Mega Code Archive
Decorator pattern in Java
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/*
The Design Patterns Java Companion
Copyright (C) 1998, by James W. Cooper
IBM Thomas J. Watson Research Center
*/
import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class DecoWindow extends JFrame implements ActionListener {
JButton Quit;
public DecoWindow() {
super("Deco Button");
addWindowListener(new WindowAdapter() {
public void windowClosing(WindowEvent e) {
System.exit(0);
}
});
JPanel jp = new JPanel();
getContentPane().add(jp);
jp.add(new CoolDecorator(new JButton("Cbutton")));
jp.add(new SlashDecorator(new CoolDecorator(new JButton("Dbutton"))));
//jp.add( new CoolDecorator(new JButton("Dbutton")));
jp.add(Quit = new JButton("Quit"));
Quit.addActionListener(this);
setSize(new Dimension(200, 100));
setVisible(true);
Quit.requestFocus();
}
public void actionPerformed(ActionEvent e) {
System.exit(0);
}
static public void main(String argv[]) {
new DecoWindow();
}
}
class Decorator extends JComponent {
public Decorator(JComponent c) {
setLayout(new BorderLayout());
add("Center", c);
}
}
class SlashDecorator extends Decorator {
int x1, y1, w1, h1;
public SlashDecorator(JComponent c) {
super(c);
}
public void setBounds(int x, int y, int w, int h) {
x1 = x;
y1 = y;
w1 = w;
h1 = h;
super.setBounds(x, y, w, h);
}
public void paint(Graphics g) {
super.paint(g);
g.setColor(Color.red);
g.drawLine(0, 0, w1, h1);
}
}
class CoolDecorator extends Decorator {
boolean mouse_over; //true when mose over button
JComponent thisComp;
public CoolDecorator(JComponent c) {
super(c);
mouse_over = false;
thisComp = this; //save this component
//catch mouse movements in inner class
c.addMouseListener(new MouseAdapter() {
public void mouseEntered(MouseEvent e) {
mouse_over = true; //set flag when mouse over
thisComp.repaint();
}
public void mouseExited(MouseEvent e) {
mouse_over = false; //clear flag when mouse not over
thisComp.repaint();
}
});
}
//paint the button
public void paint(Graphics g) {
super.paint(g); //first draw the parent button
if (!mouse_over)
//if the mouse is not over the button
//erase the borders
{
Dimension size = super.getSize();
g.setColor(Color.lightGray);
g.drawRect(0, 0, size.width - 1, size.height - 1);
g.drawLine(size.width - 2, 0, size.width - 2, size.height - 1);
g.drawLine(0, size.height - 2, size.width - 2, size.height - 2);
}
}
}
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