Conway's Game of Life

Header file:

/****************************************************************************
** $Id: qt/life.h   3.3.7   edited Aug 31 2005 $
**
** Copyright (C) 1992-2005 Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#ifndef LIFE_H
#define LIFE_H

#include <qframe.h>


class LifeWidget : public QFrame
{
    Q_OBJECT
public:
    LifeWidget( int s = 10, QWidget *parent = 0, const char *name = 0 );

    void        setPoint( int i, int j );

    int         maxCol() { return maxi; }
    int         maxRow() { return maxj; }

public slots:
    void        nextGeneration();
    void        clear();

protected:
    virtual void paintEvent( QPaintEvent * );
    virtual void mouseMoveEvent( QMouseEvent * );
    virtual void mousePressEvent( QMouseEvent * );
    virtual void resizeEvent( QResizeEvent * );
    void         mouseHandle( const QPoint &pos );

private:
    enum { MAXSIZE = 50, MINSIZE = 10, BORDER = 5 };

    bool        cells[2][MAXSIZE + 2][MAXSIZE + 2];
    int         current;
    int         maxi, maxj;

    int pos2index( int x )
    {
        return ( x - BORDER ) / SCALE + 1;
    }
    int index2pos( int i )
    {
        return  ( i - 1 ) * SCALE + BORDER;
    }

    int SCALE;
};


#endif // LIFE_H

Implementation:

/****************************************************************************
** $Id: qt/life.cpp   3.3.7   edited Aug 31 2005 $
**
** Copyright (C) 1992-2005 Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include "life.h"

#include <qpainter.h>
#include <qdrawutil.h>
#include <qcheckbox.h>
#include <qevent.h>
#include <qapplication.h>

// The main game of life widget

LifeWidget::LifeWidget( int s, QWidget *parent, const char *name )
    : QFrame( parent, name )
{
    SCALE = s;

    maxi = maxj = 50;
    setMinimumSize( MINSIZE * SCALE + 2 * BORDER,
                   MINSIZE * SCALE + 2 * BORDER );
    setMaximumSize( MAXSIZE * SCALE + 2 * BORDER,
                   MAXSIZE * SCALE + 2 * BORDER );
    setSizeIncrement( SCALE, SCALE);

    clear();
    resize( maxi * SCALE + 2 * BORDER , maxj * SCALE + 2 * BORDER );

}


void LifeWidget::clear()
{
    current = 0;
    for ( int t = 0; t < 2; t++ )
        for ( int i = 0; i < MAXSIZE + 2; i++ )
            for ( int j = 0; j < MAXSIZE + 2; j++ )
                cells[t][i][j] = FALSE;

    repaint();
}


// We assume that the size will never be beyond the maximum size set
// this is not in general TRUE, but in practice it's good enough for
// this program

void LifeWidget::resizeEvent( QResizeEvent * e )
{
    maxi = (e->size().width()  - 2 * BORDER) / SCALE;
    maxj = (e->size().height() - 2 * BORDER) / SCALE;
}


void LifeWidget::setPoint( int i, int j )
{
    if ( i < 1 || i > maxi || j < 1 || j > maxi )
        return;
    cells[current][i][j] = TRUE;
    repaint( index2pos(i), index2pos(j), SCALE, SCALE, FALSE );
}


void LifeWidget::mouseHandle( const QPoint &pos )
{
    int i = pos2index( pos.x() );
    int j = pos2index( pos.y() );
    setPoint( i, j );
}


void LifeWidget::mouseMoveEvent( QMouseEvent *e )
{
    mouseHandle( e->pos() );
}


void LifeWidget::mousePressEvent( QMouseEvent *e )
{
    if ( e->button() == QMouseEvent::LeftButton )
        mouseHandle( e->pos() );
}


void LifeWidget::nextGeneration()
{
    for ( int i = 1; i <= MAXSIZE; i++ ) {
        for ( int j = 1; j <= MAXSIZE; j++ ) {
            int t = cells[current][i - 1][j - 1]
            + cells[current][i - 1][j]
            + cells[current][i - 1][j + 1]
            + cells[current][i][j - 1]
            + cells[current][i][j + 1]
            + cells[current][i + 1][j - 1]
            + cells[current][i + 1][j]
            + cells[current][i + 1][j + 1];

            cells[!current][i][j] = ( t == 3 ||
                                      t == 2 && cells[current][i][j] );
        }
    }
    current = !current;
    repaint( FALSE );           // repaint without erase
}


void LifeWidget::paintEvent( QPaintEvent * e )
{
    int starti = pos2index( e->rect().left() );
    int stopi  = pos2index( e->rect().right() );
    int startj = pos2index( e->rect().top() );
    int stopj  = pos2index( e->rect().bottom() );

    if (stopi > maxi)
        stopi = maxi;
    if (stopj > maxj)
        stopj = maxj;

    QPainter paint( this );
    for ( int i = starti; i <= stopi; i++ ) {
        for ( int j = startj; j <= stopj; j++ ) {
            if ( cells[current][i][j] )
                qDrawShadePanel( &paint, index2pos( i ), index2pos( j ),
                                 SCALE - 1, SCALE - 1, colorGroup() );
            else if ( cells[!current][i][j] )
                erase(index2pos( i ), index2pos( j ), SCALE - 1, SCALE - 1);
        }
    }
    drawFrame( &paint );
}

Main:

/****************************************************************************
** $Id: qt/main.cpp   3.3.7   edited Aug 31 2005 $
**
** Copyright (C) 1992-2005 Trolltech AS.  All rights reserved.
**
** This file is part of an example program for Qt.  This example
** program may be used, distributed and modified without limitation.
**
*****************************************************************************/

#include "lifedlg.h"
#include <qapplication.h>
#include <stdlib.h>

void usage()
{
    qWarning( "Usage: life [-scale scale]" );
}

int main( int argc, char **argv )
{
    QApplication a( argc, argv );

    int scale = 10;

    for ( int i = 1; i < argc; i++ ){
        QString arg = argv[i];
        if ( arg == "-scale" )
            scale = atoi( argv[++i] );
        else {
            usage();
            exit(1);
        }
    }

    if ( scale < 2 )
        scale = 2;

    LifeDialog *life = new LifeDialog( scale );
    a.setMainWidget( life );
    life->setCaption("Qt Example - Life");
    life->show();

    return a.exec();
}

See also Examples.