File: sec-buildapp-properties.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 (545 lines) | stat: -rw-r--r-- 20,407 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>Properties</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-side-bar.html" title="Adding a side bar">
<link rel="next" href="sec-buildapp-header-bar.html" title="Header bar">
</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">Properties</th></tr>
<tr>
<td width="20%" align="left">
<a accesskey="p" href="sec-buildapp-side-bar.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-header-bar.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-properties"></a>Properties</h2></div></div></div>


<p>
Widgets and other objects have many useful properties. Here we show some ways to use
them in new and flexible ways, by wrapping them in actions with <code class="classname">Gio::PropertyAction</code>
or by binding them with <code class="classname">Glib::Binding</code>.
</p>

<p>
To set this up, we add two labels to the header bar in our <code class="filename">window.ui</code> file,
named <code class="literal">lines_label</code> and <code class="literal">lines</code>, and get pointers to them
in the application window's constructor, as we've seen a couple of times by now.
We add a new "Lines" menu item to the gears menu, which triggers the
<code class="literal">show-lines</code> action.
</p>

<p>
To make this menu item do something, we create a property action for the <code class="literal">visible</code>
property of the <code class="literal">lines</code> label, and add it to the actions of the window.
The effect of this is that the visibility of the label gets toggled every time the action
is activated.
Since we want both labels to appear and disappear together, we bind the <code class="literal">visible</code>
property of the <code class="literal">lines_label</code> widget to the same property of the
<code class="literal">lines</code> widget.
In <code class="classname">ExampleAppWindow</code>'s constructor:
</p>
<pre class="programlisting"><code class="code">add_action(Gio::PropertyAction::create("show-lines", m_lines-&gt;property_visible()));
m_binding_lines_visible = Glib::Binding::bind_property(m_lines-&gt;property_visible(),
  m_lines_label-&gt;property_visible());

</code></pre>

<p>
We also need a function that counts the lines of the currently active tab, and updates
the <code class="literal">lines</code> label. See the full source if you are interested in the details.
</p>

<p>
This brings our example application to this appearance:
</p>

<div class="figure">
<a name="figure-buildapp-properties"></a><p class="title"><b>Figure 31.8. Properties</b></p>
<div class="figure-contents">
  
  <div class="screenshot">
    <div class="mediaobject"><img src="figures/buildapp_properties.png" alt="Properties"></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/step8" 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 "../step4/exampleapplication.h"
// Equal to the corresponding file in step4
</code></pre>
<p>File: <code class="filename">exampleappprefs.h</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "../step5/exampleappprefs.h"
// Equal to the corresponding file in step5
</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;

#define HAS_SEARCH_ENTRY2 GTKMM_CHECK_VERSION(4,13,2)

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:
  // Signal handlers
  void on_search_text_changed();
  void on_visible_child_changed();
  void on_find_word(const Gtk::Button* button);
  void on_reveal_child_changed();

  void update_words();
  void update_lines();

  Glib::RefPtr&lt;Gtk::Builder&gt; m_refBuilder;
  Glib::RefPtr&lt;Gio::Settings&gt; m_settings;
  Gtk::Stack* m_stack {nullptr};
  Gtk::ToggleButton* m_search {nullptr};
  Gtk::SearchBar* m_searchbar {nullptr};
#if HAS_SEARCH_ENTRY2
  Gtk::SearchEntry2* m_searchentry {nullptr};
#else
  Gtk::SearchEntry* m_searchentry {nullptr};
#endif
  Gtk::MenuButton* m_gears {nullptr};
  Gtk::Revealer* m_sidebar {nullptr};
  Gtk::ListBox* m_words {nullptr};
  Gtk::Label* m_lines {nullptr};
  Gtk::Label* m_lines_label {nullptr};
  Glib::RefPtr&lt;Glib::Binding&gt; m_binding_search_enabled;
  Glib::RefPtr&lt;Glib::Binding&gt; m_binding_lines_visible;
};

#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 "../step5/exampleapplication.cc"
// Equal to the corresponding file in step5
</code></pre>
<p>File: <code class="filename">exampleappprefs.cc</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "../step5/exampleappprefs.cc"
// Equal to the corresponding file in step5
</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;
#include &lt;set&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_search = m_refBuilder-&gt;get_widget&lt;Gtk::ToggleButton&gt;("search");
  if (!m_search)
    throw std::runtime_error("No \"search\" object in window.ui");

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

#if HAS_SEARCH_ENTRY2
  m_searchentry = m_refBuilder-&gt;get_widget&lt;Gtk::SearchEntry2&gt;("searchentry");
#else
  m_searchentry = m_refBuilder-&gt;get_widget&lt;Gtk::SearchEntry&gt;("searchentry");
#endif
  if (!m_searchentry)
    throw std::runtime_error("No \"searchentry\" 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");

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

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

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

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

  // Bind settings.
  m_settings = Gio::Settings::create("org.gtkmm.exampleapp");
  m_settings-&gt;bind("transition", m_stack-&gt;property_transition_type());
  m_settings-&gt;bind("show-words", m_sidebar-&gt;property_reveal_child());

  // Bind properties of the search button to the search bar.
  m_binding_search_enabled = Glib::Binding::bind_property(m_search-&gt;property_active(),
    m_searchbar-&gt;property_search_mode_enabled(), Glib::Binding::Flags::BIDIRECTIONAL);

  // Connect signal handlers.
  m_searchentry-&gt;signal_search_changed().connect(
    sigc::mem_fun(*this, &amp;ExampleAppWindow::on_search_text_changed));
  m_stack-&gt;property_visible_child().signal_changed().connect(
    sigc::mem_fun(*this, &amp;ExampleAppWindow::on_visible_child_changed));
  m_sidebar-&gt;property_reveal_child().signal_changed().connect(
    sigc::mem_fun(*this, &amp;ExampleAppWindow::on_reveal_child_changed));

  // Connect the menu to the MenuButton m_gears, and bind the show-words setting
  // to the win.show-words action and the "Words" menu item.
  // (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);
  add_action(m_settings-&gt;create_action("show-words"));

  // Bind the "visible" property of m_lines to the win.show-lines action, to
  // the "Lines" menu item and to the "visible" property of m_lines_label.
  add_action(Gio::PropertyAction::create("show-lines", m_lines-&gt;property_visible()));
  m_binding_lines_visible = Glib::Binding::bind_property(m_lines-&gt;property_visible(),
    m_lines_label-&gt;property_visible());
}

//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);

  auto buffer = view-&gt;get_buffer();
  try
  {
    char* contents = nullptr;
    gsize length = 0;
    
    file-&gt;load_contents(contents, length);
    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;
    return;
  }

  auto tag = buffer-&gt;create_tag();
  m_settings-&gt;bind("font", tag-&gt;property_font());
  buffer-&gt;apply_tag(tag, buffer-&gt;begin(), buffer-&gt;end());

  m_search-&gt;set_sensitive(true);
  update_words();
  update_lines();
}

void ExampleAppWindow::on_search_text_changed()
{
  const auto text = m_searchentry-&gt;get_text();
  if (text.empty())
    return;

  auto tab = dynamic_cast&lt;Gtk::ScrolledWindow*&gt;(m_stack-&gt;get_visible_child());
  if (!tab)
  {
    std::cout &lt;&lt; "ExampleAppWindow::on_search_text_changed(): No visible child." &lt;&lt; std::endl;
    return;
  }

  auto view = dynamic_cast&lt;Gtk::TextView*&gt;(tab-&gt;get_child());
  if (!view)
  {
    std::cout &lt;&lt; "ExampleAppWindow::on_search_text_changed(): No visible text view." &lt;&lt; std::endl;
    return;
  }

  // Very simple-minded search implementation.
  auto buffer = view-&gt;get_buffer();
  Gtk::TextIter match_start;
  Gtk::TextIter match_end;
  if (buffer-&gt;begin().forward_search(text, Gtk::TextSearchFlags::CASE_INSENSITIVE,
      match_start, match_end))
  {
    buffer-&gt;select_range(match_start, match_end);
    view-&gt;scroll_to(match_start);
  }
}

void ExampleAppWindow::on_visible_child_changed()
{
  m_searchbar-&gt;set_search_mode(false);
  update_words();
  update_lines();  
}

void ExampleAppWindow::on_find_word(const Gtk::Button* button)
{
  m_searchentry-&gt;set_text(button-&gt;get_label());
}

void ExampleAppWindow::on_reveal_child_changed()
{
  update_words();
}

void ExampleAppWindow::update_words()
{
  auto tab = dynamic_cast&lt;Gtk::ScrolledWindow*&gt;(m_stack-&gt;get_visible_child());
  if (!tab)
    return;

  auto view = dynamic_cast&lt;Gtk::TextView*&gt;(tab-&gt;get_child());
  if (!view)
  {
    std::cout &lt;&lt; "ExampleAppWindow::update_words(): No visible text view." &lt;&lt; std::endl;
    return;
  }
  auto buffer = view-&gt;get_buffer();

  // Find all words in the text buffer.
  std::set&lt;Glib::ustring&gt; words;
  auto start = buffer-&gt;begin();
  Gtk::TextIter end;
  while (start)
  {
    while (start &amp;&amp; !start.starts_word())
      ++start;

    if (!start)
      break;

    end = start;
    end.forward_word_end();
    if (start == end)
      break;

    auto word = buffer-&gt;get_text(start, end, false);
    words.insert(word.lowercase());
    start = end;
  }

  // Remove old children from the ListBox.
  while (auto child = m_words-&gt;get_first_child())
    m_words-&gt;remove(*child);

  // Add new child buttons, one per unique word.
  for (const auto&amp; word : words)
  {
    auto row = Gtk::make_managed&lt;Gtk::Button&gt;(word);
    row-&gt;signal_clicked().connect(sigc::bind(sigc::mem_fun(*this,
      &amp;ExampleAppWindow::on_find_word), row));
    m_words-&gt;append(*row);
  }
}

void ExampleAppWindow::update_lines()
{
  auto tab = dynamic_cast&lt;Gtk::ScrolledWindow*&gt;(m_stack-&gt;get_visible_child());
  if (!tab)
    return;

  auto view = dynamic_cast&lt;Gtk::TextView*&gt;(tab-&gt;get_child());
  if (!view)
  {
    std::cout &lt;&lt; "ExampleAppWindow::update_lines(): No visible text view." &lt;&lt; std::endl;
    return;
  }
  auto buffer = view-&gt;get_buffer();

  int count = 0;
  auto iter = buffer-&gt;begin();
  while (iter)
  {
    ++count;
    if (!iter.forward_line())
      break;
  }
  m_lines-&gt;set_text(Glib::ustring::format(count));
}
</code></pre>
<p>File: <code class="filename">main.cc</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "../step6/main.cc"
// Equal to the corresponding file in step6
</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;_Words&lt;/attribute&gt;
        &lt;attribute name="action"&gt;win.show-words&lt;/attribute&gt;
      &lt;/item&gt;
      &lt;item&gt;
        &lt;attribute name="label" translatable="yes"&gt;_Lines&lt;/attribute&gt;
        &lt;attribute name="action"&gt;win.show-lines&lt;/attribute&gt;
      &lt;/item&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&gt;
          &lt;object class="GtkLabel" id="lines_label"&gt;
            &lt;property name="visible"&gt;False&lt;/property&gt;
            &lt;property name="label" translatable="yes"&gt;Lines:&lt;/property&gt;
          &lt;/object&gt;
        &lt;/child&gt;
        &lt;child&gt;
          &lt;object class="GtkLabel" id="lines"&gt;
            &lt;property name="visible"&gt;False&lt;/property&gt;
          &lt;/object&gt;
        &lt;/child&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="GtkToggleButton" id="search"&gt;
            &lt;property name="sensitive"&gt;False&lt;/property&gt;
            &lt;property name="icon-name"&gt;edit-find-symbolic&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="GtkSearchBar" id="searchbar"&gt;
            &lt;child&gt;
              &lt;object class="GtkSearchEntry" id="searchentry"&gt;
              &lt;/object&gt;
            &lt;/child&gt;
          &lt;/object&gt;
        &lt;/child&gt;
        &lt;child&gt;
          &lt;object class="GtkBox" id="hbox"&gt;
            &lt;child&gt;
              &lt;object class="GtkRevealer" id="sidebar"&gt;
                &lt;property name="transition-type"&gt;slide-right&lt;/property&gt;
                &lt;child&gt;
                  &lt;object class="GtkScrolledWindow" id="sidebar-sw"&gt;
                    &lt;property name="hscrollbar-policy"&gt;never&lt;/property&gt;
                    &lt;child&gt;
                      &lt;object class="GtkListBox" id="words"&gt;
                        &lt;property name="selection-mode"&gt;none&lt;/property&gt;
                      &lt;/object&gt;
                    &lt;/child&gt;
                  &lt;/object&gt;
                &lt;/child&gt;
              &lt;/object&gt;
            &lt;/child&gt;
            &lt;child&gt;
              &lt;object class="GtkStack" id="stack"&gt;
                &lt;property name="transition-duration"&gt;500&lt;/property&gt;
              &lt;/object&gt;
            &lt;/child&gt;
          &lt;/object&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-side-bar.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-header-bar.html"><img src="icons/next.png" alt="Next"></a>
</td>
</tr>
<tr>
<td width="40%" align="left" valign="top">Adding a side bar </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"> Header bar</td>
</tr>
</table>
</div>
</body>
</html>