Mouse Wheel Event Demo
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*
* This software is provided "AS IS," without a warranty of any kind. ALL
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* ANY IMPLIED WARRANTY OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE
* OR NON-INFRINGEMENT, ARE HEREBY EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN")
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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();
}
});
}
}
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