pango-engine-lang.xml

GTK+-2.0源码之pango-1.15.6.tar.gz

<refentry id="PangoEngineLang">
<refmeta>
<refentrytitle id="top_of_page">PangoEngineLang</refentrytitle>
<manvolnum>3</manvolnum>
<refmiscinfo>PANGO Library</refmiscinfo>
</refmeta>

<refnamediv>
<refname>PangoEngineLang</refname>
<refpurpose>Rendering-system independent script engines</refpurpose>
<!--[<xref linkend="desc" endterm="desc.title"/>]-->
</refnamediv>

<refsynopsisdiv id="synopsis">
<title id="synopsis.title">Synopsis</title>

<synopsis>



            <link linkend="PangoEngineLang-struct">PangoEngineLang</link>;
            <link linkend="PangoEngineLangClass">PangoEngineLangClass</link>;
#define     <link linkend="PANGO-ENGINE-TYPE-LANG:CAPS">PANGO_ENGINE_TYPE_LANG</link>
#define     <link linkend="PANGO-ENGINE-LANG-DEFINE-TYPE:CAPS">PANGO_ENGINE_LANG_DEFINE_TYPE</link>   (name, prefix, class_init, instance_init)


</synopsis>
</refsynopsisdiv>

<refsect1 id="object_hierarchy">
<title id="object_hierarchy.title">Object Hierarchy</title>
<synopsis>

  <link linkend="GObject">GObject</link>
   +----<link linkend="PangoEngine">PangoEngine</link>
         +----PangoEngineLang
</synopsis>

</refsect1>








<refsect1 id="desc">
<title id="desc.title">Description</title>
<para>
The <firstterm>language engines</firstterm> are rendering-system independent
engines that determine line, word, and character breaks for character strings.
These engines are used in <link linkend="pango-break"><function>pango_break()</function></link>.
</para>
</refsect1>

<refsect1 id="details">
<title id="details.title">Details</title>
<refsect2>
<title><anchor id="PangoEngineLang-struct" role="struct"/>PangoEngineLang</title>
<indexterm><primary>PangoEngineLang</primary></indexterm><programlisting>typedef struct _PangoEngineLang PangoEngineLang;</programlisting>
<para>
The <link linkend="PangoEngineLang"><type>PangoEngineLang</type></link> class is implemented by engines that
customize the rendering-system independent part of the
Pango pipeline for a particular script or language. For
instance, a custom <link linkend="PangoEngineLang"><type>PangoEngineLang</type></link> could be provided for
Thai to implement the dictionary-based word boundary
lookups needed for that language.</para>
<para>
</para></refsect2>
<refsect2>
<title><anchor id="PangoEngineLangClass" role="struct"/>PangoEngineLangClass</title>
<indexterm><primary>PangoEngineLangClass</primary></indexterm><programlisting>typedef struct {
  void (*script_break) (PangoEngineLang *engine,
			const char    *text,
			int            len,
			PangoAnalysis *analysis,
			PangoLogAttr  *attrs,
			int            attrs_len);
} PangoEngineLangClass;
</programlisting>
<para>
Class structure for <link linkend="PangoEngineLang"><type>PangoEngineLang</type></link></para>
<para>

</para><variablelist role="struct">
<varlistentry>
<term><structfield>script_break</structfield>&nbsp;()</term>
<listitem><simpara> Provides a custom implementation of <link linkend="pango-break"><function>pango_break()</function></link>.
If <link linkend="NULL:CAPS"><literal>NULL</literal></link>, <link linkend="pango-default-break"><function>pango_default_break()</function></link> is used instead. If not <link linkend="NULL:CAPS"><literal>NULL</literal></link>, for
Pango versions before 1.16 (module interface version before 1.6.0),
this was called instead of <link linkend="pango-default-break"><function>pango_default_break()</function></link>, but in newer versions,
<link linkend="pango-default-break"><function>pango_default_break()</function></link> is always called and this is called after that to
allow tailoring the breaking results.
</simpara></listitem>
</varlistentry>
</variablelist></refsect2>
<refsect2>
<title><anchor id="PANGO-ENGINE-TYPE-LANG:CAPS" role="macro"/>PANGO_ENGINE_TYPE_LANG</title>
<indexterm><primary>PANGO_ENGINE_TYPE_LANG</primary></indexterm><programlisting>#define PANGO_ENGINE_TYPE_LANG "PangoEngineLang"
</programlisting>
<para>
A string constant defining the engine type
for language engines.
These engines derive from <link linkend="PangoEngineLang"><type>PangoEngineLang</type></link>.
</para></refsect2>
<refsect2>
<title><anchor id="PANGO-ENGINE-LANG-DEFINE-TYPE:CAPS" role="macro"/>PANGO_ENGINE_LANG_DEFINE_TYPE()</title>
<indexterm><primary>PANGO_ENGINE_LANG_DEFINE_TYPE</primary></indexterm><programlisting>#define     PANGO_ENGINE_LANG_DEFINE_TYPE(name, prefix, class_init, instance_init)</programlisting>
<para>
Outputs the necessary code for GObject type registration for a
<link linkend="PangoEngineLang"><type>PangoEngineLang</type></link> class defined in a module. Two static symbols
are defined.
</para>
<para>
<programlisting>
 static GType <replaceable>prefix</replaceable>_type;
 static void <replaceable>prefix</replaceable>_register_type (GTypeModule module);
</programlisting>
</para>
<para>
The <function><replaceable>prefix</replaceable><link linkend="register-type"><function>_register_type()</function></link></function>
function should be called in your <link linkend="script-engine-init"><function>script_engine_init()</function></link> function for
each type that your module implements, and then your <link linkend="script-engine-create"><function>script_engine_create()</function></link>
function can create instances of the object as follows:
</para>
<para>
<informalexample><programlisting>
 PangoEngine *engine = g_object_new (<replaceable>prefix</replaceable>_type, NULL);
</programlisting></informalexample></para>
<para>

</para><variablelist role="params">
<varlistentry><term><parameter>name</parameter>&nbsp;:</term>
<listitem><simpara> Name of the the type to register (for example:, <literal>ArabicEngineFc</literal>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>prefix</parameter>&nbsp;:</term>
<listitem><simpara> Prefix for symbols that will be defined (for example:, <literal>arabic_engine_fc</literal>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>class_init</parameter>&nbsp;:</term>
<listitem><simpara> Class initialization function for the new type, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
<varlistentry><term><parameter>instance_init</parameter>&nbsp;:</term>
<listitem><simpara> Instance initialization function for the new type, or <link linkend="NULL:CAPS"><literal>NULL</literal></link>
</simpara></listitem></varlistentry>
</variablelist></refsect2>

</refsect1>




</refentry>