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<div class="title">hash.h File Reference</div> </div>
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<p>Provides functions and structures for producing likely-to-be-unique hash values for images.
<a href="#details">More...</a></p>
<p><a href="hash_8h_source.html">Go to the source code of this file.</a></p>
<table class="memberdecls">
<tr class="heading"><td colspan="2"><h2 class="groupheader"><a name="func-members"></a>
Functions</h2></td></tr>
<tr class="memitem:ae8243122fb0b158a22058f9dbd2bbc0c"><td class="memItemLeft" align="right" valign="top">unsigned int </td><td class="memItemRight" valign="bottom"><a class="el" href="hash_8h.html#ae8243122fb0b158a22058f9dbd2bbc0c">guac_hash_surface</a> (cairo_surface_t *surface)</td></tr>
<tr class="memdesc:ae8243122fb0b158a22058f9dbd2bbc0c"><td class="mdescLeft"> </td><td class="mdescRight">Produces a 24-bit hash value from all pixels of the given surface. <a href="#ae8243122fb0b158a22058f9dbd2bbc0c">More...</a><br/></td></tr>
<tr class="separator:ae8243122fb0b158a22058f9dbd2bbc0c"><td class="memSeparator" colspan="2"> </td></tr>
<tr class="memitem:a377c701a920281a98cbcf0842124aaac"><td class="memItemLeft" align="right" valign="top">int </td><td class="memItemRight" valign="bottom"><a class="el" href="hash_8h.html#a377c701a920281a98cbcf0842124aaac">guac_surface_cmp</a> (cairo_surface_t *a, cairo_surface_t *b)</td></tr>
<tr class="memdesc:a377c701a920281a98cbcf0842124aaac"><td class="mdescLeft"> </td><td class="mdescRight">Given two Cairo surfaces, returns zero if the data contained within each is identical, and a positive or negative value if the value of the first is found to be lexically greater or less than the second respectively. <a href="#a377c701a920281a98cbcf0842124aaac">More...</a><br/></td></tr>
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<a name="details" id="details"></a><h2 class="groupheader">Detailed Description</h2>
<div class="textblock"><p>Provides functions and structures for producing likely-to-be-unique hash values for images. </p>
</div><h2 class="groupheader">Function Documentation</h2>
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<td class="memname">unsigned int guac_hash_surface </td>
<td>(</td>
<td class="paramtype">cairo_surface_t * </td>
<td class="paramname"><em>surface</em></td><td>)</td>
<td></td>
</tr>
</table>
</div><div class="memdoc">
<p>Produces a 24-bit hash value from all pixels of the given surface. </p>
<p>The surface provided must be RGB or ARGB with each pixel stored in 32 bits. The hashing algorithm used is a variant of the cyclic polynomial rolling hash.</p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">surface</td><td>The Cairo surface to hash. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>An arbitrary 24-bit unsigned integer value intended to be well distributed across different images. </dd></dl>
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<td class="memname">int guac_surface_cmp </td>
<td>(</td>
<td class="paramtype">cairo_surface_t * </td>
<td class="paramname"><em>a</em>, </td>
</tr>
<tr>
<td class="paramkey"></td>
<td></td>
<td class="paramtype">cairo_surface_t * </td>
<td class="paramname"><em>b</em> </td>
</tr>
<tr>
<td></td>
<td>)</td>
<td></td><td></td>
</tr>
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</div><div class="memdoc">
<p>Given two Cairo surfaces, returns zero if the data contained within each is identical, and a positive or negative value if the value of the first is found to be lexically greater or less than the second respectively. </p>
<dl class="params"><dt>Parameters</dt><dd>
<table class="params">
<tr><td class="paramname">a</td><td>The first Cairo surface to compare. </td></tr>
<tr><td class="paramname">b</td><td>The Cairo surface to compare the first surface against. </td></tr>
</table>
</dd>
</dl>
<dl class="section return"><dt>Returns</dt><dd>Zero if the data contained within each is identical, and a positive or negative value if the value of the first is found to be lexically greater or less than the second respectively. </dd></dl>
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