Cannot add an image to JPanel. Nothing works:(

[Liana Norpunova]

Hi!

I would like to add an Image to JPanel after the Mouse Click. I've read dozens of information about this topic, however have a problem...I've tried three different variants of code to add an image, however each time got just a blank screen - no picture. Pliz help.

    
private void jLabel1MousePressed(java.awt.event.MouseEvent evt) {
            JLabel label = new JLabel();
            label.setSize(100, 100);
            label.setIcon(new javax.swing.ImageIcon(getClass().getResource("/sw_app/resources/smile1.png")));
            jPanel1.add(label);
            this.getContentPane().add(jPanel1);
            this.setVisible(true);
            this.repaint();
    }

I've also tried the following code:

      
ImageIcon icon = new ImageIcon("/sw_app/resources/smile1.png");
label.setIcon(icon);

...and this one:

 
Image image = ImageIO.read(getClass().getResourceAsStream("resources/smile1.png"));
Icon icon = new ImageIcon(image.getScaledInstance(100, 100, Image.SCALE_DEFAULT));

NOTHING WORKS

P.S.: I'm using NetBeans IDE 6.9.

[Rob Spoor]

What does icon.getImageWidth() print? If that's -1 then the image path isn't correct.

Also:
1) don't add the panel to the content pane again. It's already there (well, I assume).
2) call revalidate() on the JPanel after you add a control to it while it's already visible.

[Liana Norpunova]

Thanks! Everything is ok now This is the workable code:

    private void jLabel1MousePressed(java.awt.event.MouseEvent evt) {
            JLabel label = new JLabel();
            ClassLoader cldr = this.getClass().getClassLoader();

            java.net.URL imageURL = cldr.getResource("sw_app/resources/smile1.png");
            if (imageURL != null) {
                ImageIcon icon = new ImageIcon(imageURL);
                label.setIcon(icon);
                label.setSize(100, 100);
            } else {
                System.out.println("Couldn't find file: ");
            }
            this.jPanel1.add(label);
            this.setVisible(true);
            this.jPanel1.revalidate();
            this.repaint();
    }

Maybe someone could also advise me how to move the created JLabel: label with the mouse on the screen? I'd like to allow the user to position the images on the screen. I've used label.setLocation(MouseInfo.getPointerInfo().getLocation().x-jPanel1.getX(),MouseInfo.getPointerInfo().getLocation().y-jPanel1.getY()); inside the private void jLabel1MousePressed(java.awt.event.MouseEvent evt). However, it doesn't work.

[Rob Spoor]

To position components manually you must set its layout manager to null. However, this also means that you must set the preferred size manually. After that you can use setLocation or setBounds to place the component. Note that without a layout manager the added component will initially have a size of 0x0. By calling

label.setSize(label.getPreferredSize())

you can give it its desired size, then use setLocation to move it around.

If you want to drag your label around you should try searching first. There are quite some examples for that.

[Liana Norpunova]

Thanks a lot! I've updated the code by setting null layout manager and positioning JLabel: label by hand. Everything works correctly!

However, if I want JLabel: label to respond on my mouse click and get a position of the mouse cursor, then it doesn't work. What makes me confused is that MouseEvent is set to JLabel: jLabel1 and not to JLabel: label...Could someone tell me how to set the event handling to JLabel: label? Maybe some web links...? Now I have the following code (it doesn't work in the way I want):

    
private void jLabel1MousePressed(java.awt.event.MouseEvent evt) {                                     
            JLabel label = new JLabel();
            ClassLoader cldr = this.getClass().getClassLoader();

            java.net.URL imageURL = cldr.getResource("sw_app/resources/smile1.png");
            if (imageURL != null) {
                ImageIcon icon = new ImageIcon(imageURL);
                label.setIcon(icon);
                this.getContentPane().setLayout(null);
                label.setSize(label.getPreferredSize());
                label.setLocation(MouseInfo.getPointerInfo().getLocation().x-jPanel1.getX(),MouseInfo.getPointerInfo().getLocation().y-jPanel1.getY());
                System.out.println("Ok");
            } else {
                System.out.println("Couldn't find file: ");
            }
            this.jPanel1.add(label);
            this.setVisible(true);
            this.jPanel1.revalidate();
            this.repaint();
    } 

[Liana Norpunova]

This is how I try to solve my problem (still doesn't work correctly):

    
private void jLabel1MousePressed(java.awt.event.MouseEvent evt) {                                     
            JLabel label = new JLabel();
            ClassLoader cldr = this.getClass().getClassLoader();

            java.net.URL imageURL = cldr.getResource("sw_app/resources/beads_crystal.png");
            if (imageURL != null) {
                ImageIcon icon = new ImageIcon(imageURL);
                label.setIcon(icon);
                this.getContentPane().setLayout(null);
                label.setSize(label.getPreferredSize());
                //label.setLocation(MouseInfo.getPointerInfo().getLocation().x-jPanel1.getX(),MouseInfo.getPointerInfo().getLocation().y-jPanel1.getY());
                label.setTransferHandler(new ImageSelection());
                MouseListener listener = new MouseAdapter() {
                public void mousePressed(MouseEvent me) {
                    JComponent comp = (JComponent) me.getSource();
                    TransferHandler handler = comp.getTransferHandler();
                    handler.exportAsDrag(comp, me, TransferHandler.COPY);
                    }
                };
                label.addMouseListener(listener);
                System.out.println("Ok");
            } else {
                System.out.println("Couldn't find file: ");
            }
            this.jPanel1.add(label);
            this.setVisible(true);
            this.jPanel1.revalidate();
            this.repaint();
    } 

In addition, I've created the Java class:

    
package sw_app;

import java.awt.*;
import java.awt.datatransfer.DataFlavor;
import java.awt.datatransfer.Transferable;
import java.awt.datatransfer.UnsupportedFlavorException;
import java.io.IOException;
import javax.swing.*;

class ImageSelection extends TransferHandler implements Transferable {

  private static final DataFlavor flavors[] = { DataFlavor.imageFlavor };

  private Image image;

  public int getSourceActions(JComponent c) {
    return TransferHandler.COPY;
  }

  public boolean canImport(JComponent comp, DataFlavor flavor[]) {
    if (!(comp instanceof JLabel) && !(comp instanceof AbstractButton)) {
      return false;
    }
    for (int i = 0, n = flavor.length; i < n; i++) {
      for (int j = 0, m = flavors.length; j < m; j++) {
        if (flavor[i].equals(flavors[j])) {
          return true;
        }
      }
    }
    return false;
  }

  public Transferable createTransferable(JComponent comp) {
    // Clear
    image = null;

    if (comp instanceof JLabel) {
      JLabel label = (JLabel) comp;
      Icon icon = label.getIcon();
      if (icon instanceof ImageIcon) {
        image = ((ImageIcon) icon).getImage();
        return this;
      }
    } else if (comp instanceof AbstractButton) {
      AbstractButton button = (AbstractButton) comp;
      Icon icon = button.getIcon();
      if (icon instanceof ImageIcon) {
        image = ((ImageIcon) icon).getImage();
        return this;
      }
    }
    return null;
  }

  public boolean importData(JComponent comp, Transferable t) {
    if (comp instanceof JLabel) {
      JLabel label = (JLabel) comp;
      if (t.isDataFlavorSupported(flavors[0])) {
        try {
          image = (Image) t.getTransferData(flavors[0]);
          ImageIcon icon = new ImageIcon(image);
          label.setIcon(icon);
          return true;
        } catch (UnsupportedFlavorException ignored) {
        } catch (IOException ignored) {
        }
      }
    } else if (comp instanceof AbstractButton) {
      AbstractButton button = (AbstractButton) comp;
      if (t.isDataFlavorSupported(flavors[0])) {
        try {
          image = (Image) t.getTransferData(flavors[0]);
          ImageIcon icon = new ImageIcon(image);
          button.setIcon(icon);
          return true;
        } catch (UnsupportedFlavorException ignored) {
        } catch (IOException ignored) {
        }
      }
    }
    return false;
  }

  // Transferable
  public Object getTransferData(DataFlavor flavor) {
    if (isDataFlavorSupported(flavor)) {
      return image;
    }
    return null;
  }

  public DataFlavor[] getTransferDataFlavors() {
    return flavors;
  }

  public boolean isDataFlavorSupported(DataFlavor flavor) {
    return flavors[0].equals(flavor);
  }
}

Any ideas how to make it workable (drag and drop behavior of JLabel: label)?