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7<title>TIFFReadScanline</title>
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10
11<h1 align=center>TIFFReadScanline</h1>
12<a href="#NAME">NAME</a><br>
13<a href="#SYNOPSIS">SYNOPSIS</a><br>
14<a href="#DESCRIPTION">DESCRIPTION</a><br>
15<a href="#NOTES">NOTES</a><br>
16<a href="#RETURN VALUES">RETURN VALUES</a><br>
17<a href="#DIAGNOSTICS">DIAGNOSTICS</a><br>
18<a href="#BUGS">BUGS</a><br>
19<a href="#SEE ALSO">SEE ALSO</a><br>
20
21<hr>
22<a name="NAME"></a>
23<h2>NAME</h2>
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30<p>TIFFReadScanline &minus; read and decode a scanline of
31data from an open <small>TIFF</small> file</p>
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33</table>
34<a name="SYNOPSIS"></a>
35<h2>SYNOPSIS</h2>
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42<p><b>#include &lt;tiffio.h&gt;</b></p>
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44<p><b>int TIFFReadScanline(TIFF *</b><i>tif</i><b>,
45tdata_t</b> <i>buf</i><b>, uint32</b> <i>row</i><b>,
46tsample_t</b> <i>sample</i><b>)</b></p>
47</td>
48</table>
49<a name="DESCRIPTION"></a>
50<h2>DESCRIPTION</h2>
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57<p>Read the data for the specified row into the (user
58supplied) data buffer <i>buf</i>. The data are returned
59decompressed and, in the native byte- and bit-ordering, but
60are otherwise packed (see further below). The buffer must be
61large enough to hold an entire scanline of data.
62Applications should call the routine <i>TIFFScanlineSize</i>
63to find out the size (in bytes) of a scanline buffer. The
64<i>row</i> parameter is always used by
65<i>TIFFReadScanline</i>; the <i>sample</i> parameter is used
66only if data are organized in separate planes
67(<i>PlanarConfiguration</i>=2).</p>
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70<a name="NOTES"></a>
71<h2>NOTES</h2>
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78<p>The library attempts to hide bit- and byte-ordering
79differences between the image and the native machine by
80converting data to the native machine order. Bit reversal is
81done if the <i>FillOrder</i> tag is opposite to the native
82machine bit order. 16- and 32-bit samples are automatically
83byte-swapped if the file was written with a byte order
84opposite to the native machine byte order,</p>
85<!-- INDENTATION -->
86<p>In C++ the <i>sample</i> parameter defaults to 0.</p>
87</td>
88</table>
89<a name="RETURN VALUES"></a>
90<h2>RETURN VALUES</h2>
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97<p><i>TIFFReadScanline</i> returns &minus;1 if it detects an
98error; otherwise 1 is returned.</p>
99</td>
100</table>
101<a name="DIAGNOSTICS"></a>
102<h2>DIAGNOSTICS</h2>
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109<p>All error messages are directed to the
110<i>TIFFError</i>(3TIFF) routine.</p>
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112<p><b>Compression algorithm does not support random
113access</b>. Data was requested in a non-sequential order
114from a file that uses a compression algorithm and that has
115<i>RowsPerStrip</i> greater than one. That is, data in the
116image is stored in a compressed form, and with multiple rows
117packed into a strip. In this case, the library does not
118support random access to the data. The data should either be
119accessed sequentially, or the file should be converted so
120that each strip is made up of one row of data.</p>
121</td>
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123<a name="BUGS"></a>
124<h2>BUGS</h2>
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131<p>Reading subsampled YCbCR data does not work correctly
132because, for <i>PlanarConfiguration</i>=2 the size of a
133scanline is not calculated on a per-sample basis, and for
134<i>PlanarConfiguration</i>=1 the library does not unpack the
135block-interleaved samples; use the strip- and tile-based
136interfaces to read these formats.</p>
137</td>
138</table>
139<a name="SEE ALSO"></a>
140<h2>SEE ALSO</h2>
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147<p><b>TIFFOpen</b>(3TIFF),
148<b>TIFFReadEncodedStrip</b>(3TIFF),
149<b>TIFFReadRawStrip</b>(3TIFF), <b>libtiff</b>(3TIFF)</p>
150<!-- INDENTATION -->
151<p>Libtiff library home page:
152<b>http://www.remotesensing.org/libtiff/</b></p>
153</td>
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