Digital Clock

This example displays a digital LCD clock that can switch between time and date.

Header file:

/****************************************************************************
** $Id: qt/dclock.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 DCLOCK_H
#define DCLOCK_H

#include <qlcdnumber.h>


class DigitalClock : public QLCDNumber          // digital clock widget
{
    Q_OBJECT
public:
    DigitalClock( QWidget *parent=0, const char *name=0 );

protected:                                      // event handlers
    void        timerEvent( QTimerEvent * );
    void        mousePressEvent( QMouseEvent * );

private slots:                                  // internal slots
    void        stopDate();
    void        showTime();

private:                                        // internal data
    void        showDate();

    bool        showingColon;
    int         normalTimer;
    int         showDateTimer;
};


#endif // DCLOCK_H

Implementation:

/****************************************************************************
** $Id: qt/dclock.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 "dclock.h"
#include <qdatetime.h>


//
// Constructs a DigitalClock widget with a parent and a name.
//

DigitalClock::DigitalClock( QWidget *parent, const char *name )
    : QLCDNumber( parent, name )
{
    showingColon = FALSE;
    setFrameStyle( QFrame::Panel | QFrame::Raised );
    setLineWidth( 2 );                          // set frame line width
    showTime();                                 // display the current time
    normalTimer = startTimer( 500 );            // 1/2 second timer events
    showDateTimer = -1;                         // not showing date
}


//
// Handles timer events for the digital clock widget.
// There are two different timers; one timer for updating the clock
// and another one for switching back from date mode to time mode.
//

void DigitalClock::timerEvent( QTimerEvent *e )
{
    if ( e->timerId() == showDateTimer )        // stop showing date
        stopDate();
    else {                                      // normal timer
        if ( showDateTimer == -1 )              // not showing date
            showTime();
    }
}

//
// Enters date mode when the left mouse button is pressed.
//

void DigitalClock::mousePressEvent( QMouseEvent *e )
{
    if ( e->button() == QMouseEvent::LeftButton )               // left button pressed
        showDate();
}


//
// Shows the current date in the internal lcd widget.
// Fires a timer to stop showing the date.
//

void DigitalClock::showDate()
{
    if ( showDateTimer != -1 )                  // already showing date
        return;
    QDate date = QDate::currentDate();
    QString s;
    s.sprintf( "%2d %2d", date.month(), date.day() );
    display( s );                               // sets the LCD number/text
    showDateTimer = startTimer( 2000 );         // keep this state for 2 secs
}

//
// Stops showing the date.
//

void DigitalClock::stopDate()
{
    killTimer( showDateTimer );
    showDateTimer = -1;
    showTime();
}

//
// Shows the current time in the internal lcd widget.
//

void DigitalClock::showTime()
{
    showingColon = !showingColon;               // toggle/blink colon
    QString s = QTime::currentTime().toString().left(5);
    if ( !showingColon )
        s[2] = ' ';
    if ( s[0] == '0' )
        s[0] = ' ';
    display( s );                               // set LCD number/text
}

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 "dclock.h"
#include <qapplication.h>


int main( int argc, char **argv )
{
    QApplication a( argc, argv );
    DigitalClock *clock = new DigitalClock;
    clock->resize( 170, 80 );
    a.setMainWidget( clock );
    clock->setCaption("Qt Example - Digital Clock");
    clock->show();
    return a.exec();
}

See also Examples.