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- <title>TIFFReadScanline</title>
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- <h1 align=center>TIFFReadScanline</h1>
- <a href="#NAME">NAME</a><br>
- <a href="#SYNOPSIS">SYNOPSIS</a><br>
- <a href="#DESCRIPTION">DESCRIPTION</a><br>
- <a href="#NOTES">NOTES</a><br>
- <a href="#RETURN VALUES">RETURN VALUES</a><br>
- <a href="#DIAGNOSTICS">DIAGNOSTICS</a><br>
- <a href="#BUGS">BUGS</a><br>
- <a href="#SEE ALSO">SEE ALSO</a><br>
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- <a name="NAME"></a>
- <h2>NAME</h2>
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- <p>TIFFReadScanline − read and decode a scanline of
- data from an open <small>TIFF</small> file</p>
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- <a name="SYNOPSIS"></a>
- <h2>SYNOPSIS</h2>
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- <p><b>#include <tiffio.h></b></p>
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- <p><b>int TIFFReadScanline(TIFF *</b><i>tif</i><b>,
- tdata_t</b> <i>buf</i><b>, uint32_t</b> <i>row</i><b>,
- tsample_t</b> <i>sample</i><b>)</b></p>
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- <a name="DESCRIPTION"></a>
- <h2>DESCRIPTION</h2>
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- <p>Read the data for the specified row into the (user
- supplied) data buffer <i>buf</i>. The data are returned
- decompressed and, 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 <i>TIFFScanlineSize</i>
- to find out the size (in bytes) of a scanline buffer. The
- <i>row</i> parameter is always used by
- <i>TIFFReadScanline</i>; the <i>sample</i> parameter is used
- only if data are organized in separate planes
- (<i>PlanarConfiguration</i>=2).</p>
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- <a name="NOTES"></a>
- <h2>NOTES</h2>
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- <p>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
- done if the <i>FillOrder</i> tag is opposite to the native
- machine bit order. 16- and 32-bit samples are automatically
- byte-swapped if the file was written with a byte order
- opposite to the native machine byte order,</p>
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- <p>In C++ the <i>sample</i> parameter defaults to 0.</p>
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- </table>
- <a name="RETURN VALUES"></a>
- <h2>RETURN VALUES</h2>
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- <p><i>TIFFReadScanline</i> returns −1 if it detects an
- error; otherwise 1 is returned.</p>
- </td>
- </table>
- <a name="DIAGNOSTICS"></a>
- <h2>DIAGNOSTICS</h2>
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- <p>All error messages are directed to the
- <i>TIFFError</i>(3TIFF) routine.</p>
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- <p><b>Compression algorithm does not support random
- access</b>. Data was requested in a non-sequential order
- from a file that uses a compression algorithm and that has
- <i>RowsPerStrip</i> 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.</p>
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- <a name="BUGS"></a>
- <h2>BUGS</h2>
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- <p>Reading subsampled YCbCR data does not work correctly
- because, for <i>PlanarConfiguration</i>=2 the size of a
- scanline is not calculated on a per-sample basis, and for
- <i>PlanarConfiguration</i>=1 the library does not unpack the
- block-interleaved samples; use the strip- and tile-based
- interfaces to read these formats.</p>
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- </table>
- <a name="SEE ALSO"></a>
- <h2>SEE ALSO</h2>
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- <p><b>TIFFOpen</b>(3TIFF),
- <b>TIFFReadEncodedStrip</b>(3TIFF),
- <b>TIFFReadRawStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p>
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- <p>Libtiff library home page:
- <b>http://www.simplesystems.org/libtiff/</b></p>
- </td>
- </table>
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