iflConfig(3)

NAME
     iflConfig - class for pixel abstraction

INHERITS FROM
     This is a base class and therefore has no inheritance.

HEADER FILE
     #include <ifl/iflCdefs.h>

CLASS DESCRIPTION
     The iflConfig class is used to describe the configuration of pixel data.
     It is used in iflFile functions such as iflGetTile() and iflSetTile() to
     describe the configuration of data in the user's buffer.

     An iflConfig contains six public member variables describing a collection
     of pixels:


          iflType dtype               Data type of the pixels

          iflOrder order              Order of the pixels

          iflOrientation orientation  Orientation of the pixels

          int nchans                  Number of data channels the pixels
                                      contain

          int choff                   Offset in the channel list for the
                                      purpose of mapping from one collection
                                      of channels to another.

          int* channels               List that maps channels from one
                                      collection to another.  This array is
                                      not maintained by this object, the data
                                      pointed to must persist while the object
                                      is in use.

     Using iflConfig

     The iflConfig object contains a list that maps channels from one
     collection to another.  In this code fragment,

          unsigned char buffer[10*10*3];
          static int list[] = { 2, 1, 0 };
          iflConfig cfg(iflUChar, iflInterleaved, 3, list);

          someFile.getTile(0, 0, 0, 10, 10, 1, buffer, &cfg);

     cfg is used to indicate that buffer is going to receive a 10-by-10 array
     of three-component  pixels stored in interleaved order with an unsigned
     char data type.  This would override the actual configuration of the data
     in someFile.

     The channel list provides the buffer's channel information. The first
     channel of the buffer receives data from channel 2 of someFile. The
     second channel is from someFile's channel 1. The third buffer channel
     gets channel 0 of someFile.  In general, when an iflConfig is defaulted,
     the operation being performed assumes that the source and destination
     configurations match.  If someFile was actually a four-channel float
     image stored in separate order, then

          someFile.getTile(0, 0, 0, 10, 10, 1, buffer);


     would require a buffer declared as

          float buffer[10*10*4];

     and would receive a verbatim copy of the requested section of someFile.

CLASS MEMBER FUNCTION SUMMARY
     Constructor

          iflConfig* iflConfigCreate(iflDataType type, iflOrder ord,
                                     int nchan, int* chanList,
                                     int chanOff, iflOrientation ori(0))


     Destructor

          void iflConfigDelete(iflConfig *img)
FUNCTION DESCRIPTIONS
     iflConfig()

          iflConfig* iflConfigCreate(iflDataType type, iflOrder ord,
                                     int nchan, int* chanList,
                                     int chanOff, iflOrientation ori(0))


          The constructor creates an iflConfig with data type, type; data
          ordering, order; and channel list defined by chanList of
          nc channels.  If chanList is omitted, all nchan channels are used in
          ascending order.  Optionally, the orientation is set to ori.  If
          omitted, the orientation matches that of the image being accessed.

     iflConfigDelete()

          void iflConfigDelete(iflConfig *img)


          Deletes an object of class iflConfig, thus freeing any associated
          resources.

SEE ALSO
     iflFile