Qt Toolkit - movies/main.cpp example file

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# Movies
Or the Story of the Animated GIF file

The Movies example displays animated GIF files using the QMovie and QLabel classes.

Main:

    /****************************************************************************
    ** $Id: qt/examples/movies/main.cpp   2.3.7   edited 2001-10-30 $
    **
    ** 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 <qapplication.h>
    #include <qfiledialog.h>
    #include <qlabel.h>
    #include <qpainter.h>
    #include <qmessagebox.h>
    #include <qmovie.h>

    class MovieScreen : public QFrame {
        Q_OBJECT
        QMovie movie;
        QString filename;

    public:
        MovieScreen(const char* fname, QMovie m, QWidget* p=0, const char* name=0, WFlags f=0) :
            QFrame(p, name, f)
        {
            setCaption(fname);
            filename = fname;
            movie = m;

            // Set a frame around the movie.
            setFrameStyle(QFrame::WinPanel|QFrame::Sunken);

            // No background needed, since we draw on the whole widget.
            movie.setBackgroundColor(backgroundColor());
            setBackgroundMode(NoBackground);

            // Get the movie to tell use when interesting things happen.
            movie.connectUpdate(this, SLOT(movieUpdated(const QRect&)));
            movie.connectResize(this, SLOT(movieResized(const QSize&)));
            movie.connectStatus(this, SLOT(movieStatus(int)));
        }

    protected:

        // Draw the contents of the QFrame - the movie and on-screen-display
        void drawContents(QPainter* p)
        {
            // Get the current movie frame.
            QPixmap pm = movie.framePixmap();

            // Get the area we have to draw in.
            QRect r = contentsRect();

            // Only rescale is we need to - it can take CPU!
            if ( r.size() != pm.size() ) {
                QWMatrix m;
                m.scale((double)r.width()/pm.width(),
                        (double)r.height()/pm.height());
                pm = pm.xForm(m);
            }

            // Draw the [possibly scaled] frame.  movieUpdated() below calls
            // repaint with only the changed area, so clipping will ensure we
            // only do the minimum amount of rendering.
            //
            p->drawPixmap(r.x(), r.y(), pm);

            // The on-screen display

            const char* message = 0;

            if (movie.paused()) {
                message = "PAUSED";
            } else if (movie.finished()) {
                message = "THE END";
            } else if (movie.steps() > 0) {
                message = "FF >>";
            }

            if (message) {
                // Find a good font size...
                p->setFont(QFont("Helvetica", 24));

                QFontMetrics fm = p->fontMetrics();
                if ( fm.width(message) > r.width()-10 )
                    p->setFont(QFont("Helvetica", 18));

                fm = p->fontMetrics();
                if ( fm.width(message) > r.width()-10 )
                    p->setFont(QFont("Helvetica", 14));

                fm = p->fontMetrics();
                if ( fm.width(message) > r.width()-10 )
                    p->setFont(QFont("Helvetica", 12));

                fm = p->fontMetrics();
                if ( fm.width(message) > r.width()-10 )
                    p->setFont(QFont("Helvetica", 10));

                // "Shadow" effect.
                p->setPen(black);
                p->drawText(1, 1, width()-1, height()-1, AlignCenter, message);
                p->setPen(white);
                p->drawText(0, 0, width()-1, height()-1, AlignCenter, message);
            }
        }

        void mouseReleaseEvent(QMouseEvent* event)
        {
            // Do what the Help says...

            if (event->state() & ShiftButton) {
                movie.restart();
            } else if (!movie.paused()) {
                movie.pause();
            } else {
                if (event->button() & LeftButton)
                    movie.step((event->state() & ControlButton) ? 10 : 1);
                else if (event->button() & (MidButton|RightButton))
                    movie.unpause();
            }

            repaint(); // To hide/show "PAUSED".
        }

    private slots:
        void movieUpdated(const QRect& area)
        {
            if (!isVisible())
                show();

            // The given area of the movie has changed.

            QRect r = contentsRect();

            if ( r.size() != movie.framePixmap().size() ) {
                // Need to scale - redraw whole frame.
                repaint( r );
            } else {
                // Only redraw the changed area of the frame
                repaint( area.x()+r.x(), area.y()+r.x(),
                         area.width(), area.height() );
            }
        }

        void movieResized(const QSize& size)
        {
            // The movie changed size, probably from its initial zero size.

            int fw = frameWidth();
            resize( size.width() + fw*2, size.height() + fw*2 );
            qApp->setMainWidget(this); // Just geometry, etc.
            qApp->setMainWidget(0); // Not Close==Quit
        }

        void movieStatus(int status)
        {
            // The movie has sent us a status message.

            if (status < 0) {
                QString msg;
                msg.sprintf("Could not play movie \"%s\"", (const char*)filename);
                QMessageBox::message("Error", msg);
            } else if (status == QMovie::Paused || status == QMovie::EndOfMovie) {
                repaint(); // Ensure status text is displayed
            }
        }
    };

    // A QFileDialog that chooses movies.
    //
    class MovieStarter : public QFileDialog {
        Q_OBJECT
    public:
        MovieStarter(const char *dir) :
            QFileDialog(dir, "*.gif *.mng")
        {
            //behave as in getOpenFilename
            setMode( ExistingFile );
            // When a file is selected, show it as a movie.
            connect(this, SIGNAL(fileSelected(const QString&)),
                    this, SLOT(startMovie(const QString&)));
        }

    public slots:
        void startMovie(const QString& filename)
        {
            if ( filename ) // Start a new movie - have it delete when closed.
                (void)new MovieScreen(filename, QMovie(filename), 0, 0, WDestructiveClose);
        }

        // QDialog's method - normally closes the file dialog.
        // We want it left open, and we want Cancel to quit everything.
        void done( int r )
        {
            if (r != Accepted) qApp->quit(); // end on Cancel
            setResult( r );

            // And don't hide.
        }
    };

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

        if (argc > 1) {
            // Commandline mode - show movies given on the command line
            //
            for (int arg=1; arg<argc; arg++)
                (void)new MovieScreen(argv[arg], QMovie(argv[arg]), 0, 0,
                                      Qt::WDestructiveClose);
            QObject::connect(qApp, SIGNAL(lastWindowClosed()), qApp, SLOT(quit()));
        } else {
            // "GUI" mode - open a chooser for movies
            //
            MovieStarter* fd = new MovieStarter(".");
            fd->show();

            // Some help text to explain the `hidden' features.
            QLabel* help = new QLabel(
                "Choose some movies.\n\n"
                "Shift-click to Restart.\n"
                "Click to Pause,\n"
                "then left-click to Step,\n"
                "control-left-click to Step 10,\n"
                "right-click to Unpause\n\n"
                "Windows may be resized to enlarge movie.", 0 );
            help->setCaption( "Qt Examples - Movies" );
            help->setIndent( 10 );
            help->show();
        }

        // Go!
        return a.exec();
    }

    #include "main.moc"