Home | All Classes | Main Classes | Annotated | Grouped Classes | Functions |

# Digital Clock

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

Header file:

    /****************************************************************************
    ** $Id: qt/dclock.h   3.3.5   edited Aug 31 12:17 $
    **
    ** 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   3.3.5   edited Aug 31 12:13 $
    **
    ** 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   3.3.5   edited Aug 31 12:13 $
    **
    ** 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.