TIFFSetField(3T)

NAME
       TIFFSetField  -  set  the value(s) of a tag in a TIFF file
       open for writing

SYNOPSIS
       #include <<tiffio.h>>
       int TIFFSetField(TIFF* tif, ttag_t tag, ...)
       #include <<stdarg.h>>
       int TIFFVSetField(TIFF* tif, ttag_t tag, va_list ap)

DESCRIPTION
       TIFFSetField sets the value of a field  or  pseudo-tag  in
       the  current  directory associated with the open TIFF file
       tif.  (A pseudo-tag is a parameter that is used to control
       the  operation  of the TIFF library but whose value is not
       read or written to the underlying file.)   The  file  must
       have been previously opened for writing with TIFFOpen(3T).
       The field is identified by tag, one of the values  defined
       in  the  include  file  tiff.h (see also the table below).
       The actual value is specified using  a  variable  argument
       list,  as  prescribed  by  the stdarg(3) interface (or, on
       some machines, the varargs(3) interface.)

       TIFFVSetField is functionally equivalent  to  TIFFSetField
       except  that  it  takes  a  pointer to a variable argument
       list.  TIFFVSetField is useful for writing  routines  that
       are  layered on top of the functionality provided by TIFF-
       SetField.

       The tags understood by libtiff, the  number  of  parameter
       values,  and  the  expected types for the parameter values
       are shown below.  The data types are: char* is null-termi-
       nated  string  and  corresponds  to  the  ASCII data type;
       uint16 is an unsigned 16-bit value; uint32 is an  unsigned
       32-bit  value; uint16* is an array of unsigned 16-bit val-
       ues.  Consult the TIFF specification  for  information  on
       the meaning of each tag.

       Tag Name                        Count  Types             Notes
       TIFFTAG_ARTIST                  1      char*
       TIFFTAG_BADFAXLINES             1      uint32
       TIFFTAG_BITSPERSAMPLE           1      uint16
       TIFFTAG_CLEANFAXDATA            1      uint16
       TIFFTAG_COLORMAP                3      uint16*           1<SamplesPerPixel is one, then a single array is passed;
       otherwise three arrays should be passed.

RETURN VALUES
       1  is returned if the tag is defined in the current direc-
       tory; otherwise a 0 is returned.

RETURN VALUES
       1 is returned if the operation was successful.  Otherwise,
       0 is returned if an error was detected.

DIAGNOSTICS
       All  error messages are directed to the TIFFError(3T) rou-
       tine.

       %s: Cannot  modify  tag  "%s"  while  writing.   Data  has
       already  been  written to the file, so the specified tag's
       value can not be changed.  This restriction is applied  to
       all tags that affect the format of written data.

       %d: Bad value for "%s".  An invalid value was supplied for
       the named tag.

SEE ALSO
       libtiff(3T) TIFFOpen(3T) TIFFGetField(3T) TIFFSetDirec- 
       tory(3T) TIFFWriteDirectory(3T) TIFFReadDirectory(3T)