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<a href="#desc" class="shortcut">Description</a>
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<a href="#object_hierarchy" class="shortcut">Object Hierarchy</a></nobr></td></tr>
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<div class="refentry" lang="en">
<a name="PangoEngineShape"></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>PangoEngineShape</span></h2>
<p>PangoEngineShape — Rendering-system dependent script engines</p>
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<td valign="top" align="right"></td>
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<div class="refsynopsisdiv">
<a name="synopsis"></a><h2>Synopsis</h2>
<pre class="synopsis">
<a href="PangoEngineShape.html#PangoEngineShape-struct">PangoEngineShape</a>;
<a href="PangoEngineShape.html#PangoEngineShapeClass">PangoEngineShapeClass</a>;
#define <a href="PangoEngineShape.html#PANGO-ENGINE-TYPE-SHAPE:CAPS">PANGO_ENGINE_TYPE_SHAPE</a>
#define <a href="PangoEngineShape.html#PANGO-ENGINE-SHAPE-DEFINE-TYPE:CAPS">PANGO_ENGINE_SHAPE_DEFINE_TYPE</a> (name, prefix, class_init, instance_init)
</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>
+----<a href="pango-Engines.html#PangoEngine">PangoEngine</a>
+----PangoEngineShape
</pre>
</div>
<div class="refsect1" lang="en">
<a name="desc"></a><h2>Description</h2>
<p>
The <em class="firstterm">shape engines</em> are rendering-system dependent
engines that convert character strings into glyph strings.
These engines are used in <a href="pango-Text-Processing.html#pango-shape"><code class="function">pango_shape()</code></a>.
</p>
</div>
<div class="refsect1" lang="en">
<a name="details"></a><h2>Details</h2>
<div class="refsect2" lang="en">
<a name="id2911338"></a><h3>
<a name="PangoEngineShape-struct"></a>PangoEngineShape</h3>
<a class="indexterm" name="id2911349"></a><pre class="programlisting">typedef struct _PangoEngineShape PangoEngineShape;</pre>
<p>
The <a href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> class is implemented by engines that
customize the rendering-system dependent part of the
Pango pipeline for a particular script or language.
A <a href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> implementation is then specific to both
a particular rendering system or group of rendering systems
and to a particular script. For instance, there is one
<a href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> implementation to handle shaping Arabic
for Fontconfig-based backends.</p>
<p>
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2911399"></a><h3>
<a name="PangoEngineShapeClass"></a>PangoEngineShapeClass</h3>
<a class="indexterm" name="id2911412"></a><pre class="programlisting">typedef struct {
void (*script_shape) (PangoEngineShape *engine,
PangoFont *font,
const char *text,
int length,
const PangoAnalysis *analysis,
PangoGlyphString *glyphs);
PangoCoverageLevel (*covers) (PangoEngineShape *engine,
PangoFont *font,
PangoLanguage *language,
gunichar wc);
} PangoEngineShapeClass;
</pre>
<p>
Class structure for <a href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a></p>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td>
<span class="term"><em class="structfield"><code>script_shape</code></em> ()</span></td>
<td> Given a font, a piece of text, and a <a href="pango-Text-Processing.html#PangoAnalysis"><span class="type">PangoAnalysis</span></a>
structure, converts characters to glyphs and positions the
resulting glyphs. The results are stored in the <a href="pango-Glyph-Storage.html#PangoGlyphString"><span class="type">PangoGlyphString</span></a>
that is passed in. (The implementation should resize it
appropriately using <a href="pango-Glyph-Storage.html#pango-glyph-string-set-size"><code class="function">pango_glyph_string_set_size()</code></a>). All fields
of the <em class="parameter"><code>log_clusters</code></em> and <em class="parameter"><code>glyphs</code></em> array must be filled in, with
the exception that Pango will automatically generate
<code class="literal">glyphs->glyphs[i].attr.is_cluster_start</code>
using the <em class="parameter"><code>log_clusters</code></em> array. Each input character must occur in one
of the output logical clusters;
if no rendering is desired for a character, this may involve
inserting glyphs with the <a href="pango-Glyph-Storage.html#PangoGlyph"><span class="type">PangoGlyph</span></a> ID <a href="pango-Glyph-Storage.html#PANGO-GLYPH-EMPTY:CAPS"><span class="type">PANGO_GLYPH_EMPTY</span></a>, which
is guaranteed never to render. If the shaping fails for any reason,
the shaper should return with an empty (zero-size) glyph string.
If the shaper has not set the size on the glyph string yet, simply
returning signals the failure too.
</td>
</tr>
<tr>
<td>
<span class="term"><em class="structfield"><code>covers</code></em> ()</span></td>
<td> Returns the characters that this engine can cover
with a given font for a given language. If not overridden, the default
implementation simply returns the coverage information for the
font itself unmodified.
</td>
</tr>
</tbody>
</table></div>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2911561"></a><h3>
<a name="PANGO-ENGINE-TYPE-SHAPE:CAPS"></a>PANGO_ENGINE_TYPE_SHAPE</h3>
<a class="indexterm" name="id2911575"></a><pre class="programlisting">#define PANGO_ENGINE_TYPE_SHAPE "PangoEngineShape"
</pre>
<p>
A string constant defining the engine type
for shaping engines.
These engines derive from <a href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a>.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2911600"></a><h3>
<a name="PANGO-ENGINE-SHAPE-DEFINE-TYPE:CAPS"></a>PANGO_ENGINE_SHAPE_DEFINE_TYPE()</h3>
<a class="indexterm" name="id2911613"></a><pre class="programlisting">#define PANGO_ENGINE_SHAPE_DEFINE_TYPE(name, prefix, class_init, instance_init)</pre>
<p>
Outputs the necessary code for GObject type registration for a
<a href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> class defined in a module. Two static symbols
are defined.
</p>
<p>
</p>
<pre class="programlisting">
static GType <em class="replaceable"><code>prefix</code></em>_type;
static void <em class="replaceable"><code>prefix</code></em>_register_type (GTypeModule module);
</pre>
<p>
</p>
<p>
The <code class="function"><em class="replaceable"><code>prefix</code></em>, <code class="function">_register_type()</code></code>
function should be called in your <a href="pango-Engines.html#script-engine-init"><code class="function">script_engine_init()</code></a> function for
each type that your module implements, and then your <a href="pango-Engines.html#script-engine-create"><code class="function">script_engine_create()</code></a>
function can create instances of the object as follows:
</p>
<p>
</p>
<div class="informalexample"><pre class="programlisting">
PangoEngine *engine = g_object_new (<em class="replaceable"><code>prefix</code></em>_type, NULL);
</pre></div>
<p>
</p>
<div class="variablelist"><table border="0">
<col align="left" valign="top">
<tbody>
<tr>
<td>
<span class="term"><em class="parameter"><code>name</code></em> :</span></td>
<td> Name of the the type to register (for example:, <code class="literal">ArabicEngineFc</code>
</td>
</tr>
<tr>
<td>
<span class="term"><em class="parameter"><code>prefix</code></em> :</span></td>
<td> Prefix for symbols that will be defined (for example:, <code class="literal">arabic_engine_fc</code>
</td>
</tr>
<tr>
<td>
<span class="term"><em class="parameter"><code>class_init</code></em> :</span></td>
<td> Class initialization function for the new type, or <a
href="../glib/glib-Standard-Macros.html#NULL:CAPS"
><code class="literal">NULL</code></a>
</td>
</tr>
<tr>
<td>
<span class="term"><em class="parameter"><code>instance_init</code></em> :</span></td>
<td> Instance initialization function for the new type, or <a
href="../glib/glib-Standard-Macros.html#NULL:CAPS"
><code class="literal">NULL</code></a>
</td>
</tr>
</tbody>
</table></div>
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