MouseWheelEventDemo.java Source code

Introduction

Here is the source code for MouseWheelEventDemo.java

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/* From http://java.sun.com/docs/books/tutorial/index.html */
/*
 * Copyright (c) 2006 Sun Microsystems, Inc. All Rights Reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * -Redistribution of source code must retain the above copyright notice, this
 *  list of conditions and the following disclaimer.
 *
 * -Redistribution in binary form must reproduce the above copyright notice,
 *  this list of conditions and the following disclaimer in the documentation
 *  and/or other materials provided with the distribution.
 *
 * Neither the name of Sun Microsystems, Inc. or the names of contributors may
 * be used to endorse or promote products derived from this software without
 * specific prior written permission.
 *
 * This software is provided "AS IS," without a warranty of any kind. ALL
 * EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND WARRANTIES, INCLUDING
 * ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
 * OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
 * AND ITS LICENSORS SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE
 * AS A RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR ANY LOST
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 * OF LIABILITY, ARISING OUT OF THE USE OF OR INABILITY TO USE THIS SOFTWARE,
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 *
 * You acknowledge that this software is not designed, licensed or intended
 * for use in the design, construction, operation or maintenance of any
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 */
/*
 * MouseWheelEventDemo.java is a 1.4 example that requires no other files.
 */

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;

import javax.swing.BorderFactory;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;

public class MouseWheelEventDemo extends JPanel implements MouseWheelListener {
    JTextArea textArea;

    JScrollPane scrollPane;

    final static String newline = "\n";

    public MouseWheelEventDemo() {
        super(new BorderLayout());

        textArea = new JTextArea();
        textArea.setEditable(false);
        scrollPane = new JScrollPane(textArea);
        scrollPane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
        scrollPane.setPreferredSize(new Dimension(400, 250));
        add(scrollPane, BorderLayout.CENTER);
        textArea.append("This text area displays information " + "about its mouse wheel events." + newline);

        //Register for mouse-wheel events on the text area.
        textArea.addMouseWheelListener(this);

        setPreferredSize(new Dimension(450, 350));
        setBorder(BorderFactory.createEmptyBorder(20, 20, 20, 20));
    }

    public void mouseWheelMoved(MouseWheelEvent e) {
        String message;
        int notches = e.getWheelRotation();
        if (notches < 0) {
            message = "Mouse wheel moved UP " + -notches + " notch(es)" + newline;
        } else {
            message = "Mouse wheel moved DOWN " + notches + " notch(es)" + newline;
        }
        if (e.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) {
            message += "    Scroll type: WHEEL_UNIT_SCROLL" + newline;
            message += "    Scroll amount: " + e.getScrollAmount() + " unit increments per notch" + newline;
            message += "    Units to scroll: " + e.getUnitsToScroll() + " unit increments" + newline;
            message += "    Vertical unit increment: " + scrollPane.getVerticalScrollBar().getUnitIncrement(1)
                    + " pixels" + newline;
        } else { //scroll type == MouseWheelEvent.WHEEL_BLOCK_SCROLL
            message += "    Scroll type: WHEEL_BLOCK_SCROLL" + newline;
            message += "    Vertical block increment: " + scrollPane.getVerticalScrollBar().getBlockIncrement(1)
                    + " pixels" + newline;
        }
        saySomething(message, e);
    }

    //Append to the text area and make sure the new text is visible.
    void saySomething(String eventDescription, MouseWheelEvent e) {
        textArea.append(e.getComponent().getClass().getName() + ": " + eventDescription);
        textArea.setCaretPosition(textArea.getDocument().getLength());
    }

    /**
     * Create the GUI and show it. For thread safety, this method should be
     * invoked from the event-dispatching thread.
     */
    private static void createAndShowGUI() {
        //Make sure we have nice window decorations.
        JFrame.setDefaultLookAndFeelDecorated(true);

        //Create and set up the window.
        JFrame frame = new JFrame("MouseWheelEventDemo");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        //Create and set up the content pane.
        JComponent newContentPane = new MouseWheelEventDemo();
        newContentPane.setOpaque(true); //content panes must be opaque
        frame.setContentPane(newContentPane);

        //Display the window.
        frame.pack();
        frame.setVisible(true);
    }

    public static void main(String[] args) {
        //Schedule a job for the event-dispatching thread:
        //creating and showing this application's GUI.
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}