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<section id="tiffreadscanline">
<h1>TIFFReadScanline<a class="headerlink" href="#tiffreadscanline" title="Permalink to this heading">¶</a></h1>
<section id="synopsis">
<h2>Synopsis<a class="headerlink" href="#synopsis" title="Permalink to this heading">¶</a></h2>
<div class="highlight-c notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf"><tiffio.h></span>
</pre></div>
</div>
<dl class="c function">
<dt class="sig sig-object c" id="c.TIFFReadScanline">
<span class="kt"><span class="pre">int</span></span><span class="w"> </span><span class="sig-name descname"><span class="n"><span class="pre">TIFFReadScanline</span></span></span><span class="sig-paren">(</span><span class="n"><span class="pre">TIFF</span></span><span class="w"> </span><span class="p"><span class="pre">*</span></span><span class="n"><span class="pre">tif</span></span>, <span class="n"><span class="pre">tdata_t</span></span><span class="w"> </span><span class="n"><span class="pre">buf</span></span>, <span class="n"><span class="pre">uint32_t</span></span><span class="w"> </span><span class="n"><span class="pre">row</span></span>, <span class="n"><span class="pre">tsample_t</span></span><span class="w"> </span><span class="n"><span class="pre">sample</span></span><span class="sig-paren">)</span><a class="headerlink" href="#c.TIFFReadScanline" title="Permalink to this definition">¶</a><br /></dt>
<dd></dd></dl>
</section>
<section id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this heading">¶</a></h2>
<p>Read the data for the specified row into the (user supplied) data buffer
<em>buf</em>. 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 <a class="reference internal" href="TIFFsize.html#c.TIFFScanlineSize" title="TIFFScanlineSize"><code class="xref c c-func docutils literal notranslate"><span class="pre">TIFFScanlineSize()</span></code></a> to find out the size
(in bytes) of a scanline buffer.
The <em>row</em> parameter is always used by <a class="reference internal" href="#c.TIFFReadScanline" title="TIFFReadScanline"><code class="xref c c-func docutils literal notranslate"><span class="pre">TIFFReadScanline()</span></code></a>; the
<em>sample</em> parameter is used only if data are organized in separate planes
(<code class="docutils literal notranslate"><span class="pre">PlanarConfiguration</span></code> = 2).</p>
</section>
<section id="notes">
<h2>Notes<a class="headerlink" href="#notes" title="Permalink to this heading">¶</a></h2>
<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 <code class="docutils literal notranslate"><span class="pre">FillOrder</span></code> 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>
<p>In C++ the <em>sample</em> parameter defaults to 0.</p>
</section>
<section id="return-values">
<h2>Return values<a class="headerlink" href="#return-values" title="Permalink to this heading">¶</a></h2>
<p><a class="reference internal" href="#c.TIFFReadScanline" title="TIFFReadScanline"><code class="xref c c-func docutils literal notranslate"><span class="pre">TIFFReadScanline()</span></code></a> returns -1 if it detects an error; otherwise 1 is
returned.</p>
</section>
<section id="diagnostics">
<h2>Diagnostics<a class="headerlink" href="#diagnostics" title="Permalink to this heading">¶</a></h2>
<p>All error messages are directed to the <a class="reference internal" href="TIFFError.html#c.TIFFErrorExtR" title="TIFFErrorExtR"><code class="xref c c-func docutils literal notranslate"><span class="pre">TIFFErrorExtR()</span></code></a> routine.</p>
<p><code class="docutils literal notranslate"><span class="pre">"Compression</span> <span class="pre">algorithm</span> <span class="pre">does</span> <span class="pre">not</span> <span class="pre">support</span> <span class="pre">random</span> <span class="pre">access"</span></code>:</p>
<blockquote>
<div><p>Data was requested in a non-sequential order from a file that uses a
compression algorithm and that has <code class="docutils literal notranslate"><span class="pre">RowsPerStrip</span></code> 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>
</div></blockquote>
</section>
<section id="bugs">
<h2>Bugs<a class="headerlink" href="#bugs" title="Permalink to this heading">¶</a></h2>
<p>Reading subsampled YCbCR data does not work correctly because, for
<code class="docutils literal notranslate"><span class="pre">PlanarConfiguration</span></code> = 2, the size of a scanline is not calculated on a
per-sample basis, and for <code class="docutils literal notranslate"><span class="pre">PlanarConfiguration</span></code> = 1, the library does not
unpack the block-interleaved samples; use the strip- and
tile-based interfaces to read these formats.</p>
</section>
<section id="see-also">
<h2>See also<a class="headerlink" href="#see-also" title="Permalink to this heading">¶</a></h2>
<p><a class="reference internal" href="TIFFOpen.html"><span class="doc">TIFFOpen</span></a> (3tiff),
<a class="reference internal" href="TIFFReadEncodedStrip.html"><span class="doc">TIFFReadEncodedStrip</span></a> (3tiff),
<a class="reference internal" href="TIFFReadRawStrip.html"><span class="doc">TIFFReadRawStrip</span></a> (3tiff),
<a class="reference internal" href="libtiff.html"><span class="doc">libtiff</span></a> (3tiff)</p>
</section>
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<h3><a href="../index.html">Table of Contents</a></h3>
<ul>
<li><a class="reference internal" href="#">TIFFReadScanline</a><ul>
<li><a class="reference internal" href="#synopsis">Synopsis</a></li>
<li><a class="reference internal" href="#description">Description</a></li>
<li><a class="reference internal" href="#notes">Notes</a></li>
<li><a class="reference internal" href="#return-values">Return values</a></li>
<li><a class="reference internal" href="#diagnostics">Diagnostics</a></li>
<li><a class="reference internal" href="#bugs">Bugs</a></li>
<li><a class="reference internal" href="#see-also">See also</a></li>
</ul>
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