TIFFFIELDQUERY(3tiff) LibTIFF TIFFFIELDQUERY(3tiff)
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(3), TIFFFieldName(3), TIFFFieldPassCount(3),
TIFFFieldReadCount(3), TIFFFieldTag(3), TIFFFieldWriteCount(3),
libtiff(3)
AUTHOR
LibTIFF contributors
COPYRIGHT
1988-2022, LibTIFF contributors
4.6 October 9, 2023 TIFFFIELDQUERY(3tiff)
tiff 4.6.0 - Generated Sat Oct 14 16:03:32 CDT 2023