/***********************************************************
Taken from https://lexzeus.tripod.com/
(c) by LexZEUS - Alexander Yanuar Koentjara
To use:
1. Copy and paste the code to calculator.java
2. Compile it: javac calculator.java
3. Create a calc.html code as below :
<html>
<body>
<applet code=calculator.class height=250 width=200>
This is applet
</applet>
</body>
</html>
4. Open the html file using your browser, or use command: appletviewer calc.html
***********************************************************/
import java.applet.Applet;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.BufferedImage;
public class calculator extends Applet
implements MouseListener, KeyListener, MouseMotionListener
{
private static Font mainFont = new Font("Arial", Font.PLAIN, 20 );
private static Color CBack = new Color(85,85,85);
private static final String aboutStr = " ***************************** \n" +
" * Simple shaking calculator * \n" +
" * By: Alexander Yanuar K. * \n" +
" * 31-Oct-2001 * \n" +
" * * \n" +
" * * \n" +
" * A simple way for java * \n" +
" * learner to study about * \n" +
" * applet, inner class, and * \n" +
" * Thread ... * \n" +
" * * \n" +
" ***************************** \n";
private static final int _width=200; // calculator width
private static final int _height=250; // calculator height
private static final int _cubeSize=40; // button size
private static final int _leftMargin=20; // button left margin
private static final int _topMargin=60; // button top margin
private static final int _leftFontMargin=13; // font left margin
private static final int _topFontMargin=25; // font top margin
private static final Color colDarkRed = new Color (128,0,0);
private static final Color colNavy = new Color (0,0,128);
static final CalcControl nullOperator =
new CalcControl("=",false);
private static final CalcControl[] enumControl = {
new CalcControl("9",true), new CalcControl("8",true),
new CalcControl("7",true), new CalcControl("+",false),
new CalcControl("6",true), new CalcControl("5",true),
new CalcControl("4",true), new CalcControl("-",false),
new CalcControl("3",true), new CalcControl("2",true),
new CalcControl("1",true), new CalcControl("*",false),
new CalcControl("0",true), new CalcControl("C",false),
nullOperator, new CalcControl("/",false)
};
int globalPressed=-1; // what the button was previously
// pressed
int globalCursor=-1; // where the mouse pointer is ...
// the value is the first index of
// enumControl array (0-15)
// -1 means point nowhere ...
private long opr1, opr2 = 0; // operand1 and operand2
private String opr1_str = "", opr2_str = "";
private boolean swapFlag = true;
public int sx=0, sy=0;
CalcControl currentOperator=nullOperator;
// no operator at the very first time
// same effect is user press "C" button
Image myBuff; // double buffering
CalcThread animation;
public void init() {
addMouseListener(this);
addMouseMotionListener(this);
addKeyListener(this);
myBuff = createImage(_width,_height);
animation = new CalcThread(this);
}
void trigger(int key)
{
globalPressed=key;
calculate(key);
animation.enableShaking();
repaint();
}
public void keyReleased(KeyEvent me) { /* do nothing */ }
public void keyTyped(KeyEvent me) { /* do nothing */ }
public void keyPressed(KeyEvent e)
{
int code = e.getKeyCode();
switch (code)
{
case KeyEvent.VK_C: trigger(13); break;
case KeyEvent.VK_0: trigger(12); break;
case KeyEvent.VK_1: trigger(10); break;
case KeyEvent.VK_2: trigger(9); break;
case KeyEvent.VK_3: trigger(8); break;
case KeyEvent.VK_4: trigger(6); break;
case KeyEvent.VK_5: trigger(5); break;
case KeyEvent.VK_6: trigger(4); break;
case KeyEvent.VK_7: trigger(2); break;
case KeyEvent.VK_8: trigger(1); break;
case KeyEvent.VK_9: trigger(0); break;
}
char ch = e.getKeyChar();
if (ch=='=')
trigger(14);
else
if (ch=='+')
trigger(3);
else
if (ch=='-')
trigger(7);
else
if (ch=='/')
trigger(15);
else
if (ch=='*')
trigger(11);
}
public String getAppletInfo() {
return aboutStr;
}
public void mouseDragged(MouseEvent me) { /* do nothing */ }
public void mouseMoved(MouseEvent me) {
int x=me.getX()-_leftMargin,
y=me.getY()-_topMargin;
if (x<0 || x>_cubeSize*4-5 ||
y<0 || y>_cubeSize*4-5 ) {
globalCursor=-1;
repaint();
return;
}
x=(int) (Math.floor(x/_cubeSize));
y=(int) (Math.floor(y/_cubeSize));
globalCursor = y*4+x;
repaint();
}
public void mouseEntered(MouseEvent me) { /* do nothing */ }
public void mouseExited(MouseEvent me) { /* do nothing */ }
public void mouseClicked(MouseEvent me) { /* do nothing */ }
public void mouseReleased(MouseEvent me) { /* do nothing */ }
public void mousePressed(MouseEvent me) {
if (globalCursor<0) return;
if ((me.getModifiers() & MouseEvent.BUTTON1_MASK )!=0)
{
trigger(globalCursor);
}
}
void reset() {
opr1 = 0;
opr2 = 0;
currentOperator = nullOperator;
opr1_str="";
opr2_str="";
}
private void calculate(int key)
{
CalcControl calc = enumControl[key];
if (calc.isNumber) // the pressed button is a number
{
if (swapFlag)
{
swapFlag=false;
opr1 = opr2;
opr1_str = opr2_str;
opr2_str = "";
}
opr2_str += calc.representation;
opr2 = (new Long(opr2_str)).longValue();
}
else // the pressed button is an operator
{
swapFlag=true;
if (calc.representation.equals("C"))
{
reset();
return;
}
try {
opr2 = currentOperator.doCalc(opr1,opr2);
}
catch (Exception ex)
{
System.out.println(ex);
}
opr2_str = (new Long(opr2)).toString();
currentOperator=calc;
}
}
public void start() {
setBackground(Color.white);
}
public void destroy() {
animation.running=false;
super.destroy();
}
public void update(Graphics scGR) {
paint(scGR);
}
private void drawAll(Graphics Buff)
{
// DRAWING THE BACKGROUND:
Buff.setColor(Color.lightGray);
Buff.fillRect(0,0,_width,_height);
Buff.setFont(mainFont);
// DRAWING THE BUTTONS:
int num=0;
int sx2,sy2;
for (int y=0;y<4;y++)
for (int x=0;x<4;x++)
{
sx2=0;
sy2=0;
if (num!=globalCursor)
Buff.setColor(colDarkRed);
else
Buff.setColor(Color.red);
if (num==globalPressed)
{
sx2=sx;
sy2=sy;
}
Buff.fillRect(_leftMargin+_cubeSize*x+sx2,
_topMargin+_cubeSize*y+sy2,
_cubeSize-3,_cubeSize-3);
if (enumControl[num].isNumber)
Buff.setColor(Color.white);
else
Buff.setColor(Color.yellow);
Buff.drawString( enumControl[num++].representation,
_leftMargin+_leftFontMargin+x*_cubeSize,
_topMargin+_topFontMargin+y*_cubeSize);
}
// DRAWING THE DIGITS:
int maxwidth = _width-_leftMargin*2-3;
Buff.setColor(Color.white);
Buff.fillRect(_leftMargin,10,maxwidth,_topMargin-10-5);
Buff.setColor(colNavy);
String digits = null;
if (!opr2_str.equals(""))
digits=opr2_str;
else
digits="0";
FontMetrics metrics = Buff.getFontMetrics();
int wd = metrics.stringWidth(digits);
if (wd<maxwidth)
Buff.drawString(digits,_leftMargin+(maxwidth)-10-wd,40);
else
Buff.drawString("Too big",_leftMargin+5,40);
}
public void paint(Graphics scGR) {
Graphics Buff = myBuff.getGraphics();
drawAll(Buff);
scGR.drawImage(myBuff,1,1,this);
}
class CalcThread extends Thread {
public int shaking=0;
boolean running=true;
calculator calc;
CalcThread(calculator _calc)
{
calc=_calc;
this.start();
}
public void enableShaking()
{
shaking=25;
}
public void run()
{
while (running)
{
shaking--;
if (shaking>1)
{
calc.sx=(int) Math.round(Math.random()*5)-2;
calc.sy=(int) Math.round(Math.random()*5)-2;
calc.repaint();
}
else
{
calc.sx=0;
calc.sy=0;
calc.globalPressed=-1;
if (shaking==1)
calc.repaint();
shaking=0;
}
try {
this.sleep(10);
}
catch (Exception ex) { /* do nothing */ }
}
}
}
static class CalcControl { // inner class for individual button and
// the meaning of each button
public String representation = null;
public boolean isNumber;
CalcControl(String _rep, boolean _isNumber)
{
representation=_rep;
isNumber=_isNumber;
}
long doCalc(long opr1, long opr2)
throws Exception
{
if (isNumber)
throw new Exception("Number is not operator");
if (representation.equals("="))
return opr2;
else
if (representation.equals("C"))
{
return 0;
}
else
if (representation.equals("+"))
return opr1+opr2;
else
if (representation.equals("-"))
return opr1-opr2;
else
if (representation.equals("*"))
return opr1*opr2;
else
if (representation.equals("/"))
return Math.round(opr1/opr2);
throw new Exception("Unknown operator");
}
}
}