ColorDrag.java Source code

Introduction

Here is the source code for ColorDrag.java

Source

/*
 * Copyright (c) 2004 David Flanagan.  All rights reserved.
 * This code is from the book Java Examples in a Nutshell, 3nd Edition.
 * It is provided AS-IS, WITHOUT ANY WARRANTY either expressed or implied.
 * You may study, use, and modify it for any non-commercial purpose,
 * including teaching and use in open-source projects.
 * You may distribute it non-commercially as long as you retain this notice.
 * For a commercial use license, or to purchase the book, 
 * please visit http://www.davidflanagan.com/javaexamples3.
 */

import java.awt.Color;
import java.awt.FlowLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionAdapter;

import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.TransferHandler;

/**
 * Simple Drag-and-Drop customization: drag the foreground color from the first
 * label and drop it as the background color into the second one. Try it also
 * using the ShowBean program to display a JColorChooser component with
 * dragEnabled=true.
 */
public class ColorDrag {
    public static void main(String args[]) {
        // Create two JLabel objects
        final JLabel label1 = new JLabel("Drag here");
        JLabel label2 = new JLabel("Drop here");

        // Register TransferHandler objects on them: label1 transfers its
        // foreground color and label2 transfers its background color.
        label1.setTransferHandler(new TransferHandler("foreground"));
        label2.setTransferHandler(new TransferHandler("background"));

        // Give label1 a foreground color other than the default
        // Make label2 opaque so it displays its background color
        label1.setForeground(new Color(100, 100, 200));
        label2.setOpaque(true);

        // Now look for drag gestures over label1. When one occurs,
        // tell the TransferHandler to begin a drag.
        // Exercise: modify this gesture recognition so that the drag doesn't
        // begin until the mouse has moved 4 pixels. This helps to keep
        // drags distinct from sloppy clicks. To do this, you'll need both
        // a MouseListener and a MouseMotionListener.
        label1.addMouseMotionListener(new MouseMotionAdapter() {
            public void mouseDragged(MouseEvent e) {
                TransferHandler handler = label1.getTransferHandler();
                handler.exportAsDrag(label1, e, TransferHandler.COPY);
            }
        });

        // Create a window, add the labels, and make it all visible.
        JFrame f = new JFrame("ColorDrag");
        f.getContentPane().setLayout(new FlowLayout());
        f.getContentPane().add(label1);
        f.getContentPane().add(label2);
        f.pack();
        f.setVisible(true);
    }
}