tiffwritedirectory.3t

tiff文件开发库

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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 TIFFWriteDirectory 3T "September 26, 2001"
.SH NAME
TIFFWriteDirectory, TIFFRewriteDirectory, TIFFCheckpointDirectory \- write
the current directory in an open
.SM TIFF
file
.SH SYNOPSIS
.B "#include <tiffio.h>"
.br
.B "int TIFFWriteDirectory(TIFF* tif)"
.br
.B "int TIFFRewriteDirectory(TIFF* tif)"
.br
.B "int TIFFCheckpointDirectory(TIFF* tif)"
.SH DESCRIPTION
.IR TIFFWriteDirectory 
will write the contents of the current directory to the file and setup
to create a new subfile in the same file.
Applications only need to call
.IR TIFFWriteDirectory
when writing multiple subfiles to a single
.SM TIFF
file.
.IR TIFFWriteDirectory
is automatically called by
.IR TIFFClose
and
.IR TIFFFlush
to write a modified directory if the file is open for writing.
.PP
The 
.IR TIFFRewriteDirectory
function operates similarly to 
.IR TIFFWriteDirectory,
but can be called with directories previously read or written that already
have an established location in the file.  It will rewrite the directory,
but instead of place it at it's old location (as 
.IR TIFFWriteDirectory
would) it will place them at the end of the file, correcting the pointer from
the preceeding directory or file header to point to it's new location.  This
is particularly important in cases where the size of the directory and
pointed to data has grown, so it won't fit in the space available at the
old location.
.PP
The
.IR TIFFCheckpointDirectory
writes the current state of the tiff directory into the file to make what
is currently in the file readable.  Unlike
.IR TIFFWriteDirectory,
.IR TIFFCheckpointDirectory
does not free up the directory data structures in memory, so they can be
updated (as strips/tiles are written) and written again.  Reading such
a partial file you will at worst get a tiff read error for the first
strip/tile encountered that is incomplete, but you will at least get
all the valid data in the file before that.  When the file is complete,
just use
.IR TIFFWriteDirectory
as usual to finish it off cleanly.
.SH "RETURN VALUES"
1 is returned when the contents are successfully
written to the file.
Otherwise, 0 is returned if an error was encountered when writing
the directory contents.
.SH DIAGNOSTICS
All error messages are directed to the
.IR TIFFError (3T)
routine.
.PP
.BR "Error post-encoding before directory write" .
Before writing the contents of the current directory, any pending
data are flushed.
This message indicates that an error occurred while doing this.
.PP
.BR "Error flushing data before directory write" .
Before writing the contents of the current directory, any pending
data are flushed.
This message indicates that an error occurred while doing this.
.PP
.BR "Cannot write directory, out of space" .
There was not enough space to allocate a temporary area for
the directory that was to be written.
.PP
.BR "Error writing directory count" .
A write error occurred when writing the count of fields in the directory.
.PP
.BR "Error writing directory contents" .
A write error occurred when writing the directory fields.
.PP
.BR "Error writing directory link" .
A write error occurred when writing the link to the next directory.
.PP
\fBError writing data for field "%s"\fP.
A write error occurred when writing indirect data for the specified field.
.PP
.BR "Error writing TIFF header" .
A write error occurred when re-writing header at the front of the file.
.PP
.BR "Error fetching directory count" .
A read error occurred when fetching the directory count field for
a previous directory.
This can occur when setting up a link to the directory that is being
written.
.PP
.BR "Error fetching directory link" .
A read error occurred when fetching the directory link field for
a previous directory.
This can occur when setting up a link to the directory that is being
written.
.SH "SEE ALSO"
.IR libtiff (3T),
.IR TIFFOpen (3T),
.IR TIFFError (3T),
.IR TIFFReadDirectory (3T),
.IR TIFFSetDirectory (3T)