Dragging a JLabel with a TransferHandler (Drag and Drop)

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I am using a TransferHandler to pass data from a JPanel to a JTextArea as a JLabel (Click somewhere in the left panel to create the JLabel to drag)

The transfer of the data works fine, but I'd like to also "show" the JLabel as its being dragged along with the mouse pointer.

If you comment out

dropLabel.setTransferHandler(new TransferHandler("text"));

dropLabel.getTransferHandler().exportAsDrag(dropLabel, e,
            TransferHandler.COPY);

you will see how I want it to look. (but of course then the data won't be transferred).

How can I get both the transfer to work and the JLabel to follow the mouse cursor?

Here is the code:

import java.awt.*;
import java.awt.datatransfer.Transferable;
import java.awt.event.*;

import javax.swing.*;
import javax.swing.border.Border;

public class DragTest extends JFrame implements MouseMotionListener,
        MouseListener {

    private JPanel leftPanel = new JPanel(null);
    private JPanel rightPanel = new JPanel(null);
    private JLabel dragLabel = new JLabel("drop");
    private final JWindow window = new JWindow();
    JLabel dropLabel;

    public DragTest() {
        this.setLayout(new GridLayout(1, 2));

        leftPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        rightPanel.setBorder(BorderFactory.createLineBorder(Color.black));
        this.add(leftPanel);
        this.add(rightPanel);
        leftPanel.addMouseListener(this);
        leftPanel.addMouseMotionListener(this);

        JTextArea area = new JTextArea();

        rightPanel.setLayout(new GridLayout(1, 1));
        rightPanel.add(area);

        dragLabel.setFont(new Font("Serif", Font.BOLD, 48));
    }

    @Override
    public void mousePressed(MouseEvent e) {

        dropLabel = new JLabel("drop");

        Dimension labelSize = dropLabel.getPreferredSize();
        dropLabel.setSize(labelSize);
        int x = e.getX() - labelSize.width / 2;
        int y = e.getY() - labelSize.height / 2;
        dropLabel.setLocation(x, y);
        leftPanel.add(dropLabel);

        dropLabel.setTransferHandler(new TransferHandler("text"));

        dropLabel.getTransferHandler().exportAsDrag(dropLabel, e,
                TransferHandler.COPY);

        repaint();

    }

    @Override
    public void mouseDragged(MouseEvent me) {
        dragLabel = new JLabel("drop");
        dragLabel.setFont(new Font("Serif", Font.BOLD, 48));
        int x = me.getPoint().x;
        int y = me.getPoint().y;
        window.add(dragLabel);
        window.pack();
        Point pt = new Point(x, y);
        Component c = (Component) me.getSource();
        SwingUtilities.convertPointToScreen(pt, c);
        window.setLocation(pt);
        window.setVisible(true);
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }

    @Override
    public void mouseClicked(MouseEvent e) {

    }

    @Override
    public void mouseReleased(MouseEvent e) {

//      leftPanel.remove(dropLabel);

        window.remove(dragLabel);
        window.setVisible(false);

        repaint();
    }

    @Override
    public void mouseEntered(MouseEvent e) {

    }

    @Override
    public void mouseExited(MouseEvent e) {

    }

    public static void main(String[] args) {

        DragTest frame = new DragTest();
        frame.setVisible(true);
        frame.setSize(600, 400);
        frame.setResizable(false);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    }
}
3 Answers
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