ImfChannelList.h

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


#ifndef INCLUDED_IMF_CHANNEL_LIST_H
#define INCLUDED_IMF_CHANNEL_LIST_H

//-----------------------------------------------------------------------------
//
//      class Channel
//      class ChannelList
//
//-----------------------------------------------------------------------------

#include "ImfForward.h"

#include "ImfName.h"
#include "ImfPixelType.h"


#include <map>
#include <set>
#include <string>

OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_ENTER


struct IMF_EXPORT_TYPE Channel
{
    //------------------------------
    // Data type; see ImfPixelType.h
    //------------------------------

    PixelType           type;


    //--------------------------------------------
    // Subsampling: pixel (x, y) is present in the
    // channel only if 
    //
    //  x % xSampling == 0 && y % ySampling == 0
    //
    //--------------------------------------------

    int                 xSampling;
    int                 ySampling;


    //--------------------------------------------------------------
    // Hint to lossy compression methods that indicates whether
    // human perception of the quantity represented by this channel
    // is closer to linear or closer to logarithmic.  Compression
    // methods may optimize image quality by adjusting pixel data
    // quantization according to this hint.
    // For example, perception of red, green, blue and luminance is
    // approximately logarithmic; the difference between 0.1 and 0.2
    // is perceived to be roughly the same as the difference between
    // 1.0 and 2.0.  Perception of chroma coordinates tends to be
    // closer to linear than logarithmic; the difference between 0.1
    // and 0.2 is perceived to be roughly the same as the difference
    // between 1.0 and 1.1.
    //--------------------------------------------------------------

    bool                pLinear;


    //------------
    // Constructor
    //------------
    
    IMF_EXPORT
    Channel (PixelType type = HALF,
             int xSampling = 1,
             int ySampling = 1,
             bool pLinear = false);


    //------------
    // Operator ==
    //------------

    IMF_EXPORT
    bool                operator == (const Channel &other) const;
};


class IMF_EXPORT_TYPE ChannelList
{
  public:

    //--------------
    // Add a channel
    //--------------

    IMF_EXPORT
    void                        insert (const char name[],
                                        const Channel &channel);

    IMF_EXPORT
    void                        insert (const std::string &name,
                                        const Channel &channel);

    //------------------------------------------------------------------
    // Access to existing channels:
    //
    // [n]              Returns a reference to the channel with name n.
    //                  If no channel with name n exists, an IEX_NAMESPACE::ArgExc
    //                  is thrown.
    //
    // findChannel(n)   Returns a pointer to the channel with name n,
    //                  or 0 if no channel with name n exists.
    //
    //------------------------------------------------------------------

    IMF_EXPORT
    Channel &                   operator [] (const char name[]);
    IMF_EXPORT
    const Channel &             operator [] (const char name[]) const;

    IMF_EXPORT
    Channel &                   operator [] (const std::string &name);
    IMF_EXPORT
    const Channel &             operator [] (const std::string &name) const;

    IMF_EXPORT
    Channel *                   findChannel (const char name[]);
    IMF_EXPORT
    const Channel *             findChannel (const char name[]) const;

    IMF_EXPORT
    Channel *                   findChannel (const std::string &name);
    IMF_EXPORT
    const Channel *             findChannel (const std::string &name) const;


    //-------------------------------------------
    // Iterator-style access to existing channels
    //-------------------------------------------

    typedef std::map <Name, Channel> ChannelMap;

    class Iterator;
    class ConstIterator;

    IMF_EXPORT
    Iterator                    begin ();
    IMF_EXPORT
    ConstIterator               begin () const;

    IMF_EXPORT
    Iterator                    end ();
    IMF_EXPORT
    ConstIterator               end () const;

    IMF_EXPORT
    Iterator                    find (const char name[]);
    IMF_EXPORT
    ConstIterator               find (const char name[]) const;

    IMF_EXPORT
    Iterator                    find (const std::string &name);
    IMF_EXPORT
    ConstIterator               find (const std::string &name) const;

    
    //-----------------------------------------------------------------
    // Support for image layers:
    //
    // In an image file with many channels it is sometimes useful to
    // group the channels into "layers", that is, into sets of channels
    // that logically belong together.  Grouping channels into layers
    // is done using a naming convention:  channel C in layer L is
    // called "L.C".
    //
    // For example, a computer graphic image may contain separate
    // R, G and B channels for light that originated at each of
    // several different virtual light sources.  The channels in
    // this image might be called "light1.R", "light1.G", "light1.B",
    // "light2.R", "light2.G", "light2.B", etc.
    // 
    // Note that this naming convention allows layers to be nested;
    // for example, "light1.specular.R" identifies the "R" channel
    // in the "specular" sub-layer of layer "light1".
    //
    // Channel names that don't contain a "." or that contain a
    // "." only at the beginning or at the end are not considered
    // to be part of any layer.
    //
    // layers(lns)              sorts the channels in this ChannelList
    //                          into layers and stores the names of
    //                          all layers, sorted alphabetically,
    //                          into string set lns.
    //
    // channelsInLayer(ln,f,l)  stores a pair of iterators in f and l
    //                          such that the loop
    //
    //                          for (ConstIterator i = f; i != l; ++i)
    //                             ...
    //
    //                          iterates over all channels in layer ln.
    //                          channelsInLayer (ln, l, p) calls
    //                          channelsWithPrefix (ln + ".", l, p).
    //
    //-----------------------------------------------------------------

    IMF_EXPORT
    void                layers (std::set <std::string> &layerNames) const;

    IMF_EXPORT
    void                channelsInLayer (const std::string &layerName,
                                         Iterator &first,
                                         Iterator &last);

    IMF_EXPORT
    void                channelsInLayer (const std::string &layerName,
                                         ConstIterator &first,
                                         ConstIterator &last) const;


    //-------------------------------------------------------------------
    // Find all channels whose name begins with a given prefix:
    //
    // channelsWithPrefix(p,f,l) stores a pair of iterators in f and l
    // such that the following loop iterates over all channels whose name
    // begins with string p:
    //
    //          for (ConstIterator i = f; i != l; ++i)
    //              ...
    //
    //-------------------------------------------------------------------

    IMF_EXPORT
    void                        channelsWithPrefix (const char prefix[],
                                                    Iterator &first,
                                                    Iterator &last);

    IMF_EXPORT
    void                        channelsWithPrefix (const char prefix[],
                                                    ConstIterator &first,
                                                    ConstIterator &last) const;

    IMF_EXPORT
    void                        channelsWithPrefix (const std::string &prefix,
                                                    Iterator &first,
                                                    Iterator &last);

    IMF_EXPORT
    void                        channelsWithPrefix (const std::string &prefix,
                                                    ConstIterator &first,
                                                    ConstIterator &last) const;

    //------------
    // Operator ==
    //------------

    IMF_EXPORT
    bool                        operator == (const ChannelList &other) const;

  private:

    ChannelMap                  _map;
};


//----------
// Iterators
//----------

class IMF_EXPORT_TYPE ChannelList::Iterator
{
  public:

    IMF_EXPORT
    Iterator ();
    IMF_EXPORT
    Iterator (const ChannelList::ChannelMap::iterator &i);

    IMF_EXPORT
    Iterator &                  operator ++ ();
    IMF_EXPORT
    Iterator                    operator ++ (int);

    IMF_EXPORT
    const char *                name () const;
    IMF_EXPORT
    Channel &                   channel () const;

  private:

    friend class ChannelList::ConstIterator;

    ChannelList::ChannelMap::iterator _i;
};


class IMF_EXPORT_TYPE ChannelList::ConstIterator
{
  public:

    IMF_EXPORT
    ConstIterator ();
    IMF_EXPORT
    ConstIterator (const ChannelList::ChannelMap::const_iterator &i);
    IMF_EXPORT
    ConstIterator (const ChannelList::Iterator &other);

    IMF_EXPORT
    ConstIterator &             operator ++ ();
    IMF_EXPORT
    ConstIterator               operator ++ (int);

    IMF_EXPORT
    const char *                name () const;
    IMF_EXPORT
    const Channel &             channel () const;

  private:

    friend bool operator == (const ConstIterator &, const ConstIterator &);
    friend bool operator != (const ConstIterator &, const ConstIterator &);

    ChannelList::ChannelMap::const_iterator _i;
};


//-----------------
// Inline Functions
//-----------------

inline
ChannelList::Iterator::Iterator (): _i()
{
    // empty
}


inline
ChannelList::Iterator::Iterator (const ChannelList::ChannelMap::iterator &i):
    _i (i)
{
    // empty
}


inline ChannelList::Iterator &          
ChannelList::Iterator::operator ++ ()
{
    ++_i;
    return *this;
}


inline ChannelList::Iterator    
ChannelList::Iterator::operator ++ (int)
{
    Iterator tmp = *this;
    ++_i;
    return tmp;
}


inline const char *
ChannelList::Iterator::name () const
{
    return *_i->first;
}


inline Channel &        
ChannelList::Iterator::channel () const
{
    return _i->second;
}


inline
ChannelList::ConstIterator::ConstIterator (): _i()
{
    // empty
}

inline
ChannelList::ConstIterator::ConstIterator
    (const ChannelList::ChannelMap::const_iterator &i): _i (i)
{
    // empty
}


inline
ChannelList::ConstIterator::ConstIterator (const ChannelList::Iterator &other):
    _i (other._i)
{
    // empty
}

inline ChannelList::ConstIterator &
ChannelList::ConstIterator::operator ++ ()
{
    ++_i;
    return *this;
}


inline ChannelList::ConstIterator               
ChannelList::ConstIterator::operator ++ (int)
{
    ConstIterator tmp = *this;
    ++_i;
    return tmp;
}


inline const char *
ChannelList::ConstIterator::name () const
{
    return *_i->first;
}

inline const Channel &  
ChannelList::ConstIterator::channel () const
{
    return _i->second;
}


inline bool
operator == (const ChannelList::ConstIterator &x,
             const ChannelList::ConstIterator &y)
{
    return x._i == y._i;
}


inline bool
operator != (const ChannelList::ConstIterator &x,
             const ChannelList::ConstIterator &y)
{
    return !(x == y);
}


OPENEXR_IMF_INTERNAL_NAMESPACE_HEADER_EXIT

#endif