Java example source code file (DrawTest.java)

This example Java source code file (DrawTest.java) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

arraylist, awt, center, checkbox, choice, drawcontrols, drawpanel, drawtest, event, frame, lines, override, points, rectangle, string, suppresswarnings, util

The DrawTest.java Java example source code

/*
 * Copyright (c) 1997, 2011, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */



import java.applet.Applet;
import java.awt.BorderLayout;
import java.awt.Checkbox;
import java.awt.CheckboxGroup;
import java.awt.Choice;
import java.awt.Color;
import java.awt.Component;
import java.awt.Dimension;
import java.awt.FlowLayout;
import java.awt.Frame;
import java.awt.Graphics;
import java.awt.Panel;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.ItemEvent;
import java.awt.event.ItemListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.event.MouseMotionListener;
import java.util.ArrayList;
import java.util.List;


@SuppressWarnings("serial")
public class DrawTest extends Applet {

    DrawPanel panel;
    DrawControls controls;

    @Override
    public void init() {
        setLayout(new BorderLayout());
        panel = new DrawPanel();
        controls = new DrawControls(panel);
        add("Center", panel);
        add("South", controls);
    }

    @Override
    public void destroy() {
        remove(panel);
        remove(controls);
    }

    public static void main(String args[]) {
        Frame f = new Frame("DrawTest");
        DrawTest drawTest = new DrawTest();
        drawTest.init();
        drawTest.start();

        f.add("Center", drawTest);
        f.setSize(300, 300);
        f.setVisible(true);
    }

    @Override
    public String getAppletInfo() {
        return "A simple drawing program.";
    }
}


@SuppressWarnings("serial")
class DrawPanel extends Panel implements MouseListener, MouseMotionListener {

    public static final int LINES = 0;
    public static final int POINTS = 1;
    int mode = LINES;
    List<Rectangle> lines = new ArrayList();
    List<Color> colors = new ArrayList();
    int x1, y1;
    int x2, y2;

    @SuppressWarnings("LeakingThisInConstructor")
    public DrawPanel() {
        setBackground(Color.white);
        addMouseMotionListener(this);
        addMouseListener(this);
    }

    public void setDrawMode(int mode) {
        switch (mode) {
            case LINES:
            case POINTS:
                this.mode = mode;
                break;
            default:
                throw new IllegalArgumentException();
        }
    }

    @Override
    public void mouseDragged(MouseEvent e) {
        e.consume();
        switch (mode) {
            case LINES:
                x2 = e.getX();
                y2 = e.getY();
                break;
            case POINTS:
            default:
                colors.add(getForeground());
                lines.add(new Rectangle(x1, y1, e.getX(), e.getY()));
                x1 = e.getX();
                y1 = e.getY();
                break;
        }
        repaint();
    }

    @Override
    public void mouseMoved(MouseEvent e) {
    }

    @Override
    public void mousePressed(MouseEvent e) {
        e.consume();
        switch (mode) {
            case LINES:
                x1 = e.getX();
                y1 = e.getY();
                x2 = -1;
                break;
            case POINTS:
            default:
                colors.add(getForeground());
                lines.add(new Rectangle(e.getX(), e.getY(), -1, -1));
                x1 = e.getX();
                y1 = e.getY();
                repaint();
                break;
        }
    }

    @Override
    public void mouseReleased(MouseEvent e) {
        e.consume();
        switch (mode) {
            case LINES:
                colors.add(getForeground());
                lines.add(new Rectangle(x1, y1, e.getX(), e.getY()));
                x2 = -1;
                break;
            case POINTS:
            default:
                break;
        }
        repaint();
    }

    @Override
    public void mouseEntered(MouseEvent e) {
    }

    @Override
    public void mouseExited(MouseEvent e) {
    }

    @Override
    public void mouseClicked(MouseEvent e) {
    }

    @Override
    public void paint(Graphics g) {
        int np = lines.size();

        /* draw the current lines */
        g.setColor(getForeground());
        for (int i = 0; i < np; i++) {
            Rectangle p = lines.get(i);
            g.setColor(colors.get(i));
            if (p.width != -1) {
                g.drawLine(p.x, p.y, p.width, p.height);
            } else {
                g.drawLine(p.x, p.y, p.x, p.y);
            }
        }
        if (mode == LINES) {
            g.setColor(getForeground());
            if (x2 != -1) {
                g.drawLine(x1, y1, x2, y2);
            }
        }
    }
}


@SuppressWarnings("serial")
class DrawControls extends Panel implements ItemListener {

    DrawPanel target;

    @SuppressWarnings("LeakingThisInConstructor")
    public DrawControls(DrawPanel target) {
        this.target = target;
        setLayout(new FlowLayout());
        setBackground(Color.lightGray);
        target.setForeground(Color.red);
        CheckboxGroup group = new CheckboxGroup();
        Checkbox b;
        add(b = new Checkbox(null, group, false));
        b.addItemListener(this);
        b.setForeground(Color.red);
        add(b = new Checkbox(null, group, false));
        b.addItemListener(this);
        b.setForeground(Color.green);
        add(b = new Checkbox(null, group, false));
        b.addItemListener(this);
        b.setForeground(Color.blue);
        add(b = new Checkbox(null, group, false));
        b.addItemListener(this);
        b.setForeground(Color.pink);
        add(b = new Checkbox(null, group, false));
        b.addItemListener(this);
        b.setForeground(Color.orange);
        add(b = new Checkbox(null, group, true));
        b.addItemListener(this);
        b.setForeground(Color.black);
        target.setForeground(b.getForeground());
        Choice shapes = new Choice();
        shapes.addItemListener(this);
        shapes.addItem("Lines");
        shapes.addItem("Points");
        shapes.setBackground(Color.lightGray);
        add(shapes);
    }

    @Override
    public void paint(Graphics g) {
        Rectangle r = getBounds();
        g.setColor(Color.lightGray);
        g.draw3DRect(0, 0, r.width, r.height, false);

        int n = getComponentCount();
        for (int i = 0; i < n; i++) {
            Component comp = getComponent(i);
            if (comp instanceof Checkbox) {
                Point loc = comp.getLocation();
                Dimension d = comp.getSize();
                g.setColor(comp.getForeground());
                g.drawRect(loc.x - 1, loc.y - 1, d.width + 1, d.height + 1);
            }
        }
    }

    @Override
    public void itemStateChanged(ItemEvent e) {
        if (e.getSource() instanceof Checkbox) {
            target.setForeground(((Component) e.getSource()).getForeground());
        } else if (e.getSource() instanceof Choice) {
            String choice = (String) e.getItem();
            if (choice.equals("Lines")) {
                target.setDrawMode(DrawPanel.LINES);
            } else if (choice.equals("Points")) {
                target.setDrawMode(DrawPanel.POINTS);
            }
        }
    }
}