Java 1.2 How-To/JavaHowTo.iso/code/ch05.txt

Text File | 1998-12-14 | 17.6 KB | 842 lines

testActionEvents.java:

/*
Example 5.1 This example shows how an action listener
 can be used to coordinate activities among various
components on an applet
 */

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

public class testActionEvents extends Applet
{
    public void init()
    {
       super.init();
        setLayout(null);
        btnHello = new Button("Say Hello");
        btnHello.setBounds(36,12,108,43);
        add(btnHello);
        Action btnAction = new Action();
        btnHello.addActionListener(btnAction);
        txtField1 = new TextField();
        txtField1.setBounds(36,96,144,31);
        add(txtField1);

    }


    /* Declare Components */
    Button btnHello;
    TextField txtField1;

    class Action implements ActionListener
    {
        public void actionPerformed(ActionEvent event)
        {
            Object object1 = event.getSource();
            if (object1 == btnHello)
                btnHelloAction(event);
        }
    }

    void btnHelloAction(ActionEvent e)
    {
        txtField1.setText("Hi,Mom");
    }
}










testAdjustEvent.java:

/*
    A basic extension of the java.applet.Applet class
 */

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

public class testAdjustEvent extends Applet
{
    void ScrollValueChanged( AdjustmentEvent event)
    {
        int intValue = scoreBar.getValue();
        String strValue = String.valueOf(intValue);

        txtScore.setText(strValue);
    }

    public void init()
    {
          super.init();

      setLayout(null);
      label1 = new Label("Score:", Label.RIGHT);
      label1.setBounds(36,36,60,21);
      add(label1);
      txtScore = new TextField();
      txtScore.setEditable(false);
      txtScore.setBounds(108,36,48,23);
      add(txtScore);
      scoreBar = new Scrollbar(Scrollbar.HORIZONTAL,0,10,0,100);
      scoreBar.setBounds(180,36,137,26);
      add(scoreBar);
      txtScore.setText(String.valueOf(scoreBar.getValue()));

      Adjustment1 lAdjustment = new Adjustment1();
      scoreBar.addAdjustmentListener(lAdjustment);
    }


    Label label1;
    TextField txtScore;
    Scrollbar scoreBar;

    class Adjustment1 implements AdjustmentListener
    {
        public void adjustmentValueChanged(AdjustmentEvent event)
        {
        Object object1 = event.getSource();
        if (object1==scoreBar)
           ScrollValueChanged(event);
        }
    }
}









Doodle.java:

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 ();
}
}







Windows1.java:

import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.text.*;

public class Windows1 extends Object implements WindowListener
{
    public void windowOpened(WindowEvent e)
    {
        System.out.println("Window opened.");
    }

    public void windowClosing(WindowEvent e)
    {
        System.out.println("Window closing.");
 System.exit(0);

    }

    public void windowClosed(WindowEvent e)
    {
        System.out.println("Window closed.");
    }

    public void windowIconified(WindowEvent e)
    {
        System.out.println("Window iconified.");
    }

    public void windowDeiconified(WindowEvent e)
    {
        System.out.println("Window deiconified.");
    }

    public void windowActivated(WindowEvent e)
    {

        System.out.println("Window activated.");
    }

    public void windowDeactivated(WindowEvent e)
    {
        System.out.println("Window deactivated");
    }

    public static void main(String s[])
    {
        JFrame frame = new JFrame("Windows1");

        frame.setDefaultCloseOperation(JFrame.DO_NOTHING_ON_CLOSE);
        frame.addWindowListener(new Windows1());



frame.getContentPane().add( new Label("Hello World"), "Center");

        frame.pack();
        frame.setVisible(true);
    }


}







ScrollApp.java:

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

class Scroll {

int xstart, ystart;
int width, height;
String text;
int deltaX, deltaY;
int xpos, ypos;
Color color;

/**
 * Text scrolls in different directions.
 * @param xpos      initial x position
 * @param ypos      initial y position
 * @param deltax    velocity in x direction
 * @param deltay    velocity in y direction
 * @param width     bounding point for window panel width
 * @param height    bounding point for window panel height
 * @param text      text that is scrolled on the window
 * @param color     color of the text
 */
public Scroll (int x, int y, int dx, int dy, int w,int h, String t, Color c) {

    xstart = x;
    ystart = y;
    width = w;
    height = h;
    text = t;
    deltaX = dx;
    deltaY = dy;
    color = c;
    xpos = xstart;
    ypos = ystart;
}

/**
 * Called from update() in response to repaint()
 * @param g - destination graphics object
 */
void paint (Graphics g) {

    g.setColor (color);
    g.drawString (text, xpos, ypos);
    xpos += deltaX;
    ypos += deltaY;

    FontMetrics fm = g.getFontMetrics ();
    int textw = fm.stringWidth (text);
    int texth = fm.getHeight ();
    if (deltaX < 0 && xpos < -textw) xpos = xstart;
    if (deltaX > 0 && xpos > width) xpos = xstart;
    if (deltaY < 0 && ypos < 0) ypos = ystart;
    if (deltaY > 0 && ypos > height+texth) ypos = ystart;
}
} // Class Scroll


/*
 * The applet/application class
 */
public class ScrollApp extends Applet implements Runnable{

/*
 * Width and height of the bounding panel
 */
int width, height;

/*
 * Instance of a left-scrolling Scroll object
 */
Scroll left;
String input_text;
Font font = new Font("Helvetica",1,24);
Thread thread;

/*
 * Called when the applet is loaded
 * Create instances of FIFO, Source, Sink, and Thread.
 */
public void init () {

    input_text=getParameter("text");
    Dimension d = getSize ();

    width = d.width;
    height = d.height;

    left = new Scroll (400, 50, -5, 0, width, height,
        input_text, Color.red);
} // init()

/*
 * Start the graphics update thread.
 */
public void start() {

    thread = new Thread(this);
    thread.start();
} // start()

/*
 * The graphics update thread
 * Call repaint every 100 ms.
 */
public void run() {

    while (true) {
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) { }
        repaint();
    }
} // run()

/*
 * Stop the graphics update thread.
 */
public void stop() {

    if (thread != null)
    thread = null;
} // stop()

/**
 * Called from update() in response to repaint()
 * @param g - destination graphics object
 */
public void paint (Graphics g) {

    g.setFont(font);
    left.paint (g);
} // paint()
} // class ScrollApp






ScrollApp.java:

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

class Scroll {

int xstart, ystart;
int width, height;
String text;
int deltaX, deltaY;
int xpos, ypos;
Color color;

/**
 * Text scrolls in different directions.
 * @param xpos          initial x position
 * @param ypos          initial y position
 * @param deltax        velocity in x direction
 * @param deltay        velocity in y direction
 * @param width         bounding point for window panel width
 * @param height        bounding point for window panel height
 * @param text          text that is scrolled on the window
 * @param color         color of the text
 */
public Scroll (int x, int y, int dx, int dy, int w,σ
 int h, String t, Color ?c) {

    xstart = x;
    ystart = y;
    width = w;
    height = h;
    text = t;
    deltaX = dx;
    deltaY = dy;
    color = c;
    xpos = xstart;
    ypos = ystart;
}

/**
 * Called from update() in response to repaint()
 * @param g - destination graphics object
 */
void paint (Graphics g) {

    g.setColor (color);
    g.drawString (text, xpos, ypos);
    xpos += deltaX;
    ypos += deltaY;

    FontMetrics fm = g.getFontMetrics ();
    int textw = fm.stringWidth (text);
    int texth = fm.getHeight ();
    if (deltaX < 0 && xpos < -textw) xpos = xstart;
    if (deltaX > 0 && xpos > width) xpos = xstart;
    if (deltaY < 0 && ypos < 0) ypos = ystart;
    if (deltaY > 0 && ypos > height+texth) ypos = ystart;
}
} // Class Scroll

/*
 * The applet class
 */
public class ScrollApp extends Applet implements Runnable {

/*
 * Width and height of the bounding panel
 */
int width, height;

/*
 * The number of scrolling objects
 */
int nscroll = 0;

/*
 * Array of scrolling objects
 */
Scroll scr[] = new Scroll[5];
Font font = new Font("Helvetica",1,24);
Thread thread;

/*
 * Called when the applet is loaded
 * Parses applet parameters
 */
public void init () {

    String scr_text[] = {"test1","test2","test3","test4","test5"};
    int scr_xvel[] =  {-5,5,0,0,7};
    int scr_yvel[] =  {0,0,-5,5,3};
    int scr_xpos[] =  {400,0,100,200,0};
    int scr_ypos[] =  {50,150,200,0,0};
    int scr_red[] =   {255,0,0,100,200};
    int scr_green[] = {0,255,0,200,100};
    int scr_blue[] =  {0,0,255,50,50};
    Color scr_color[] = new Color[5];
    int i;
    Dimension d = getSize ();

    width = d.width;
    height = d.height;
    for (i=1; i<=5; i+=1) {
        String param, token;
        int j = 0;

        param = getParameter ("Scroll"+i);
        if (param == null) break;

        StringTokenizer st = new StringTokenizer (param, ",");
        token = st.nextToken ();
        scr_text[nscroll] = token;

        token = st.nextToken ();
        try {
            j = Integer.valueOf (token).intValue();
        } catch (NumberFormatException e){
        }

        switch (j) {
            case 0: //Scroll left.
                scr_xvel[nscroll] = -5;
                scr_yvel[nscroll] = 0;
                scr_xpos[nscroll] = 400;
                scr_ypos[nscroll] = 50;
                break;

            case 1: //Scroll right.
                scr_xvel[nscroll] = 5;
                scr_yvel[nscroll] = 0;
                scr_xpos[nscroll] = 0;
                scr_ypos[nscroll] = 150;
                break;

            case 2: //Scroll up.
                scr_xvel[nscroll] = 0;
                scr_yvel[nscroll] = -5;
                scr_xpos[nscroll] = 100;
                scr_ypos[nscroll] = 200;
                break;

            case 3: //Scroll down.
                scr_xvel[nscroll] = 0;
                scr_yvel[nscroll] = 5;
                scr_xpos[nscroll] = 200;
                scr_ypos[nscroll] = 0;
                break;

            case 4: //Scroll diagonally.
                scr_xvel[nscroll] = 7;
                scr_yvel[nscroll] = 3;
                scr_xpos[nscroll] = 0;
                scr_ypos[nscroll] = 0;
                break;
        }

        token = st.nextToken ();
        try {
            scr_red[nscroll] = Integer.valueOf(token).intValue();
        } catch (NumberFormatException e) {
        }

        token = st.nextToken ();
        try {
            scr_green[nscroll] = Integer.valueOf(token).intValue();
        } catch (NumberFormatException e) {
        }

        token = st.nextToken ();
        try {
            scr_blue[nscroll] = Integer.valueOf(token).intValue();
        } catch (NumberFormatException e) {
        }

        scr_color[nscroll] = new Color(scr_red[nscroll],
            scr_green[nscroll], scr_blue[nscroll]);
        nscroll +=1;
    }
    for (i=0; i<nscroll; i+=1) {
        scr[i] = new Scroll (scr_xpos[i], scr_ypos[i],
            scr_xvel[i], scr_yvel[i], width, height,
            scr_text[i], scr_color[i]);
    }
} // init()

/*
 * Start the graphics update thread.
 */
public void start() {

    thread = new Thread(this);
    thread.start ();
} // start()

/*
 * The graphics update thread
 * Call repaint every 100 ms.
 */
public void run() {

    while (true) {
        try {
            Thread.sleep(100);
        } catch (InterruptedException e) { }
        repaint();
    }
} // run()

/*
 * Stop the graphics update thread.
 */
public void stop() {

if (thread != null)
   thread = null;


} // stop();

/**
 * Called from update() in response to repaint()
 * @param g - destination graphics object
 */
public void paint (Graphics g) {

    int i;

    g.setFont(font);
    for (i=0; i<nscroll; i+=1) {
        scr[i].paint (g);
    }
} // paint()
} // Class ScrollApp