TIFFWriteScanline(3T)                Image Format Library C++ Reference Manual



NAME
     TIFFWriteScanline - write a scanline to an open TIFF file

SYNOPSIS
     #include <tiffio.h>
     int TIFFWriteScanline(TIFF* tif, tdatat buf, uint32 row, tsamplet
     sample)

DESCRIPTION
     Write data to a file at the specified row.  The sample parameter is used
     only if data are organized in separate planes (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 TIFF directory (see
     further below).  If the current scanline is past the end of the current
     subfile, the ImageLength field is automatically increased to include the
     scanline (except for PlanarConfiguration=2, where the ImageLength cannot
     be changed once the first data are written).  If the ImageLength is
     increased, the StripOffsets and StripByteCounts fields are similarly
     enlarged to reflect data written past the previous end of image.

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

     In C++ the sample parameter defaults to 0.

     Once data are written to a file for the current directory, the values of
     certain tags may not be altered; see TIFFSetField(3T) for more
     information.

     It is not possible to write scanlines to a file that uses a tiled
     organization.  The routine TIFFIsTiled can be used to determine if the
     file is organized as tiles or strips.

RETURN VALUES
     TIFFWriteScanline returns -1 if it immediately detects an error and 1 for
     a successful write.

DIAGNOSTICS
     All error messages are directed to the TIFFError(3T) routine.

     %s: File not open for writing .  The file was opened for reading, not
     writing.

     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 TileWidth and TileLength tags have been set with



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TIFFWriteScanline(3T)                Image Format Library C++ Reference Manual



     TIFFSetField(3T).

     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 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 RowsPerStrip should be set to one.

     %s: Must set "ImageWidth" before writing data.  The image's width has not
     be set before the first write.  See TIFFSetField(3T) for information on
     how to do this.

     %s: Must set "PlanarConfiguration" before writing data.  The organization
     of data has not be defined before the first write.  See TIFFSetField(3T)
     for information on how to do this.

     Can not change "ImageLength" when using separate planes.  Separate image
     planes are being used (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 (PlanarConfiguration=1).

     %d: Sample out of range, max %d.  The sample parameter was greater than
     the value of the SamplesPerPixel tag.

     %s: No space for strip arrays .  There was not enough space for the
     arrays that hold strip offsets and byte counts.

BUGS
     Writing subsampled YCbCR data does not work correctly because, for
     PlanarConfiguration=2 the size of a scanline is not calculated on a per-
     sample basis, and for PlanarConfiguration=1 the library does not pack the
     block-interleaved samples.

SEE ALSO
     libtiff(3T), TIFFOpen(3T), TIFFWriteEncodedStrip(3T),
     TIFFWriteRawStrip(3T)
















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