epfl-archive/cs440-acg/ext/openexr/OpenEXR_Viewers/playexr/ImageBuffers.h

///////////////////////////////////////////////////////////////////////////
//
// Copyright (c) 2006, Industrial Light & Magic, a division of Lucas
// Digital Ltd. LLC
// 
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///////////////////////////////////////////////////////////////////////////

#ifndef INCLUDED_IMAGE_BUFFERS_H
#define INCLUDED_IMAGE_BUFFERS_H

//-----------------------------------------------------------------------------
//
//	class ImageBuffers
//
//	This class implements a ring buffer for a fixed number frames
//	of an image sequence.  The playExr program uses this ring buffer
//	to transport images from the file reading thread to the display
//	thread.  For each frame, the ImageBuffer contains:
//
//	* buffers for the pixels in the frame's thee channels,
//	  either R, G, B or Y, RY, BY
//
//	* An Imf::FrameBuffer object that describes the layout of
//	  the pixel buffers.  This is used by the file reading thread.
//
//	The ImageBuffer also stores the data window of the frames in
//	the image sequence, and a flag that indicates if the frames
//	contain RGB or luminance/chroma (Y, RY, BY) data.
//
//	Two semaphores indicate which frames in the ring buffer are
//	empty and how many are full.  The file reading thread fills
//	frames and the display thread empties them.
//
//	The file reading thread executes a loop that looks like this:
//
//		int i = 0;
//
//		while (true)
//		{
//		    emptyBuffersSemaphore.wait();
//		    read next frame from a file, store it in buffer i;
//		    fullBuffersSemaphore.post();
//		    i = (i + 1) % numBuffers();
//		}
//
//	The corresponding loop in the display thread looks like this:
//
//		int i = 0;
//
//		while (true)
//		{
//		    fullBuffersSemaphore.wait();
//		    display the image in buffer i;
//		    emptyBuffersSemaphore.post();
//		    i = (i + 1) % numBuffers();
//		}
//
//-----------------------------------------------------------------------------

#include <ImfFrameBuffer.h>
#include <ImathBox.h>
#include <IlmThreadSemaphore.h>


class ImageBuffers
{
  public:

    ImageBuffers ();

    //----------------------------------------------------------
    // Flag that indicates if we are playing forward or backward
    //----------------------------------------------------------

    bool 			forward;

    //-----------------------------------------------------------------------
    // Flag that indicates if the frames contain RGB or luminance/chroma data
    //-----------------------------------------------------------------------

    bool 			rgbMode;

    //------------------------------------
    // Number of frames in the ring buffer
    //------------------------------------

    int				numBuffers ();

    //------------------------------------------------
    // Access to the Imf::FrameBuffers
    // i must be in the range from 0 to numBuffers()-1
    //------------------------------------------------

    OPENEXR_IMF_NAMESPACE::FrameBuffer & frameBuffer (int i);


    //------------------------------------------------
    // Access to the pixel buffers
    // i must be in the range from 0 to numBuffers()-1
    // channel must be in the range from 0 to 2
    //------------------------------------------------

    char * &			pixels (int i, int channel);


    //-----------------------------------------------------------
    // Access to frame numbers that correspond the pixel buffers.
    // i must be in the range from 0 to numBuffers()-1
    //-----------------------------------------------------------

    int &			frameNumber (int i);


    //---------------------------
    // Data window for all frames
    //---------------------------

    IMATH_NAMESPACE::Box2i		dataWindow;


    //-----------
    // Semaphores
    //-----------

    ILMTHREAD_NAMESPACE::Semaphore	emptyBuffersSemaphore;
    ILMTHREAD_NAMESPACE::Semaphore	fullBuffersSemaphore;
    ILMTHREAD_NAMESPACE::Semaphore	exitSemaphore1;
    ILMTHREAD_NAMESPACE::Semaphore	exitSemaphore2;
	 
  private:

    static const int NUM_BUFFERS = 3;

    OPENEXR_IMF_NAMESPACE::FrameBuffer	_frameBuffers[NUM_BUFFERS];
    char *			_pixels[NUM_BUFFERS][3];
    int				_frameNumbers[NUM_BUFFERS];
};


#endif