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<div class="sect1" title="Accessing widgets">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-builder-accessing-widgets"></a>Accessing widgets</h2></div></div></div>
<p>
To access a widget, for instance to <code class="methodname">show()</code> a dialog, use
the <code class="methodname">get_widget()</code> method, providing the widget's name. This
name should be specified in the <span class="application">Glade</span> Properties
window. If the widget could not be found, or is of the wrong type, then the
pointer will be set to 0.
</p>
<pre class="programlisting">
Gtk::Dialog* pDialog = 0;
builder->get_widget("DialogBasic", pDialog);
</pre>
<p>
</p>
<p>
<span class="application">Gtk::Builder</span> checks for a null pointer, and checks
that the widget is of the expected type, and will show warnings on the command
line about these.
</p>
<p>
Remember that you are not instantiating a widget with
<code class="methodname">get_widget()</code>, you are just obtaining a pointer to one that
already exists. You will always receive a pointer to the same instance when you
call <code class="methodname">get_widget()</code> on the same
<code class="classname">Gtk::Builder</code>, with the same widget name. The
widgets are instantiated during <code class="methodname">Gtk::Builder::create()</code>.
</p>
<p>
<code class="methodname">get_widget()</code> returns child widgets that are
<code class="function">manage()</code>ed (see the <a class="link" href="chapter-memory.html" title="Chapter 22. Memory management">Memory
Management</a> chapter), so they will be deleted when their parent
container is deleted. So, if you get only a child widget from
<span class="application">Gtk::Builder</span>, instead of a whole window, then you must
either put it in a <code class="classname">Container</code> or delete it.
<code class="classname">Windows</code> (such as <code class="classname">Dialogs</code>) cannot
be managed because they have no parent container, so you must delete them at
some point.
</p>
<div class="sect2" title="Example">
<div class="titlepage"><div><div><h3 class="title">
<a name="builder-example-loading"></a>Example</h3></div></div></div>
<p>
This simple example shows how to load a <span class="application">Glade</span> file at runtime and access the widgets with
<span class="application">Gtk::Builder</span>.
</p>
<p><a class="ulink" href="http://git.gnome.org/cgit/gtkmm-documentation/tree/examples/book/builder/basic" target="_top">Source Code</a></p>
<p>File: <code class="filename">main.cc</code>
</p>
<pre class="programlisting">
#include <gtkmm.h>
#include <iostream>
Gtk::Dialog* pDialog = 0;
static
void on_button_clicked()
{
if(pDialog)
pDialog->hide(); //hide() will cause main::run() to end.
}
int main (int argc, char **argv)
{
Gtk::Main kit(argc, argv);
//Load the GtkBuilder file and instantiate its widgets:
Glib::RefPtr<Gtk::Builder> refBuilder = Gtk::Builder::create();
#ifdef GLIBMM_EXCEPTIONS_ENABLED
try
{
refBuilder->add_from_file("basic.ui");
}
catch(const Glib::FileError& ex)
{
std::cerr << "FileError: " << ex.what() << std::endl;
return 1;
}
catch(const Gtk::BuilderError& ex)
{
std::cerr << "BuilderError: " << ex.what() << std::endl;
return 1;
}
#else
std::auto_ptr<Glib::Error> error;
if (!refBuilder->add_from_file("basic.ui", error))
{
std::cerr << error->what() << std::endl;
return 1;
}
#endif /* !GLIBMM_EXCEPTIONS_ENABLED */
//Get the GtkBuilder-instantiated Dialog:
refBuilder->get_widget("DialogBasic", pDialog);
if(pDialog)
{
//Get the GtkBuilder-instantiated Button, and connect a signal handler:
Gtk::Button* pButton = 0;
refBuilder->get_widget("quit_button", pButton);
if(pButton)
{
pButton->signal_clicked().connect( sigc::ptr_fun(on_button_clicked) );
}
kit.run(*pDialog);
}
return 0;
}
</pre>
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distrib
>
Mandriva
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2010.0
>
i586
>
media
>
contrib-release
>
by-pkgid
>
345aa895e80053137c21f8693106c3a0
>
files
>
124
