ClipArea.java Source code

Introduction

Here is the source code for ClipArea.java

Source

import java.awt.BorderLayout;
import java.awt.Canvas;
import java.awt.Color;
import java.awt.Container;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.GridLayout;
import java.awt.Rectangle;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import java.awt.geom.Ellipse2D;

import javax.swing.ButtonGroup;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JRadioButton;
import javax.swing.border.TitledBorder;

public class ClipArea extends JFrame {
    MyCanvas canvas;

    JRadioButton clipButton, clipFurButton;

    public ClipArea() {
        super();
        Container contentPane = getContentPane();

        canvas = new MyCanvas();
        contentPane.add(canvas);

        JPanel panel = new JPanel();
        panel.setLayout(new GridLayout(1, 2));
        clipButton = new JRadioButton("Clip", true);
        clipButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                canvas.clip = true;
                canvas.clipFurther = false;
                canvas.repaint();
            }
        });
        clipFurButton = new JRadioButton("Clip Further");
        clipFurButton.addActionListener(new ActionListener() {
            public void actionPerformed(ActionEvent e) {
                canvas.clipFurther = true;
                canvas.repaint();
            }
        });
        ButtonGroup group = new ButtonGroup();
        group.add(clipButton);
        group.add(clipFurButton);

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

        // 4. Add a window listener to close the frame properly.
        addWindowListener(new WindowAdapter() {
            public void windowClosing(WindowEvent e) {
                System.exit(0);
            }
        });
        pack();
        setVisible(true);
    }

    public static void main(String arg[]) {
        new ClipArea();
    }
}

class MyCanvas extends JPanel {
    boolean clip = true;

    boolean clipFurther = false;

    MyCanvas() {
        setSize(300, 300);
        setBackground(Color.white);
    }

    public void paint(Graphics g) {
        Graphics2D g2 = (Graphics2D) g;

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

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

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

        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);
        }
    }
}