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  44 <a href="#PangoEngineShape.synopsis" class="shortcut">Top</a>
  45                  |
  46                 <a href="#PangoEngineShape.description" class="shortcut">Description</a>
  47                  |
  48                 <a href="#PangoEngineShape.object-hierarchy" class="shortcut">Object Hierarchy</a>
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  51 <div class="refentry" lang="en">
  52 <a name="PangoEngineShape"></a><div class="titlepage"></div>
  53 <div class="refnamediv"><table width="100%"><tr>
  54 <td valign="top">
  55 <h2><span class="refentrytitle"><a name="PangoEngineShape.top_of_page"></a>PangoEngineShape</span></h2>
  56 <p>PangoEngineShape — Rendering-system dependent script engines</p>
  57 </td>
  58 <td valign="top" align="right"></td>
  59 </tr></table></div>
  60 <div class="refsect1" lang="en">
  61 <a name="PangoEngineShape.stability-level"></a><h2>Stability Level</h2>
  62 Unstable, unless otherwise indicated
  63 </div>
  64 <div class="refsynopsisdiv">
  65 <a name="PangoEngineShape.synopsis"></a><h2>Synopsis</h2>
  66 <pre class="synopsis">
  67                     <a class="link" href="PangoEngineShape.html#PangoEngineShape-struct" title="PangoEngineShape">PangoEngineShape</a>;
  68                     <a class="link" href="PangoEngineShape.html#PangoEngineShapeClass" title="PangoEngineShapeClass">PangoEngineShapeClass</a>;
  69 #define             <a class="link" href="PangoEngineShape.html#PANGO-ENGINE-TYPE-SHAPE--CAPS" title="PANGO_ENGINE_TYPE_SHAPE">PANGO_ENGINE_TYPE_SHAPE</a>
  70 #define             <a class="link" href="PangoEngineShape.html#PANGO-ENGINE-SHAPE-DEFINE-TYPE--CAPS" title="PANGO_ENGINE_SHAPE_DEFINE_TYPE()">PANGO_ENGINE_SHAPE_DEFINE_TYPE</a>      (name, prefix, class_init, instance_init)
  71 </pre>
  72 </div>
  73 <div class="refsect1" lang="en">
  74 <a name="PangoEngineShape.object-hierarchy"></a><h2>Object Hierarchy</h2>
  75 <pre class="synopsis">
  76   <a
  77 href="http://library.gnome.org/devel/gobject/unstable/gobject-The-Base-Object-Type.html#GObject"
  78 >GObject</a>
  79    +----<a class="link" href="pango-Engines.html#PangoEngine">PangoEngine</a>
  80          +----PangoEngineShape
  81 </pre>
  82 </div>
  83 <div class="refsect1" lang="en">
  84 <a name="PangoEngineShape.description"></a><h2>Description</h2>
  85 <p>
  86 The <em class="firstterm">shape engines</em> are rendering-system dependent
  87 engines that convert character strings into glyph strings.
  88 These engines are used in <a class="link" href="pango-Text-Processing.html#pango-shape" title="pango_shape ()"><code class="function">pango_shape()</code></a>.
  89 </p>
  90 </div>
  91 <div class="refsect1" lang="en">
  92 <a name="PangoEngineShape.details"></a><h2>Details</h2>
  93 <div class="refsect2" lang="en">
  94 <a name="PangoEngineShape-struct"></a><h3>PangoEngineShape</h3>
  95 <pre class="programlisting">typedef struct _PangoEngineShape PangoEngineShape;</pre>
  96 <p>
  97 The <a class="link" href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> class is implemented by engines that
  98 customize the rendering-system dependent part of the
  99 Pango pipeline for a particular script or language.
 100 A <a class="link" href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> implementation is then specific to both
 101 a particular rendering system or group of rendering systems
 102 and to a particular script. For instance, there is one
 103 <a class="link" href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> implementation to handle shaping Arabic
 104 for Fontconfig-based backends.</p>
 105 <p>
 106 </p>
 107 </div>
 108 <hr>
 109 <div class="refsect2" lang="en">
 110 <a name="PangoEngineShapeClass"></a><h3>PangoEngineShapeClass</h3>
 111 <pre class="programlisting">typedef struct {
 112   void (*script_shape) (PangoEngineShape *engine,
 113                         PangoFont        *font,
 114                         const char       *text,
 115                         int               length,
 116                         const PangoAnalysis *analysis,
 117                         PangoGlyphString *glyphs);
 118   PangoCoverageLevel (*covers)   (PangoEngineShape *engine,
 119                                   PangoFont        *font,
 120                                   PangoLanguage    *language,
 121                                   gunichar          wc);
 122 } PangoEngineShapeClass;
 123 </pre>
 124 <p>
 125 Class structure for <a class="link" href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a></p>
 126 <p>
 127 </p>
 128 <div class="variablelist"><table border="0">
 129 <col align="left" valign="top">
 130 <tbody>
 131 <tr>
 132 <td><p><span class="term"><em class="structfield"><code>script_shape</code></em> ()</span></p></td>
 133 <td> Given a font, a piece of text, and a <a class="link" href="pango-Text-Processing.html#PangoAnalysis" title="PangoAnalysis"><span class="type">PangoAnalysis</span></a>
 134   structure, converts characters to glyphs and positions the
 135   resulting glyphs. The results are stored in the <a class="link" href="pango-Glyph-Storage.html#PangoGlyphString" title="PangoGlyphString"><span class="type">PangoGlyphString</span></a>
 136   that is passed in. (The implementation should resize it
 137   appropriately using <a class="link" href="pango-Glyph-Storage.html#pango-glyph-string-set-size" title="pango_glyph_string_set_size ()"><code class="function">pango_glyph_string_set_size()</code></a>). All fields
 138   of the <em class="parameter"><code>log_clusters</code></em> and <em class="parameter"><code>glyphs</code></em> array must be filled in, with
 139   the exception that Pango will automatically generate
 140   <code class="literal">glyphs-&gt;glyphs[i].attr.is_cluster_start</code>
 141   using the <em class="parameter"><code>log_clusters</code></em> array. Each input character must occur in one
 142   of the output logical clusters;
 143   if no rendering is desired for a character, this may involve
 144   inserting glyphs with the <a class="link" href="pango-Glyph-Storage.html#PangoGlyph" title="PangoGlyph"><span class="type">PangoGlyph</span></a> ID <a class="link" href="pango-Glyph-Storage.html#PANGO-GLYPH-EMPTY--CAPS" title="PANGO_GLYPH_EMPTY"><span class="type">PANGO_GLYPH_EMPTY</span></a>, which
 145   is guaranteed never to render. If the shaping fails for any reason,
 146   the shaper should return with an empty (zero-size) glyph string.
 147   If the shaper has not set the size on the glyph string yet, simply
 148   returning signals the failure too.
 149 </td>
 150 </tr>
 151 <tr>
 152 <td><p><span class="term"><em class="structfield"><code>covers</code></em> ()</span></p></td>
 153 <td> Returns the characters that this engine can cover
 154   with a given font for a given language. If not overridden, the default
 155   implementation simply returns the coverage information for the
 156   font itself unmodified.
 157 </td>
 158 </tr>
 159 </tbody>
 160 </table></div>
 161 </div>
 162 <hr>
 163 <div class="refsect2" lang="en">
 164 <a name="PANGO-ENGINE-TYPE-SHAPE--CAPS"></a><h3>PANGO_ENGINE_TYPE_SHAPE</h3>
 165 <pre class="programlisting">#define PANGO_ENGINE_TYPE_SHAPE "PangoEngineShape"
 166 </pre>
 167 <p>
 168 A string constant defining the engine type
 169 for shaping engines.
 170 These engines derive from <a class="link" href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a>.
 171 </p>
 172 </div>
 173 <hr>
 174 <div class="refsect2" lang="en">
 175 <a name="PANGO-ENGINE-SHAPE-DEFINE-TYPE--CAPS"></a><h3>PANGO_ENGINE_SHAPE_DEFINE_TYPE()</h3>
 176 <pre class="programlisting">#define             PANGO_ENGINE_SHAPE_DEFINE_TYPE(name, prefix, class_init, instance_init)</pre>
 177 <p>
 178 Outputs the necessary code for GObject type registration for a
 179 <a class="link" href="PangoEngineShape.html" title="PangoEngineShape"><span class="type">PangoEngineShape</span></a> class defined in a module. Two static symbols
 180 are defined.
 181 </p>
 182 <p>
 183 </p>
 184 <pre class="programlisting">
 185  static GType <em class="replaceable"><code>prefix</code></em>_type;
 186  static void <em class="replaceable"><code>prefix</code></em>_register_type (GTypeModule module);
 187 </pre>
 188 <p>
 189 </p>
 190 <p>
 191 The <code class="function"><em class="replaceable"><code>prefix</code></em>, <code class="function">_register_type()</code></code>
 192 function should be called in your <a class="link" href="pango-Engines.html#script-engine-init" title="script_engine_init ()"><code class="function">script_engine_init()</code></a> function for
 193 each type that your module implements, and then your <a class="link" href="pango-Engines.html#script-engine-create" title="script_engine_create ()"><code class="function">script_engine_create()</code></a>
 194 function can create instances of the object as follows:
 195 </p>
 196 <p>
 197 </p>
 198 <div class="informalexample"><pre class="programlisting">
 199  PangoEngine *engine = g_object_new (<em class="replaceable"><code>prefix</code></em>_type, NULL);
 200 </pre></div>
 201 <p>
 202 </p>
 203 <div class="variablelist"><table border="0">
 204 <col align="left" valign="top">
 205 <tbody>
 206 <tr>
 207 <td><p><span class="term"><em class="parameter"><code>name</code></em> :</span></p></td>
 208 <td> Name of the the type to register (for example:, <code class="literal">ArabicEngineFc</code>
 209 </td>
 210 </tr>
 211 <tr>
 212 <td><p><span class="term"><em class="parameter"><code>prefix</code></em> :</span></p></td>
 213 <td> Prefix for symbols that will be defined (for example:, <code class="literal">arabic_engine_fc</code>
 214 </td>
 215 </tr>
 216 <tr>
 217 <td><p><span class="term"><em class="parameter"><code>class_init</code></em> :</span></p></td>
 218 <td> Class initialization function for the new type, or <a
 219 href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL--CAPS"
 220 ><code class="literal">NULL</code></a>
 221 </td>
 222 </tr>
 223 <tr>
 224 <td><p><span class="term"><em class="parameter"><code>instance_init</code></em> :</span></p></td>
 225 <td> Instance initialization function for the new type, or <a
 226 href="http://library.gnome.org/devel/glib/unstable/glib-Standard-Macros.html#NULL--CAPS"
 227 ><code class="literal">NULL</code></a>
 228 </td>
 229 </tr>
 230 </tbody>
 231 </table></div>
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