ImfCompressor.h

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//
// SPDX-License-Identifier: BSD-3-Clause
// Copyright (c) Contributors to the OpenEXR Project.
//

#ifndef INCLUDED_IMF_COMPRESSOR_H
#define INCLUDED_IMF_COMPRESSOR_H

//-----------------------------------------------------------------------------
//
//      class Compressor
//
//-----------------------------------------------------------------------------

#include "ImfForward.h"

#include "ImfCompression.h"

#include <ImathBox.h>

#include <stdlib.h>

OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER

class IMF_EXPORT_TYPE Compressor
{
public:
    //---------------------------------------------
    // Constructor -- hdr is the header of the file
    // that will be compressed or uncompressed
    //---------------------------------------------

    IMF_EXPORT
    Compressor (const Header& hdr);

    //-----------
    // Destructor
    //-----------

    IMF_EXPORT
    virtual ~Compressor ();

    //----------------------------------------------
    // Maximum number of scan lines processed by
    // a single call to compress() and uncompress().
    //----------------------------------------------

    IMF_EXPORT
    virtual int numScanLines () const = 0;

    //--------------------------------------------
    // Format of the pixel data read and written
    // by the compress() and uncompress() methods.
    // The default implementation of format()
    // returns XDR.
    //--------------------------------------------

    enum IMF_EXPORT_ENUM Format
    {
        NATIVE, // the machine's native format
        XDR     // Xdr format
    };

    IMF_EXPORT
    virtual Format format () const;

    //----------------------------
    // Access to the file's header
    //----------------------------

    const Header& header () const { return _header; }

    //-------------------------------------------------------------------------
    // Compress an array of bytes that represents the contents of up to
    // numScanLines() scan lines:
    //
    //      inPtr               Input buffer (uncompressed data).
    //
    //      inSize              Number of bytes in the input buffer
    //
    //      minY                Minimum y coordinate of the scan lines to
    //                          be compressed
    //
    //      outPtr              Pointer to output buffer
    //
    //      return value        Size of compressed data in output buffer
    //
    // Arrangement of uncompressed pixel data in the input buffer:
    //
    //  Before calling
    //
    //          compress (buf, size, minY, ...);
    //
    //  the InputFile::writePixels() method gathers pixel data from the
    //  frame buffer, fb, and places them in buffer buf, like this:
    //
    //  char *endOfBuf = buf;
    //
    //  for (int y = minY;
    //       y <= min (minY + numScanLines() - 1, header().dataWindow().max.y);
    //       ++y)
    //  {
    //      for (ChannelList::ConstIterator c = header().channels().begin();
    //           c != header().channels().end();
    //           ++c)
    //      {
    //          if (modp (y, c.channel().ySampling) != 0)
    //              continue;
    //
    //          for (int x = header().dataWindow().min.x;
    //               x <= header().dataWindow().max.x;
    //               ++x)
    //          {
    //              if (modp (x, c.channel().xSampling) != 0)
    //                  continue;
    //
    //              Xdr::write<CharPtrIO> (endOfBuf, fb.pixel (c, x, y));
    //          }
    //      }
    //  }
    //
    //  int size = endOfBuf - buf;
    //
    //-------------------------------------------------------------------------

    virtual int
    compress (const char* inPtr, int inSize, int minY, const char*& outPtr) = 0;

    IMF_EXPORT
    virtual int compressTile (
        const char*            inPtr,
        int                    inSize,
        IMATH_NAMESPACE::Box2i range,
        const char*&           outPtr);

    //-------------------------------------------------------------------------
    // Uncompress an array of bytes that has been compressed by compress():
    //
    //      inPtr               Input buffer (compressed data).
    //
    //      inSize              Number of bytes in the input buffer
    //
    //      minY                Minimum y coordinate of the scan lines to
    //                          be uncompressed
    //
    //      outPtr              Pointer to output buffer
    //
    //      return value        Size of uncompressed data in output buffer
    //
    //-------------------------------------------------------------------------

    virtual int uncompress (
        const char* inPtr, int inSize, int minY, const char*& outPtr) = 0;

    IMF_EXPORT
    virtual int uncompressTile (
        const char*            inPtr,
        int                    inSize,
        IMATH_NAMESPACE::Box2i range,
        const char*&           outPtr);

private:
    const Header& _header;
};

//--------------------------------------
// Test if c is a valid compression type
//--------------------------------------

IMF_EXPORT
bool isValidCompression (Compression c);

//--------------------------------------
// Test if c is valid for deep data
//--------------------------------------

IMF_EXPORT
bool isValidDeepCompression (Compression c);

//---------------------------------------
// Return true for compression types which
// do not guarantee that HALF type values
// are preserved precisely
//---------------------------------------
IMF_EXPORT
bool isLossyCompression (Compression c);

//-----------------------------------------------------------------
// Construct a Compressor for compression type c:
//
//  maxScanLineSize     Maximum number of bytes per uncompressed
//                      scan line.
//
//  header              Header of the input or output file whose
//                      pixels will be compressed or uncompressed.
//
//  return value        A pointer to a new Compressor object (it
//                      is the caller's responsibility to delete
//                      the object), or 0 (if c is NO_COMPRESSION).
//
//-----------------------------------------------------------------

IMF_EXPORT
Compressor*
newCompressor (Compression c, size_t maxScanLineSize, const Header& hdr);

//-----------------------------------------------------------------
// Construct a Compressor for compression type c for a tiled image:
//
//  tileLineSize        Maximum number of bytes per uncompressed
//                      line in a tile.
//
//  numTileLines        Maximum number of lines in a tile.
//
//  header              Header of the input or output file whose
//                      pixels will be compressed or uncompressed.
//
//  return value        A pointer to a new Compressor object (it
//                      is the caller's responsibility to delete
//                      the object), or 0 (if c is NO_COMPRESSION).
//
//-----------------------------------------------------------------

IMF_EXPORT
Compressor* newTileCompressor (
    Compression c, size_t tileLineSize, size_t numTileLines, const Header& hdr);

//-----------------------------------------------------------------
// Return the maximum number of scanlines in each chunk
// of a scanline image using the given compression scheme
//-----------------------------------------------------------------

IMF_EXPORT
int numLinesInBuffer (Compression comp);

OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT

#endif