glib-the-main-event-loop.html

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                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> data,
                                                         <a class="link" href="glib-Datasets.html#GDestroyNotify">GDestroyNotify</a> notify);

                    <a class="link" href="glib-The-Main-Event-Loop.html#GPollFD">GPollFD</a>;

                    <a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a>;
void                (<a class="link" href="glib-The-Main-Event-Loop.html#GSourceDummyMarshal">*GSourceDummyMarshal</a>)              (void);
                    <a class="link" href="glib-The-Main-Event-Loop.html#GSourceFuncs">GSourceFuncs</a>;
                    <a class="link" href="glib-The-Main-Event-Loop.html#GSourceCallbackFuncs">GSourceCallbackFuncs</a>;
<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a>*            <a class="link" href="glib-The-Main-Event-Loop.html#g-source-new">g_source_new</a>                        (<a class="link" href="glib-The-Main-Event-Loop.html#GSourceFuncs">GSourceFuncs</a> *source_funcs,
                                                         <a class="link" href="glib-Basic-Types.html#guint">guint</a> struct_size);
<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a>*            <a class="link" href="glib-The-Main-Event-Loop.html#g-source-ref">g_source_ref</a>                        (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-unref">g_source_unref</a>                      (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-set-funcs">g_source_set_funcs</a>                  (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-The-Main-Event-Loop.html#GSourceFuncs">GSourceFuncs</a> *funcs);
<a class="link" href="glib-Basic-Types.html#guint">guint</a>               <a class="link" href="glib-The-Main-Event-Loop.html#g-source-attach">g_source_attach</a>                     (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-The-Main-Event-Loop.html#GMainContext">GMainContext</a> *context);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-destroy">g_source_destroy</a>                    (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
<a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            <a class="link" href="glib-The-Main-Event-Loop.html#g-source-is-destroyed">g_source_is_destroyed</a>               (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-set-priority">g_source_set_priority</a>               (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-Basic-Types.html#gint">gint</a> priority);
<a class="link" href="glib-Basic-Types.html#gint">gint</a>                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-get-priority">g_source_get_priority</a>               (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-set-can-recurse">g_source_set_can_recurse</a>            (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a> can_recurse);
<a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            <a class="link" href="glib-The-Main-Event-Loop.html#g-source-get-can-recurse">g_source_get_can_recurse</a>            (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
<a class="link" href="glib-Basic-Types.html#guint">guint</a>               <a class="link" href="glib-The-Main-Event-Loop.html#g-source-get-id">g_source_get_id</a>                     (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
<a class="link" href="glib-The-Main-Event-Loop.html#GMainContext">GMainContext</a>*       <a class="link" href="glib-The-Main-Event-Loop.html#g-source-get-context">g_source_get_context</a>                (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-set-callback">g_source_set_callback</a>               (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-The-Main-Event-Loop.html#GSourceFunc">GSourceFunc</a> func,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> data,
                                                         <a class="link" href="glib-Datasets.html#GDestroyNotify">GDestroyNotify</a> notify);
<a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            (<a class="link" href="glib-The-Main-Event-Loop.html#GSourceFunc">*GSourceFunc</a>)                      (<a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> data);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-set-callback-indirect">g_source_set_callback_indirect</a>      (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> callback_data,
                                                         <a class="link" href="glib-The-Main-Event-Loop.html#GSourceCallbackFuncs">GSourceCallbackFuncs</a> *callback_funcs);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-add-poll">g_source_add_poll</a>                   (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-The-Main-Event-Loop.html#GPollFD">GPollFD</a> *fd);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-remove-poll">g_source_remove_poll</a>                (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-The-Main-Event-Loop.html#GPollFD">GPollFD</a> *fd);
void                <a class="link" href="glib-The-Main-Event-Loop.html#g-source-get-current-time">g_source_get_current_time</a>           (<a class="link" href="glib-The-Main-Event-Loop.html#GSource">GSource</a> *source,
                                                         <a class="link" href="glib-Date-and-Time-Functions.html#GTimeVal">GTimeVal</a> *timeval);
<a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            <a class="link" href="glib-The-Main-Event-Loop.html#g-source-remove">g_source_remove</a>                     (<a class="link" href="glib-Basic-Types.html#guint">guint</a> tag);
<a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            <a class="link" href="glib-The-Main-Event-Loop.html#g-source-remove-by-funcs-user-data">g_source_remove_by_funcs_user_data</a>  (<a class="link" href="glib-The-Main-Event-Loop.html#GSourceFuncs">GSourceFuncs</a> *funcs,
                                                         <a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> user_data);
<a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a>            <a class="link" href="glib-The-Main-Event-Loop.html#g-source-remove-by-user-data">g_source_remove_by_user_data</a>        (<a class="link" href="glib-Basic-Types.html#gpointer">gpointer</a> user_data);

</pre>
</div>
<div class="refsect1" lang="en">
<a name="id2856540"></a><h2>Description</h2>
<p>
    The main event loop manages all the available sources of events for
    GLib and GTK+ applications. These events can come from any number of
    different types of sources such as file descriptors (plain files,
    pipes or sockets) and timeouts.  New types of event sources can also
    be added using <a class="link" href="glib-The-Main-Event-Loop.html#g-source-attach"><code class="function">g_source_attach()</code></a>.
  </p>
<p>
    To allow multiple independent sets of sources to be handled in
    different threads, each source is associated with a <a class="link" href="glib-The-Main-Event-Loop.html#GMainContext"><span class="type">GMainContext</span></a>.
    A <a class="link" href="glib-The-Main-Event-Loop.html#GMainContext"><span class="type">GMainContext</span></a> can only be running in a single thread, but
    sources can be added to it and removed from it from other threads.
  </p>
<p>
    Each event source is assigned a priority.  The default priority,
    <a class="link" href="glib-The-Main-Event-Loop.html#G-PRIORITY-DEFAULT:CAPS"><span class="type">G_PRIORITY_DEFAULT</span></a>, is 0.  Values less than 0 denote higher
    priorities.  Values greater than 0 denote lower priorities.  Events
    from high priority sources are always processed before events from
    lower priority sources.
  </p>
<p>
    Idle functions can also be added, and assigned a priority. These will
    be run whenever no events with a higher priority are ready to be
    processed.
  </p>
<p>
    The <a class="link" href="glib-The-Main-Event-Loop.html#GMainLoop"><span class="type">GMainLoop</span></a> data type represents a main event loop.  A <a class="link" href="glib-The-Main-Event-Loop.html#GMainLoop"><span class="type">GMainLoop</span></a>
    is created with <a class="link" href="glib-The-Main-Event-Loop.html#g-main-loop-new"><code class="function">g_main_loop_new()</code></a>. After adding the initial event sources,
    <a class="link" href="glib-The-Main-Event-Loop.html#g-main-loop-run"><code class="function">g_main_loop_run()</code></a> is called. This continuously checks for new events from
    each of the event sources and dispatches them.  Finally, the
    processing of an event from one of the sources leads to a call to
    <a class="link" href="glib-The-Main-Event-Loop.html#g-main-loop-quit"><code class="function">g_main_loop_quit()</code></a> to exit the main loop, and <a class="link" href="glib-The-Main-Event-Loop.html#g-main-loop-run"><code class="function">g_main_loop_run()</code></a> returns.
  </p>
<p>
    It is possible to create new instances of <a class="link" href="glib-The-Main-Event-Loop.html#GMainLoop"><span class="type">GMainLoop</span></a> recursively.
    This is often used in GTK+ applications when showing modal dialog
    boxes. Note that event sources are associated with a particular
    <a class="link" href="glib-The-Main-Event-Loop.html#GMainContext"><span class="type">GMainContext</span></a>, and will be checked and dispatched for all main
    loops associated with that <a class="link" href="glib-The-Main-Event-Loop.html#GMainContext"><span class="type">GMainContext</span></a>.
  </p>
<p>
    GTK+ contains wrappers of some of these functions, e.g. <a
href="/usr/share/gtk-doc/html/gtk/gtk-General.html#gtk-main"
><code class="function">gtk_main()</code></a>,
    <a
href="/usr/share/gtk-doc/html/gtk/gtk-General.html#gtk-main-quit"
><code class="function">gtk_main_quit()</code></a> and <a
href="/usr/share/gtk-doc/html/gtk/gtk-General.html#gtk-events-pending"
><code class="function">gtk_events_pending()</code></a>. 
  </p>
<div class="refsect2" lang="en">
<a name="id2856757"></a><h3>Creating new sources types</h3>
<p>
      One of the unusual features of the GTK+ main loop functionality
      is that new types of event source can be created and used in
      addition to the builtin type of event source. A new event source
      type is used for handling GDK events. A new source type is
      created by <em class="firstterm">deriving</em> from the <a class="link" href="glib-The-Main-Event-Loop.html#GSource"><span class="type">GSource</span></a>
      structure. The derived type of source is represented by a
      structure that has the <a class="link" href="glib-The-Main-Event-Loop.html#GSource"><span class="type">GSource</span></a> structure as a first element,
      and other elements specific to the new source type. To create
      an instance of the new source type, call <a class="link" href="glib-The-Main-Event-Loop.html#g-source-new"><code class="function">g_source_new()</code></a> passing
      in the size of the derived structure and a table of functions.
      These <a class="link" href="glib-The-Main-Event-Loop.html#GSourceFuncs"><span class="type">GSourceFuncs</span></a> determine the behavior of the new source
      types.
    </p>
<p>
      New source types basically interact with the main context
      in two ways. Their prepare function in <a class="link" href="glib-The-Main-Event-Loop.html#GSourceFuncs"><span class="type">GSourceFuncs</span></a> can set
      a timeout to determine the maximum amount of time that the
      main loop will sleep before checking the source again.  In
      addition, or as well, the source can add file descriptors to
      the set that the main context checks using <a class="link" href="glib-The-Main-Event-Loop.html#g-source-add-poll"><code class="function">g_source_add_poll()</code></a>.
    </p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2856845"></a><h3>Customizing the main loop iteration</h3>
<p>
      Single iterations of a <a class="link" href="glib-The-Main-Event-Loop.html#GMainContext"><span class="type">GMainContext</span></a> can be run with
      <a class="link" href="glib-The-Main-Event-Loop.html#g-main-context-iteration"><code class="function">g_main_context_iteration()</code></a>. In some cases, more detailed control
      of exactly how the details of the main loop work is desired,
      for instance, when integrating the <a class="link" href="glib-The-Main-Event-Loop.html#GMainLoop"><span class="type">GMainLoop</span></a> with an external
      main loop. In such cases, you can call the component functions
      of <a class="link" href="glib-The-Main-Event-Loop.html#g-main-context-iteration"><code class="function">g_main_context_iteration()</code></a> directly. These functions
      are <a class="link" href="glib-The-Main-Event-Loop.html#g-main-context-prepare"><code class="function">g_main_context_prepare()</code></a>, <a class="link" href="glib-The-Main-Event-Loop.html#g-main-context-query"><code class="function">g_main_context_query()</code></a>,
      <a class="link" href="glib-The-Main-Event-Loop.html#g-main-context-check"><code class="function">g_main_context_check()</code></a> and <a class="link" href="glib-The-Main-Event-Loop.html#g-main-context-dispatch"><code class="function">g_main_context_dispatch()</code></a>.
    </p>
<p>
      The operation of these functions can best be seen in terms
      of a state diagram, as shown in <a class="xref" href="glib-The-Main-Event-Loop.html#mainloop-states" title="Figure&#160;1.&#160;States of a Main Context">Figure&#160;1, &#8220;States of a Main Context&#8221;</a>.
    </p>
<div class="figure">
<a name="mainloop-states"></a><p class="title"><b>Figure&#160;1.&#160;States of a Main Context</b></p>
<div class="figure-contents"><div><img src="mainloop-states.gif" alt="States of a Main Context"></div></div>
</div>
<br class="figure-break">
</div>
</div>
<div class="refsect1" lang="en">
<a name="id2856976"></a><h2>Details</h2>
<div class="refsect2" lang="en">
<a name="id2856986"></a><h3>
<a name="GMainLoop"></a>GMainLoop</h3>
<a class="indexterm" name="id2856998"></a><pre class="programlisting">typedef struct _GMainLoop GMainLoop;</pre>
<p>
The <span class="structname">GMainLoop</span> struct is an opaque data type 
representing the main event loop of a GLib or GTK+ application.
</p>
</div>
<hr>
<div class="refsect2" lang="en">
<a name="id2857019"></a><h3>
<a name="g-main-loop-new"></a>g_main_loop_new ()</h3>
<a class="indexterm" name="id2857032"></a><pre class="programlisting"><a class="link" href="glib-The-Main-Event-Loop.html#GMainLoop">GMainLoop</a>*          g_main_loop_new                     (<a class="link" href="glib-The-Main-Event-Loop.html#GMainContext">GMainContext</a> *context,
                                                         <a class="link" href="glib-Basic-Types.html#gboolean">gboolean</a> is_running);</pre>
<p>
Creates a new <a class="link" href="glib-The-Main-Event-Loop.html#GMainLoop"><span class="type">GMainLoop</span></a> structure.</p>
<p>

</p>
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