NAME¶
TIFFWriteScanline - write a scanline to an open
TIFF file
SYNOPSIS¶
#include <tiffio.h>
int TIFFWriteScanline(TIFF *tif, tdata_t buf,
uint32 row, tsample_t 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(3TIFF) 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(3TIFF) 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
TIFFSetField(3TIFF).
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(3TIFF)
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(3TIFF) 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¶
TIFFOpen(3TIFF),
TIFFWriteEncodedStrip(3TIFF),
TIFFWriteRawStrip(3TIFF),
libtiff(3TIFF)
Libtiff library home page:
http://www.remotesensing.org/libtiff/