TIFFReadScanline(3T)      UNIX System V(May 9, 1990)       TIFFReadScanline(3T)


NAME
      TIFFReadScanline - read and decode a scanline from an open TIFF file

SYNOPSIS
      #include <tiffio.h>
      int TIFFReadScanline(TIFF* tif, u_char* buf, u_int row, u_int sample)

DESCRIPTION
      Return the data for the specified row in the data buffer buf.  The data
      are returned decompressed and, typically, in the native byte- and bit-
      ordering, but are otherwise packed (see further below).  The buffer must
      be large enough to hold an entire scanline of data.  Applications should
      call the routine TIFFScanlineSize() to find out the size (in bytes) of a
      scanline buffer.  The row parameter is always used by TIFFReadScanline();
      the sample parameter is used only if data are organized in separate
      planes (PlanarConfiguration=2).  TIFFReadScanline returns -1 if it
      detects an error; otherwise 1 is returned.

NOTES
      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 always done if the FillOrder tag is opposite to
      the native machine bit order.  Byte swapping of 16- and 32-bit samples is
      automatically done when Compression=1 (``no compression''), but otherwise
      is left to the decompression algorithms (which should generate
      decompressed data in the native byte ordering of the machine).

      In C++ the sample parameter defaults to 0.

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

      Compression algorithm does not support random access.  Data was requested
      in a non-sequential order from a file that uses a compression algorithm
      and that has RowsPerStrip greater than one.  That is, data in the image
      is 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 accessed sequentially, or the file
      should be converted so that each strip is made up of one row of data.

SEE ALSO
      intro(3T), TIFFOpen(3T), TIFFReadEncodedStrip(3T), TIFFReadRawStrip(3T)












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