abstractmediastream2.h

/*  This file is part of the KDE project
    Copyright (C) 2007-2008 Matthias Kretz <kretz@kde.org>
 
    This library is free software; you can redistribute it and/or
    modify it under the terms of the GNU Lesser General Public
    License as published by the Free Software Foundation; either
    version 2.1 of the License, or (at your option) version 3, or any
    later version accepted by the membership of KDE e.V. (or its
    successor approved by the membership of KDE e.V.), Nokia Corporation 
    (or its successors, if any) and the KDE Free Qt Foundation, which shall
    act as a proxy defined in Section 6 of version 3 of the license.
 
    This library is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
    Lesser General Public License for more details.
 
    You should have received a copy of the GNU Lesser General Public 
    License along with this library.  If not, see <http://www.gnu.org/licenses/>.
 
*/
 
#ifndef PHONON_ABSTRACTMEDIASTREAM2_H
#define PHONON_ABSTRACTMEDIASTREAM2_H
 
#include "abstractmediastream.h"
 
 
class QByteArray;
 
namespace Phonon
{
class MediaObject;
class AbstractMediaStream2Private;
 
/** \class AbstractMediaStream2 abstractmediastream2.h phonon/AbstractMediaStream2
 * \brief Base class for custom media data streams.
 *
 * Implement this class to provide a custom data stream to the backend. The class supports both, the
 * push and the pull model.
 *
 * Push:
 * \code
 * PushStream::PushStream(QObject *parent)
 *   : AbstractMediaStream2(parent), m_timer(new QTimer(this))
 * {
 *   setStreamSize(getMediaStreamSize());
 *
 *   connect(m_timer, SIGNAL(timeout()), SLOT(moreData()));
 *   m_timer->setInterval(0);
 * }
 *
 * void PushStream::moreData()
 * {
 *   const QByteArray data = getMediaData();
 *   if (data.isEmpty()) {
 *     endOfData();
 *   } else {
 *     writeData(data);
 *   }
 * }
 *
 * void PushStream::needData()
 * {
 *   m_timer->start();
 *   moreData();
 * }
 *
 * void PushStream::enoughData()
 * {
 *   m_timer->stop();
 * }
 * \endcode
 *
 * Pull:
 * \code
 * PullStream::PullStream(QObject *parent)
 *   : AbstractMediaStream2(parent)
 * {
 *   setStreamSize(getMediaStreamSize());
 * }
 *
 * void PullStream::needData()
 * {
 *   const QByteArray data = getMediaData();
 *   if (data.isEmpty()) {
 *     endOfData();
 *   } else {
 *     writeData(data);
 *   }
 * }
 * \endcode
 *
 * \ingroup Playback
 * \author Matthias Kretz <kretz@kde.org>
 */
class PHONON_EXPORT AbstractMediaStream2 : public AbstractMediaStream
{
    Q_OBJECT
    Q_DECLARE_PRIVATE(AbstractMediaStream2)
    friend class MediaObject;
    friend class MediaObjectPrivate;
    friend class MediaSourcePrivate;
    protected:
        /////////////////////////////////////////////////////////////
        // functions an implementation will call:
        /////////////////////////////////////////////////////////////
 
        /**
         * Constructs an AbstractMediaStream2 object with a \p parent.
         */
        explicit AbstractMediaStream2(QObject *parent = 0);
 
        void resetDone();
        void seekStreamDone();
 
        /////////////////////////////////////////////////////////////
        // functions to implement:
        /////////////////////////////////////////////////////////////
 
        /**
         * Reimplement this function to be notified when the backend needs data.
         *
         * When this function is called you should try to call writeData or endOfData before
         * returning.
         *
         * \param size The number of bytes that are needed. If possible, pass \p size bytes of media
         *             data in the next writeData call.
         */
        virtual void needData(quint32 size) = 0;
 
        /////////////////////////////////////////////////////////////
        // internal
        /////////////////////////////////////////////////////////////
 
        bool event(QEvent *e);
        AbstractMediaStream2(AbstractMediaStream2Private &dd, QObject *parent);
 
    private:
        // hide needData() explicitly
        virtual void needData() {}
 
        Q_PRIVATE_SLOT(d_func(), void _k_handleStreamEvent())
};
 
} // namespace Phonon
 
 
#endif // PHONON_ABSTRACTMEDIASTREAM2_H