Java 1.2 How-To/JavaHowTo.iso/javafile/ch05/Doodle.java

Java Source | 1998-12-14 | 5.2 KB | 252 lines

import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;

/**
 * The ColorBar class displays a color bar for color selection.
 */
class ColorBar {

/*
 * the top-left coordinate of the color bar
 */
int xpos, ypos;

/*
 * the width and height of the color bar
 */
int width, height;

/*
 * the current color selection index into the colors array
 */
int selectedColor = 3;

/*
 * the array of colors available for selection
 */
static Color colors[] = {
    Color.white, Color.gray, Color.red, Color.pink,
    Color.orange, Color.yellow, Color.green, Color.magenta,
    Color.cyan, Color.blue
};

/**
 * Create the color bar
 */
public ColorBar (int x, int y, int w, int h) {

    xpos = x;
    ypos = y;
    width = w;
    height = h;
}

/**
 * Paint the color bar
 * @param g - destination graphics object
 */
void paint (Graphics g) {

    int x, y;    // position of each color box
    int w, h;    // size of each color box

    for (int i=0; i<colors.length; i+=1) {
        w = width;
        h = height/colors.length;
        x = xpos;
        y = ypos + (i * h);
        g.setColor (Color.black);
        g.fillRect (x, y, w, h);
        if (i == selectedColor) {
            x += 5;
            y += 5;
            w -= 10;
            h -= 10;
        } else {
            x += 1;
            y += 1;
            w -= 2;
            h -= 2;
        }
        g.setColor (colors[i]);
        g.fillRect (x, y, w, h);
    }
}

/**
 * Check to see if the mouse is inside a palette box.
 * If so, set selectedColor and return true,
 *        otherwise return false.
 * @param x, y - x and y position of mouse
 */
boolean inside (int x, int y) {

    int i, h;

    if (x < xpos || x > xpos+width) return false;
    if (y < ypos || y > ypos+height) return false;

    h = height/colors.length;
    for (i=0; i<colors.length; i+=1) {
        if (y < (i+1)*h+ypos) {
            selectedColor = i;
            return true;
        }
    }
    return false;
}

}

/**
 * The Doodle applet implements a drawable surface
 * with a limited choice of colors to draw with.
 */
public class Doodle extends Applet
        implements MouseListener, MouseMotionListener
{

/*
 * the maximum number of points that can be
 * saved in the xpoints, ypoints, and color arrays
 */
static final int MaxPoints = 1000;

/*
 * arrays to hold the points where the user draws
 */
int xpoints[] = new int[MaxPoints];
int ypoints[] = new int[MaxPoints];

/*
 * the color of each point
 */
int color[] = new int[MaxPoints];

/*
 * used to keep track of the previous mouse
 * click to avoid filling arrays with the
 * same point
 */
int lastx;
int lasty;

/*
 * the number of points in the arrays
 */
int npoints = 0;
ColorBar colorBar;
boolean inColorBar;

/**
 * Initialize the drawing space
 */
public void init () {

    setBackground(Color.white);
    colorBar = new ColorBar (10, 10, 30, 200);
    addMouseListener(this);
    addMouseMotionListener(this);
}

/**
 * Redisplay the drawing space
 * @param g - destination graphics object
 */
public void update (Graphics g) {

    int i;

    for (i=0; i<npoints; i+=1) {
        g.setColor (colorBar.colors[color[i]]);
        g.fillOval (xpoints[i]-5, ypoints[i]-5, 10, 10);
    }
    colorBar.paint (g);
}

/**
 * Repaint the drawing space when required
 * @param g - destination graphics object
 */
public void paint (Graphics g) {

    update (g);
}



public void mouseClicked(MouseEvent e){}
public void mouseEntered(MouseEvent e){}
public void mouseExited(MouseEvent e){}
public void mouseReleased(MouseEvent e){}
public void mouseMoved(MouseEvent e){}

public void mousePressed(MouseEvent e)
{
    int x =e.getX();
    int y =e.getY();

    if (colorBar.inside (x, y)) {
        inColorBar = true;
        repaint ();
    }
    inColorBar = false;
    if (npoints < MaxPoints) {
        lastx = x;
        lasty = y;
        xpoints[npoints] = x;
        ypoints[npoints] = y;
        color[npoints] = colorBar.selectedColor;
        npoints += 1;
        repaint();
        return;
    }
}

public void mouseDragged(MouseEvent e)
{
    if (inColorBar) return;

    int x =e.getX();
    int y =e.getY();

    if ((x != lastx || y != lasty) && npoints < MaxPoints) {
        lastx = x;
        lasty = y;
        xpoints[npoints] = x;
        ypoints[npoints] = y;
        color[npoints] = colorBar.selectedColor;
        npoints += 1;
        repaint ();
    }

}

/**
 * The main method allows this class to be run as an application
 * in addition to being run as an applet.
 * @param args - command-line arguments
 */

public static void main (String args[]) {

    Frame f = new Frame ("Doodle");
    Doodle doodle = new Doodle ();
       WindowListener l = new WindowAdapter()
       {
            public void windowClosing(WindowEvent e)
            {
                System.exit(0);
            }//windowClosing
       };//WindowListener
       f.addWindowListener(l);


    f.setSize (410, 430);
    f.add ("Center", doodle);
    f.show ();
    doodle.init ();
}
}