Sophie: gtkmm2.4-documentation-2.17.4-1mdv2010.0 noarch

gtkmm2.4-documentation-2.17.4-1mdv2010.0.noarch.rpm

<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Chapter 9. Combo Boxes</title>
<link rel="stylesheet" href="style.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.75.1">
<link rel="home" href="index.html" title="Programming with gtkmm">
<link rel="up" href="index.html" title="Programming with gtkmm">
<link rel="prev" href="sec-treeview-examples.html" title="Examples">
<link rel="next" href="sec-comboboxentry.html" title="ComboBoxEntry">
</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">Chapter 9. Combo Boxes</th></tr>
<tr>
<td width="20%" align="left">
<a accesskey="p" href="sec-treeview-examples.html"><img src="icons/prev.png" alt="Prev"></a> </td>
<th width="60%" align="center"> </th>
<td width="20%" align="right"> <a accesskey="n" href="sec-comboboxentry.html"><img src="icons/next.png" alt="Next"></a>
</td>
</tr>
</table>
<hr>
</div>
<div class="chapter" title="Chapter 9. Combo Boxes">
<div class="titlepage"><div><div><h2 class="title">
<a name="chapter-combobox"></a>Chapter 9. Combo Boxes</h2></div></div></div>
<div class="toc">
<p><b>Table of Contents</b></p>
<ul>
<li><span class="sect1"><a href="chapter-combobox.html#sec-combobox">ComboBox</a></span></li>
<li><span class="sect1"><a href="sec-comboboxentry.html">ComboBoxEntry</a></span></li>
</ul>
</div>
<p>The <code class="classname">ComboBox</code> and <code class="classname">ComboBoxEntry</code> widgets offers a list (or tree) of choices in a dropdown menu. If appropriate, they can show extra information about each item, such as text, a picture, a checkbox, or a progress bar. The <code class="classname">ComboBox</code> widget restricts the user to the available choices, but the <code class="classname">ComboBoxEntry</code> contains an <code class="classname">Entry</code>, allowing the user to enter arbitrary text if the none of the available choices are suitable.
</p>
<p>For both widgets, the list is provided via a <code class="classname">TreeModel</code>, and columns from this model are added to the ComboBox's view with the <code class="methodname">ComboBox::pack_start()</code>. This provides a great deal of flexibility and compile-time type-safety, but the <code class="classname">ComboBoxText</code> and <code class="classname">ComboBoxEntryText</code> classes provide a simple text-based specialisation in case that flexibility is not required.
</p>
<div class="sect1" title="ComboBox">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-combobox"></a>ComboBox</h2></div></div></div>
<p><a class="ulink" href="http://library.gnome.org/devel/gtkmm/unstable/classGtk_1_1ComboBox.html" target="_top">Reference</a></p>
<div class="sect2" title="The model">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-combobox-model"></a>The model</h3></div></div></div>
<p>The model for a ComboBox can be defined and filled exactly as for a <code class="classname">TreeView</code>. For instance, you might derive a ComboBox class with one integer and one text columns, like so:
</p>
<pre class="programlisting">ModelColumns()
{ add(m_col_id); add(m_col_name); }

  Gtk::TreeModelColumn&lt;int&gt; m_col_id;
  Gtk::TreeModelColumn&lt;Glib::ustring&gt; m_col_name;
};

ModelColumns m_columns;</pre>
<p>After appending rows to this model, you should provide the model to the <code class="classname">ComboBox</code> with the <code class="methodname">set_model()</code> method. Then use the <code class="methodname">pack_start()</code> or <code class="methodname">pack_end()</code> methods to specify what methods will be displayed in the ComboBox. As with the TreeView you may either use the default cell renderer by passing the <code class="classname">TreeModelColumn</code> to the pack methods, or you may instantiate a specific <code class="classname">CellRenderer</code> and specify a particular mapping with either <code class="methodname">add_attribute()</code> or <code class="methodname">set_cell_data_func()</code>. Note that these methods are in the <code class="classname">CellLayout</code> base class.</p>
</div>
<div class="sect2" title="The chosen item">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-combobox-get"></a>The chosen item</h3></div></div></div>
<p>To discover what item, if any, the user has chosen from the ComboBox, call <code class="methodname">ComboBox::get_active()</code>. This returns a <code class="classname">TreeModel::iterator</code> that you can dereference to a <code class="classname">Row</code> in order to read the values in your columns. For instance, you might read an integer ID value from the model, even though you have chosen only to show the human-readable description in the Combo. For instance:
</p>
<pre class="programlisting">Gtk::TreeModel::iterator iter = m_Combo.get_active();
if(iter)
{
  Gtk::TreeModel::Row row = *iter;

  //Get the data for the selected row, using our knowledge
  //of the tree model:
  int id = row[m_Columns.m_col_id];
  set_something_id_chosen(id); //Your own function.
}
else
  set_nothing_chosen(); //Your own function.</pre>
</div>
<div class="sect2" title="Responding to changes">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-combobox-changes"></a>Responding to changes</h3></div></div></div>
<p>
You might need to react to every change of selection in the ComboBox, for instance to update other widgets. To do so, you should handle the "changed" signal. For instance:
</p>
<pre class="programlisting">m_combo.signal_changed().connect( sigc::mem_fun(*this,
      &amp;ExampleWindow::on_combo_changed) );</pre>
</div>
<div class="sect2" title="Full Example">
<div class="titlepage"><div><div><h3 class="title">
<a name="combobox-example-full"></a>Full Example</h3></div></div></div>
<div class="figure">
<a name="figure-combobox-complex"></a><p class="title"><b>Figure 9.1. ComboBox</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="figures/combobox_complex.png" alt="ComboBox"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="http://git.gnome.org/cgit/gtkmm-documentation/tree/examples/book/combobox/complex" target="_top">Source Code</a></p>
<p>File: <code class="filename">examplewindow.h</code>
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

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

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

protected:  
  //Signal handlers:
  void on_combo_changed();

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

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

    Gtk::TreeModelColumn&lt;int&gt; m_col_id;
    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
</pre>
<p>File: <code class="filename">examplewindow.cc</code>
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;gtkmm/stock.h&gt;
#include &lt;iostream&gt;

ExampleWindow::ExampleWindow()
{
  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:
  Gtk::TreeModel::Row row = *(m_refTreeModel-&gt;append());
  row[m_Columns.m_col_id] = 1;
  row[m_Columns.m_col_name] = "Billy Bob";
  /*
  Gtk::TreeModel::Row 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:
  m_Combo.pack_start(m_Columns.m_col_id);
  m_Combo.pack_start(m_Columns.m_col_name);

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

  //Connect signal handler:
  m_Combo.signal_changed().connect( sigc::mem_fun(*this, &amp;ExampleWindow::on_combo_changed) );

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

void ExampleWindow::on_combo_changed()
{
  Gtk::TreeModel::iterator iter = m_Combo.get_active();
  if(iter)
  {
    Gtk::TreeModel::Row row = *iter;
    if(row)
    {
      //Get the data for the selected row, using our knowledge of the tree
      //model:
      int id = row[m_Columns.m_col_id];
      Glib::ustring name = row[m_Columns.m_col_name];

      std::cout &lt;&lt; " ID=" &lt;&lt; id &lt;&lt; ", name=" &lt;&lt; name &lt;&lt; std::endl;
    }
  }
  else
    std::cout &lt;&lt; "invalid iter" &lt;&lt; std::endl;
}

</pre>
<p>File: <code class="filename">main.cc</code>
</p>
<pre class="programlisting">
#include &lt;gtkmm/main.h&gt;
#include "examplewindow.h"

int main(int argc, char *argv[])
{
  Gtk::Main kit(argc, argv);

  ExampleWindow window;
  //Shows the window and returns when it is closed.
  Gtk::Main::run(window);

  return 0;
}
</pre>
</div>
<div class="sect2" title="Simple Text Example">
<div class="titlepage"><div><div><h3 class="title">
<a name="combobox-example-simple"></a>Simple Text Example</h3></div></div></div>
<div class="figure">
<a name="figure-combobox-text"></a><p class="title"><b>Figure 9.2. ComboBox</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="figures/combobox_text.png" alt="ComboBox"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="http://git.gnome.org/cgit/gtkmm-documentation/tree/examples/book/combobox/text" target="_top">Source Code</a></p>
<p>File: <code class="filename">examplewindow.h</code>
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

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

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

protected:
  //Signal handlers:
  void on_combo_changed();

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

#endif //GTKMM_EXAMPLEWINDOW_H
</pre>
<p>File: <code class="filename">examplewindow.cc</code>
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;gtkmm/stock.h&gt;
#include &lt;iostream&gt;

ExampleWindow::ExampleWindow()
{
  set_title("ComboBoxText example");

  //Fill the combo:
  m_Combo.append_text("something");
  m_Combo.append_text("something else");
  m_Combo.append_text("something or other");

  add(m_Combo);

  //Connect signal handler:
  m_Combo.signal_changed().connect(sigc::mem_fun(*this,
              &amp;ExampleWindow::on_combo_changed) );

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

void ExampleWindow::on_combo_changed()
{
  Glib::ustring text = m_Combo.get_active_text();
  if(!(text.empty()))
    std::cout &lt;&lt; "Combo changed: " &lt;&lt; text &lt;&lt; std::endl;
}

</pre>
<p>File: <code class="filename">main.cc</code>
</p>
<pre class="programlisting">
#include &lt;gtkmm/main.h&gt;
#include "examplewindow.h"

int main(int argc, char *argv[])
{
  Gtk::Main kit(argc, argv);

  ExampleWindow window;
  //Shows the window and returns when it is closed.
  Gtk::Main::run(window);

  return 0;
}
</pre>
</div>
</div>
</div>
<div class="navfooter">
<hr>
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left">
<a accesskey="p" href="sec-treeview-examples.html"><img src="icons/prev.png" alt="Prev"></a> </td>
<td width="20%" align="center"> </td>
<td width="40%" align="right"> <a accesskey="n" href="sec-comboboxentry.html"><img src="icons/next.png" alt="Next"></a>
</td>
</tr>
<tr>
<td width="40%" align="left" valign="top">Examples </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"> ComboBoxEntry</td>
</tr>
</table>
</div>
</body>
</html>