/*
 *  ==========================================================================
 *  DemoClipping.java : This applet demonstrates clipping along a circle
 *  positioned at the center of a canvas. The program clips the already 
 *  clipped portion when the radio button "Clip Further" is selected. If the
 *  radio button "Clip" is selected again, the program clips the canvas as in
 *  the beginning.
 * 
 *  This program is an applet implementation of a standalone program presented
 *  in S. Pantham (1999). 
 * 
 *  Adapted from : Pantham S., Pure JFC Swing, 1999.
 *  Modified by : Mark Austin                                      March, 2001
 *  ==========================================================================
 */

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.geom.*;

public class DemoClipping extends JApplet {
    DemoClippingCanvas canvas;
    JRadioButton clipButton, clipFurButton;
    
    public void init() {

        // 1. Get the content pane

        Container contentPane = getContentPane();
        contentPane.setBackground( Color.white );

        // 2. Create a display canvas and add it to the frame

        canvas = new DemoClippingCanvas();

        contentPane.add(canvas);

        // 3. Create a panel and add mutually exclusive radio buttons;
        // then add the panel to the frame's content panel 

        JPanel panel = new JPanel();
        panel.setBorder(new TitledBorder(
           "Clip or Clip Further Using the Radio Buttons..."));

        panel.setLayout( new GridLayout(1, 2) );

        clipButton = new JRadioButton("Clip", true);
        clipButton.addActionListener(new RadioButtonListener());
        clipFurButton = new JRadioButton("Clip Further");
        clipFurButton.addActionListener(new RadioButtonListener());
        ButtonGroup group = new ButtonGroup();
        group.add(clipButton); group.add(clipFurButton);

        panel.add(clipButton);
        panel.add(clipFurButton);
        contentPane.add(BorderLayout.SOUTH, panel);
    }

    // 4. Radio button listener

    class RadioButtonListener implements ActionListener {
        public void actionPerformed(ActionEvent e) {
            JRadioButton temp = (JRadioButton) e.getSource();

            if (temp.equals(clipButton)) {
                canvas.clip = true;
                canvas.clipFurther = false;
                canvas.repaint();
            }
            else if (temp.equals(clipFurButton)) {
                canvas.clipFurther = true;
                canvas.repaint();
            }
        }
    }
}

// 5. Canvas to paint the "Hello! Graphics World!" text

class DemoClippingCanvas extends Canvas {
    boolean clip = true;
    boolean clipFurther = false;

    DemoClippingCanvas() {
        setBackground( Color.white );
    }

    public void paint(Graphics g) {

        // 6. Set up the 2D graphics context

        Graphics2D g2 = (Graphics2D) g;

        // 7. Retrieve the size of the canvas

        int w = getSize().width;
        int h = getSize().height;

        // 8. if the clip button is selected or when the frame is
        //    initially loaded, clip along or show a circle using
        //    the setClip() method.

        if (clip) {
            Ellipse2D e = new Ellipse2D.Float(w/4.0f, h/4.0f,
                                             w/2.0f, h/2.0f);
            g2.setClip(e);

            // Draw a filled rectangle with red color. Rectangle is
            // of the size of the canvas.
            g2.setColor(Color.red);
            g2.fillRect(0, 0, w, h);
        }

        // 9. if the clipFurther button is selected, use clip() method
        //    to clip along a rectangle over the existing circle. 

        if (clipFurther) {
            Rectangle r = new Rectangle(w/2, h/2, w/2, h/2);
            g2.clip(r);

            g2.setColor(Color.green);
            g2.fillRect(0, 0, w, h);
        }
    }
}