File: sec-buildapp-menu.html

package info (click to toggle)
gtkmm-documentation 4.12.0-1
links: PTS, VCS
area: main
in suites: forky, sid, trixie
size: 25,772 kB
sloc: cpp: 15,541; javascript: 1,208; makefile: 1,080; python: 401; xml: 106; perl: 67; sh: 8
file content (411 lines) | stat: -rw-r--r-- 14,640 bytes
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link rel="stylesheet" href="highlight.min.css">
<script src="highlight.min.js"></script><script>
      hljs.configure({languages: ['cpp']});
      hljs.highlightAll();
    </script><title>A menu</title>
<link rel="stylesheet" type="text/css" href="style.css">
<meta name="generator" content="DocBook XSL Stylesheets Vsnapshot">
<link rel="home" href="index.html" title="Programming with gtkmm 4">
<link rel="up" href="chapter-building-applications.html" title="Chapter 31. Building applications">
<link rel="prev" href="sec-buildapp-opening-files.html" title="Opening files">
<link rel="next" href="sec-buildapp-pref-dialog.html" title="A preference dialog">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr><th colspan="3" align="center">A menu</th></tr>
<tr>
<td width="20%" align="left">
<a accesskey="p" href="sec-buildapp-opening-files.html"><img src="icons/prev.png" alt="Prev"></a> </td>
<th width="60%" align="center">Chapter 31. Building applications</th>
<td width="20%" align="right"> <a accesskey="n" href="sec-buildapp-pref-dialog.html"><img src="icons/next.png" alt="Next"></a>
</td>
</tr>
</table>
<hr>
</div>
<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-buildapp-menu"></a>A menu</h2></div></div></div>


<p>
The menu is shown at the right side of the headerbar. It is meant to collect
infrequently used actions that affect the whole application.
</p>

<p>
Just like the application window, we specify our menu in a ui file, and add it
as a resource to our binary.
</p>

<p>
To make the menu appear, we have to load the ui file and associate the
resulting menu model with the menu button that we've added to the headerbar.
Since menus work by activating <code class="classname">Gio::Action</code>s, we also
have to add a suitable set of actions to our application.
</p>

<p>
Adding the actions is best done in the <code class="methodname">on_startup()</code> default
signal handler, which is guaranteed to be called once for each primary application instance.
</p>

<p>
Our preferences menu item does not do anything yet, but the Quit menu item is fully
functional. It can also be activated by the usual Ctrl-Q shortcut. The shortcut
is added with <code class="methodname">Gtk::Application::set_accel_for_action()</code>.
</p>

<p>
The menu looks like this:
</p>

<div class="figure">
<a name="figure-buildapp-menu"></a><p class="title"><b>Figure 31.4. A menu</b></p>
<div class="figure-contents">
  
  <div class="screenshot">
    <div class="mediaobject"><img src="figures/buildapp_menu.png" alt="A menu"></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/step4" 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">#ifndef GTKMM_EXAMPLEAPPLICATION_H
#define GTKMM_EXAMPLEAPPLICATION_H

#include &lt;gtkmm.h&gt;

class ExampleAppWindow;

class ExampleApplication: public Gtk::Application
{
protected:
  ExampleApplication();

public:
  static Glib::RefPtr&lt;ExampleApplication&gt; create();

protected:
  // Override default signal handlers:
  void on_startup() override;
  void on_activate() override;
  void on_open(const Gio::Application::type_vec_files&amp; files,
    const Glib::ustring&amp; hint) override;

private:
  ExampleAppWindow* create_appwindow();
  void on_action_preferences();
  void on_action_quit();
};

#endif /* GTKMM_EXAMPLEAPPLICATION_H */
</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;
  Gtk::Stack* m_stack {nullptr};
  Gtk::MenuButton* m_gears {nullptr};
};

#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_startup()
{
  // Call the base class's implementation.
  Gtk::Application::on_startup();

  // Add actions and keyboard accelerators for the menu.
  add_action("preferences", sigc::mem_fun(*this, &amp;ExampleApplication::on_action_preferences));
  add_action("quit", sigc::mem_fun(*this, &amp;ExampleApplication::on_action_quit));
  set_accel_for_action("app.quit", "&lt;Ctrl&gt;Q");
}

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;
  }
}

void ExampleApplication::on_action_preferences()
{

}

void ExampleApplication::on_action_quit()
{
  // Gio::Application::quit() will make Gio::Application::run() return,
  // but it's a crude way of ending the program. The window is not removed
  // from the application. Neither the window's nor the application's
  // destructors will be called, because there will be remaining reference
  // counts in both of them. If we want the destructors to be called, we
  // must remove the window from the application. One way of doing this
  // is to hide the window. See comment in create_appwindow().
  auto windows = get_windows();
  for (auto window : windows)
    window-&gt;set_visible(false);

  // Not really necessary, when Gtk::Widget::set_visible(false) is called,
  // unless Gio::Application::hold() has been called without a corresponding
  // call to Gio::Application::release().
  quit();
}
</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;iostream&gt;
#include &lt;stdexcept&gt;

ExampleAppWindow::ExampleAppWindow(BaseObjectType* cobject,
  const Glib::RefPtr&lt;Gtk::Builder&gt;&amp; refBuilder)
: Gtk::ApplicationWindow(cobject),
  m_refBuilder(refBuilder)
{
  // Get widgets from the Gtk::Builder file.
  m_stack = m_refBuilder-&gt;get_widget&lt;Gtk::Stack&gt;("stack");
  if (!m_stack)
    throw std::runtime_error("No \"stack\" object in window.ui");

  m_gears = m_refBuilder-&gt;get_widget&lt;Gtk::MenuButton&gt;("gears");
  if (!m_gears)
    throw std::runtime_error("No \"gears\" object in window.ui");

  // Connect the menu to the MenuButton m_gears.
  // (The connection between action and menu item is specified in gears_menu.ui.)
  auto menu_builder = Gtk::Builder::create_from_resource("/org/gtkmm/exampleapp/gears_menu.ui");
  auto menu = menu_builder-&gt;get_object&lt;Gio::MenuModel&gt;("menu");
  if (!menu)
    throw std::runtime_error("No \"menu\" object in gears_menu.ui");

  m_gears-&gt;set_menu_model(menu);
}

//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)
{
  const Glib::ustring basename = file-&gt;get_basename();

  auto scrolled = Gtk::make_managed&lt;Gtk::ScrolledWindow&gt;();
  scrolled-&gt;set_expand(true);
  auto view = Gtk::make_managed&lt;Gtk::TextView&gt;();
  view-&gt;set_editable(false);
  view-&gt;set_cursor_visible(false);
  scrolled-&gt;set_child(*view);
  m_stack-&gt;add(*scrolled, basename, basename);

  try
  {
    char* contents = nullptr;
    gsize length = 0;
    
    file-&gt;load_contents(contents, length);
    view-&gt;get_buffer()-&gt;set_text(contents, contents+length);
    g_free(contents);
  }
  catch (const Glib::Error&amp; ex)
  {
    std::cout &lt;&lt; "ExampleAppWindow::open_file_view(\"" &lt;&lt; file-&gt;get_parse_name()
      &lt;&lt; "\"):\n  " &lt;&lt; ex.what() &lt;&lt; std::endl;
  }
}
</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;file preprocess="xml-stripblanks"&gt;gears_menu.ui&lt;/file&gt;
  &lt;/gresource&gt;
&lt;/gresources&gt;
</code></pre>
<p>File: <code class="filename">gears_menu.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;menu id="menu"&gt;
    &lt;section&gt;
      &lt;item&gt;
        &lt;attribute name="label" translatable="yes"&gt;_Preferences&lt;/attribute&gt;
        &lt;attribute name="action"&gt;app.preferences&lt;/attribute&gt;
      &lt;/item&gt;
    &lt;/section&gt;
    &lt;section&gt;
      &lt;item&gt;
        &lt;attribute name="label" translatable="yes"&gt;_Quit&lt;/attribute&gt;
        &lt;attribute name="action"&gt;app.quit&lt;/attribute&gt;
      &lt;/item&gt;
    &lt;/section&gt;
  &lt;/menu&gt;
&lt;/interface&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 type="titlebar"&gt;
      &lt;object class="GtkHeaderBar" id="header"&gt;
        &lt;child type="title"&gt;
          &lt;object class="GtkStackSwitcher" id="tabs"&gt;
            &lt;property name="stack"&gt;stack&lt;/property&gt;
          &lt;/object&gt;
        &lt;/child&gt;
        &lt;child type="end"&gt;
          &lt;object class="GtkMenuButton" id="gears"&gt;
            &lt;property name="direction"&gt;none&lt;/property&gt;
          &lt;/object&gt;
        &lt;/child&gt;
      &lt;/object&gt;
    &lt;/child&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>


</div>
<div class="navfooter">
<hr>
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left">
<a accesskey="p" href="sec-buildapp-opening-files.html"><img src="icons/prev.png" alt="Prev"></a> </td>
<td width="20%" align="center"><a accesskey="u" href="chapter-building-applications.html"><img src="icons/up.png" alt="Up"></a></td>
<td width="40%" align="right"> <a accesskey="n" href="sec-buildapp-pref-dialog.html"><img src="icons/next.png" alt="Next"></a>
</td>
</tr>
<tr>
<td width="40%" align="left" valign="top">Opening files </td>
<td width="20%" align="center"><a accesskey="h" href="index.html"><img src="icons/home.png" alt="Home"></a></td>
<td width="40%" align="right" valign="top"> A preference dialog</td>
</tr>
</table>
</div>
</body>
</html>