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<title>VipsOperation: VIPS Reference Manual</title>
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<a name="VipsOperation"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
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<h2><span class="refentrytitle"><a name="VipsOperation.top_of_page"></a>VipsOperation</span></h2>
<p>VipsOperation — the VIPS operation base object class</p>
</td>
<td class="gallery_image" valign="top" align="right"></td>
</tr></table></div>
<div class="refsect1">
<a name="VipsOperation.stability-level"></a><h2>Stability Level</h2>
<acronym title="The intention of a Stable interface is to enable arbitrary third parties to
develop applications to these interfaces, release them, and have confidence that
they will run on all minor releases of the product (after the one in which the
interface was introduced, and within the same major release). Even at a major
release, incompatible changes are expected to be rare, and to have strong
justifications.
"><span class="acronym">Stable</span></acronym>, unless otherwise indicated
</div>
<div class="refsect1">
<a name="VipsOperation.functions"></a><h2>Functions</h2>
<div class="informaltable"><table class="informaltable" 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">gboolean</span>
</td>
<td class="function_name">
<span class="c_punctuation">(</span><a class="link" href="VipsOperation.html#VipsOperationBuildFn" title="VipsOperationBuildFn ()">*VipsOperationBuildFn</a><span class="c_punctuation">)</span> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="VipsOperation.html#VipsOperationFlags" title="enum VipsOperationFlags"><span class="returnvalue">VipsOperationFlags</span></a>
</td>
<td class="function_name">
<a class="link" href="VipsOperation.html#vips-operation-get-flags" title="vips_operation_get_flags ()">vips_operation_get_flags</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="VipsOperation.html#vips-operation-class-print-usage" title="vips_operation_class_print_usage ()">vips_operation_class_print_usage</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="VipsOperation.html#vips-operation-invalidate" title="vips_operation_invalidate ()">vips_operation_invalidate</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="VipsOperation.html#vips-operation-call-valist" title="vips_operation_call_valist ()">vips_operation_call_valist</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="VipsOperation.html" title="VipsOperation"><span class="returnvalue">VipsOperation</span></a> *
</td>
<td class="function_name">
<a class="link" href="VipsOperation.html#vips-operation-new" title="vips_operation_new ()">vips_operation_new</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="VipsOperation.html#vips-call-required-optional" title="vips_call_required_optional ()">vips_call_required_optional</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="VipsOperation.html#vips-call" title="vips_call ()">vips_call</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="VipsOperation.html#vips-call-split" title="vips_call_split ()">vips_call_split</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="VipsOperation.html#vips-call-split-option-string" title="vips_call_split_option_string ()">vips_call_split_option_string</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="VipsOperation.html#vips-call-options" title="vips_call_options ()">vips_call_options</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="VipsOperation.html#vips-call-argv" title="vips_call_argv ()">vips_call_argv</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="VipsOperation.html#vips-cache-drop-all" title="vips_cache_drop_all ()">vips_cache_drop_all</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="VipsOperation.html" title="VipsOperation"><span class="returnvalue">VipsOperation</span></a> *
</td>
<td class="function_name">
<a class="link" href="VipsOperation.html#vips-cache-operation-lookup" title="vips_cache_operation_lookup ()">vips_cache_operation_lookup</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="VipsOperation.html#vips-cache-operation-add" title="vips_cache_operation_add ()">vips_cache_operation_add</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="VipsOperation.html#vips-cache-operation-buildp" title="vips_cache_operation_buildp ()">vips_cache_operation_buildp</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<a class="link" href="VipsOperation.html" title="VipsOperation"><span class="returnvalue">VipsOperation</span></a> *
</td>
<td class="function_name">
<a class="link" href="VipsOperation.html#vips-cache-operation-build" title="vips_cache_operation_build ()">vips_cache_operation_build</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="VipsOperation.html#vips-cache-print" title="vips_cache_print ()">vips_cache_print</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="VipsOperation.html#vips-cache-set-max" title="vips_cache_set_max ()">vips_cache_set_max</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="VipsOperation.html#vips-cache-set-max-mem" title="vips_cache_set_max_mem ()">vips_cache_set_max_mem</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="VipsOperation.html#vips-cache-get-max" title="vips_cache_get_max ()">vips_cache_get_max</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="VipsOperation.html#vips-cache-get-size" title="vips_cache_get_size ()">vips_cache_get_size</a> <span class="c_punctuation">()</span>
</td>
</tr>
<tr>
<td class="function_type">
<span class="returnvalue">size_t</span>
</td>
<td class="function_name">
<a class="link" href="VipsOperation.html#vips-cache-get-max-mem" title="vips_cache_get_max_mem ()">vips_cache_get_max_mem</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="VipsOperation.html#vips-cache-get-max-files" title="vips_cache_get_max_files ()">vips_cache_get_max_files</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="VipsOperation.html#vips-cache-set-max-files" title="vips_cache_set_max_files ()">vips_cache_set_max_files</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="VipsOperation.html#vips-cache-set-dump" title="vips_cache_set_dump ()">vips_cache_set_dump</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="VipsOperation.html#vips-cache-set-trace" title="vips_cache_set_trace ()">vips_cache_set_trace</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="VipsOperation.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="VipsOperation.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="VipsOperation.signals"></a><h2>Signals</h2>
<div class="informaltable"><table class="informaltable" border="0">
<colgroup>
<col width="150px" class="signals_return">
<col width="300px" class="signals_name">
<col width="200px" class="signals_flags">
</colgroup>
<tbody><tr>
<td class="signal_type"><span class="returnvalue">void</span></td>
<td class="signal_name"><a class="link" href="VipsOperation.html#VipsOperation-invalidate" title="The “invalidate” signal">invalidate</a></td>
<td class="signal_flags">Run Last</td>
</tr></tbody>
</table></div>
</div>
<div class="refsect1">
<a name="VipsOperation.other"></a><h2>Types and Values</h2>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="150px" class="name">
<col class="description">
</colgroup>
<tbody><tr>
<td class="datatype_keyword">enum</td>
<td class="function_name"><a class="link" href="VipsOperation.html#VipsOperationFlags" title="enum VipsOperationFlags">VipsOperationFlags</a></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect1">
<a name="VipsOperation.object-hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="screen"> GObject
<span class="lineart">╰──</span> <a class="link" href="VipsObject.html" title="VipsObject">VipsObject</a>
<span class="lineart">╰──</span> VipsOperation
<span class="lineart">╰──</span> <a class="link" href="VipsForeignSave.html#VipsForeign">VipsForeign</a>
</pre>
</div>
<div class="refsect1">
<a name="VipsOperation.includes"></a><h2>Includes</h2>
<pre class="synopsis">#include <vips/vips.h>
</pre>
</div>
<div class="refsect1">
<a name="VipsOperation.description"></a><h2>Description</h2>
<p>The <a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> class and associated types and macros.</p>
<p><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> is the base class for all operations in libvips. It builds
on <a class="link" href="VipsObject.html" title="VipsObject"><span class="type">VipsObject</span></a> to provide the introspection and command-line interface to
libvips. </p>
<p>It also maintains a cache of recent operations. See below. </p>
<p>vips_call(), <a class="link" href="VipsOperation.html#vips-call-split" title="vips_call_split ()"><code class="function">vips_call_split()</code></a> and <a class="link" href="VipsOperation.html#vips-call-split-option-string" title="vips_call_split_option_string ()"><code class="function">vips_call_split_option_string()</code></a> are used
by vips to implement the C API. They can execute any <a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a>,
passing in a set of required and optional arguments. Normally you would not
use these functions directly: every operation has a tiny wrapper function
which provides type-safety for the required arguments. For example,
<a class="link" href="libvips-conversion.html#vips-embed" title="vips_embed ()"><code class="function">vips_embed()</code></a> is defined as:</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
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12
13</pre></td>
<td class="listing_code"><pre class="programlisting"><span class="gtkdoc kwb">int</span>
<span class="function"><a href="libvips-conversion.html#vips-embed">vips_embed</a></span><span class="gtkdoc opt">(</span> VipsImage <span class="gtkdoc opt">*</span>in<span class="gtkdoc opt">,</span> VipsImage <span class="gtkdoc opt">**</span>out<span class="gtkdoc opt">,</span>
<span class="gtkdoc kwb">int</span> x<span class="gtkdoc opt">,</span> <span class="gtkdoc kwb">int</span> y<span class="gtkdoc opt">,</span> <span class="gtkdoc kwb">int</span> width<span class="gtkdoc opt">,</span> <span class="gtkdoc kwb">int</span> height<span class="gtkdoc opt">, ... )</span>
<span class="gtkdoc opt">{</span>
<span class="gtkdoc kwb">va_list</span> ap<span class="gtkdoc opt">;</span>
<span class="gtkdoc kwb">int</span> result<span class="gtkdoc opt">;</span>
<span class="function">va_start</span><span class="gtkdoc opt">(</span> ap<span class="gtkdoc opt">,</span> height <span class="gtkdoc opt">);</span>
result <span class="gtkdoc opt">=</span> <span class="function"><a href="VipsOperation.html#vips-call-split">vips_call_split</a></span><span class="gtkdoc opt">(</span> <span class="string">"embed"</span><span class="gtkdoc opt">,</span> ap<span class="gtkdoc opt">,</span> in<span class="gtkdoc opt">,</span> out<span class="gtkdoc opt">,</span> x<span class="gtkdoc opt">,</span> y<span class="gtkdoc opt">,</span> width<span class="gtkdoc opt">,</span> height <span class="gtkdoc opt">);</span>
<span class="function">va_end</span><span class="gtkdoc opt">(</span> ap <span class="gtkdoc opt">);</span>
<span class="keyword">return</span><span class="gtkdoc opt">(</span> result <span class="gtkdoc opt">);</span>
<span class="gtkdoc opt">}</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p></p>
<p>Use <a class="link" href="VipsOperation.html#vips-call-argv" title="vips_call_argv ()"><code class="function">vips_call_argv()</code></a> to run any vips operation from a command-line style
argc/argv array. This is the thing used by the vips main program to
implement the vips command-line interface. </p>
<div class="refsect3">
<a name="id-1.3.6.9.9"></a><h4>
<a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> and reference counting</h4>
<p>After calling a <a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> you are responsible for unreffing any output
objects. For example, consider:</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5</pre></td>
<td class="listing_code"><pre class="programlisting">VipsImage <span class="gtkdoc opt">*</span>im <span class="gtkdoc opt">= ...;</span>
VipsImage <span class="gtkdoc opt">*</span>t1<span class="gtkdoc opt">;</span>
<span class="keyword">if</span> <span class="gtkdoc opt">(</span><span class="function"><a href="libvips-arithmetic.html#vips-invert">vips_invert</a></span> <span class="gtkdoc opt">(</span>im<span class="gtkdoc opt">, &</span>t1<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">))</span>
error <span class="gtkdoc opt">..</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p></p>
<p>This will invert <em class="parameter"><code>im</code></em>
and return a new <a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a>, <em class="parameter"><code>t1</code></em>
. As the caller
of <a class="link" href="libvips-arithmetic.html#vips-invert" title="vips_invert ()"><code class="function">vips_invert()</code></a>, you are responsible for <em class="parameter"><code>t1</code></em>
and must unref it when you no
longer need it. If <a class="link" href="libvips-arithmetic.html#vips-invert" title="vips_invert ()"><code class="function">vips_invert()</code></a> fails, no <em class="parameter"><code>t1</code></em>
is returned and you don't
need to do anything. </p>
<p>If you don't need to use <em class="parameter"><code>im</code></em>
for another operation,
you can unref <em class="parameter"><code>im</code></em>
immediately after the call. If <em class="parameter"><code>im</code></em>
is needed to calculate
<em class="parameter"><code>t1</code></em>
, <a class="link" href="libvips-arithmetic.html#vips-invert" title="vips_invert ()"><code class="function">vips_invert()</code></a> will add a ref to <em class="parameter"><code>im</code></em>
and automatically drop it when <em class="parameter"><code>t1</code></em>
is unreffed.</p>
<p>Consider running two operations, one after the other. You could write:</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7
8
9
10
11
12
13
14</pre></td>
<td class="listing_code"><pre class="programlisting">VipsImage <span class="gtkdoc opt">*</span>im <span class="gtkdoc opt">= ...;</span>
VipsImage <span class="gtkdoc opt">*</span>t1<span class="gtkdoc opt">, *</span>t2<span class="gtkdoc opt">;</span>
<span class="keyword">if</span> <span class="gtkdoc opt">(</span><span class="function"><a href="libvips-arithmetic.html#vips-invert">vips_invert</a></span> <span class="gtkdoc opt">(</span>im<span class="gtkdoc opt">, &</span>t1<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">)) {</span>
<span class="function">g_object_unref</span> <span class="gtkdoc opt">(</span>im<span class="gtkdoc opt">);</span>
<span class="keyword">return</span> <span class="gtkdoc opt">-</span><span class="number">1</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
<span class="function">g_object_unref</span> <span class="gtkdoc opt">(</span>im<span class="gtkdoc opt">);</span>
<span class="keyword">if</span> <span class="gtkdoc opt">(</span><span class="function"><a href="libvips-conversion.html#vips-flip">vips_flip</a></span> <span class="gtkdoc opt">(</span>t1<span class="gtkdoc opt">, &</span>t2<span class="gtkdoc opt">,</span> VIPS_DIRECTION_HORIZONTAL<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">)) {</span>
<span class="function">g_object_unref</span> <span class="gtkdoc opt">(</span>t1<span class="gtkdoc opt">);</span>
<span class="keyword">return</span> <span class="gtkdoc opt">-</span><span class="number">1</span><span class="gtkdoc opt">;</span>
<span class="gtkdoc opt">}</span>
<span class="function">g_object_unref</span> <span class="gtkdoc opt">(</span>t1<span class="gtkdoc opt">);</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p></p>
<p>This is correct, but rather long-winded. libvips provides a handy thing to
make a vector of auto-freeing object references. You can write this as:</p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7</pre></td>
<td class="listing_code"><pre class="programlisting">VipsObject <span class="gtkdoc opt">*</span>parent <span class="gtkdoc opt">= ...;</span>
VipsImage <span class="gtkdoc opt">*</span>im <span class="gtkdoc opt">= ...;</span>
VipsImage <span class="gtkdoc opt">*</span>t <span class="gtkdoc opt">= (</span>VipsImage <span class="gtkdoc opt">**)</span> <span class="function"><a href="VipsObject.html#vips-object-local-array">vips_object_local_array</a></span> <span class="gtkdoc opt">(</span>parent<span class="gtkdoc opt">,</span> <span class="number">2</span><span class="gtkdoc opt">);</span>
<span class="keyword">if</span> <span class="gtkdoc opt">(</span><span class="function"><a href="libvips-arithmetic.html#vips-invert">vips_invert</a></span> <span class="gtkdoc opt">(</span>im<span class="gtkdoc opt">, &</span>t<span class="gtkdoc opt">[</span><span class="number">0</span><span class="gtkdoc opt">],</span> NULL<span class="gtkdoc opt">) ||</span>
<span class="function"><a href="libvips-conversion.html#vips-flip">vips_flip</a></span> <span class="gtkdoc opt">(</span>t<span class="gtkdoc opt">[</span><span class="number">0</span><span class="gtkdoc opt">], &</span>t<span class="gtkdoc opt">[</span><span class="number">1</span><span class="gtkdoc opt">],</span> VIPS_DIRECTION_HORIZONTAL<span class="gtkdoc opt">,</span> NULL<span class="gtkdoc opt">))</span>
<span class="keyword">return</span> <span class="gtkdoc opt">-</span><span class="number">1</span><span class="gtkdoc opt">;</span></pre></td>
</tr>
</tbody>
</table>
</div>
<p></p>
<p>where <em class="parameter"><code>parent</code></em>
is some enclosing object which will be unreffed when this
task is complete. <a class="link" href="VipsObject.html#vips-object-local-array" title="vips_object_local_array ()"><code class="function">vips_object_local_array()</code></a> makes an array of <a class="link" href="VipsObject.html" title="VipsObject"><span class="type">VipsObject</span></a>
(or <a class="link" href="VipsImage.html" title="VipsImage"><span class="type">VipsImage</span></a>, in this case) where when <em class="parameter"><code>parent</code></em>
is freed, all non-NULL
<a class="link" href="VipsObject.html" title="VipsObject"><span class="type">VipsObject</span></a> in the array are also unreffed.</p>
</div>
<div class="refsect3">
<a name="id-1.3.6.9.10"></a><h4>The <a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> cache</h4>
<p>Because all <a class="link" href="VipsObject.html" title="VipsObject"><span class="type">VipsObject</span></a> are immutable, they can be cached. The cache is
very simple to use: instead of calling <a class="link" href="VipsObject.html#vips-object-build" title="vips_object_build ()"><code class="function">vips_object_build()</code></a>, call
<a class="link" href="VipsOperation.html#vips-cache-operation-build" title="vips_cache_operation_build ()"><code class="function">vips_cache_operation_build()</code></a>. This function calculates a hash from the
operations's input arguments and looks it up in table of all recent
operations. If there's a hit, the new operation is unreffed, the old
operation reffed, and the old operation returned in place of the new one.</p>
<p>The cache size is controlled with <a class="link" href="VipsOperation.html#vips-cache-set-max" title="vips_cache_set_max ()"><code class="function">vips_cache_set_max()</code></a> and friends.</p>
</div>
</div>
<div class="refsect1">
<a name="VipsOperation.functions_details"></a><h2>Functions</h2>
<div class="refsect2">
<a name="VipsOperationBuildFn"></a><h3>VipsOperationBuildFn ()</h3>
<pre class="programlisting"><span class="returnvalue">gboolean</span>
<span class="c_punctuation">(</span>*VipsOperationBuildFn<span class="c_punctuation">)</span> (<em class="parameter"><code><a class="link" href="VipsObject.html" title="VipsObject"><span class="type">VipsObject</span></a> *object</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-operation-get-flags"></a><h3>vips_operation_get_flags ()</h3>
<pre class="programlisting"><a class="link" href="VipsOperation.html#VipsOperationFlags" title="enum VipsOperationFlags"><span class="returnvalue">VipsOperationFlags</span></a>
vips_operation_get_flags (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>);</pre>
<p>Returns the set of flags for this operation.</p>
<div class="refsect3">
<a name="vips-operation-get-flags.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation</p></td>
<td class="parameter_description"><p>operation to fetch flags from</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-operation-get-flags.returns"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error.</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-operation-class-print-usage"></a><h3>vips_operation_class_print_usage ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_operation_class_print_usage (<em class="parameter"><code><span class="type">VipsOperationClass</span> *operation_class</code></em>);</pre>
<p>Print a usage message for the operation to stdout.</p>
<p><span class="annotation">[<acronym title="Exposed in C code, not necessarily available in other languages."><span class="acronym">skip</span></acronym>]</span></p>
<div class="refsect3">
<a name="vips-operation-class-print-usage.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation_class</p></td>
<td class="parameter_description"><p>class to print usage for</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-operation-invalidate"></a><h3>vips_operation_invalidate ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_operation_invalidate (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-operation-call-valist"></a><h3>vips_operation_call_valist ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_operation_call_valist (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>,
<em class="parameter"><code><span class="type">va_list</span> ap</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-operation-new"></a><h3>vips_operation_new ()</h3>
<pre class="programlisting"><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="returnvalue">VipsOperation</span></a> *
vips_operation_new (<em class="parameter"><code>const <span class="type">char</span> *name</code></em>);</pre>
<p>Return a new <a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> with the specified nickname. Useful for
language bindings. </p>
<p>You'll need to set
any arguments and build the operation before you can use it. See
<a class="link" href="VipsOperation.html#vips-call" title="vips_call ()"><code class="function">vips_call()</code></a> for a higher-level way to make new operations.</p>
<div class="refsect3">
<a name="vips-operation-new.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>name</p></td>
<td class="parameter_description"><p>nickname of operation to create</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-operation-new.returns"></a><h4>Returns</h4>
<p> the new operation. </p>
<p><span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-call-required-optional"></a><h3>vips_call_required_optional ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_call_required_optional (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> **operation</code></em>,
<em class="parameter"><code><span class="type">va_list</span> required</code></em>,
<em class="parameter"><code><span class="type">va_list</span> optional</code></em>);</pre>
<p>This is the main entry point for the C and C++ varargs APIs. <em class="parameter"><code>operation</code></em>
is executed, supplying <em class="parameter"><code>required</code></em>
and <em class="parameter"><code>optional</code></em>
arguments. </p>
<p>Beware, this can change <em class="parameter"><code>operation</code></em>
to point at an old, cached one.</p>
<div class="refsect3">
<a name="vips-call-required-optional.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation</p></td>
<td class="parameter_description"><p>the operation to execute</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>required</p></td>
<td class="parameter_description"><p><code class="literal">va_list</code> of required arguments</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>optional</p></td>
<td class="parameter_description"><p>NULL-terminated <code class="literal">va_list</code> of name / value pairs </p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-call-required-optional.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-call"></a><h3>vips_call ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_call (<em class="parameter"><code>const <span class="type">char</span> *operation_name</code></em>,
<em class="parameter"><code>...</code></em>);</pre>
<p>vips_call() calls the named operation, passing in required arguments and
then setting any optional ones from the remainder of the arguments as a set
of name/value pairs. </p>
<p>For example, <a class="link" href="libvips-conversion.html#vips-embed" title="vips_embed ()"><code class="function">vips_embed()</code></a> takes six required arguments, <em class="parameter"><code>in</code></em>
, <em class="parameter"><code>out</code></em>
, <em class="parameter"><code>x</code></em>
, <em class="parameter"><code>y</code></em>
,
<em class="parameter"><code>width</code></em>
, <em class="parameter"><code>height</code></em>
, and has two optional arguments, <em class="parameter"><code>extend</code></em>
and <em class="parameter"><code>background</code></em>
.
You can run it with <a class="link" href="VipsOperation.html#vips-call" title="vips_call ()"><code class="function">vips_call()</code></a> like this: </p>
<div class="informalexample">
<table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
<tbody>
<tr>
<td class="listing_lines" align="right"><pre>1
2
3
4
5
6
7</pre></td>
<td class="listing_code"><pre class="programlisting">VipsImage <span class="gtkdoc opt">*</span>in <span class="gtkdoc opt">= ...</span>
VipsImage <span class="gtkdoc opt">*</span>out<span class="gtkdoc opt">;</span>
<span class="keyword">if</span><span class="gtkdoc opt">(</span> <span class="function"><a href="VipsOperation.html#vips-call">vips_call</a></span><span class="gtkdoc opt">(</span> <span class="string">"embed"</span><span class="gtkdoc opt">,</span> in<span class="gtkdoc opt">, &</span>out<span class="gtkdoc opt">,</span> <span class="number">10</span><span class="gtkdoc opt">,</span> <span class="number">10</span><span class="gtkdoc opt">,</span> <span class="number">100</span><span class="gtkdoc opt">,</span> <span class="number">100</span><span class="gtkdoc opt">,</span>
<span class="string">"extend"</span><span class="gtkdoc opt">,</span> VIPS_EXTEND_COPY<span class="gtkdoc opt">,</span>
NULL <span class="gtkdoc opt">) )</span>
<span class="gtkdoc opt">...</span> error</pre></td>
</tr>
</tbody>
</table>
</div>
<p></p>
<p>Normally of course you'd just use the <a class="link" href="libvips-conversion.html#vips-embed" title="vips_embed ()"><code class="function">vips_embed()</code></a> wrapper function and get
type-safety for the required arguments. </p>
<p>See also: <a class="link" href="VipsOperation.html#vips-call-split" title="vips_call_split ()"><code class="function">vips_call_split()</code></a>, <a class="link" href="VipsOperation.html#vips-call-options" title="vips_call_options ()"><code class="function">vips_call_options()</code></a>.</p>
<div class="refsect3">
<a name="vips-call.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation_name</p></td>
<td class="parameter_description"><p>name of operation to call</p></td>
<td class="parameter_annotations"> </td>
</tr>
<tr>
<td class="parameter_name"><p>...</p></td>
<td class="parameter_description"><p>required args, then a <code class="literal">NULL</code>-terminated list of argument/value pairs</p></td>
<td class="parameter_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-call.returns"></a><h4>Returns</h4>
<p> 0 on success, -1 on error</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-call-split"></a><h3>vips_call_split ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_call_split (<em class="parameter"><code>const <span class="type">char</span> *operation_name</code></em>,
<em class="parameter"><code><span class="type">va_list</span> optional</code></em>,
<em class="parameter"><code>...</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-call-split-option-string"></a><h3>vips_call_split_option_string ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_call_split_option_string (<em class="parameter"><code>const <span class="type">char</span> *operation_name</code></em>,
<em class="parameter"><code>const <span class="type">char</span> *option_string</code></em>,
<em class="parameter"><code><span class="type">va_list</span> optional</code></em>,
<em class="parameter"><code>...</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-call-options"></a><h3>vips_call_options ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_call_options (<em class="parameter"><code><span class="type">GOptionGroup</span> *group</code></em>,
<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-call-argv"></a><h3>vips_call_argv ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_call_argv (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>,
<em class="parameter"><code><span class="type">int</span> argc</code></em>,
<em class="parameter"><code><span class="type">char</span> **argv</code></em>);</pre>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-drop-all"></a><h3>vips_cache_drop_all ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_drop_all (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Drop the whole operation cache, handy for leak tracking. Also called
automatically on <a class="link" href="libvips-vips.html#vips-shutdown" title="vips_shutdown ()"><code class="function">vips_shutdown()</code></a>.</p>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-operation-lookup"></a><h3>vips_cache_operation_lookup ()</h3>
<pre class="programlisting"><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="returnvalue">VipsOperation</span></a> *
vips_cache_operation_lookup (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>);</pre>
<p>Look up an unbuilt <em class="parameter"><code>operation</code></em>
in the cache. If we get a hit, ref and
return the old operation. If there's no hit, return NULL.</p>
<div class="refsect3">
<a name="vips-cache-operation-lookup.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation</p></td>
<td class="parameter_description"><p> pointer to operation to lookup. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="Don't free data after the code is done."><span class="acronym">transfer none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-cache-operation-lookup.returns"></a><h4>Returns</h4>
<p> the cache hit, if any. </p>
<p><span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-operation-add"></a><h3>vips_cache_operation_add ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_operation_add (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>);</pre>
<p>Add a built operation to the cache. The cache will ref the operation.</p>
<div class="refsect3">
<a name="vips-cache-operation-add.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation</p></td>
<td class="parameter_description"><p> pointer to operation to add. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="Don't free data after the code is done."><span class="acronym">transfer none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-operation-buildp"></a><h3>vips_cache_operation_buildp ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_cache_operation_buildp (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> **operation</code></em>);</pre>
<p>Look up <em class="parameter"><code>operation</code></em>
in the cache. If we get a hit, unref <em class="parameter"><code>operation</code></em>
, ref the
old one and return that through the argument pointer. </p>
<p>If we miss, build and add <em class="parameter"><code>operation</code></em>
.</p>
<p><span class="annotation">[<acronym title="Exposed in C code, not necessarily available in other languages."><span class="acronym">skip</span></acronym>]</span></p>
<div class="refsect3">
<a name="vips-cache-operation-buildp.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation</p></td>
<td class="parameter_description"><p>pointer to operation to lookup</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-cache-operation-buildp.returns"></a><h4>Returns</h4>
<p> 0 on success, or -1 on error.</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-operation-build"></a><h3>vips_cache_operation_build ()</h3>
<pre class="programlisting"><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="returnvalue">VipsOperation</span></a> *
vips_cache_operation_build (<em class="parameter"><code><a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *operation</code></em>);</pre>
<p>A binding-friendly version of <a class="link" href="VipsOperation.html#vips-cache-operation-buildp" title="vips_cache_operation_buildp ()"><code class="function">vips_cache_operation_buildp()</code></a>.</p>
<p>After calling this, <em class="parameter"><code>operation</code></em>
has the same ref count as when it went in,
and the result must be freed with <a class="link" href="VipsObject.html#vips-object-unref-outputs" title="vips_object_unref_outputs ()"><code class="function">vips_object_unref_outputs()</code></a> and
<code class="function">g_object_unref()</code>.</p>
<div class="refsect3">
<a name="vips-cache-operation-build.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>operation</p></td>
<td class="parameter_description"><p> operation to lookup. </p></td>
<td class="parameter_annotations"><span class="annotation">[<acronym title="Don't free data after the code is done."><span class="acronym">transfer none</span></acronym>]</span></td>
</tr></tbody>
</table></div>
</div>
<div class="refsect3">
<a name="vips-cache-operation-build.returns"></a><h4>Returns</h4>
<p> The built operation. </p>
<p><span class="annotation">[<acronym title="Free data after the code is done."><span class="acronym">transfer full</span></acronym>]</span></p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-print"></a><h3>vips_cache_print ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_print (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Print the whole operation cache to stdout. Handy for debugging.</p>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-set-max"></a><h3>vips_cache_set_max ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_set_max (<em class="parameter"><code><span class="type">int</span> max</code></em>);</pre>
<p>Set the maximum number of operations we keep in cache.</p>
<div class="refsect3">
<a name="vips-cache-set-max.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>max</p></td>
<td class="parameter_description"><p>maximum number of operation to cache</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-set-max-mem"></a><h3>vips_cache_set_max_mem ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_set_max_mem (<em class="parameter"><code><span class="type">size_t</span> max_mem</code></em>);</pre>
<p>Set the maximum amount of tracked memory we allow before we start dropping
cached operations. See <a class="link" href="libvips-memory.html#vips-tracked-get-mem" title="vips_tracked_get_mem ()"><code class="function">vips_tracked_get_mem()</code></a>.</p>
<p>See also: <a class="link" href="libvips-memory.html#vips-tracked-get-mem" title="vips_tracked_get_mem ()"><code class="function">vips_tracked_get_mem()</code></a>.</p>
<div class="refsect3">
<a name="vips-cache-set-max-mem.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>max_mem</p></td>
<td class="parameter_description"><p>maximum amount of tracked memory we use </p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-get-max"></a><h3>vips_cache_get_max ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_cache_get_max (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Get the maximum number of operations we keep in cache.</p>
<div class="refsect3">
<a name="vips-cache-get-max.returns"></a><h4>Returns</h4>
<p> the maximum number of operations we keep in cache</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-get-size"></a><h3>vips_cache_get_size ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_cache_get_size (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Get the current number of operations in cache.</p>
<div class="refsect3">
<a name="vips-cache-get-size.returns"></a><h4>Returns</h4>
<p> get the current number of operations in cache.</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-get-max-mem"></a><h3>vips_cache_get_max_mem ()</h3>
<pre class="programlisting"><span class="returnvalue">size_t</span>
vips_cache_get_max_mem (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Get the maximum amount of tracked memory we allow before we start dropping
cached operations. See <a class="link" href="libvips-memory.html#vips-tracked-get-mem" title="vips_tracked_get_mem ()"><code class="function">vips_tracked_get_mem()</code></a>.</p>
<p>See also: <a class="link" href="libvips-memory.html#vips-tracked-get-mem" title="vips_tracked_get_mem ()"><code class="function">vips_tracked_get_mem()</code></a>.</p>
<div class="refsect3">
<a name="vips-cache-get-max-mem.returns"></a><h4>Returns</h4>
<p> the maximum amount of tracked memory we allow</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-get-max-files"></a><h3>vips_cache_get_max_files ()</h3>
<pre class="programlisting"><span class="returnvalue">int</span>
vips_cache_get_max_files (<em class="parameter"><code><span class="type">void</span></code></em>);</pre>
<p>Get the maximum number of tracked files we allow before we start dropping
cached operations. See <a class="link" href="libvips-memory.html#vips-tracked-get-files" title="vips_tracked_get_files ()"><code class="function">vips_tracked_get_files()</code></a>.</p>
<p>See also: <a class="link" href="libvips-memory.html#vips-tracked-get-files" title="vips_tracked_get_files ()"><code class="function">vips_tracked_get_files()</code></a>.</p>
<div class="refsect3">
<a name="vips-cache-get-max-files.returns"></a><h4>Returns</h4>
<p> the maximum number of tracked files we allow</p>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-set-max-files"></a><h3>vips_cache_set_max_files ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_set_max_files (<em class="parameter"><code><span class="type">int</span> max_files</code></em>);</pre>
<p>Set the maximum number of tracked files we allow before we start dropping
cached operations. See <a class="link" href="libvips-memory.html#vips-tracked-get-files" title="vips_tracked_get_files ()"><code class="function">vips_tracked_get_files()</code></a>.</p>
<p>See also: <a class="link" href="libvips-memory.html#vips-tracked-get-files" title="vips_tracked_get_files ()"><code class="function">vips_tracked_get_files()</code></a>.</p>
<div class="refsect3">
<a name="vips-cache-set-max-files.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>max_files</p></td>
<td class="parameter_description"><p>max open files we allow</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-set-dump"></a><h3>vips_cache_set_dump ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_set_dump (<em class="parameter"><code><span class="type">gboolean</span> dump</code></em>);</pre>
<p>Handy for debugging. Print the operation cache to stdout just before exit.</p>
<p>See also: <a class="link" href="VipsOperation.html#vips-cache-set-trace" title="vips_cache_set_trace ()"><code class="function">vips_cache_set_trace()</code></a>.</p>
<div class="refsect3">
<a name="vips-cache-set-dump.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>dump</p></td>
<td class="parameter_description"><p>if <code class="literal">TRUE</code>, dump the operation cache on exit</p></td>
<td class="parameter_annotations"> </td>
</tr></tbody>
</table></div>
</div>
</div>
<hr>
<div class="refsect2">
<a name="vips-cache-set-trace"></a><h3>vips_cache_set_trace ()</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
vips_cache_set_trace (<em class="parameter"><code><span class="type">gboolean</span> trace</code></em>);</pre>
<p>Handy for debugging. Print operation cache actions to stdout as we run.</p>
<p>You can set the environment variable <code class="literal">VIPS_TRACE</code> to turn this option on, or
use the command-line flag <code class="literal">--vips-cache-trace</code>.</p>
<p>See also: <a class="link" href="VipsOperation.html#vips-cache-set-dump" title="vips_cache_set_dump ()"><code class="function">vips_cache_set_dump()</code></a>.</p>
<div class="refsect3">
<a name="vips-cache-set-trace.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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>trace</p></td>
<td class="parameter_description"><p>if <code class="literal">TRUE</code>, trace the operation cache </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 environment variable VIPS_CONCURRENCY, or if that is not set, the
number of threads availble on the host machine. </p>
<p>See also: <a class="link" href="VipsOperation.html#vips-concurrency-get" title="vips_concurrency_get ()"><code class="function">vips_concurrency_get()</code></a>.</p>
<div class="refsect3">
<a name="vips-concurrency-set.parameters"></a><h4>Parameters</h4>
<div class="informaltable"><table class="informaltable" 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="VipsOperation.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="VipsOperation.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="VipsOperation.html#vips-concurrency-get" title="vips_concurrency_get ()"><code class="function">vips_concurrency_get()</code></a>.</p>
<div class="refsect3">
<a name="vips-concurrency-get.returns"></a><h4>Returns</h4>
<p> number of worker threads to use.</p>
</div>
</div>
</div>
<div class="refsect1">
<a name="VipsOperation.other_details"></a><h2>Types and Values</h2>
<div class="refsect2">
<a name="VipsOperationFlags"></a><h3>enum VipsOperationFlags</h3>
<p>Flags we associate with an operation.</p>
<p><em class="parameter"><code>VIPS_OPERATION_SEQUENTIAL</code></em>
means that the operation works like <a class="link" href="libvips-convolution.html#vips-conv" title="vips_conv ()"><code class="function">vips_conv()</code></a>:
it can process images top-to-bottom with only small non-local
references. </p>
<p>Every scan-line must be requested, you are not allowed to skip
ahead, but as a special case, the very first request can be for a region
not at the top of the image. In this case, the first part of the image will
be read and discarded</p>
<p><em class="parameter"><code>VIPS_OPERATION_SEQUENTIAL_UNBUFFERED</code></em>
means that the operation works like
<a class="link" href="libvips-conversion.html#vips-copy" title="vips_copy ()"><code class="function">vips_copy()</code></a>: it can process images top-to-bottom and makes no
non-local references. </p>
<p>Every scan-line must be requested, you are not allowed to skip
ahead, but as a special case, the very first request can be for a region
not at the top of the image. In this case, the first part of the image will
be read and discarded</p>
<p><em class="parameter"><code>VIPS_OPERATION_NOCACHE</code></em>
means that the operation must not be cached by
vips. </p>
<p><em class="parameter"><code>VIPS_OPERATION_DEPRECATED</code></em>
means this is an old operation kept in vips for
compatibility only and should be hidden from users.</p>
<div class="refsect3">
<a name="VipsOperationFlags.members"></a><h4>Members</h4>
<div class="informaltable"><table class="informaltable" width="100%" border="0">
<colgroup>
<col width="300px" class="enum_members_name">
<col class="enum_members_description">
<col width="200px" class="enum_members_annotations">
</colgroup>
<tbody>
<tr>
<td class="enum_member_name"><p><a name="VIPS-OPERATION-NONE:CAPS"></a>VIPS_OPERATION_NONE</p></td>
<td class="enum_member_description">
<p>no flags</p>
</td>
<td class="enum_member_annotations"> </td>
</tr>
<tr>
<td class="enum_member_name"><p><a name="VIPS-OPERATION-SEQUENTIAL:CAPS"></a>VIPS_OPERATION_SEQUENTIAL</p></td>
<td class="enum_member_description">
<p>can work sequentially with a small buffer</p>
</td>
<td class="enum_member_annotations"> </td>
</tr>
<tr>
<td class="enum_member_name"><p><a name="VIPS-OPERATION-SEQUENTIAL-UNBUFFERED:CAPS"></a>VIPS_OPERATION_SEQUENTIAL_UNBUFFERED</p></td>
<td class="enum_member_description">
<p>can work sequentially with no buffer</p>
</td>
<td class="enum_member_annotations"> </td>
</tr>
<tr>
<td class="enum_member_name"><p><a name="VIPS-OPERATION-NOCACHE:CAPS"></a>VIPS_OPERATION_NOCACHE</p></td>
<td class="enum_member_description">
<p>must not be cached</p>
</td>
<td class="enum_member_annotations"> </td>
</tr>
<tr>
<td class="enum_member_name"><p><a name="VIPS-OPERATION-DEPRECATED:CAPS"></a>VIPS_OPERATION_DEPRECATED</p></td>
<td class="enum_member_description">
<p>a compatibility thing</p>
</td>
<td class="enum_member_annotations"> </td>
</tr>
</tbody>
</table></div>
</div>
</div>
</div>
<div class="refsect1">
<a name="VipsOperation.signal-details"></a><h2>Signal Details</h2>
<div class="refsect2">
<a name="VipsOperation-invalidate"></a><h3>The <code class="literal">“invalidate”</code> signal</h3>
<pre class="programlisting"><span class="returnvalue">void</span>
user_function (<a class="link" href="VipsOperation.html" title="VipsOperation"><span class="type">VipsOperation</span></a> *vipsoperation,
<span class="type">gpointer</span> user_data)</pre>
<p>Flags: Run Last</p>
</div>
</div>
<div class="refsect1">
<a name="VipsOperation.see-also"></a><h2>See Also</h2>
<a class="link" href="VipsObject.html" title="VipsObject">object</a>
</div>
</div>
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