ghostglasspane.java

oraily的Swing hacks code

import java.awt.AlphaComposite;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.image.BufferedImage;

import javax.swing.JPanel;

public class GhostGlassPane extends JPanel
{
	private AlphaComposite composite;
    private BufferedImage dragged = null;
    private Point location = new Point(0, 0);

    public GhostGlassPane()
    {
        setOpaque(false);
        composite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f);
    }

    public void setImage(BufferedImage dragged)
    {
        this.dragged = dragged;
    }

    public void setPoint(Point location)
    {
        this.location = location;
    }

    public void paintComponent(Graphics g)
    {
        if (dragged == null)
            return;

        Graphics2D g2 = (Graphics2D) g;
        g2.setComposite(composite);
        g2.drawImage(dragged,
                     (int) (location.getX() - (dragged.getWidth(this)  / 2)),
                     (int) (location.getY() - (dragged.getHeight(this) / 2)),
                     null);
    }
}