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<a href="#desc" class="shortcut">Description</a>
 | 
<a href="#object_hierarchy" class="shortcut">Object Hierarchy</a></nobr></td></tr>
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<div class="refentry" lang="en">
<a name="pango-Engines"></a><div class="titlepage"></div>
<div class="refnamediv"><table width="100%"><tr>
<td valign="top">
<h2><span class="refentrytitle"><a name="top_of_page"></a>Engines</span></h2>
<p>Engines — Language-specific and rendering-system-specific processing</p>
</td>
<td valign="top" align="right"></td>
</tr></table></div>
<div class="refsynopsisdiv">
<a name="synopsis"></a><h2>Synopsis</h2>
<a name="PangoEngine"></a><pre class="synopsis">
<a href="pango-Engines.html#PangoEngineInfo">PangoEngineInfo</a>;
<a href="pango-Engines.html#PangoEngineScriptInfo">PangoEngineScriptInfo</a>;
<a href="pango-Engines.html#PangoEngine-struct">PangoEngine</a>;
<a href="pango-Engines.html#PangoEngineClass">PangoEngineClass</a>;
#define <a href="pango-Engines.html#PANGO-RENDER-TYPE-NONE:CAPS">PANGO_RENDER_TYPE_NONE</a>
void <a href="pango-Engines.html#script-engine-list">script_engine_list</a> (<a href="pango-Engines.html#PangoEngineInfo">PangoEngineInfo</a> **engines,
int *n_engines);
void <a href="pango-Engines.html#script-engine-init">script_engine_init</a> (<a
href="../gobject/GTypeModule.html"
>GTypeModule</a> *module);
void <a href="pango-Engines.html#script-engine-exit">script_engine_exit</a> (void);
<a href="pango-Engines.html#PangoEngine">PangoEngine</a>* <a href="pango-Engines.html#script-engine-create">script_engine_create</a> (const char *id);
</pre>
</div>
<div class="refsect1" lang="en">
<a name="object_hierarchy"></a><h2>Object Hierarchy</h2>
<pre class="synopsis">
<a
href="../gobject/gobject-The-Base-Object-Type.html#GObject"
>GObject</a>
+----PangoEngine
+----<a href="PangoEngineLang.html" title="PangoEngineLang">PangoEngineLang</a>
+----<a href="PangoEngineShape.html" title="PangoEngineShape">PangoEngineShape</a>
</pre>
</div>
<div class="refsect1" lang="en">
<a name="desc"></a><h2>Description</h2>
<p>
Pango utilizes a module architecture in which the language-specific
and render-system-specific components are provided by loadable
modules. Each loadable module supplies one or more
<em class="firstterm">engines</em>. Each <em class="firstterm">engine</em>
has an associated <em class="firstterm">engine type</em> and
<em class="firstterm">render type</em>. These two types are represented by
strings.
</p>
<p>
Each dynamically-loaded module exports several functions which provide
the public API. These functions are <a href="pango-Engines.html#script-engine-list"><code class="function">script_engine_list()</code></a>,
<a href="pango-Engines.html#script-engine-init"><code class="function">script_engine_init()</code></a> and script_engine_exit, and
<a href="pango-Engines.html#script-engine-create"><code class="function">script_engine_create()</code></a>. The latter three functions are used when
creating engines from the module at run time, while the first
function is used when building a catalog of all available modules.
</p>
</div>
<div class="refsect1" lang="en">
<a name="details"></a><h2>Details</h2>
<div class="refsect2" lang="en">
<a name="id2908328"></a><h3>
<a name="PangoEngineInfo"></a>PangoEngineInfo</h3>
<a class="indexterm" name="id2908340"></a><pre class="programlisting">typedef struct {
const gchar *id;
const gchar *engine_type;
const gchar *render_type;
PangoEngineScriptInfo *scripts;
gint n_scripts;
} PangoEngineInfo;
</pre>
<p>
The <a href="pango-Engines.html#PangoEngineInfo"><span class="type">PangoEngineInfo</span></a> structure contains information about a particular
engine. It contains the following fields:
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td>
<span class="term">const <a
href="../glib/glib-Basic-Types.html#gchar"
>gchar</a> *<em class="structfield"><code>id</code></em>;</span></td>
<td>a unique string ID for the engine.
</td>
</tr>
<tr>
<td>
<span class="term">const <a
href="../glib/glib-Basic-Types.html#gchar"
>gchar</a> *<em class="structfield"><code>engine_type</code></em>;</span></td>
<td>a string identifying the engine type.
</td>
</tr>
<tr>
<td>
<span class="term">const <a
href="../glib/glib-Basic-Types.html#gchar"
>gchar</a> *<em class="structfield"><code>render_type</code></em>;</span></td>
<td>a string identifying the render type.
</td>
</tr>
<tr>
<td>
<span class="term"><a href="pango-Engines.html#PangoEngineScriptInfo">PangoEngineScriptInfo</a> *<em class="structfield"><code>scripts</code></em>;</span></td>
<td>array of scripts this engine supports.
</td>
</tr>
<tr>
<td>
<span class="term"><a
href="../glib/glib-Basic-Types.html#gint"
>gint</a> <em class="structfield"><code>n_scripts</code></em>;</span></td>
<td>number of items in <em class="parameter"><code>scripts</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908485"></a><h3>
<a name="PangoEngineScriptInfo"></a>PangoEngineScriptInfo</h3>
<a class="indexterm" name="id2908499"></a><pre class="programlisting">typedef struct {
PangoScript script;
const gchar *langs;
} PangoEngineScriptInfo;
</pre>
<p>
The PangoEngineScriptInfo structure contains
information about how the shaper covers a particular
script.
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td>
<span class="term"><a href="pango-Scripts.html#PangoScript">PangoScript</a> <em class="structfield"><code>script</code></em>;</span></td>
<td>a <a href="pango-Scripts.html#PangoScript"><span class="type">PangoScript</span></a>. The value <a href="pango-Scripts.html#PANGO-SCRIPT-COMMON:CAPS"><code class="literal">PANGO_SCRIPT_COMMON</code></a> has
the special meaning here of "all scripts"
</td>
</tr>
<tr>
<td>
<span class="term">const <a
href="../glib/glib-Basic-Types.html#gchar"
>gchar</a> *<em class="structfield"><code>langs</code></em>;</span></td>
<td>a semicolon separated list of languages that this
engine handles for this script. This may be empty,
in which case the engine is saying that it is a
fallback choice for all languages for this range,
but should not be used if another engine
indicates that it is specific for the language for
a given code point. An entry in this list of "*"
indicates that this engine is specific to all
languages for this range.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908592"></a><h3>
<a name="PangoEngine-struct"></a>PangoEngine</h3>
<a class="indexterm" name="id2908605"></a><pre class="programlisting">typedef struct _PangoEngine PangoEngine;</pre>
<p>
<a href="pango-Engines.html#PangoEngine"><span class="type">PangoEngine</span></a> is the base class for all types of language and
script specific engines. It has no functionality by itself.</p>
<p>
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908633"></a><h3>
<a name="PangoEngineClass"></a>PangoEngineClass</h3>
<a class="indexterm" name="id2908646"></a><pre class="programlisting">typedef struct {
} PangoEngineClass;
</pre>
<p>
Class structure for <a href="pango-Engines.html#PangoEngine"><span class="type">PangoEngine</span></a></p>
<p>
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908672"></a><h3>
<a name="PANGO-RENDER-TYPE-NONE:CAPS"></a>PANGO_RENDER_TYPE_NONE</h3>
<a class="indexterm" name="id2908685"></a><pre class="programlisting">#define PANGO_RENDER_TYPE_NONE "PangoRenderNone"
</pre>
<p>
A string constant defining the render type
for engines that are not rendering-system
specific.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908702"></a><h3>
<a name="script-engine-list"></a>script_engine_list ()</h3>
<a class="indexterm" name="id2908716"></a><pre class="programlisting">void script_engine_list (<a href="pango-Engines.html#PangoEngineInfo">PangoEngineInfo</a> **engines,
int *n_engines);</pre>
<p>
Function to be provided by a module to list the engines that the
module supplies. The function stores a pointer to an array
of <a href="pango-Engines.html#PangoEngineInfo"><span class="type">PangoEngineInfo</span></a> structures and the length of that array in
the given location.
</p>
<p>
Note that <a href="pango-Engines.html#script-engine-init"><code class="function">script_engine_init()</code></a> will not be called before this
function.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td>
<span class="term"><em class="parameter"><code>engines</code></em> :</span></td>
<td> location to store a pointer to an array of engines.
</td>
</tr>
<tr>
<td>
<span class="term"><em class="parameter"><code>n_engines</code></em> :</span></td>
<td> location to store the number of elements in <em class="parameter"><code>engines</code></em>.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908820"></a><h3>
<a name="script-engine-init"></a>script_engine_init ()</h3>
<a class="indexterm" name="id2908833"></a><pre class="programlisting">void script_engine_init (<a
href="../gobject/GTypeModule.html"
>GTypeModule</a> *module);</pre>
<p>
Function to be provided by a module to register any
GObject types in the module.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody><tr>
<td>
<span class="term"><em class="parameter"><code>module</code></em> :</span></td>
<td> a <a
href="../gobject/GTypeModule.html"
><span class="type">GTypeModule</span></a> structure used to associate any
GObject types created in this module with the module.
</td>
</tr></tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908893"></a><h3>
<a name="script-engine-exit"></a>script_engine_exit ()</h3>
<a class="indexterm" name="id2908906"></a><pre class="programlisting">void script_engine_exit (void);</pre>
<p>
Function to be provided by the module that is called
when the module is unloading. Frequently does nothing.</p>
<p>
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2908932"></a><h3>
<a name="script-engine-create"></a>script_engine_create ()</h3>
<a class="indexterm" name="id2908945"></a><pre class="programlisting"><a href="pango-Engines.html#PangoEngine">PangoEngine</a>* script_engine_create (const char *id);</pre>
<p>
Function to be provided by the module to create an instance
of one of the engines implemented by the module.</p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td>
<span class="term"><em class="parameter"><code>id</code></em> :</span></td>
<td> the ID of an engine as reported by script_engine_list.
</td>
</tr>
<tr>
<td>
<span class="term"><span class="emphasis"><em>Returns</em></span> :</span></td>
<td> a newly created <a href="pango-Engines.html#PangoEngine"><span class="type">PangoEngine</span></a> of the specified
type, or <a
href="../glib/glib-Standard-Macros.html#NULL:CAPS"
><code class="literal">NULL</code></a> if an error occurred. (In normal operation,
a module should not return <a
href="../glib/glib-Standard-Macros.html#NULL:CAPS"
><code class="literal">NULL</code></a>. A <a
href="../glib/glib-Standard-Macros.html#NULL:CAPS"
><code class="literal">NULL</code></a> return is only
acceptable in the case where system misconfiguration or
bugs in the driver routine are encountered.)
</td>
</tr>
</tbody>
</table></div>
</div>
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