OpenVideo Documentation

State.h

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/* ========================================================================
 * Copyright (C) 2005  Graz University of Technology
 *
 * This framework is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This framework 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 General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this framework; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * For further information please contact Denis Kalkofen under
 * <kalkofen@icg.tu-graz.ac.at> or write to Denis Kalkofen,
 * Graz University of Technology, Inffeldgasse 16a, A8010 Graz,
 * Austria.
 * ========================================================================
 * PROJECT: OpenVideo
 * ======================================================================== */
 /* ======================================================================= */

#ifndef _STATEOV_H
#define _STATEOV_H


#include "openVideo.h"
#include "PixelFormat.h"

#include <map>
#include <string>
#include <vector>
#include <assert.h>


class ACE_Thread_Mutex;


namespace openvideo {


class DSVLSrc;


class OPENVIDEO_API Buffer
{
public:
    Buffer();

    virtual ~Buffer();

    virtual const unsigned char* getPixels() const  {  return buffer;  }

    virtual int getWidth() const  {  return width;  }

    virtual int getHeight() const  {  return height;  }

    virtual PIXEL_FORMAT getFormat() const  {  return format;  }

    virtual int getLockCounter() const  {  return lockCtr;  }

    virtual void lock();

    virtual void unlock();

    virtual bool isLocked() const  {  return lockCtr>0;  }

    virtual unsigned int getUpdateCounter() const  {  return updateCtr;  }

protected:
    unsigned char*      buffer;
    int                 lockCtr;
    unsigned int        updateCtr;
    ACE_Thread_Mutex*   mutex;
    int                 width,height;
    PIXEL_FORMAT        format;
};


typedef std::vector<Buffer*> BufferVector;

class OPENVIDEO_API State
{
public:
    State();
    
    virtual ~State();
    
    int width;

    int height;

    PIXEL_FORMAT format;

    void clear();

    void  addElement(std::string key,void* value);

    void* getElementData(std::string key);

    void  removeElement(std::string key);

    virtual Buffer* getCurrentBuffer()  {  return currentBuffer;  }

    void unlockAllBuffers();


    Buffer* findFreeBuffer();

    int getNumFrames() const  {  return buffers.size();  }

    int getNumLockedBuffers() const;

private:
    std::map<std::string,void*> elements;


protected:
    BufferVector buffers;
    Buffer* currentBuffer;
};



// This class prevents a problem that could happen
// in a usual client internal thread:
//
//   buffer = currentBuffer;
//   buffer->lock();
//   ...
//   buffer->unlock();
//
// The internal thread makes a copy of the variable to
// make sure that another thread can update currentBuffer at any time.
// The problem happens if currentBuffer is unlocked between
// 'buffer = currentBuffer;' and 'buffer->lock();'
// To prevent this a client should use BufferSynchronizer which
// provides an atomic action for getting a locked buffer
// without overwriting the variable before it is locked
//
class OPENVIDEO_API BufferSynchronizer
{
public:
    BufferSynchronizer();
    ~BufferSynchronizer();


    void assign(Buffer* newBuffer);


    Buffer* getLocked();

protected:
    Buffer*             buffer;
    ACE_Thread_Mutex*   mutex;
};



// ----> inlines <-----
// constructor method.
using namespace openvideo;

inline State::State()
{
    clear();
}
inline State::~State()
{
    clear();
}

inline void 
State::clear()
{
    elements.clear();
    width = height =0;
    format = FORMAT_UNKNOWN;
    currentBuffer = NULL;
    // FIXME: should this methods also free all buffers?
}
inline void 
State::addElement(std::string key,void* value)
{
    elements[key]=value;
}

inline void* 
State::getElementData(std::string key)
{
    std::map<std::string,void*>::iterator it = elements.find( key );
    if( it == elements.end())
        return NULL;
 
    return it->second;
}

inline void 
State::removeElement(std::string key)
{
    elements.erase(key);
}


}  //namespace openvideo


#endif //_STATEOV_H

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