MouseTest.java Source code

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Here is the source code for MouseTest.java

Source

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)
    
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
    
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
    
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

import java.awt.Cursor;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.geom.Point2D;
import java.awt.geom.Rectangle2D;
import java.util.ArrayList;

import javax.swing.JComponent;
import javax.swing.JFrame;

/**
 * @version 1.32 2007-06-12
 * @author Cay Horstmann
 */
public class MouseTest {
    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                MouseFrame frame = new MouseFrame();
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.setVisible(true);
            }
        });
    }
}

/**
 * A frame containing a panel for testing mouse operations
 */
class MouseFrame extends JFrame {
    public MouseFrame() {
        setTitle("MouseTest");
        setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

        // add component to frame

        MouseComponent component = new MouseComponent();
        add(component);
    }

    public static final int DEFAULT_WIDTH = 300;
    public static final int DEFAULT_HEIGHT = 200;
}

/**
 * A component with mouse operations for adding and removing squares.
 */
class MouseComponent extends JComponent {
    public MouseComponent() {
        squares = new ArrayList<Rectangle2D>();
        current = null;

        addMouseListener(new MouseHandler());
        addMouseMotionListener(new MouseMotionHandler());
    }

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

        // draw all squares
        for (Rectangle2D r : squares)
            g2.draw(r);
    }

    /**
     * Finds the first square containing a point.
     * @param p a point
     * @return the first square that contains p
     */
    public Rectangle2D find(Point2D p) {
        for (Rectangle2D r : squares) {
            if (r.contains(p))
                return r;
        }
        return null;
    }

    /**
     * Adds a square to the collection.
     * @param p the center of the square
     */
    public void add(Point2D p) {
        double x = p.getX();
        double y = p.getY();

        current = new Rectangle2D.Double(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH);
        squares.add(current);
        repaint();
    }

    /**
     * Removes a square from the collection.
     * @param s the square to remove
     */
    public void remove(Rectangle2D s) {
        if (s == null)
            return;
        if (s == current)
            current = null;
        squares.remove(s);
        repaint();
    }

    private static final int SIDELENGTH = 10;
    private ArrayList<Rectangle2D> squares;
    private Rectangle2D current;

    // the square containing the mouse cursor

    private class MouseHandler extends MouseAdapter {
        public void mousePressed(MouseEvent event) {
            // add a new square if the cursor isn't inside a square
            current = find(event.getPoint());
            if (current == null)
                add(event.getPoint());
        }

        public void mouseClicked(MouseEvent event) {
            // remove the current square if double clicked
            current = find(event.getPoint());
            if (current != null && event.getClickCount() >= 2)
                remove(current);
        }
    }

    private class MouseMotionHandler implements MouseMotionListener {
        public void mouseMoved(MouseEvent event) {
            // set the mouse cursor to cross hairs if it is inside
            // a rectangle

            if (find(event.getPoint()) == null)
                setCursor(Cursor.getDefaultCursor());
            else
                setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
        }

        public void mouseDragged(MouseEvent event) {
            if (current != null) {
                int x = event.getX();
                int y = event.getY();

                // drag the current rectangle to center it at (x, y)
                current.setFrame(x - SIDELENGTH / 2, y - SIDELENGTH / 2, SIDELENGTH, SIDELENGTH);
                repaint();
            }
        }
    }
}