/**
 * TricolorPanel.java
 * @author Jeff Ondich, 27 October 2010
 *
 * Support class for the LayoutExample.java program.
 */
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class TricolorPanel extends JPanel
                           implements ActionListener
{
    private JPanel topSubpanel;
    private JPanel middleSubpanel;
    private JPanel bottomSubpanel;

    public TricolorPanel(Color topColor, Color middleColor, Color bottomColor)
    {
        this.setOpaque(true);
        this.setLayout(new GridLayout(0, 1));

        this.topSubpanel = new JPanel();
        this.topSubpanel.setOpaque(true);
        this.topSubpanel.setBackground(topColor);
        this.add(this.topSubpanel);

        this.middleSubpanel = new JPanel();
        this.middleSubpanel.setOpaque(true);
        this.middleSubpanel.setBackground(middleColor);
        this.add(this.middleSubpanel);

        this.bottomSubpanel = new JPanel();
        this.bottomSubpanel.setOpaque(true);
        this.bottomSubpanel.setBackground(bottomColor);
        this.add(this.bottomSubpanel);
    }

    public void actionPerformed(ActionEvent event)
    {
        // Rotate the background colors of the three subpanels.
        Color topColor = this.topSubpanel.getBackground();
        Color middleColor = this.middleSubpanel.getBackground();
        Color bottomColor = this.bottomSubpanel.getBackground();

        this.topSubpanel.setBackground(bottomColor);
        this.middleSubpanel.setBackground(topColor);
        this.bottomSubpanel.setBackground(middleColor);
    }
}