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Add a note about autoregistered tags.

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This commit is contained in:
Andrey Kiselev 2005-03-18 08:44:05 +00:00
parent 3784c28bdd
commit d5848b4fc5
1 changed files with 33 additions and 12 deletions
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man/TIFFGetField.3tiff
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@ -1,4 +1,4 @@
.\" $Id: TIFFGetField.3tiff,v 1.1 2004-11-11 14:39:16 dron Exp $
.\" $Id: TIFFGetField.3tiff,v 1.2 2005-03-18 08:44:05 dron Exp $
.\"
.\" Copyright (c) 1988-1997 Sam Leffler
.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
@ -23,7 +23,7 @@
.\" OF THIS SOFTWARE.
.\"
.if n .po 0
.TH TIFFGetField 3TIFF "November 04, 2004" "libtiff"
.TH TIFFGetField 3TIFF "March 18, 2005" "libtiff"
.SH NAME
TIFFGetField, TIFFVGetField \- get the value(s) of a tag in an open
.SM TIFF
@ -43,7 +43,7 @@ file
.SH DESCRIPTION
.IR TIFFGetField
returns the value of a tag or pseudo-tag associated with the the current
directory of the open
directory of the opened
.SM TIFF
file
.IR tif .
@ -58,10 +58,9 @@ The tag is identified by
.IR tag ,
one of the values defined in the include file
.B tiff.h
(see also the table below).
The type and number of values returned is dependent on the tag being
requested. The programming interface uses a variable argument list as
prescribed by the
(see also the table below). The type and number of values returned is
dependent on the tag being requested. The programming interface uses a
variable argument list as prescribed by the
.IR stdarg (3)
interface. The returned values should only be interpreted if
.IR TIFFGetField
@ -86,7 +85,7 @@ except that if a tag is not defined in the current directory and it has a
default value, then the default value is returned.
.PP
The tags understood by
.IR libtiff ,
.IR libtiff(3TIFF),
the number of parameter values, and the types for the returned values are
shown below. The data types are specified as in C and correspond to the types
used to specify tag values to
@ -179,16 +178,38 @@ TIFFTAG_ICCPROFILE 2 uint32*,void** count, profile data\(dd
.fi
\(dg If
.I SamplesPerPixel
is one, then a single array is returned; otherwise three arrays are
returned.
is one, then a single array is returned; otherwise three arrays are returned.
.fi
\(dd The contents of this field are quite complex. See
.IR "The ICC Profile Format Specification" ,
Annex B.3 "Embedding ICC Profiles in TIFF Files" (available at
http://www.color.org) for an explanation.
.SH "RETURN VALUES"
.SH AUTOREGISTERED TAGS
If you can't find the tag in the table above that means this is unsupported
tag. But you still be able to read it's value if you know the data type of
that tag. For example, if you want to read the LONG value from the tag 33424
and ASCII string from the tag 36867 you can use the following code:
.PP
.RS
.nf
uint16 count;
void *data;
TIFFGetField(tiff, 33424, &count, &data);
printf("Tag %d: %d, count %d\n", 33424, *(uint32 *)data, count);
TIFFGetField(tiff, 36867, &count, &data);
printf("Tag %d: %s, count %d\n", 36867, (char *)data, count);
.fi
.RE
.PP
is not supported by
.IR libtiff(3TIFF),
library
.SH RETURN VALUES
1 is returned if the tag is defined in the current directory; otherwise a 0 is
returned.
returned.
.SH DIAGNOSTICS
All error messages are directed to the
.IR TIFFError (3TIFF)