| Classes - Annotated - Tree - Functions - Home - Structure

# Progress Bar

This example shows how to use a progressbar.

Header file:

    /****************************************************************************
    ** $Id: qt/examples/progressbar/progressbar.h   2.3.2   edited 2001-01-26 $
    **
    ** Copyright (C) 1992-2000 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 PROGRESSBAR_H
    #define PROGRESSBAR_H

    #include <qbuttongroup.h>
    #include <qtimer.h>

    class QRadioButton;
    class QPushButton;
    class QProgressBar;

    class ProgressBar : public QButtonGroup
    {
        Q_OBJECT

    public:
        ProgressBar( QWidget *parent = 0, const char *name = 0 );

    protected:
        QRadioButton *slow, *normal, *fast;
        QPushButton *start, *pause, *reset;
        QProgressBar *progress;
        QTimer timer;

    protected slots:
        void slotStart();
        void slotReset();
        void slotTimeout();

    };

    #endif

Implementation:

    /****************************************************************************
    ** $Id: qt/examples/progressbar/progressbar.cpp   2.3.2   edited 2001-01-26 $
    **
    ** Copyright (C) 1992-2000 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 "progressbar.h"

    #include <qradiobutton.h>
    #include <qpushbutton.h>
    #include <qprogressbar.h>
    #include <qlayout.h>

    /*
     * Constructor
     *
     * Creates child widgets of the ProgressBar widget
     */

    ProgressBar::ProgressBar( QWidget *parent, const char *name )
        : QButtonGroup( 0, Horizontal, "Progress Bar", parent, name ), timer()
    {
        setMargin( 10 );

        QGridLayout* toplayout = new QGridLayout( layout(), 2, 2, 5);

        setRadioButtonExclusive( TRUE );

        // insert three radiobuttons which the user can use
        // to set the speed of the progress and two pushbuttons
        // to start/pause/continue and reset the progress
        slow = new QRadioButton( "&Slow", this );
        normal = new QRadioButton( "&Normal", this );
        fast = new QRadioButton( "&Fast", this );
        QVBoxLayout* vb1 = new QVBoxLayout;
        toplayout->addLayout( vb1, 0, 0 );
        vb1->addWidget( slow );
        vb1->addWidget( normal );
        vb1->addWidget( fast );

        // two push buttons, one for start, for for reset.
        start = new QPushButton( "&Start", this );
        reset = new QPushButton( "&Reset", this );
        QVBoxLayout* vb2 = new QVBoxLayout;
        toplayout->addLayout( vb2, 0, 1 );
        vb2->addWidget( start );
        vb2->addWidget( reset );

        // Create the progressbar
        progress = new QProgressBar( 100, this );
        toplayout->addMultiCellWidget( progress, 1, 1, 0, 1 );

        // connect the clicked() SIGNALs of the pushbuttons to SLOTs
        connect( start, SIGNAL( clicked() ), this, SLOT( slotStart() ) );
        connect( reset, SIGNAL( clicked() ), this, SLOT( slotReset() ) );

        // connect the timeout() SIGNAL of the progress-timer to a SLOT
        connect( &timer, SIGNAL( timeout() ), this, SLOT( slotTimeout() ) );

        // Let's start with normal speed...
        normal->setChecked( TRUE );

        // some contraints
        start->setFixedWidth( 80 );
        setMinimumWidth( 300 );
    }

    /*
     * SLOT slotStart
     *
     * This SLOT is called if the user clicks start/pause/continue
     * button
     */

    void ProgressBar::slotStart()
    {
        // If the progress bar is at the beginning...
        if ( progress->progress() == -1 ) {
            // ...set according to the checked speed-radiobutton
            // the number of steps which are needed to complete the process
            if ( slow->isChecked() )
                progress->setTotalSteps( 10000 );
            else if ( normal->isChecked() )
                progress->setTotalSteps( 1000 );
            else
                progress->setTotalSteps( 50 );

            // disable the speed-radiobuttons
            slow->setEnabled( FALSE );
            normal->setEnabled( FALSE );
            fast->setEnabled( FALSE );
        }

        // If the progress is not running...
        if ( !timer.isActive() ) {
            // ...start the timer (and so the progress) with a interval of 1 ms...
            timer.start( 1 );
            // ...and rename the start/pause/continue button to Pause
            start->setText( "&Pause" );
        } else { // if the prgress is running...
            // ...stop the timer (and so the prgress)...
            timer.stop();
            // ...and rename the start/pause/continue button to Continue
            start->setText( "&Continue" );
        }
    }

    /*
     * SLOT slotReset
     *
     * This SLOT is called when the user clicks the reset button
     */

    void ProgressBar::slotReset()
    {
        // stop the timer and progress
        timer.stop();

        // rename the start/pause/continue button to Start...
        start->setText( "&Start" );
        // ...and enable this button
        start->setEnabled( TRUE );

        // enable the speed-radiobuttons
        slow->setEnabled( TRUE );
        normal->setEnabled( TRUE );
        fast->setEnabled( TRUE );

        // reset the progressbar
        progress->reset();
    }

    /*
     * SLOT slotTimeout
     *
     * This SLOT is called each ms when the timer is
     * active (== progress is running)
     */

    void ProgressBar::slotTimeout()
    {
        int p = progress->progress();

        // If the progress is complete...
        if ( p == progress->totalSteps() )  {
            // ...rename the start/pause/continue button to Start...
            start->setText( "&Start" );
            // ...and disable it...
            start->setEnabled( FALSE );
            // ...and return
            return;
        }

        // If the process is not complete increase it
        progress->setProgress( ++p );
    }

Main:

    /****************************************************************************
    ** $Id: qt/examples/progressbar/main.cpp   2.3.2   edited 2001-06-12 $
    **
    ** Copyright (C) 1992-2000 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 "progressbar.h"
    #include <qapplication.h>

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

        ProgressBar progressbar;
        progressbar.setCaption("Qt Example - ProgressBar");
        a.setMainWidget(&progressbar);
        progressbar.show();

        return a.exec();
    }