Movies or the Story of the Animated GIF file

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

The movies will only read an animated GIF if GIF reading was enabled when Qt was built.

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 <qapplication.h>
#include <qfiledialog.h>
#include <qpushbutton.h>
#include <qlabel.h>
#include <qpainter.h>
#include <qmessagebox.h>
#include <qmovie.h>
#include <qvbox.h>


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

public:
    MovieScreen(const char* fname, QMovie m, QWidget* p=0, const char* name=0, WFlags f=0) :
        QFrame(p, name, f),
        sh(100,100)
    {
        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)));

        setSizePolicy(QSizePolicy(QSizePolicy::Expanding,QSizePolicy::Expanding));
    }

    QSize sizeHint() const
    {
        return sh;
    }

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();

        if ( !pm.isNull() ) {
            // 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);
        }
    }

public slots:
    void restart()
    {
        movie.restart();
        repaint();
    }

    void togglePause()
    {
        if ( movie.paused() )
            movie.unpause();
        else
            movie.pause();
        repaint();
    }

    void step()
    {
        movie.step();
        repaint();
    }

    void step10()
    {
        movie.step(10);
        repaint();
    }

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();
        sh = QSize( size.width() + fw*2, size.height() + fw*2 );
        updateGeometry();
        if ( parentWidget() && parentWidget()->isHidden() )
            parentWidget()->show();
    }

    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::warning(this, "movies", msg);
            parentWidget()->close();
        } else if (status == QMovie::Paused || status == QMovie::EndOfMovie) {
            repaint(); // Ensure status text is displayed
        }
    }
};

class MoviePlayer : public QVBox {
    MovieScreen* movie;
public:
    MoviePlayer(const char* fname, QMovie m, QWidget* p=0, const char* name=0, WFlags f=0) :
        QVBox(p,name,f)
    {
        movie = new MovieScreen(fname, m, this);
        QHBox* hb = new QHBox(this);
        QPushButton* btn;
        btn = new QPushButton("<<", hb);
        connect(btn, SIGNAL(clicked()), movie, SLOT(restart()));
        btn = new QPushButton("||", hb);
        connect(btn, SIGNAL(clicked()), movie, SLOT(togglePause()));
        btn = new QPushButton(">|", hb);
        connect(btn, SIGNAL(clicked()), movie, SLOT(step()));
        btn = new QPushButton(">>|", hb);
        connect(btn, SIGNAL(clicked()), movie, SLOT(step10()));
    }
};


// A QFileDialog that chooses movies.
//
class MovieStarter: public QFileDialog {
    Q_OBJECT
public:
    MovieStarter(const char *dir);

public slots:
    void startMovie(const QString& filename);
    // QDialog's method - normally closes the file dialog.
    // We want it left open, and we want Cancel to quit everything.
    void done( int r );
};


MovieStarter::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&)));
}


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

void MovieStarter::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
        //
        bool gui=TRUE;
        for (int arg=1; arg<argc; arg++) {
            if ( QString(argv[arg]) == "-i" )
                gui = !gui;
            else if ( gui )
                (void)new MoviePlayer(argv[arg], QMovie(argv[arg]), 0, 0,
                                      Qt::WDestructiveClose);
            else
                (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();
    }

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

#include "main.moc"

See also Examples.