green);
}
public void paint(Graphics g) {
super.paint(g); // did not do background. Rectangle r = g.getClipBounds(); // needs this
g.setColor(getBackground());
g.fillRect(r.x, r.y, r.width, r.height);
/* Variations such as these don't work */
_text1.setOpaque(true);
_text1.setVisible(true);
_text1.paintComponents(g);
}
}
class TestJPanel extends JPanel {
TestJPanel() {
_text2 = new JTextField(6);
_text2.addKeyListener(new KeyAdapter() {
public void keyPressed(KeyEvent e) {
_label2.setText(_text2.getText());
_label2.repaint();
}
});
add(_text2);
setBackground(Color.blue);
}
}
}

Edit: you need to give your JComponent a layout such as FlowLayout for components to show properly since it does not have a default layout like JPanel has. So add setLayout(new FlowLayout()) into your JComponent's constructor
You have:
frame.setLayout(new GridLayout(3, 2));
and then try to add components to the JFrame's contentPane using GridBagConstraints, and this doesn't make sense. If you want to use these constraints, then the container needs to use GridBagLayout, not GridLayout.
Also this is dangerous code:
public void paint(Graphics g) {
super.paint(g); // did not do background. Rectangle r = g.getClipBounds(); // needs this
g.setColor(getBackground());
g.fillRect(r.x, r.y, r.width, r.height);
/* Variations such as these don't work */
_text1.setOpaque(true);
_text1.setVisible(true);
_text1.paintComponents(g);
}
You should be overriding JComponent's paintComponent method, not its paint method (call super.paintComponent) and should not be setting component visibility or calling a component's paintComponents method directly within any painting method.
Another issue: don't use KeyListeners within Swing text components but rather add a DocumentListener to the component's Document. Otherwise you risk breaking some of the functionality of the text component, and also your listener won't work for copy/paste, while the DocumentListener will.
And another issue, your main issue: you need to give the JComponent a layout. It does not default to FlowLayout like a JPanel does. This is why the added components are not showing within it.
For example:
import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.Graphics;
import java.awt.GridLayout;
import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
public class TestPaints2 {
private JTextField textField1 = new JTextField(8);
private JTextField textField2 = new JTextField(8);
private JLabel label1 = new JLabel("Text1");
private JLabel label2 = new JLabel("Text2");
public TestPaints2() {
textField1.getDocument().addDocumentListener(new MyDocListener(label1));
textField2.getDocument().addDocumentListener(new MyDocListener(label2));
TestJComponent2 jComponent = new TestJComponent2();
jComponent.add(textField1);
TestJPanel2 jPanel = new TestJPanel2();
jPanel.add(textField2);
JPanel mainPanel = new JPanel(new GridLayout(0, 2));
mainPanel.add(new JLabel("JComponent"));
mainPanel.add(new JLabel("JPanel"));
mainPanel.add(jComponent);
mainPanel.add(jPanel);
mainPanel.add(label1);
mainPanel.add(label2);
JFrame frame = new JFrame("Test");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(mainPanel);
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
private class MyDocListener implements DocumentListener {
private JLabel label;
public MyDocListener(JLabel label) {
this.label = label;
}
#Override
public void changedUpdate(DocumentEvent e) {
updateLabel(e);
}
#Override
public void insertUpdate(DocumentEvent e) {
updateLabel(e);
}
#Override
public void removeUpdate(DocumentEvent e) {
updateLabel(e);
}
private void updateLabel(DocumentEvent e) {
Document doc = e.getDocument();
int offset = doc.getLength();
try {
String text = doc.getText(0, offset);
label.setText(text);
} catch (BadLocationException e1) {
e1.printStackTrace();
}
}
}
public static void main(String[] args) {
SwingUtilities.invokeLater(() -> new TestPaints2());
}
}
class TestJComponent2 extends JComponent {
private static final Color BG = Color.GREEN;
private static final int GAP = 5;
public TestJComponent2() {
setOpaque(true);
setBackground(BG);
setLayout(new FlowLayout());
setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
g.setColor(getBackground());
g.fillRect(0, 0, getWidth(), getHeight());
}
}
class TestJPanel2 extends JPanel {
private static final Color BG = Color.BLUE;
private static final int GAP = 5;
public TestJPanel2() {
setBackground(BG);
setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
}
}

Simple paint program using JPanel shows random images of JButtons

I'm trying to make a simple paint program in Java. It has 3 colors and a JField to enter the thickness. It works, except every time I enter a button, an image of that button shows up in the JPanel that contains the drawing portion.
I know that I can set the paintPane JPanel to opaque, but it relies on drawing over it self for the painting to work - otherwise it just drags a point around the screen. Thanks!!!
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
class SimplePainting
{
//The main method simply creates a frame, and terminates the program
//once that frame is closed.
public static void main (String [] args)
{
PaintFrame frame = new PaintFrame();
frame.addWindowListener(new WindowAdapter()
{
public void windowClosing(WindowEvent e)
{
System.exit(0);
}
}
);
}
}
class PaintFrame extends JFrame implements ActionListener
{
JPanel pane;
PaintPane drawPane;
Color paintColor = Color.black;
private int radius = 5;
//holds the thickness of the line
JTextField thick;
public PaintFrame ()
{
//We use the JFrame consturctor to add a title to the frame
super("Windows Paint");
//set the main content pane
pane = (JPanel)getContentPane();
pane.setLayout(new BorderLayout());
//make a pane to hold the drawing
drawPane = new PaintPane();
drawPane.addMouseMotionListener(drawPane);
//Make a JPanle to hold all of the buttons
JPanel buttonPane = new JPanel();
buttonPane.setLayout(new GridLayout(1,6));
//add the buttons
JButton black = new JButton("Black");
buttonPane.add(black);
JButton red = new JButton("Red");
buttonPane.add(red);
JButton green = new JButton("Green");
buttonPane.add(green);
//Make a field to re-enter the thickness
thick = new JTextField(3);
thick.setText("5");
JButton thickness = new JButton("Reset Thickness");
thickness.addActionListener(this);
buttonPane.add(thickness);
buttonPane.add(thick);
JButton reset = new JButton("New Drawing");
reset.addActionListener(this);
buttonPane.add(reset);
black.addActionListener(this);
red.addActionListener(this);
green.addActionListener(this);
pane.add(drawPane, BorderLayout.CENTER);
pane.add(buttonPane, BorderLayout.SOUTH);
setSize(500,200);
setVisible(true);
}
public void actionPerformed(ActionEvent e)
{
if (e.getActionCommand().equals("Black"))
paintColor = Color.black;
else if (e.getActionCommand().equals("Red"))
paintColor = Color.red;
else if (e.getActionCommand().equals("Green"))
paintColor = Color.green;
else if (e.getActionCommand().equals("Reset Thickness"))
{
if (thick.getText() != "")
{
int lineThickness = Integer.parseInt(thick.getText());
radius = lineThickness;
}
}
else if (e.getActionCommand().equals("New Drawing"))
{
drawPane.startPaint = false;
drawPane.repaint();
}
}
class PaintPane extends JPanel implements MouseMotionListener
{
private int x;
private int y;
// don't paint a point until mouse is dragged
boolean startPaint = false;
public PaintPane()
{
setBackground(Color.white);
}
//paints a circle centered at x,y
public void paint(Graphics g)
{
//recall that the frist (x,y) coordiantes represent the top left
//corner of a box holding the circle
g.setColor(paintColor);
if (startPaint)
g.fillOval(x-radius,y-radius, 2*radius, 2*radius);
else
super.paintComponent(g);
}
public void mouseDragged(MouseEvent e)
{
startPaint = true;
x = e.getX();
y = e.getY();
repaint();
}
public void mouseMoved(MouseEvent e)
{
}
}
}

Drawing Captured Screen Image in JPanel ,Image is displayed one more time ?How can I fix it to be display one timw?

I Want to capture Image from screen and draw it in JPanel , it works but it is displayed one more time like entering in a loop , I am confused by this , How can I fix it ,Please?
Varibles Iwidth,Ihieght ares above initiaized, but I take the block of code that cause the problem
protected void paintComponent(Graphics g)
{
super.paintComponent(g);
Image img;
ImageIcon i = null;
Rectangle screenRect=new Rectangle(Toolkit.getDefaultToolkit().getScreenSize());
try {
BufferedImage capture=new Robot().createScreenCapture(screenRect);
capture.getHeight();
capture.getWidth();
i=new ImageIcon(capture);
} catch (AWTException ex) {
Logger.getLogger(TestDrawing.class.getName()).log(Level.SEVERE, null, ex);
}
img = i.getImage();
g.drawImage(img,Iwidth,Ihieght,null);
super.repaint();
}

Never have code like that inside of paintComponent. That method should be reserved for painting and painting only, and is a method that you don't really have full control over since it is called by the JVM in response to both your request, and to requests from the OS, and even if you request a repaint, there's no guarantee that it will be complied with, especially if the requests are stacking up. Also, your GUI's perceived responsiveness will often depend on how quick painting is done, which is while file reading and image capturing should never be done inside of paintComponent.
Instead, you should read the image in as a reaction to some event, perhaps a Timer, then after the image is read, call repaint() and in paintComponent draw the obtained image.
Never call repaint() inside of paintComponent either.
Something like in pseudo code
// inside of the ActionListener of a Swing Timer (if you want to do this repeatedly)
get screen image from robot and feed it into the capture BufferedImage field
consider doing this in a SwingWorker
call repaint() when SwingWorker is done (via a PropertyChangeListener)
Inside of paintComponent:
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (capture != null) {
g.drawImage(capture, capture.getWidth(), capture.getHeight());
}
}
Edit
For example:
import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Rectangle;
import java.awt.Robot;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.util.concurrent.ExecutionException;
import javax.swing.*;
import javax.swing.SwingWorker.StateValue;
public class ScreenCaptureTest extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = 400;
private JButton btn = new JButton(new ScreenCaptureAction(this,
"Capture Screen", KeyEvent.VK_C));
private ImagePanel imagePanel = new ImagePanel();
public ScreenCaptureTest() {
JPanel buttonPanel = new JPanel();
buttonPanel.add(btn);
setLayout(new BorderLayout());
add(new JScrollPane(imagePanel), BorderLayout.CENTER);
add(buttonPanel, BorderLayout.SOUTH);
}
public void setImagePanelImage(BufferedImage img) {
imagePanel.setImage(img);
revalidate();
repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
ScreenCaptureTest mainPanel = new ScreenCaptureTest();
JFrame frame = new JFrame("ScreenCaptureTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
class ImagePanel extends JPanel {
private BufferedImage image;
public void setImage(BufferedImage image) {
this.image = image;
revalidate();
repaint();
}
#Override
protected void paintComponent(Graphics g) {
super.paintComponent(g);
if (image != null) {
g.drawImage(image, 0, 0, null);
}
}
#Override
public Dimension getPreferredSize() {
if (image != null) {
return new Dimension(image.getWidth(), image.getHeight());
}
return super.getPreferredSize();
}
}
class ScreenCaptureAction extends AbstractAction {
private ScreenCaptureTest screenCaptureTest;
public ScreenCaptureAction(ScreenCaptureTest screenCaptureTest, String name,
int mnemonic) {
super(name);
putValue(MNEMONIC_KEY, mnemonic);
this.screenCaptureTest = screenCaptureTest;
}
#Override
public void actionPerformed(ActionEvent e) {
setEnabled(false);
final SwingWorker<BufferedImage, Void> mySwingWorker = new SwingWorker<BufferedImage, Void>() {
#Override
protected BufferedImage doInBackground() throws Exception {
Toolkit toolkit = Toolkit.getDefaultToolkit();
Dimension screenSize = toolkit.getScreenSize();
Robot robot = new Robot();
BufferedImage capture = robot.createScreenCapture(new Rectangle(
screenSize));
return capture;
}
};
mySwingWorker.addPropertyChangeListener(new PropertyChangeListener() {
#Override
public void propertyChange(PropertyChangeEvent pcEvt) {
if ("state".equals(pcEvt.getPropertyName())
&& pcEvt.getNewValue() == StateValue.DONE) {
setEnabled(true);
try {
screenCaptureTest.setImagePanelImage(mySwingWorker.get());
} catch (InterruptedException | ExecutionException e) {
e.printStackTrace();
}
}
}
});
mySwingWorker.execute();
}
}
Edit
Note, that if this were my program, I'd display the image as an ImageIcon in a JLabel as it is much simpler to code. Then you could do away with the ImagePanel class and its paintComponent method, and simply code the main as:
public class ScreenCaptureTest extends JPanel {
private static final int PREF_W = 600;
private static final int PREF_H = 400;
private JButton btn = new JButton(new ScreenCaptureAction(this,
"Capture Screen", KeyEvent.VK_C));
//!! private ImagePanel imagePanel = new ImagePanel();
private JLabel screenLabel = new JLabel(); //!!
public ScreenCaptureTest() {
JPanel buttonPanel = new JPanel();
buttonPanel.add(btn);
setLayout(new BorderLayout());
//!! add(new JScrollPane(imagePanel), BorderLayout.CENTER);
add(new JScrollPane(screenLabel), BorderLayout.CENTER); //!!
add(buttonPanel, BorderLayout.SOUTH);
}
public void setImagePanelImage(BufferedImage img) {
//!! imagePanel.setImage(img);
Icon icon = new ImageIcon(img);
screenLabel.setIcon(icon);
//!! revalidate();
//!! repaint();
}
#Override
public Dimension getPreferredSize() {
return new Dimension(PREF_W, PREF_H);
}
private static void createAndShowGui() {
ScreenCaptureTest mainPanel = new ScreenCaptureTest();
JFrame frame = new JFrame("ScreenCaptureTest");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

How do I set hard limit on a JComponent when setMaximumSize() and setPrefferedSize() don't work?

I'm trying to make an image processing frame similar to one found in something like Photoshop or Paint Shop Pro and I'm running into problems.
Right now I have a JFrame window with a JDesktopPane. When I click a button, a JInternalFrame is made with the following components in it:
imageLabel = new JLabel("picture.png");
scrollPane.setViewPort(imageLabel);
internalFrame.add(scrollPane); // I also tried with a BorderLayout()
desktopPane.add(internalFrame);
My problem is this: I don't want the JLabel or the JScrollPane to stretch to the size of the JInternalFrame if the JLabel is smaller than the JInternalFrame.
I've tried padding the space around the JLabel with "empty" JLabels. I've tried switching layout styles of the JScrollPane. I've tried setting the preferred and maximum sizes of the JLabel and the JScrollPane to that of picture.png. None of it works for what I need. I don't want the blank "space" around the JLabel to be a part of the JScrollPane or the JLabel so that I can use various MouseEvents to trigger on the picture itself rather than the space left by the "stretched" JLabel or JScrollPane whenever I resize the JInternalFrame.
Thanks in advance.
Edit1: Here is a bit of code that highlights the problem.
import java.awt.*;
import java.awt.event.*;
class fooFrame extends JFrame implements MouseListener
{
private static fooFrame frame;
JLabel fooLabel;
public fooFrame()
{
JDesktopPane background = new JDesktopPane();
JInternalFrame internalFrame = new JInternalFrame("Internal Frame", true, true, true, true);
internalFrame.setSize(500, 500);
internalFrame.setLocation(20, 20);
internalFrame.setVisible(true);
Image image = Toolkit.getDefaultToolkit().getImage("test.gif");
fooLabel = new JLabel(new ImageIcon("test.gif"));
fooLabel.setPreferredSize(new Dimension(image.getWidth(null), image.getHeight(null)));
JScrollPane fooScrollPane = new JScrollPane(fooLabel, JScrollPane.VERTICAL_SCROLLBAR_NEVER, JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
fooScrollPane.setPreferredSize(new Dimension(fooLabel.getWidth(), fooLabel.getHeight()));
fooScrollPane.setViewportView(fooLabel); // add JLabel to JScrollPane
internalFrame.add(fooScrollPane); // add JScrollPane to JInternalFrame
background.add(internalFrame); // add JInternalFrame to JDesktopPanel
this.setContentPane(background); // add JDesktopPanel to JFrame
fooLabel.addMouseListener(this);
}
public void mouseClicked(MouseEvent me)
{
if (me.getSource() == fooLabel)
System.out.println("Clicked the picture.");
}
public void mouseEntered(MouseEvent me)
{
if (me.getSource() == fooLabel)
System.out.println("Entered the picture.");
}
public void mouseExited(MouseEvent me)
{
if (me.getSource() == fooLabel)
System.out.println("Exited the picture.");
}
public void mousePressed(MouseEvent me){}
public void mouseReleased(MouseEvent me){}
public static void createAndShowGUI()
{
try
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
}
catch (Exception e) { }
frame = new fooFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("foo");
frame.setSize(800,600);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}
You will have to get your own "test.gif" and if you make the internalFrame larger than the picture it fills the remaining space with the label. As all the mouseEvents fire when I cross the internalFrame rather than onto the picture like I want to have happen.
Edit2: Code modified with Kleopatra's suggestions.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.LineBorder;
public class a1
{
public static void main(String[] args)
{
fooFrame.createAndShowGUI();
}
}
class fooFrame extends JFrame implements MouseListener
{
private static fooFrame frame;
JLabel fooLabel;
public fooFrame()
{
JDesktopPane background = new JDesktopPane();
JInternalFrame internalFrame = new JInternalFrame("Internal Frame", true, true, true, true);
internalFrame.setLocation(20, 20);
internalFrame.setVisible(true);
internalFrame.pack();
Image image = Toolkit.getDefaultToolkit().getImage("test.gif");
fooLabel = new JLabel(new ImageIcon(image));
fooLabel.setBorder(new LineBorder(Color.PINK));
JScrollPane fooScrollPane = new JScrollPane((fooLabel), JScrollPane.VERTICAL_SCROLLBAR_AS_NEEDED, JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
internalFrame.setLayout(new BoxLayout(internalFrame.getContentPane(), BoxLayout.LINE_AXIS));
fooScrollPane.setViewportView(fooLabel); // add JLabel to JScrollPane
internalFrame.add(fooScrollPane); // add JScrollPane to JInternalFrame
background.add(internalFrame); // add JInternalFrame to JDesktopPanel
this.setContentPane(background); // add JDesktopPanel to JFrame
fooLabel.addMouseListener(this);
}
public void mouseClicked(MouseEvent me)
{
if (me.getSource() == fooLabel)
System.out.println("Clicked the picture.");
}
public void mouseEntered(MouseEvent me)
{
if (me.getSource() == fooLabel)
System.out.println("Entered the picture.");
}
public void mouseExited(MouseEvent me)
{
if (me.getSource() == fooLabel)
System.out.println("Exited the picture.");
}
public void mousePressed(MouseEvent me)
{
}
public void mouseReleased(MouseEvent me)
{
}
#Override
public Dimension getMaximumSize()
{
return getPreferredSize();
}
public static void createAndShowGUI()
{
try
{
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception e)
{
}
frame = new fooFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("foo");
frame.setSize(800, 600);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}

In this example, the internal frame will initially be no more than MAX_SIZE pixels. Smaller pictures will be sized so that scrolling is not required.
Addendum: Reading the title more closely, you may also want to limit the internal frame's maximum size:
internalFrame.setMaximumSize(new Dimension(fooLabel.getPreferredSize()));
Addendum: This variation may help clarify the problem. With the default layout, BorderLayout.CENTER, the scroll bars appear as required, but the MouseListener does not behave as desired. With a layout that respects preferred sizes, FlowLayout, the MouseListener reports correctly, but the the scroll bars never appear, as the label's preferred size never changes. I've added synthetic images for convenience.
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
import javax.swing.*;
class PictureFrame extends JFrame {
private static final String NAME = "image.jpg";
public PictureFrame() {
JDesktopPane dtp = new JDesktopPane();
dtp.add(new MyFrame("Large", FauxImage.create(300, 500), 50));
dtp.add(new MyFrame("Small", FauxImage.create(200, 200), 25));
this.add(dtp);
}
private static class MyFrame extends JInternalFrame {
private static final int MAX_SIZE = 256;
public MyFrame(String title, Image image, int offset) {
super(title, true, true, true, true);
//this.setLayout(new FlowLayout());
final JLabel label = new JLabel(new ImageIcon(image));
this.add(new JScrollPane(label));
this.pack();
int w = Math.min(MAX_SIZE, image.getWidth(null));
int h = Math.min(MAX_SIZE, image.getHeight(null));
Insets i = this.getInsets();
this.setSize(w + i.left + i.right, h + i.top + i.bottom);
this.setLocation(offset, offset);
this.setVisible(true);
label.addMouseListener(new MouseAdapter() {
#Override
public void mouseEntered(MouseEvent me) {
if (me.getSource() == label) {
System.out.println("Entered.");
}
}
#Override
public void mouseExited(MouseEvent me) {
if (me.getSource() == label) {
System.out.println("Exited.");
}
}
});
}
}
private static class FauxImage {
static public Image create(int w, int h) {
BufferedImage bi = new BufferedImage(
w, h, BufferedImage.TYPE_INT_ARGB);
Graphics2D g2d = bi.createGraphics();
g2d.setPaint(Color.lightGray);
g2d.fillRect(0, 0, w, h);
g2d.setColor(Color.black);
String s = w + "\u00D7" + h;
int x = (w - g2d.getFontMetrics().stringWidth(s)) / 2;
g2d.drawString(s, x, 24);
g2d.dispose();
return bi;
}
}
public static void createAndShowGUI() {
PictureFrame frame = new PictureFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setTitle("PictureFrame");
frame.setSize(640, 400);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
createAndShowGUI();
}
});
}
}

The answer to layout problems is LayoutManager. Always. It's never setXXSize (though nothing is absolutely absolute :-)
Just to be sure I understand what you are after:
always have the label at its pref size (which by default is the size of its icon)
allow scrolling if the internalFrame is smaller than the pref, that is the scrollpane is resized to smaller, label remains at its pref
disallow strectching of the scrollPane and its content if the internalframe is larger than pref
The important LayoutManager in this scenario is the one which control the size of the scrollpane: that's the LayoutManager of the internalFrame's contentPane. The default manager is a BorderLayout: sizing its center to whatever space is available. We need to replace that with one that respects max and make the center component (the scrollpane) report a max (which typically is Short.MAX)
internalFrame.setLayout(new BoxLayout(internalFrame.getContentPane(), BoxLayout.LINE_AXIS));
Image image = Toolkit.getDefaultToolkit().getImage("test.gif");
fooLabel = new JLabel(new ImageIcon(image));
JScrollPane fooScrollPane = new JScrollPane(fooLabel),
JScrollPane.VERTICAL_SCROLLBAR_NEVER,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER) {
#Override
public Dimension getMaximumSize() {
return getPreferredSize();
}
};
internalFrame.add(fooScrollPane); // add JScrollPane to JInternalFrame

Adding a JLabel on top of a JPanel

I attempting to place a .jpg icon on top of a JPanel in order to represent a board piece on a board. I have a GUI folder with the .java files and another folder containing the .jpg files.
--Major Edit--
Example Code
When a square is clicked a white icon is meant to be placed then black etc etc. This is a very basic example of what im trying to achieve
import java.awt.Dimension;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class gui extends JFrame implements MouseListener {
/**
*
*/
private static final long serialVersionUID = -973341728129968945L;
JLayeredPane layeredPane;
JPanel board;
JLabel piece;
int numSquares;
private boolean currentPlayer;
public gui(){
Dimension boardSize = new Dimension(600, 600);
numSquares = 6;
currentPlayer = true;
layeredPane = new JLayeredPane();
getContentPane().add(layeredPane);
layeredPane.setPreferredSize(boardSize);
layeredPane.addMouseListener(this);
board = new JPanel();
layeredPane.add(board, JLayeredPane.DEFAULT_LAYER);
board.setLayout( new GridLayout(numSquares, numSquares) );
board.setPreferredSize( boardSize );
board.setBounds(0, 0, boardSize.width, boardSize.height);
for (int i = 0; i < (numSquares * numSquares); i++) {
JPanel square = new JPanel( new BorderLayout() );
square.setBorder(BorderFactory.createLineBorder(Color.black));
square.setBackground(Color.green);
board.add( square );
}
}
public static void main(String[] args) {
JFrame frame = new gui();
frame.setDefaultCloseOperation(DISPOSE_ON_CLOSE );
frame.pack();
frame.setResizable(true);
frame.setLocationRelativeTo( null );
frame.setVisible(true);
}
#Override
public void mouseClicked(MouseEvent e) {
JPanel temp = (JPanel)board.findComponentAt(e.getX(), e.getY());
System.out.println(e.getX() + " " + e.getY());
if( currentPlayer ){
ImageIcon white = new ImageIcon("l/Images/white.jpg");
piece = new JLabel(white);
temp.add(piece);
}
else{
ImageIcon black = new ImageIcon( "/Images/black.jpg");
piece = new JLabel(black);
temp.add(piece);
}
currentPlayer = !currentPlayer;
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mousePressed(MouseEvent arg0) {
// TODO Auto-generated method stub
}
#Override
public void mouseReleased(MouseEvent e) {
}
}

Don't forget to revalidate and repaint if adding or removing components from a container. I've modified your SSCCE, and have gotten rid of the need to use images to make it runnable by folks who don't have access to your image files (like me!). Changes are noted by the // !! comments:
import java.awt.Color;
import java.awt.Dimension;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
public class Gui2 extends JFrame implements MouseListener {
private static final long serialVersionUID = -973341728129968945L;
JLayeredPane layeredPane;
JPanel board;
JLabel piece;
int numSquares;
private boolean currentPlayer;
// !!
private ImageIcon whiteIcon;
private ImageIcon blackIcon;
public Gui2() {
// !!
whiteIcon = createIcon(Color.white);
blackIcon = createIcon(Color.black);
Dimension boardSize = new Dimension(600, 600);
numSquares = 6;
currentPlayer = true;
layeredPane = new JLayeredPane();
getContentPane().add(layeredPane);
layeredPane.setPreferredSize(boardSize);
layeredPane.addMouseListener(this);
board = new JPanel();
layeredPane.add(board, JLayeredPane.DEFAULT_LAYER);
board.setLayout(new GridLayout(numSquares, numSquares));
board.setPreferredSize(boardSize);
board.setBounds(0, 0, boardSize.width, boardSize.height);
for (int i = 0; i < (numSquares * numSquares); i++) {
// !! JPanel square = new JPanel(new BorderLayout());
JPanel square = new JPanel(new GridBagLayout()); // !!
square.setBorder(BorderFactory.createLineBorder(Color.black));
square.setBackground(Color.green);
square.setName(String.format("[%d, %d]", i % numSquares, i
/ numSquares)); // !!
board.add(square);
}
}
// !!
private ImageIcon createIcon(Color color) {
int width = 40;
int height = width;
BufferedImage img = new BufferedImage(width, height,
BufferedImage.TYPE_INT_ARGB);
Graphics2D g2 = img.createGraphics();
g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
RenderingHints.VALUE_ANTIALIAS_ON);
g2.setColor(color);
g2.fillOval(0, 0, width, height);
g2.dispose();
ImageIcon icon = new ImageIcon(img);
return icon;
}
public static void main(String[] args) {
JFrame frame = new Gui2();
frame.setDefaultCloseOperation(DISPOSE_ON_CLOSE);
frame.pack();
frame.setResizable(true);
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
#Override
// !!
public void mousePressed(MouseEvent e) {
JPanel temp = (JPanel) board.findComponentAt(e.getX(), e.getY());
System.out.println(e.getX() + " " + e.getY());
System.out.println(temp.getName()); // !!
if (currentPlayer) {
// !! ImageIcon white = new ImageIcon("l/Images/white.jpg");
// !! piece = new JLabel(white);
piece = new JLabel(whiteIcon); // !!
temp.add(piece);
} else {
// !! ImageIcon black = new ImageIcon("/Images/black.jpg");
// !! piece = new JLabel(black);
piece = new JLabel(blackIcon); // !!
temp.add(piece);
}
temp.revalidate(); // !!
temp.repaint(); // !!
currentPlayer = !currentPlayer;
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent arg0) {
}
#Override
public void mouseClicked(MouseEvent arg0) {
}
#Override
public void mouseReleased(MouseEvent e) {
}
}
Also class names should be capitalized, and also you should again make your ImageIcons once. Again, one ImageIcon can be shared by many JLabels. You'll also want to respond to mousePressed not mouseClicked as mouseClicked can be fussy, especially if you move the mouse between press down and mouse release.
Hopefully you've also seen the value of an SSCCE. :)