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<div class="chapter">
<div class="titlepage"><div><div><h2 class="title">
<a name="gtk-migrating-unique-GtkApplication"></a>Migrating from libunique to GApplication or GtkApplication</h2></div></div></div>
<div class="toc"><dl class="toc">
<dt><span class="section"><a href="gtk-migrating-unique-GtkApplication.html#id-1.6.5.5">Uniqueness</a></span></dt>
<dt><span class="section"><a href="ch28s02.html">Commands and Messages</a></span></dt>
</dl></div>
<p>
    libunique offers 'unique application' support as well as ways to
    communicate with a running application instance. This is implemented
    in various ways, either using D-Bus, or socket-based communication.
  </p>
<p>
    Starting with GLib 2.26, D-Bus support has been integrated into GIO
    in the form of GDBus, and <a href="https://developer.gnome.org/gio/unstable/GApplication.html#GApplication-struct"><span class="type">GApplication</span></a> has been added to provide
    the same level of application support as libunique.
  </p>
<div class="example">
<a name="id-1.6.5.4"></a><p class="title"><b>Example 52. A unique application</b></p>
<div class="example-contents">
<p>Here is a simple application using libunique:
  </p>
<div class="informalexample">
  <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
    <tbody>
      <tr>
        <td class="listing_lines" align="right"><pre>1
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        <td class="listing_code"><pre class="programlisting"><span class="type">int</span>
<span class="function">main</span><span class="normal"> </span><span class="symbol">(</span><span class="type">int</span><span class="normal"> argc</span><span class="symbol">,</span><span class="normal"> </span><span class="type">char</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">argv</span><span class="symbol">[])</span>
<span class="cbracket">{</span>
<span class="normal">  </span><span class="usertype">UniqueApp</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">app</span><span class="symbol">;</span>
<span class="normal">  </span><span class="usertype">GtkWidget</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">window</span><span class="symbol">;</span>

<span class="normal">  </span><span class="function"><a href="gtk3-General.html#gtk-init">gtk_init</a></span><span class="normal"> </span><span class="symbol">(&amp;</span><span class="normal">argc</span><span class="symbol">,</span><span class="normal"> </span><span class="symbol">&amp;</span><span class="normal">argv</span><span class="symbol">);</span>

<span class="normal">  app </span><span class="symbol">=</span><span class="normal"> </span><span class="function">unique_app_new</span><span class="normal"> </span><span class="symbol">(</span><span class="string">"org.gtk.TestApplication"</span><span class="symbol">,</span><span class="normal"> <a href="https://developer.gnome.org/glib/unstable/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">);</span>

<span class="normal">  </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="function">unique_app_is_running</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">))</span>
<span class="normal">    </span><span class="cbracket">{</span>
<span class="normal">      </span><span class="usertype">UniqueResponse</span><span class="normal"> response</span><span class="symbol">;</span>

<span class="normal">      response </span><span class="symbol">=</span><span class="normal"> </span><span class="function">unique_app_send_message</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">,</span><span class="normal"> UNIQUE_ACTIVATE</span><span class="symbol">,</span><span class="normal"> <a href="https://developer.gnome.org/glib/unstable/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">);</span>
<span class="normal">      </span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#g-object-unref">g_object_unref</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">);</span>

<span class="normal">      </span><span class="keyword">return</span><span class="normal"> response </span><span class="symbol">==</span><span class="normal"> UNIQUE_RESPONSE_OK </span><span class="symbol">?</span><span class="normal"> </span><span class="number">0</span><span class="normal"> </span><span class="symbol">:</span><span class="normal"> </span><span class="number">1</span><span class="symbol">;</span>
<span class="normal">    </span><span class="cbracket">}</span>

<span class="normal">  window </span><span class="symbol">=</span><span class="normal"> </span><span class="function">create_my_window</span><span class="normal"> </span><span class="symbol">();</span>

<span class="normal">  </span><span class="function">unique_app_watch_window</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">,</span><span class="normal"> </span><span class="function">GTK_WINDOW</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">window</span><span class="symbol">));</span>

<span class="normal">  </span><span class="function"><a href="GtkWidget.html#gtk-widget-show">gtk_widget_show</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">window</span><span class="symbol">);</span>

<span class="normal">  </span><span class="function"><a href="gtk3-General.html#gtk-main">gtk_main</a></span><span class="normal"> </span><span class="symbol">();</span>

<span class="normal">  </span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#g-object-unref">g_object_unref</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">);</span>

<span class="normal">  </span><span class="keyword">return</span><span class="normal"> </span><span class="number">0</span><span class="symbol">;</span>
<span class="cbracket">}</span></pre></td>
      </tr>
    </tbody>
  </table>
</div>

<p>
The same application using GtkApplication:
</p>
<div class="informalexample">
  <table class="listing_frame" border="0" cellpadding="0" cellspacing="0">
    <tbody>
      <tr>
        <td class="listing_lines" align="right"><pre>1
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35</pre></td>
        <td class="listing_code"><pre class="programlisting"><span class="keyword">static</span><span class="normal"> </span><span class="type">void</span>
<span class="function">activate</span><span class="normal"> </span><span class="symbol">(</span><span class="usertype">GtkApplication</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">app</span><span class="symbol">)</span>
<span class="cbracket">{</span>
<span class="normal">  </span><span class="usertype">GList</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">list</span><span class="symbol">;</span>
<span class="normal">  </span><span class="usertype">GtkWidget</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">window</span><span class="symbol">;</span>

<span class="normal">  list </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkApplication.html#gtk-application-get-windows">gtk_application_get_windows</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">);</span>

<span class="normal">  </span><span class="keyword">if</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">list</span><span class="symbol">)</span>
<span class="normal">    </span><span class="cbracket">{</span>
<span class="normal">      </span><span class="function"><a href="GtkWindow.html#gtk-window-present">gtk_window_present</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">GTK_WINDOW</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">list</span><span class="symbol">-&gt;</span><span class="normal">data</span><span class="symbol">));</span>
<span class="normal">    </span><span class="cbracket">}</span>
<span class="normal">  </span><span class="keyword">else</span>
<span class="normal">    </span><span class="cbracket">{</span>
<span class="normal">      window </span><span class="symbol">=</span><span class="normal"> </span><span class="function">create_my_window</span><span class="normal"> </span><span class="symbol">();</span>
<span class="normal">      </span><span class="function"><a href="GtkWindow.html#gtk-window-set-application">gtk_window_set_application</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">GTK_WINDOW</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">window</span><span class="symbol">),</span><span class="normal"> app</span><span class="symbol">);</span>
<span class="normal">      </span><span class="function"><a href="GtkWidget.html#gtk-widget-show">gtk_widget_show</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">window</span><span class="symbol">);</span>
<span class="normal">    </span><span class="cbracket">}</span>
<span class="cbracket">}</span>

<span class="type">int</span>
<span class="function">main</span><span class="normal"> </span><span class="symbol">(</span><span class="type">int</span><span class="normal"> argc</span><span class="symbol">,</span><span class="normal"> </span><span class="type">char</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">argv</span><span class="symbol">[])</span>
<span class="cbracket">{</span>
<span class="normal">  </span><span class="usertype">GtkApplication</span><span class="normal"> </span><span class="symbol">*</span><span class="normal">app</span><span class="symbol">;</span>
<span class="normal">  </span><span class="usertype">gint</span><span class="normal"> status</span><span class="symbol">;</span>

<span class="normal">  app </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="GtkApplication.html#gtk-application-new">gtk_application_new</a></span><span class="normal"> </span><span class="symbol">(</span><span class="string">"org.gtk.TestApplication"</span><span class="symbol">,</span><span class="normal"> </span><span class="number">0</span><span class="symbol">);</span>
<span class="normal">  </span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Signals.html#g-signal-connect">g_signal_connect</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">,</span><span class="normal"> </span><span class="string">"activate"</span><span class="symbol">,</span><span class="normal"> </span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-Closures.html#G-CALLBACK:CAPS">G_CALLBACK</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">activate</span><span class="symbol">),</span><span class="normal"> <a href="https://developer.gnome.org/glib/unstable/glib-Standard-Macros.html#NULL:CAPS">NULL</a></span><span class="symbol">);</span>

<span class="normal">  status </span><span class="symbol">=</span><span class="normal"> </span><span class="function"><a href="https://developer.gnome.org/gio/unstable/GApplication.html#g-application-run">g_application_run</a></span><span class="normal"> </span><span class="symbol">(</span><span class="function">G_APPLICATION</span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">),</span><span class="normal"> argc</span><span class="symbol">,</span><span class="normal"> argv</span><span class="symbol">);</span>

<span class="normal">  </span><span class="function"><a href="https://developer.gnome.org/gobject/unstable/gobject-The-Base-Object-Type.html#g-object-unref">g_object_unref</a></span><span class="normal"> </span><span class="symbol">(</span><span class="normal">app</span><span class="symbol">);</span>

<span class="normal">  </span><span class="keyword">return</span><span class="normal"> status</span><span class="symbol">;</span>
<span class="cbracket">}</span></pre></td>
      </tr>
    </tbody>
  </table>
</div>

<p>
</p>
</div>
</div>
<br class="example-break"><div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="id-1.6.5.5"></a>Uniqueness</h2></div></div></div>
<p>
      Instead of creating a UniqueApp with unique_app_new(), create
      a <a href="https://developer.gnome.org/gio/unstable/GApplication.html#GApplication-struct"><span class="type">GApplication</span></a> with <a href="https://developer.gnome.org/gio/unstable/GApplication.html#g-application-new"><code class="function">g_application_new()</code></a> or a <a class="link" href="GtkApplication.html" title="GtkApplication"><span class="type">GtkApplication</span></a>
      with <a class="link" href="GtkApplication.html#gtk-application-new" title="gtk_application_new ()"><code class="function">gtk_application_new()</code></a>. The <em class="parameter"><code>name</code></em> that was used with
      <code class="function">unique_app_new()</code> is very likely usable as the <em class="parameter"><code>application_id</code></em> for
      <a href="https://developer.gnome.org/gio/unstable/GApplication.html#g-application-new"><code class="function">g_application_new()</code></a> without any changes, and GtkApplication passes
      the <code class="envar">DESKTOP_STARTUP_ID</code> environment variable
      automatically.
    </p>
<p>
      While libunique expects you to check for an already running instance
      yourself and activate it manually, GApplication handles all this on
      its own in <a href="https://developer.gnome.org/gio/unstable/GApplication.html#g-application-run"><code class="function">g_application_run()</code></a>. If you still need to find out if there
      is a running instance of your application, use
      <a href="https://developer.gnome.org/gio/unstable/GApplication.html#g-application-get-is-remote"><code class="function">g_application_get_is_remote()</code></a> instead of <code class="function">unique_app_is_running()</code>.
    </p>
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