NAME

       TIFFFieldQuery - routines to query TIFF field information

SYNOPSIS

          #include <tiffio.h>

       const TIFFField *TIFFFieldWithName(TIFF *tif, const char *field_name)

       const TIFFField *TIFFFieldWithTag(TIFF *tif, uint32_t tag)

       const TIFFField *TIFFFindField(TIFF *tif, uint32_t tag, TIFFDataType dt)

       int TIFFFieldIsAnonymous(const TIFFField *fip)

       int TIFFFieldSetGetSize(const TIFFField *fip)

       int TIFFFieldSetGetCountSize(const TIFFField *fip)

DESCRIPTION

       TIFFFieldWithName()  and  TIFFFieldWithTag()  return a pointer to TIFF field information structure fip by
       the tag's field_name or its tag number.

       TIFFFindField() searches for the TIFF field information structure  fip  of  a  given  tag  number  and  a
       specific TIFFDataType dt.  With dt== TIFF_ANY the behaviour is the same than for TIFFFieldWithTag().

       All  three  functions  return  NULL,  when the tag is not registered within libtiff (see also Default Tag
       Auto-registration ).
          Such a TIFFDataType dependent search could be useful when the same  tag  is  defined  twice  but  with
          different  data  types, which is true for rare cases like TIFFTAG_XCLIPPATHUNITS. However, the libtiff
          does currently not support multiple definitions of the same tag.

       The following routines return status information about TIFF fields.

       fip  is  a  field  information  pointer  previously  returned  by  TIFFFindField(),   TIFFFieldWithTag(),
       TIFFFieldWithName().

       TIFFFieldIsAnonymous()  returns true (nonzero) if the field, read from file, is unknown to libtiff and an
       anonymous field has been auto-registered. Return is zero "0" if field is known to libtiff.  See   Default
       Tag Auto-registration   for more information.

       TIFFFieldSetGetSize()  returns  the  data  size in bytes of the field data type used for libtiff internal
       storage.   This  is  also  the  data  size  of  the  parameter  to  be  provided  to  TIFFSetField()  and
       TIFFGetField().  Custom  TIFF_RATIONAL  values  can  be  stored  internally  either  as  float or double.
       TIFFFieldSetGetSize() would then return "4" or "8", respectively.

       TIFFFieldSetGetCountSize() returns size of count parameter of TIFFSetField() and TIFFGetField() and  also
       if it is required:  0=none, 2= uint16_t, 4= uint32_t.  See also description of TIFFFieldReadCount().

DIAGNOSTICS

       None.

SEE ALSO

       TIFFFieldDataType (3tiff), TIFFFieldName (3tiff), TIFFFieldPassCount (3tiff), TIFFFieldReadCount (3tiff),
       TIFFFieldTag (3tiff), TIFFFieldWriteCount (3tiff), libtiff (3tiff)

AUTHOR

       LibTIFF contributors

COPYRIGHT

       1988-2022, LibTIFF contributors

4.7                                               Apr 30, 2025                             TIFFFIELDQUERY(3tiff)