.\" $Id: TIFFWriteScanline.3tiff,v 1.2 2005-11-02 11:07:18 dron Exp $

.\"

.\" Copyright (c) 1988-1997 Sam Leffler

.\" Copyright (c) 1991-1997 Silicon Graphics, Inc.

.\"

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.\" its documentation for any purpose is hereby granted without fee, provided

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.\" IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR

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.\" OF THIS SOFTWARE.

.\"

.if n .po 0

.TH TIFFWriteScanline 3TIFF "December 16, 1991" "libtiff"

.SH NAME

TIFFWriteScanline \- write a scanline to an open

.SM TIFF

file

.SH SYNOPSIS

.B "#include <tiffio.h>"</tiffio.h>

.sp

.BI "int TIFFWriteScanline(TIFF *" tif ", tdata_t " buf ", uint32 " row ", tsample_t " sample ")"

.SH DESCRIPTION

Write data to a file at the specified row. The

.I sample

parameter is used only if data are organized in separate planes (\c

.IR PlanarConfiguration =2).

The data are assumed to be uncompressed and in the native bit- and byte-order

of the host machine. The data written to the file is compressed according to

the compression scheme of the current

.SM TIFF

directory (see further below). If the current scanline is past the end of the

current subfile, the

.I ImageLength

field is automatically increased to include the scanline (except

for

.IR PlanarConfiguration =2,

where the

.I ImageLength

cannot be changed once the first data are written). If the

.I ImageLength

is increased, the

.I StripOffsets

and

.I StripByteCounts

fields are similarly enlarged to reflect data written past the previous end of

image.

.SH NOTES

The library writes encoded data using the native machine byte order. Correctly

implemented

.SM TIFF

readers are expected to do any necessary byte-swapping to correctly process

image data with BitsPerSample greater than 8. The library attempts to hide

bit-ordering differences between the image and the native machine by

converting data from the native machine order.

.PP

In C++ the

.I sample

parameter defaults to 0.

.PP

Once data are written to a file for the current directory, the values of

certain tags may not be altered; see

.IR TIFFSetField (3TIFF)

for more information.

.PP

It is not possible to write scanlines to a file that uses a tiled

organization.  The routine

.IR TIFFIsTiled

can be used to determine if the file is organized as tiles or strips.

.SH "RETURN VALUES"

.IR TIFFWriteScanline

returns \-1 if it immediately detects an error and 1 for a successful write.

.SH DIAGNOSTICS

All error messages are directed to the

.IR TIFFError (3TIFF)

routine.

.PP

.BR "%s: File not open for writing .

The file was opened for reading, not writing.

.PP

.BR "Can not write scanlines to a tiled image" .

An attempt was made to write a scanline to a tiled image. The image is assumed

to be organized in tiles because the

.I TileWidth

and

.I TileLength

tags have been set with

.IR TIFFSetField (3TIFF).

.PP

.BR "Compression algorithm does not support random access" .

Data was written in a non-sequential order to a file that uses a compression

algorithm and that has

.I RowsPerStrip

greater than one. That is, data in the image is to be stored in a compressed

form, and with multiple rows packed into a strip. In this case, the library

does not support random access to the data. The data should either be written

as entire strips, sequentially by rows, or the value of

.I RowsPerStrip

should be set to one.

.PP

\fB%s: Must set "ImageWidth" before writing data\fP.

The image's width has not be set before the first write.

See

.BR TIFFSetField (3TIFF)

for information on how to do this.

.PP

\fB%s: Must set "PlanarConfiguration" before writing data\fP.

The organization of data has not be defined before the first write.

See

.BR TIFFSetField (3TIFF)

for information on how to do this.

.PP

\fBCan not change "ImageLength" when using separate planes\fP. Separate image

planes are being used (\c

.IR PlanarConfiguration =2),

but the number of rows has not been specified before the first write. The

library supports the dynamic growth of an image only when data are organized

in a contiguous manner (\c

.IR PlanarConfiguration =1).

.PP

.BR "%d: Sample out of range, max %d" .

The

.I sample

parameter was greater than the value of the SamplesPerPixel tag.

.PP

.BR "%s: No space for strip arrays .

There was not enough space for the arrays that hold strip offsets and byte

counts.

.SH BUGS

Writing subsampled YCbCR data does not work correctly because, for 

.IR PlanarConfiguration =2

the size of a scanline is not calculated on a per-sample basis, and for

.IR PlanarConfiguration =1

the library does not pack the block-interleaved samples.

.SH "SEE ALSO"

.BR TIFFOpen (3TIFF),

.BR TIFFWriteEncodedStrip (3TIFF),

.BR TIFFWriteRawStrip (3TIFF),

.BR libtiff (3TIFF)

.PP

Libtiff library home page:

.BR http://www.remotesensing.org/libtiff/