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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
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<title>VIPS Reference Manual: VipsThreadState</title>
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<a href="#" class="shortcut">Top</a><span id="nav_description"> <span class="dim">|</span> 
                  <a href="#VipsThreadState.description" class="shortcut">Description</a></span><span id="nav_hierarchy"> <span class="dim">|</span> 
                  <a href="#VipsThreadState.object-hierarchy" class="shortcut">Object Hierarchy</a></span>
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<div class="refentry">
<a name="VipsThreadState"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="VipsThreadState.top_of_page"></a>VipsThreadState</span></h2>
<p>VipsThreadState — pools of worker threads</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="VipsThreadState.stability-level"></a><h2>Stability Level</h2>
Stable, unless otherwise indicated
</div>
<div class="refsect1">
<a name="VipsThreadState.functions"></a><h2>Functions</h2>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="functions_return">
<col class="functions_name">
</colgroup>
<tbody>
<tr>
<td class="function_type">
<span class="returnvalue">void</span> *
</td>
<td class="function_name">
<a class="link" href="VipsThreadState.html#vips-thread-state-set" title="vips_thread_state_set ()">vips_thread_state_set</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="VipsThreadState.html" title="VipsThreadState"><span class="returnvalue">VipsThreadState</span></a> *
</td>
<td class="function_name">
<a class="link" href="VipsThreadState.html#vips-thread-state-new" title="vips_thread_state_new ()">vips_thread_state_new</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="VipsThreadState.html" title="VipsThreadState"><span class="returnvalue">VipsThreadState</span></a> *
</td>
<td class="function_name">
<span class="c_punctuation">(</span><a class="link" href="VipsThreadState.html#VipsThreadStartFn" title="VipsThreadStartFn ()">*VipsThreadStartFn</a><span class="c_punctuation">)</span> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<span class="c_punctuation">(</span><a class="link" href="VipsThreadState.html#VipsThreadpoolAllocateFn" title="VipsThreadpoolAllocateFn ()">*VipsThreadpoolAllocateFn</a><span class="c_punctuation">)</span> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<span class="c_punctuation">(</span><a class="link" href="VipsThreadState.html#VipsThreadpoolWorkFn" title="VipsThreadpoolWorkFn ()">*VipsThreadpoolWorkFn</a><span class="c_punctuation">)</span> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<span class="c_punctuation">(</span><a class="link" href="VipsThreadState.html#VipsThreadpoolProgressFn" title="VipsThreadpoolProgressFn ()">*VipsThreadpoolProgressFn</a><span class="c_punctuation">)</span> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsThreadState.html#vips-threadpool-run" title="vips_threadpool_run ()">vips_threadpool_run</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsThreadState.html#vips-get-tile-size" title="vips_get_tile_size ()">vips_get_tile_size</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">void</span>
</td>
<td class="function_name">
<a class="link" href="VipsThreadState.html#vips-concurrency-set" title="vips_concurrency_set ()">vips_concurrency_set</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">int</span>
</td>
<td class="function_name">
<a class="link" href="VipsThreadState.html#vips-concurrency-get" title="vips_concurrency_get ()">vips_concurrency_get</a> <span class="c_punctuation">()</span>
</td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="VipsThreadState.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="screen">    <a href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject">GObject</a>
    <span class="lineart">╰──</span> <a class="link" href="VipsObject.html" title="VipsObject">VipsObject</a>
        <span class="lineart">╰──</span> VipsThreadState
</pre>
</div>
<div class="refsect1">
<a name="VipsThreadState.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include &lt;vips/vips.h&gt;
</pre>
</div>
<div class="refsect1">
<a name="VipsThreadState.description"></a><h2>Description</h2>
<p>vips_threadpool_run() loops a set of threads over an image. Threads take it
in turns to allocate units of work (a unit might be a tile in an image),
then run in parallel to process those units. An optional progress function
can be used to give feedback.</p>
</div>
<div class="refsect1">
<a name="VipsThreadState.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="vips-thread-state-set"></a><h3>vips_thread_state_set ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span> *
vips_thread_state_set (<em class="parameter"><code><a class="link" href="VipsObject.html" title="VipsObject"><span class="type">VipsObject</span></a> *object</code></em>,
                       <em class="parameter"><code><span class="type">void</span> *a</code></em>,
                       <em class="parameter"><code><span class="type">void</span> *b</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-thread-state-new"></a><h3>vips_thread_state_new ()</h3>
<pre class="programlisting"><a class="link" href="VipsThreadState.html" title="VipsThreadState"><span class="returnvalue">VipsThreadState</span></a> *
vips_thread_state_new (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *im</code></em>,
                       <em class="parameter"><code><span class="type">void</span> *a</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="VipsThreadStartFn"></a><h3>VipsThreadStartFn ()</h3>
<pre class="programlisting"><a class="link" href="VipsThreadState.html" title="VipsThreadState"><span class="returnvalue">VipsThreadState</span></a> *
<span class="c_punctuation">(</span>*VipsThreadStartFn<span class="c_punctuation">)</span> (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *im</code></em>,
                      <em class="parameter"><code><span class="type">void</span> *a</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="VipsThreadpoolAllocateFn"></a><h3>VipsThreadpoolAllocateFn ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
<span class="c_punctuation">(</span>*VipsThreadpoolAllocateFn<span class="c_punctuation">)</span> (<em class="parameter"><code><a class="link" href="VipsThreadState.html" title="VipsThreadState"><span class="type">VipsThreadState</span></a> *state</code></em>,
                             <em class="parameter"><code><span class="type">void</span> *a</code></em>,
                             <em class="parameter"><code><a href="http://library.gnome.org/devel/glib/unstable/glib-Basic-Types.html#gboolean"><span class="type">gboolean</span></a> *stop</code></em>);</pre>
<p>This function is called to allocate a new work unit for the thread. It is
always single-threaded, so it can modify per-pool state (such as a
counter). </p>
<p><em class="parameter"><code>a</code></em>
, <em class="parameter"><code>b</code></em>
, <em class="parameter"><code>c</code></em>
 are the values supplied to the call to 
<a class="link" href="VipsThreadState.html#vips-threadpool-run" title="vips_threadpool_run ()"><code class="function">vips_threadpool_run()</code></a>.</p>
<p>It should set <em class="parameter"><code>stop</code></em>
 to <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#TRUE:CAPS"><code class="literal">TRUE</code></a> to indicate that no work could be allocated
because the job is done.</p>
<p>See also: <a class="link" href="VipsThreadState.html#vips-threadpool-run" title="vips_threadpool_run ()"><code class="function">vips_threadpool_run()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.13.8.5.8"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>state</p></td>
<td class="parameter_description"><p>per-thread state</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>a</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>b</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>c</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>stop</p></td>
<td class="parameter_description"><p>set this to signal end of computation</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.13.8.5.9"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="VipsThreadpoolWorkFn"></a><h3>VipsThreadpoolWorkFn ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
<span class="c_punctuation">(</span>*VipsThreadpoolWorkFn<span class="c_punctuation">)</span> (<em class="parameter"><code><a class="link" href="VipsThreadState.html" title="VipsThreadState"><span class="type">VipsThreadState</span></a> *state</code></em>,
                         <em class="parameter"><code><span class="type">void</span> *a</code></em>);</pre>
<p>This function is called to process a work unit. Many copies of this can run
at once, so it should not write to the per-pool state. It can write to
per-thread state.</p>
<p><em class="parameter"><code>a</code></em>
, <em class="parameter"><code>b</code></em>
, <em class="parameter"><code>c</code></em>
 are the values supplied to the call to 
<a class="link" href="VipsThreadState.html#vips-threadpool-run" title="vips_threadpool_run ()"><code class="function">vips_threadpool_run()</code></a>.</p>
<p>See also: <a class="link" href="VipsThreadState.html#vips-threadpool-run" title="vips_threadpool_run ()"><code class="function">vips_threadpool_run()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.13.8.6.7"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>state</p></td>
<td class="parameter_description"><p>per-thread state</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>a</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>b</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>c</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.13.8.6.8"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="VipsThreadpoolProgressFn"></a><h3>VipsThreadpoolProgressFn ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
<span class="c_punctuation">(</span>*VipsThreadpoolProgressFn<span class="c_punctuation">)</span> (<em class="parameter"><code><span class="type">void</span> *a</code></em>);</pre>
<p>This function is called by the main thread once for every work unit
processed. It can be used to give the user progress feedback.</p>
<p>See also: <a class="link" href="VipsThreadState.html#vips-threadpool-run" title="vips_threadpool_run ()"><code class="function">vips_threadpool_run()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.13.8.7.6"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>a</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>b</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>c</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.13.8.7.7"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-threadpool-run"></a><h3>vips_threadpool_run ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_threadpool_run (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *im</code></em>,
                     <em class="parameter"><code><a class="link" href="VipsThreadState.html#VipsThreadStartFn" title="VipsThreadStartFn ()"><span class="type">VipsThreadStartFn</span></a> start</code></em>,
                     <em class="parameter"><code><a class="link" href="VipsThreadState.html#VipsThreadpoolAllocateFn" title="VipsThreadpoolAllocateFn ()"><span class="type">VipsThreadpoolAllocateFn</span></a> allocate</code></em>,
                     <em class="parameter"><code><a class="link" href="VipsThreadState.html#VipsThreadpoolWorkFn" title="VipsThreadpoolWorkFn ()"><span class="type">VipsThreadpoolWorkFn</span></a> work</code></em>,
                     <em class="parameter"><code><a class="link" href="VipsThreadState.html#VipsThreadpoolProgressFn" title="VipsThreadpoolProgressFn ()"><span class="type">VipsThreadpoolProgressFn</span></a> progress</code></em>,
                     <em class="parameter"><code><span class="type">void</span> *a</code></em>);</pre>
<p>This function runs a set of threads over an image. Each thread first calls
<em class="parameter"><code>start</code></em>
 to create new per-thread state, then runs
<em class="parameter"><code>allocate</code></em>
 to set up a new work unit (perhaps the next tile in an image, for
example), then <em class="parameter"><code>work</code></em>
 to process that work unit. After each unit is
processed, <em class="parameter"><code>progress</code></em>
 is called, so that the operation can give
progress feedback. <em class="parameter"><code>progress</code></em>
 may be <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a>.</p>
<p>The object returned by <em class="parameter"><code>start</code></em>
 must be an instance of a subclass of
<a class="link" href="VipsThreadState.html" title="VipsThreadState"><span class="type">VipsThreadState</span></a>. Use this to communicate between <em class="parameter"><code>allocate</code></em>
 and <em class="parameter"><code>work</code></em>
. </p>
<p><em class="parameter"><code>allocate</code></em>
 and <em class="parameter"><code>start</code></em>
 are always single-threaded (so they can write to the 
per-pool state), whereas <em class="parameter"><code>work</code></em>
 can be executed concurrently. <em class="parameter"><code>progress</code></em>
 is 
always called by 
the main thread (ie. the thread which called <a class="link" href="VipsThreadState.html#vips-threadpool-run" title="vips_threadpool_run ()"><code class="function">vips_threadpool_run()</code></a>).</p>
<p>See also: <a class="link" href="VipsThreadState.html#vips-concurrency-set" title="vips_concurrency_set ()"><code class="function">vips_concurrency_set()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.13.8.8.8"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>im</p></td>
<td class="parameter_description"><p>image to loop over</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>start</p></td>
<td class="parameter_description"><p>allocate per-thread state</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>allocate</p></td>
<td class="parameter_description"><p>allocate a work unit</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>work</p></td>
<td class="parameter_description"><p>process a work unit</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>progress</p></td>
<td class="parameter_description"><p>give progress feedback about a work unit, or <a href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL:CAPS"><code class="literal">NULL</code></a></p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>a</p></td>
<td class="parameter_description"><p>client data</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="id-1.3.13.8.8.9"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error.</p>
<p></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-get-tile-size"></a><h3>vips_get_tile_size ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_get_tile_size (<em class="parameter"><code><a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a> *im</code></em>,
                    <em class="parameter"><code><span class="type">int</span> *tile_width</code></em>,
                    <em class="parameter"><code><span class="type">int</span> *tile_height</code></em>,
                    <em class="parameter"><code><span class="type">int</span> *nlines</code></em>);</pre>
<p>Pick a tile size and a buffer height for this image and the current
value of <a class="link" href="VipsThreadState.html#vips-concurrency-get" title="vips_concurrency_get ()"><code class="function">vips_concurrency_get()</code></a>. The buffer height 
will always be a multiple of tile_height.</p>
<div class="refsect3">
<a name="id-1.3.13.8.9.5"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody>
<tr>
<td class="parameter_name"><p>im</p></td>
<td class="parameter_description"><p>image to guess for</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>tile_width</p></td>
<td class="parameter_description"><p>return selected tile width </p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>tile_height</p></td>
<td class="parameter_description"><p>return selected tile height </p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>n_lines</p></td>
<td class="parameter_description"><p>return buffer height in scanlines</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-concurrency-set"></a><h3>vips_concurrency_set ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_concurrency_set (<em class="parameter"><code><span class="type">int</span> concurrency</code></em>);</pre>
<p>Sets the number of worker threads that vips should use when running a
<span class="type">VipsThreadPool</span>. </p>
<p>The special value 0 means "default". In this case, the number of threads is
set by the environmnt variable VIPS_CONCURRENCY, or if that is not set, the
number of threads availble on the hist machine. </p>
<p>See also: <a class="link" href="VipsThreadState.html#vips-concurrency-get" title="vips_concurrency_get ()"><code class="function">vips_concurrency_get()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.13.8.10.7"></a><h4>Parameters</h4>
<div class="informaltable"><table width="100%" border="0">
<colgroup>
<col width="150px" class="parameters_name">
<col class="parameters_description">
<col width="200px" class="parameters_annotations">
</colgroup>
<tbody><tr>
<td class="parameter_name"><p>concurrency</p></td>
<td class="parameter_description"><p>number of threads to run</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-concurrency-get"></a><h3>vips_concurrency_get ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_concurrency_get (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Returns the number of worker threads that vips should use when running a
<span class="type">VipsThreadPool</span>. </p>
<p>vips gets this values from these sources in turn:</p>
<p>If <a class="link" href="VipsThreadState.html#vips-concurrency-set" title="vips_concurrency_set ()"><code class="function">vips_concurrency_set()</code></a> has been called, this value is used. The special
value 0 means "default". You can also use the command-line argument
"--vips-concurrency" to set this value.</p>
<p>If <a class="link" href="VipsThreadState.html#vips-concurrency-set" title="vips_concurrency_set ()"><code class="function">vips_concurrency_set()</code></a> has not been called and no command-line argument
was used, vips uses the value of the environment variable VIPS_CONCURRENCY,</p>
<p>If VIPS_CONCURRENCY has not been set, vips find the number of hardware
threads that the host machine can run in parallel and uses that value. </p>
<p>The final value is clipped to the range 1 - 1024.</p>
<p>See also: <a class="link" href="VipsThreadState.html#vips-concurrency-get" title="vips_concurrency_get ()"><code class="function">vips_concurrency_get()</code></a>.</p>
<div class="refsect3">
<a name="id-1.3.13.8.11.11"></a><h4>Returns</h4>
<p> number of worker threads to use.</p>
<p></p>
</div>
</div>
</div>
<div class="refsect1">
<a name="VipsThreadState.other_details"></a><h2>Types and Values</h2>
</div>
<div class="refsect1">
<a name="VipsThreadState.see-also"></a><h2>See Also</h2>
<a class="link" href="libvips-generate.html" title="generate">generate</a>
</div>
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