tiffreadencodedtile.3t

tiff文件开发库

.\" $Header: /cvsroot/osrs/libtiff/man/TIFFReadEncodedTile.3t,v 1.1.1.1 1999/07/27 21:50:27 mike Exp $
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.\" Copyright (c) 1988-1997 Sam Leffler
.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.
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.if n .po 0
.TH TIFFReadEncodedTile 3T "October 15, 1995"
.SH NAME
TIFFReadEncodedTile \- read and decode a tile of data from an open
.SM TIFF
file
.SH SYNOPSIS
.B "#include <tiffio.h>"
.br
.B "int TIFFReadEncodedTile(TIFF* tif, u_long tile, u_char* buf, u_long size)"
.SH DESCRIPTION
Read the specified tile of data and place up to
.I size
bytes of decompressed information in the (user supplied) data buffer.
.SH NOTES
The value of
.I tile
is a ``raw tile number.''
That is, the caller must take into account whether or not the
data are organized in separate planes (\c
.IR PlanarConfiguration =2).
.IR TIFFComputeTile
automatically does this when converting an (x,y,z,sample)
coordinate quadruple to a tile number.
To read a full tile of data the data buffer should be
at least as large as the value returned by
.IR TIFFTileSize .
.PP
The library attempts to hide bit- and byte-ordering differences
between the image and the native machine by converting data
to the native machine order.
Bit reversal is done if the
.I FillOrder
tag is opposite to the native machine bit order.
16- and 32-bit samples are automatically byte-swapped if the
file was written with a byte order opposite to the native
machine byte order,
.SH "RETURN VALUES"
The actual number of bytes of data that were placed in
.I buf
is returned;
.IR TIFFReadEncodedTile
returns \-1 if an error was encountered.
.SH DIAGNOSTICS
All error messages are directed to the
.IR TIFFError (3T)
routine.
.SH "SEE ALSO"
.IR libtiff (3T),
.IR TIFFOpen (3T),
.IR TIFFReadRawTile (3T),
.IR TIFFReadTile (3T)