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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-buildapp-populating-window"></a>Populating the window</h2></div></div></div>


<p>
In this step, we use a <code class="classname">Gtk::Builder</code> instance to associate a
<code class="classname">Gtk::Builder</code> ui file with our application window class.
</p>

<p>
Our simple ui file gives the window a title, and puts a <code class="classname">Gtk::Stack</code>
widget as the main content.
</p>

<p>
To make use of this file in our application, we revisit our
<code class="classname">Gtk::ApplicationWindow</code> subclass, and call
<code class="methodname">Gtk::Builder::create_from_resource()</code> and
<code class="methodname">Gtk::Builder::get_widget_derived()</code> from the
<code class="methodname">ExampleAppWindow::create()</code> method to get an instance of
our subclassed <code class="classname">Gtk::ApplicationWindow</code>. See the
<a class="link" href="sec-builder-using-derived-widgets.html" title="Using derived widgets">Using derived widgets</a> section
for more information about <code class="methodname">get_widget_derived()</code>.
</p>

<p>
You may have noticed that we use the <code class="methodname">_from_resource()</code> variant
of the method that reads the ui file. Now we need to use <span class="application">GLib</span>'s
resource functionality to include the ui file in the binary. This is commonly done by
listing all resources in a .gresource.xml file.
This file has to be converted into a C source file that will be compiled and linked
into the application together with the other source files. To do so, we use the
<span class="application">glib-compile-resources</span> utility:
</p>
<pre class="screen">$ glib-compile-resources --target=resources.c --generate-source exampleapp.gresource.xml</pre>
<p>
The <a class="link" href="sec-gio-resource.html" title="Gio::Resource and glib-compile-resources">Gio::Resource and glib-compile-resources</a>
section contains more information about resource files. If you build with Meson,
use the <code class="function">compile_resources()</code> function in Meson's
<a class="ulink" href="https://mesonbuild.com/Gnome-module.html" target="_top">GNOME module</a>.
</p>

<p>
Our application now looks like this:
</p>

<div class="figure">
<a name="figure-buildapp-populating-window"></a><p class="title"><b>Figure 31.2. Populating the window</b></p>
<div class="figure-contents">
  
  <div class="screenshot">
    <div class="mediaobject"><img src="figures/buildapp_populating_window.png" alt="Populating the window"></div>
  </div>
</div>
</div>
<br class="figure-break">

<p><a class="ulink" href="https://gitlab.gnome.org/GNOME/gtkmm-documentation/tree/master/examples/book/buildapp/step2" target="_top">Source Code</a></p>

<p>File: <code class="filename">exampleapplication.h</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "../step1/exampleapplication.h"
// Equal to the corresponding file in step1
</code></pre>
<p>File: <code class="filename">exampleappwindow.h</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#ifndef GTKMM_EXAMPLEAPPWINDOW_H_
#define GTKMM_EXAMPLEAPPWINDOW_H_

#include &lt;gtkmm.h&gt;

class ExampleAppWindow : public Gtk::ApplicationWindow
{
public:
  ExampleAppWindow(BaseObjectType* cobject,
    const Glib::RefPtr&lt;Gtk::Builder&gt;&amp; refBuilder);

  static ExampleAppWindow* create();

  void open_file_view(const Glib::RefPtr&lt;Gio::File&gt;&amp; file);

protected:
  Glib::RefPtr&lt;Gtk::Builder&gt; m_refBuilder;
};

#endif /* GTKMM_EXAMPLEAPPWINDOW_H */
</code></pre>
<p>File: <code class="filename">exampleapplication.cc</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "exampleapplication.h"
#include "exampleappwindow.h"
#include &lt;iostream&gt;
#include &lt;exception&gt;

ExampleApplication::ExampleApplication()
: Gtk::Application("org.gtkmm.examples.application", Gio::Application::Flags::HANDLES_OPEN)
{
}

Glib::RefPtr&lt;ExampleApplication&gt; ExampleApplication::create()
{
  return Glib::make_refptr_for_instance&lt;ExampleApplication&gt;(new ExampleApplication());
}

ExampleAppWindow* ExampleApplication::create_appwindow()
{
  auto appwindow = ExampleAppWindow::create();

  // Make sure that the application runs for as long this window is still open.
  add_window(*appwindow);

  // A window can be added to an application with Gtk::Application::add_window()
  // or Gtk::Window::set_application(). When all added windows have been hidden
  // or removed, the application stops running (Gtk::Application::run() returns()),
  // unless Gio::Application::hold() has been called.

  // Delete the window when it is hidden.
  appwindow-&gt;signal_hide().connect([appwindow](){ delete appwindow; });

  return appwindow;
}

void ExampleApplication::on_activate()
{
  try
  {
    // The application has been started, so let's show a window.
    auto appwindow = create_appwindow();
    appwindow-&gt;present();
  }
  // If create_appwindow() throws an exception (perhaps from Gtk::Builder),
  // no window has been created, no window has been added to the application,
  // and therefore the application will stop running.
  catch (const Glib::Error&amp; ex)
  {
    std::cerr &lt;&lt; "ExampleApplication::on_activate(): " &lt;&lt; ex.what() &lt;&lt; std::endl;
  }
  catch (const std::exception&amp; ex)
  {
    std::cerr &lt;&lt; "ExampleApplication::on_activate(): " &lt;&lt; ex.what() &lt;&lt; std::endl;
  }
}

void ExampleApplication::on_open(const Gio::Application::type_vec_files&amp; files,
  const Glib::ustring&amp; /* hint */)
{
  // The application has been asked to open some files,
  // so let's open a new view for each one.
  ExampleAppWindow* appwindow = nullptr;
  auto windows = get_windows();
  if (windows.size() &gt; 0)
    appwindow = dynamic_cast&lt;ExampleAppWindow*&gt;(windows[0]);

  try
  {
    if (!appwindow)
      appwindow = create_appwindow();

    for (const auto&amp; file : files)
      appwindow-&gt;open_file_view(file);

    appwindow-&gt;present();
  }
  catch (const Glib::Error&amp; ex)
  {
    std::cerr &lt;&lt; "ExampleApplication::on_open(): " &lt;&lt; ex.what() &lt;&lt; std::endl;
  }
  catch (const std::exception&amp; ex)
  {
    std::cerr &lt;&lt; "ExampleApplication::on_open(): " &lt;&lt; ex.what() &lt;&lt; std::endl;
  }
}
</code></pre>
<p>File: <code class="filename">exampleappwindow.cc</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "exampleappwindow.h"
#include &lt;stdexcept&gt;

ExampleAppWindow::ExampleAppWindow(BaseObjectType* cobject,
  const Glib::RefPtr&lt;Gtk::Builder&gt;&amp; refBuilder)
: Gtk::ApplicationWindow(cobject),
  m_refBuilder(refBuilder)
{
}

//static
ExampleAppWindow* ExampleAppWindow::create()
{
  // Load the Builder file and instantiate its widgets.
  auto refBuilder = Gtk::Builder::create_from_resource("/org/gtkmm/exampleapp/window.ui");

  auto window = Gtk::Builder::get_widget_derived&lt;ExampleAppWindow&gt;(refBuilder, "app_window");
  if (!window)
    throw std::runtime_error("No \"app_window\" object in window.ui");

  return window;
}

void ExampleAppWindow::open_file_view(const Glib::RefPtr&lt;Gio::File&gt;&amp; /* file */)
{
}
</code></pre>
<p>File: <code class="filename">main.cc</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "../step1/main.cc"
// Equal to the corresponding file in step1
</code></pre>
<p>File: <code class="filename">exampleapp.gresource.xml</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;gresources&gt;
  &lt;gresource prefix="/org/gtkmm/exampleapp"&gt;
    &lt;file preprocess="xml-stripblanks"&gt;window.ui&lt;/file&gt;
  &lt;/gresource&gt;
&lt;/gresources&gt;
</code></pre>
<p>File: <code class="filename">window.ui</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">&lt;?xml version="1.0" encoding="UTF-8"?&gt;
&lt;interface&gt;
  &lt;object class="GtkApplicationWindow" id="app_window"&gt;
    &lt;property name="title" translatable="yes"&gt;Example Application&lt;/property&gt;
    &lt;property name="default-width"&gt;600&lt;/property&gt;
    &lt;property name="default-height"&gt;400&lt;/property&gt;
    &lt;property name="hide-on-close"&gt;True&lt;/property&gt;
    &lt;child&gt;
      &lt;object class="GtkBox" id="content_box"&gt;
        &lt;property name="orientation"&gt;vertical&lt;/property&gt;
        &lt;child&gt;
          &lt;object class="GtkStack" id="stack"/&gt;
        &lt;/child&gt;
      &lt;/object&gt;
    &lt;/child&gt;
  &lt;/object&gt;
&lt;/interface&gt;
</code></pre>


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