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

# Progress Bar and Dialog Example

This example displays either a simple (text-only) or a custom-labelled (user-supplied widget) progress dialog. It also demonstrates simple use of menus.

Implementation:

    /****************************************************************************
    ** $Id:  qt/progress.cpp   3.0.0   edited Jun 22 13:24 $
    **
    ** 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 <qprogressdialog.h>
    #include <qapplication.h>
    #include <qmenubar.h>
    #include <qpopupmenu.h>
    #include <qpainter.h>
    #include <stdlib.h>

    class AnimatedThingy : public QLabel {
    public:
        AnimatedThingy( QWidget* parent, const QString& s ) :
            QLabel(parent),
            label(s),
            step(0)
        {
            label+="\n... and wasting CPU\nwith this animation!\n";

            for (int i=0; i<nqix; i++)
                ox[0][i] = oy[0][i] = ox[1][i] = oy[1][i] = 0;
            x0 = y0 = x1 = y1 = 0;
            dx0 = rand()%8+2;
            dy0 = rand()%8+2;
            dx1 = rand()%8+2;
            dy1 = rand()%8+2;
        }

        void show()
        {
            if (!isVisible()) startTimer(100);
            QWidget::show();
        }

        void hide()
        {
            QWidget::hide();
            killTimers();
        }

        QSize sizeHint() const
        {
            return QSize(120,100);
        }

    protected:
        void timerEvent(QTimerEvent*)
        {
            QPainter p(this);
            QPen pn=p.pen();
            pn.setWidth(2);
            pn.setColor(backgroundColor());
            p.setPen(pn);

            step = (step + 1) % nqix;

            p.drawLine(ox[0][step], oy[0][step], ox[1][step], oy[1][step]);

            inc(x0, dx0, width());
            inc(y0, dy0, height());
            inc(x1, dx1, width());
            inc(y1, dy1, height());
            ox[0][step] = x0;
            oy[0][step] = y0;
            ox[1][step] = x1;
            oy[1][step] = y1;

            QColor c;
            c.setHsv( (step*255)/nqix, 255, 255 ); // rainbow effect
            pn.setColor(c);
            p.setPen(pn);
            p.drawLine(ox[0][step], oy[0][step], ox[1][step], oy[1][step]);
            p.setPen(colorGroup().text());
            p.drawText(rect(), AlignCenter, label);
        }

        void paintEvent(QPaintEvent* event)
        {
            QPainter p(this);
            QPen pn=p.pen();
            pn.setWidth(2);
            p.setPen(pn);
            p.setClipRect(event->rect());
            for (int i=0; i<nqix; i++) {
                QColor c;
                c.setHsv( (i*255)/nqix, 255, 255 ); // rainbow effect
                pn.setColor(c);
                p.setPen(pn);
                p.drawLine(ox[0][i], oy[0][i], ox[1][i], oy[1][i]);
            }
            p.setPen(colorGroup().text());
            p.drawText(rect(), AlignCenter, label);
        }

    private:
        void inc(int& x, int& dx, int b)
        {
            x+=dx;
            if (x<0) { x=0; dx=rand()%8+2; }
            else if (x>=b) { x=b-1; dx=-(rand()%8+2); }
        }

        enum {nqix=10};
        int ox[2][nqix];
        int oy[2][nqix];
        int x0,y0,x1,y1;
        int dx0,dy0,dx1,dy1;
        QString label;
        int step;
    };

    class CPUWaster : public QWidget
    {
        Q_OBJECT

        enum { first_draw_item = 1000, last_draw_item = 1006 };

        int drawItemRects(int id)
        {
            int n = id - first_draw_item;
            int r = 100;
            while (n--) r*=(n%3 ? 5 : 4);
            return r;
        }
        QString drawItemText(int id)
        {
            QString str;
            str.sprintf("%d Rectangles", drawItemRects(id));
            return str;
        }

    public:
        CPUWaster() :
            pb(0)
        {
            menubar = new QMenuBar( this, "menu" );
            Q_CHECK_PTR( menubar );

            QPopupMenu* file = new QPopupMenu();
            Q_CHECK_PTR( file );
            menubar->insertItem( "&File", file );
            for (int i=first_draw_item; i<=last_draw_item; i++)
                file->insertItem( drawItemText(i), i );
            connect( menubar, SIGNAL(activated(int)), this, SLOT(doMenuItem(int)) );
            file->insertSeparator();
            file->insertItem( "Quit", qApp,  SLOT(quit()) );

            options = new QPopupMenu();
            Q_CHECK_PTR( options );
            menubar->insertItem( "&Options", options );
            td_id = options->insertItem( "Timer driven", this, SLOT(timerDriven()) );
            ld_id = options->insertItem( "Loop driven", this, SLOT(loopDriven()) );
            options->insertSeparator();
            dl_id = options->insertItem( "Default label", this, SLOT(defaultLabel()) );
            cl_id = options->insertItem( "Custom label", this, SLOT(customLabel()) );
            options->insertSeparator();
            md_id = options->insertItem( "No minimum duration", this, SLOT(toggleMinimumDuration()) );
            options->setCheckable( TRUE );
            loopDriven();
            defaultLabel();

            setFixedSize( 400, 300 );

            setBackgroundColor( black );
        }

    public slots:
        void doMenuItem(int id)
        {
            if (id >= first_draw_item && id <= last_draw_item)
                draw(drawItemRects(id));
        }

        void stopDrawing() { got_stop = TRUE; }

        void timerDriven()
        {
            timer_driven = TRUE;
            options->setItemChecked( td_id, TRUE );
            options->setItemChecked( ld_id, FALSE );
        }

        void loopDriven()
        {
            timer_driven = FALSE;
            options->setItemChecked( ld_id, TRUE );
            options->setItemChecked( td_id, FALSE );
        }

        void defaultLabel()
        {
            default_label = TRUE;
            options->setItemChecked( dl_id, TRUE );
            options->setItemChecked( cl_id, FALSE );
        }

        void customLabel()
        {
            default_label = FALSE;
            options->setItemChecked( dl_id, FALSE );
            options->setItemChecked( cl_id, TRUE );
        }

        void toggleMinimumDuration()
        {
            options->setItemChecked( md_id,
               !options->isItemChecked( md_id ) );
        }

    private:
        void timerEvent( QTimerEvent* )
        {
            pb->setProgress( pb->totalSteps() - rects );
            rects--;

            {
                QPainter p(this);

                int ww = width();
                int wh = height();

                if ( ww > 8 && wh > 8 ) {
                    QColor c(rand()%255, rand()%255, rand()%255);
                    int x = rand() % (ww-8);
                    int y = rand() % (wh-8);
                    int w = rand() % (ww-x);
                    int h = rand() % (wh-y);
                    p.fillRect( x, y, w, h, c );
                }
            }

            if (!rects || got_stop) {
                pb->setProgress( pb->totalSteps() );
                QPainter p(this);
                p.fillRect(0, 0, width(), height(), backgroundColor());
                enableDrawingItems(TRUE);
                killTimers();
                delete pb;
                pb = 0;
            }
        }

        QProgressDialog* newProgressDialog( const char* label, int steps, bool modal )
        {
            QProgressDialog *d = new QProgressDialog(label, "Cancel", steps, this,
                                                     "progress", modal);
            if ( options->isItemChecked( md_id ) )
                d->setMinimumDuration(0);
            if ( !default_label )
                d->setLabel( new AnimatedThingy(d,label) );
            return d;
        }

        void enableDrawingItems(bool yes)
        {
            for (int i=first_draw_item; i<=last_draw_item; i++) {
                menubar->setItemEnabled(i, yes);
            }
        }

        void draw(int n)
        {
            if ( timer_driven ) {
                if ( pb ) {
                    qWarning("This cannot happen!");
                    return;
                }
                rects = n;
                pb = newProgressDialog("Drawing rectangles.\n"
                                       "Using timer event.", n, FALSE);
                pb->setCaption("Please Wait");
                connect(pb, SIGNAL(cancelled()), this, SLOT(stopDrawing()));
                enableDrawingItems(FALSE);
                startTimer(0);
                got_stop = FALSE;
            } else {
                QProgressDialog* lpb = newProgressDialog(
                            "Drawing rectangles.\nUsing loop.", n, TRUE);
                lpb->setCaption("Please Wait");

                QPainter p(this);
                for (int i=0; i<n; i++) {
                    lpb->setProgress(i);
                    if ( lpb->wasCancelled() )
                        break;

                    QColor c(rand()%255, rand()%255, rand()%255);
                    int x = rand()%(width()-8);
                    int y = rand()%(height()-8);
                    int w = rand()%(width()-x);
                    int h = rand()%(height()-y);
                    p.fillRect(x,y,w,h,c);
                }

                p.fillRect(0, 0, width(), height(), backgroundColor());

                delete lpb;
            }
        }

        QMenuBar* menubar;
        QProgressDialog* pb;
        QPopupMenu* options;
        int td_id, ld_id;
        int dl_id, cl_id;
        int md_id;
        int rects;
        bool timer_driven;
        bool default_label;
        bool got_stop;
    };

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

        int wincount = argc > 1 ? atoi(argv[1]) : 1;

        for ( int i=0; i<wincount; i++ ) {
            CPUWaster* cpuw = new CPUWaster;
            if ( i == 0 ) a.setMainWidget(cpuw);
            cpuw->show();
        }
        return a.exec();
    }

    #include "progress.moc"

See also Examples.