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<th width="60%" align="center">Chapter 13. Combo Boxes</th>
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<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-comboboxentry"></a>ComboBox with an Entry</h2></div></div></div>


<p>A <code class="classname">ComboBox</code> may contain an <code class="classname">Entry</code> widget for entering of arbitrary text, by specifying <code class="literal">true</code> for the constructor's <code class="literal">has_entry</code> parameter.</p>

<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-comboboxentry-text-column"></a>The text column</h3></div></div></div>


<p>So that the <code class="classname">Entry</code> can interact with the drop-down list of choices, you must specify which of your model columns is the text column, with <code class="methodname">set_entry_text_column()</code>. For instance:
</p>
<pre class="programlisting"><code class="code">m_combo.set_entry_text_column(m_columns.m_col_name);</code></pre>
<p>
When you select a choice from the drop-down menu, the value from this column will be placed in the <code class="classname">Entry</code>.
</p>
</div>

<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-comboboxentry-model"></a>The entry</h3></div></div></div>


<p>Because the user may enter arbitrary text, an active model row isn't enough to tell us what text the user has entered. Therefore, you should retrieve the <code class="classname">Entry</code> widget with the <code class="methodname">ComboBox::get_entry()</code> method and call <code class="methodname">get_text()</code> on that.
</p>
</div>

<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-comboboxentry-changes"></a>Responding to changes</h3></div></div></div>


<p>
When the user enters arbitrary text, it may not be enough to connect to the
<code class="literal">changed</code> signal, which is emitted for every typed character.
It is not emitted when the user presses the <span class="keycap"><strong>Enter</strong></span> key.
Pressing the <span class="keycap"><strong>Enter</strong></span> key or moving the keyboard focus to another
widget may signal that the user has finished entering text. To be notified of
these events, connect to the <code class="classname">Entry</code>'s <code class="literal">activate</code>
signal (available since <span class="application">gtkmm</span> 4.8), and add a <code class="classname">Gtk::EventControllerFocus</code>
and connect to its <code class="literal">leave</code> signal, like so
</p>
<pre class="programlisting"><code class="code">auto entry = m_Combo.get_entry();
if (entry)
{
  // Alternatively you can connect to m_Combo.signal_changed().
  entry-&gt;signal_changed().connect(sigc::mem_fun(*this,
    &amp;ExampleWindow::on_entry_changed));
  entry-&gt;signal_activate().connect(sigc::mem_fun(*this,
    &amp;ExampleWindow::on_entry_activate));
  // The Entry shall receive focus-leave events.
  auto controller = Gtk::EventControllerFocus::create();
  m_ConnectionFocusLeave = controller-&gt;signal_leave().connect(
    sigc::mem_fun(*this, &amp;ExampleWindow::on_entry_focus_leave));
  entry-&gt;add_controller(controller);
}</code></pre>
<p>
The <code class="literal">changed</code> signals of <code class="classname">ComboBox</code> and
<code class="classname">Entry</code> are both emitted for every change. It doesn't matter
which one you connect to. But the <code class="classname">EventControllerFocus</code>
must be added to the <code class="classname">Entry</code>.
</p>
</div>

<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="comboboxentry-example-full"></a>Full Example</h3></div></div></div>


<div class="figure">
<a name="figure-comboboxentry-complex"></a><p class="title"><b>Figure 13.3. ComboBox with Entry</b></p>
<div class="figure-contents">
  
  <div class="screenshot">
    <div class="mediaobject"><img src="figures/comboboxentry_complex.png" alt="ComboBox with Entry"></div>
  </div>
</div>
</div>
<br class="figure-break">

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

<p>File: <code class="filename">examplewindow.h</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include &lt;gtkmm/window.h&gt;
#include &lt;gtkmm/combobox.h&gt;
#include &lt;gtkmm/liststore.h&gt;
#include &lt;gtkmm/version.h&gt;

#define HAS_SIGNAL_ACTIVATE GTKMM_CHECK_VERSION(4,7,1)

class ExampleWindow : public Gtk::Window
{
public:
  ExampleWindow();
  ~ExampleWindow() override;

protected:
  //Signal handlers:
  void on_entry_changed();
#if HAS_SIGNAL_ACTIVATE
  void on_entry_activate();
#endif
  void on_entry_focus_leave();

  //Signal connection:
  sigc::connection m_ConnectionFocusLeave;

  //Tree model columns:
  class ModelColumns : public Gtk::TreeModel::ColumnRecord
  {
  public:

    ModelColumns()
    { add(m_col_id); add(m_col_name); }

    Gtk::TreeModelColumn&lt;Glib::ustring&gt; m_col_id; //The data to choose - this must be text.
    Gtk::TreeModelColumn&lt;Glib::ustring&gt; m_col_name;
  };

  ModelColumns m_Columns;

  //Child widgets:
  Gtk::ComboBox m_Combo;
  Glib::RefPtr&lt;Gtk::ListStore&gt; m_refTreeModel;
};

#endif //GTKMM_EXAMPLEWINDOW_H
</code></pre>
<p>File: <code class="filename">examplewindow.cc</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "examplewindow.h"
#include &lt;gtkmm/eventcontrollerfocus.h&gt;
#include &lt;iostream&gt;

ExampleWindow::ExampleWindow()
: m_Combo(true /* has_entry */)
{
  set_title("ComboBox example");

  //Create the Tree model:
  //m_refTreeModel = Gtk::TreeStore::create(m_Columns);
  m_refTreeModel = Gtk::ListStore::create(m_Columns);
  m_Combo.set_model(m_refTreeModel);

  //Fill the ComboBox's Tree Model:
  auto row = *(m_refTreeModel-&gt;append());
  row[m_Columns.m_col_id] = "1";
  row[m_Columns.m_col_name] = "Billy Bob";
  /*
  auto childrow = *(m_refTreeModel-&gt;append(row.children()));
  childrow[m_Columns.m_col_id] = 11;
  childrow[m_Columns.m_col_name] = "Billy Bob Junior";

  childrow = *(m_refTreeModel-&gt;append(row.children()));
  childrow[m_Columns.m_col_id] = 12;
  childrow[m_Columns.m_col_name] = "Sue Bob";
  */

  row = *(m_refTreeModel-&gt;append());
  row[m_Columns.m_col_id] = "2";
  row[m_Columns.m_col_name] = "Joey Jojo";

  row = *(m_refTreeModel-&gt;append());
  row[m_Columns.m_col_id] = "3";
  row[m_Columns.m_col_name] = "Rob McRoberts";

  /*
  childrow = *(m_refTreeModel-&gt;append(row.children()));
  childrow[m_Columns.m_col_id] = 31;
  childrow[m_Columns.m_col_name] = "Xavier McRoberts";
  */

  //Add the model columns to the Combo (which is a kind of view),
  //rendering them in the default way:
  //This is automatically rendered when we use set_entry_text_column().
  //m_Combo.pack_start(m_Columns.m_col_id, Gtk::PackOptions::EXPAND_WIDGET);
  m_Combo.pack_start(m_Columns.m_col_name);

  m_Combo.set_entry_text_column(m_Columns.m_col_id);
  m_Combo.set_active(1);

  //Add the ComboBox to the window.
  set_child(m_Combo);

  //Connect signal handlers:
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    // Alternatively you can connect to m_Combo.signal_changed().
    entry-&gt;signal_changed().connect(sigc::mem_fun(*this,
      &amp;ExampleWindow::on_entry_changed));
#if HAS_SIGNAL_ACTIVATE
    entry-&gt;signal_activate().connect(sigc::mem_fun(*this,
      &amp;ExampleWindow::on_entry_activate));
#endif
    // The Entry shall receive focus-leave events.
    auto controller = Gtk::EventControllerFocus::create();
    m_ConnectionFocusLeave = controller-&gt;signal_leave().connect(
      sigc::mem_fun(*this, &amp;ExampleWindow::on_entry_focus_leave));
    entry-&gt;add_controller(controller);
  }
  else
    std::cout &lt;&lt; "No Entry ???" &lt;&lt; std::endl;
}

ExampleWindow::~ExampleWindow()
{
  // The focus-leave signal may be emitted while m_Combo is being destructed.
  // The signal handler can generate critical messages, if it's called when
  // m_Combo has been partly destructed.
  m_ConnectionFocusLeave.disconnect();
}

void ExampleWindow::on_entry_changed()
{
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    std::cout &lt;&lt; "on_entry_changed(): Row=" &lt;&lt; m_Combo.get_active_row_number()
      &lt;&lt; ", ID=" &lt;&lt; entry-&gt;get_text() &lt;&lt; std::endl;
  }
}

#if HAS_SIGNAL_ACTIVATE
void ExampleWindow::on_entry_activate()
{
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    std::cout &lt;&lt; "on_entry_activate(): Row=" &lt;&lt; m_Combo.get_active_row_number()
      &lt;&lt; ", ID=" &lt;&lt; entry-&gt;get_text() &lt;&lt; std::endl;
  }
}
#endif

void ExampleWindow::on_entry_focus_leave()
{
  auto entry = m_Combo.get_entry();
  if (entry)
  {
    std::cout &lt;&lt; "on_entry_focus_leave(): Row=" &lt;&lt; m_Combo.get_active_row_number()
      &lt;&lt; ", ID=" &lt;&lt; entry-&gt;get_text() &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 "examplewindow.h"
#include &lt;gtkmm/application.h&gt;

int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create("org.gtkmm.example");

  //Shows the window and returns when it is closed.
  return app-&gt;make_window_and_run&lt;ExampleWindow&gt;(argc, argv);
}
</code></pre>


</div>

<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="comboboxentry-example-simple"></a>Simple Text Example</h3></div></div></div>


<div class="figure">
<a name="figure-comboboxentry-text"></a><p class="title"><b>Figure 13.4. ComboBoxText with Entry</b></p>
<div class="figure-contents">
  
  <div class="screenshot">
    <div class="mediaobject"><img src="figures/comboboxentry_text.png" alt="ComboBoxText with Entry"></div>
  </div>
</div>
</div>
<br class="figure-break">

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

<p>File: <code class="filename">examplewindow.h</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include &lt;gtkmm/window.h&gt;
#include &lt;gtkmm/comboboxtext.h&gt;
#include &lt;gtkmm/version.h&gt;

#define HAS_SIGNAL_ACTIVATE GTKMM_CHECK_VERSION(4,7,1)

class ExampleWindow : public Gtk::Window
{
public:
  ExampleWindow();
  ~ExampleWindow() override;

protected:
  //Signal handlers:
  void on_combo_changed();
#if HAS_SIGNAL_ACTIVATE
  void on_entry_activate();
#endif
  void on_entry_focus_leave();

  //Signal connection:
  sigc::connection m_ConnectionFocusLeave;

  //Child widgets:
  Gtk::ComboBoxText m_Combo;
};

#endif //GTKMM_EXAMPLEWINDOW_H
</code></pre>
<p>File: <code class="filename">examplewindow.cc</code> (For use with gtkmm 4)</p>
<pre class="programlisting"><code class="code">#include "examplewindow.h"
#include &lt;gtkmm/eventcontrollerfocus.h&gt;
#include &lt;iostream&gt;

ExampleWindow::ExampleWindow()
: m_Combo(true /* has_entry */)
{
  set_title("ComboBoxText example");

  //Fill the combo:
  m_Combo.append("something");
  m_Combo.append("something else");
  m_Combo.append("something or other");
  m_Combo.set_active(0);

  set_child(m_Combo);

  //Connect signal handlers:
  auto entry = m_Combo.get_entry();
  // Alternatively you can connect to entry-&gt;signal_changed().
  m_Combo.signal_changed().connect(sigc::mem_fun(*this,
    &amp;ExampleWindow::on_combo_changed) );

  if (entry)
  {
#if HAS_SIGNAL_ACTIVATE
    entry-&gt;signal_activate().connect(sigc::mem_fun(*this,
      &amp;ExampleWindow::on_entry_activate));
#endif
    // The Entry shall receive focus-leave events.
    auto controller = Gtk::EventControllerFocus::create();
    m_ConnectionFocusLeave = controller-&gt;signal_leave().connect(
      sigc::mem_fun(*this, &amp;ExampleWindow::on_entry_focus_leave));
    entry-&gt;add_controller(controller);
  }
  else
    std::cout &lt;&lt; "No Entry ???" &lt;&lt; std::endl;

  m_Combo.property_has_frame() = false;
}

ExampleWindow::~ExampleWindow()
{
  // The focus-leave signal may be emitted while m_Combo is being destructed.
  // The signal handler can generate critical messages, if it's called when
  // m_Combo has been partly destructed.
  m_ConnectionFocusLeave.disconnect();
}

void ExampleWindow::on_combo_changed()
{
  std::cout &lt;&lt; "on_combo_changed(): Row=" &lt;&lt; m_Combo.get_active_row_number()
    &lt;&lt; ", Text=" &lt;&lt; m_Combo.get_active_text() &lt;&lt; std::endl;
}

#if HAS_SIGNAL_ACTIVATE
void ExampleWindow::on_entry_activate()
{
  std::cout &lt;&lt; "on_entry_activate(): Row=" &lt;&lt; m_Combo.get_active_row_number()
    &lt;&lt; ", Text=" &lt;&lt; m_Combo.get_active_text() &lt;&lt; std::endl;
}
#endif

void ExampleWindow::on_entry_focus_leave()
{
  std::cout &lt;&lt; "on_entry_focus_leave(): Row=" &lt;&lt; m_Combo.get_active_row_number()
    &lt;&lt; ", Text=" &lt;&lt; m_Combo.get_active_text() &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 "examplewindow.h"
#include &lt;gtkmm/application.h&gt;

int main(int argc, char *argv[])
{
  auto app = Gtk::Application::create("org.gtkmm.example");

  //Shows the window and returns when it is closed.
  return app-&gt;make_window_and_run&lt;ExampleWindow&gt;(argc, argv);
}
</code></pre>


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