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1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 | <html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>lqr_rwindow_read</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2"><link rel="home" href="index.html" title="The Liquid Rescale library Manual"><link rel="up" href="ref-energy.html" title="Energy"><link rel="prev" href="ref-lqr-carver-get-energy.html" title="lqr_carver_get_energy"><link rel="next" href="ref-lqr-rwindow-get-read-t.html" title="lqr_rwindow_get_read_t"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center"><code class="function">lqr_rwindow_read</code></th></tr><tr><td width="20%" align="left"><a accesskey="p" href="ref-lqr-carver-get-energy.html">Prev</a> </td><th width="60%" align="center">Energy</th><td width="20%" align="right"> <a accesskey="n" href="ref-lqr-rwindow-get-read-t.html">Next</a></td></tr></table><hr></div><div class="refentry" title="lqr_rwindow_read"><a name="ref-lqr-rwindow-read"></a><div class="titlepage"></div><div class="refnamediv"><h2>Name</h2><p>lqr_rwindow_read — read the content of a <code class="classname">LqrReadingWindow</code> object</p></div><div class="refsynopsisdiv" title="Synopsis"><h2>Synopsis</h2><div class="funcsynopsis"><pre class="funcsynopsisinfo">#include <lqr.h></pre><table border="0" summary="Function synopsis" cellspacing="0" cellpadding="0" class="funcprototype-table"><tr><td><code class="funcdef">gfloat <b class="fsfunc">lqr_rwindow_read</b>(</code></td><td>LqrReadingWindow* <var class="pdparam">rwindow</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">x</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">y</var>, </td></tr><tr><td> </td><td>gint <var class="pdparam">channel</var><code>)</code>;</td></tr></table><div class="funcprototype-spacer"> </div></div></div><div class="refsect1" title="Description"><a name="idp33825840"></a><h2>Description</h2><p>
The function <code class="function">lqr_rwindow_read</code> returns the content of the reading window
<em class="parameter"><code>rwindow</code></em> at point <em class="parameter"><code>x</code></em>, <em class="parameter"><code>y</code></em> and at channel
<em class="parameter"><code>channel</code></em>.
</p><p>
The coordinates <em class="parameter"><code>x</code></em> and <em class="parameter"><code>y</code></em> are relative to the <em class="parameter"><code>rwindow</code></em>
centre, and they both can range from <code class="literal">-radius</code> to <code class="literal">radius</code>
(extremes included), where <code class="literal">radius</code> can be obtained with the function
<a class="xref" href="ref-lqr-rwindow-get-radius.html" title="lqr_rwindow_get_radius"><span class="refentrytitle"><code class="function">lqr_rwindow_get_radius</code></span>(3)</a>.
</p><p>
The function returns <code class="literal">0</code> when the coordinates are out of range, either because
they are beyond the <em class="parameter"><code>rwindow</code></em> radius or because they are outside the image
boundary.
</p><p>
The <em class="parameter"><code>channel</code></em> parameter specifies which channel to read out; depending on
the <em class="parameter"><code>rwindow</code></em> reader type, the range and meaning of this parameter changes:
for the cases <code class="literal">LQR_ER_BRIGHTNESS</code> and <code class="literal">LQR_ER_LUMA</code> it must be
<code class="literal">0</code>, because the readout consists of a single channel, for
<code class="literal">LQR_ER_RGBA</code> it must be between <code class="literal">0</code> and <code class="literal">3</code>
(and then the readout will contain the RGBA information), while for
<code class="literal">LQR_ER_CUSTOM</code> it must be one of the original image channels.
</p></div><div class="refsect1" title="See also"><a name="idp33845264"></a><h2>See also</h2><p>
<span class="simplelist"><a class="xref" href="ref-lqr-carver-set-energy-function.html" title="lqr_carver_set_energy_function"><span class="refentrytitle"><code class="function">lqr_carver_set_energy_function</code></span>(3)</a>, <a class="xref" href="ref-lqr-rwindow-get-read-t.html" title="lqr_rwindow_get_read_t"><span class="refentrytitle"><code class="function">lqr_rwindow_get_read_t</code></span>(3)</a>, <a class="xref" href="ref-lqr-rwindow-get-radius.html" title="lqr_rwindow_get_radius"><span class="refentrytitle"><code class="function">lqr_rwindow_get_radius</code></span>(3)</a>, <a class="xref" href="ref-lqr-rwindow-get-channels.html" title="lqr_rwindow_get_channels"><span class="refentrytitle"><code class="function">lqr_rwindow_get_channels</code></span>(3)</a></span>
</p></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ref-lqr-carver-get-energy.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="ref-energy.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="ref-lqr-rwindow-get-read-t.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><code class="function">lqr_carver_get_energy</code> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <code class="function">lqr_rwindow_get_read_t</code></td></tr></table></div></body></html>
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