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<div class="chapter">
<div class="titlepage"><div><div><h1 class="title">
<a name="chapter-container-widgets"></a>Chapter 8. Container Widgets</h1></div></div></div>
<div class="toc">
<p><b>Table of Contents</b></p>
<ul class="toc">
<li><span class="sect1"><a href="chapter-container-widgets.html#sec-single-item-containers">Single-item Containers</a></span></li>
<li><span class="sect1"><a href="sec-multi-item-containers.html">Multiple-item widgets </a></span></li>
</ul>
</div>
<p>
All container widgets derive from <code class="classname">Gtk::Container</code>, not
always directly. Some container widgets, such as
<code class="classname">Gtk::Grid</code> can hold many child widgets, so these
typically have more complex interfaces. Others, such as
<code class="classname">Gtk::Frame</code> contain only one child widget.
</p>
<div class="sect1">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-single-item-containers"></a>Single-item Containers</h2></div></div></div>
<p>
The single-item container widgets derive from <code class="classname">Gtk::Bin</code>,
which provides the <code class="methodname">add()</code> and <code class="methodname">remove()</code>
methods for the child widget. Note that <code class="classname">Gtk::Button</code> and
<code class="classname">Gtk::Window</code> are technically single-item containers, but
we have discussed them already elsewhere.
</p>
<p>
We also discuss the <code class="classname">Gtk::Paned</code> widget, which allows you
to divide a window into two separate "panes". This widget actually contains
two child widgets, but the number is fixed so it seems appropriate.
</p>
<div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-frame"></a>Frame</h3></div></div></div>
<p>
Frames can enclose one or a group of widgets within a box, optionally with a
title. For instance, you might place a group of
<code class="classname">RadioButton</code>s or <code class="classname">CheckButton</code>s in a
<code class="classname">Frame</code>.
</p>
<p><a class="ulink" href="http://developer.gnome.org/gtkmm/3.24/classGtk_1_1Frame.html" target="_top">Reference</a></p>
<div class="sect3">
<div class="titlepage"><div><div><h4 class="title">
<a name="frame-example"></a>Example</h4></div></div></div>
<div class="figure">
<a name="figure-frame"></a><p class="title"><b>Figure 8.1. Frame</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="figures/frame.png" alt="Frame"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="http://git.gnome.org/browse/gtkmm-documentation/tree/examples/book/frame?h=gtkmm-3-24" target="_top">Source Code</a></p>
<p>File: <code class="filename">examplewindow.h</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include &lt;gtkmm.h&gt;

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

protected:

  //Child widgets:
  Gtk::Frame m_Frame;
};

#endif //GTKMM_EXAMPLEWINDOW_H
</pre>
<p>File: <code class="filename">main.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;gtkmm/application.h&gt;

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

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app-&gt;run(window);
}
</pre>
<p>File: <code class="filename">examplewindow.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"

ExampleWindow::ExampleWindow()
{
 /* Set some window properties */
  set_title("Frame Example");
  set_size_request(300, 300);

  /* Sets the border width of the window. */
  set_border_width(10);

  add(m_Frame);

  /* Set the frames label */
  m_Frame.set_label("Gtk::Frame Widget");

  /* Align the label at the right of the frame */
  //m_Frame.set_label_align(Gtk::ALIGN_END, Gtk::ALIGN_START);

  /* Set the style of the frame */
  m_Frame.set_shadow_type(Gtk::SHADOW_ETCHED_OUT);

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

</pre>
</div>
</div>
<div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-paned"></a>Paned</h3></div></div></div>
<p>
Panes divide a widget into two halves, separated by a moveable divider.
The two halves (panes) can be oriented either horizontally (side by side) or
vertically (one above the other).
</p>
<p>
Unlike the other widgets in this section, pane widgets contain not one but two
child widgets, one in each pane. Therefore, you should use
<code class="methodname">add1()</code> and <code class="methodname">add2()</code> instead of the
<code class="methodname">add()</code> method.
</p>
<p>
You can adjust the position of the divider using the
<code class="methodname">set_position()</code> method, and you will probably need to do
so.
</p>
<p><a class="ulink" href="http://developer.gnome.org/gtkmm/3.24/classGtk_1_1Paned.html" target="_top">Reference</a></p>
<div class="sect3">
<div class="titlepage"><div><div><h4 class="title">
<a name="paned-example"></a>Example</h4></div></div></div>
<div class="figure">
<a name="figure-paned"></a><p class="title"><b>Figure 8.2. Paned</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="figures/paned.png" alt="Paned"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="http://git.gnome.org/browse/gtkmm-documentation/tree/examples/book/paned?h=gtkmm-3-24" target="_top">Source Code</a></p>
<p>File: <code class="filename">examplewindow.h</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include "messageslist.h"
#include "messagetext.h"
#include &lt;gtkmm.h&gt;

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

protected:

  //Child widgets:
  Gtk::Paned m_VPaned;
  MessagesList m_MessagesList;
  MessageText m_MessageText;
};

#endif //GTKMM_EXAMPLEWINDOW_H
</pre>
<p>File: <code class="filename">messageslist.h</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLE_MESSAGESLIST_H
#define GTKMM_EXAMPLE_MESSAGESLIST_H

#include &lt;gtkmm.h&gt;

class MessagesList: public Gtk::ScrolledWindow
{
public:
  MessagesList();
  virtual ~MessagesList();

  class ModelColumns : public Gtk::TreeModel::ColumnRecord
  {
  public:

    ModelColumns()
    { add(m_col_text); }

    Gtk::TreeModelColumn&lt;Glib::ustring&gt; m_col_text;
  };

  ModelColumns m_Columns;

protected:
  Glib::RefPtr&lt;Gtk::ListStore&gt; m_refListStore; //The Tree Model.
  Gtk::TreeView m_TreeView; //The Tree View.
};
#endif //GTKMM_EXAMPLE_MESSAGESLIST_H
</pre>
<p>File: <code class="filename">messagetext.h</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLE_MESSAGETEXT_H
#define GTKMM_EXAMPLE_MESSAGETEXT_H

#include &lt;gtkmm.h&gt;

class MessageText : public Gtk::ScrolledWindow
{
public:
  MessageText();
  virtual ~MessageText();

  void insert_text();

protected:
  Gtk::TextView m_TextView;
};

#endif //GTKMM_EXAMPLE_MESSAGETEXT_H
</pre>
<p>File: <code class="filename">messageslist.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "messageslist.h"
#include &lt;sstream&gt;

MessagesList::MessagesList()
{
  /* Create a new scrolled window, with scrollbars only if needed */
  set_policy(Gtk::POLICY_AUTOMATIC, Gtk::POLICY_AUTOMATIC);

  add(m_TreeView);

  /* create list store */
  m_refListStore = Gtk::ListStore::create(m_Columns);

  m_TreeView.set_model(m_refListStore);

  /* Add some messages to the window */
  for(int i = 0; i &lt; 10; ++i)
  {
    std::ostringstream text;
    text &lt;&lt; "message #" &lt;&lt; i;

    Gtk::TreeModel::Row row = *(m_refListStore-&gt;append());
    row[m_Columns.m_col_text] = text.str();
  }

  //Add the Model's column to the View's columns:
  m_TreeView.append_column("Messages", m_Columns.m_col_text);

  show_all_children();
}

MessagesList::~MessagesList()
{
}
</pre>
<p>File: <code class="filename">main.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;gtkmm/application.h&gt;

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

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app-&gt;run(window);
}
</pre>
<p>File: <code class="filename">messagetext.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "messagetext.h"

MessageText::MessageText()
{
  set_policy(Gtk::POLICY_AUTOMATIC, Gtk::POLICY_AUTOMATIC);

  add(m_TextView);
  insert_text();

  show_all_children();
}

MessageText::~MessageText()
{
}

void MessageText::insert_text()
{
  auto refTextBuffer = m_TextView.get_buffer();

  Gtk::TextBuffer::iterator iter = refTextBuffer-&gt;get_iter_at_offset(0);
  refTextBuffer-&gt;insert(iter,
    "From: pathfinder@nasa.gov\n"
    "To: mom@nasa.gov\n"
    "Subject: Made it!\n"
    "\n"
    "We just got in this morning. The weather has been\n"
    "great - clear but cold, and there are lots of fun sights.\n"
    "Sojourner says hi. See you soon.\n"
    " -Path\n");
}
</pre>
<p>File: <code class="filename">examplewindow.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"

ExampleWindow::ExampleWindow()
: m_VPaned(Gtk::ORIENTATION_VERTICAL)
{
  set_title ("Paned Windows");
  set_border_width(10);
  set_default_size(450, 400);

  /* Add a vpaned widget to our toplevel window */
  add(m_VPaned);

  /* Now add the contents of the two halves of the window */
  m_VPaned.add1(m_MessagesList);
  m_VPaned.add2(m_MessageText);

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}
</pre>
</div>
</div>
<div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-scrolledwindow"></a>ScrolledWindow</h3></div></div></div>
<p>
<code class="classname">ScrolledWindow</code> widgets create a scrollable
area. You can insert any type of widget into a
<code class="classname">ScrolledWindow</code> window, and it will be accessible
regardless of its size by using the scrollbars. Note that
<code class="classname">ScrolledWindow</code> is not a
<code class="classname">Gtk::Window</code> despite the slightly misleading name.
</p>
<p>
Scrolled windows have <span class="emphasis"><em>scrollbar policies</em></span> which determine
whether the <code class="classname">Scrollbar</code>s will be displayed. The policies
can be set with the <code class="methodname">set_policy()</code> method. The policy may be
one of <code class="literal">Gtk::POLICY_AUTOMATIC</code> or
<code class="literal">Gtk::POLICY_ALWAYS</code>.
<code class="literal">Gtk::POLICY_AUTOMATIC</code> will cause the scrolled window
to display the scrollbar only if the contained widget is larger than the
visible area. <code class="literal">Gtk::POLICY_ALWAYS</code> will cause the
scrollbar to be displayed always.
</p>
<p><a class="ulink" href="http://developer.gnome.org/gtkmm/3.24/classGtk_1_1ScrolledWindow.html" target="_top">Reference</a></p>
<div class="sect3">
<div class="titlepage"><div><div><h4 class="title">
<a name="scrolledwindow-example"></a>Example</h4></div></div></div>
<p>
Here is a simple example that packs 100 toggle buttons into a ScrolledWindow. Try resizing the window to see the scrollbars react.
</p>
<div class="figure">
<a name="figure-scrolledwindow"></a><p class="title"><b>Figure 8.3. ScrolledWindow</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="figures/scrolledwindow.png" alt="ScrolledWindow"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="http://git.gnome.org/browse/gtkmm-documentation/tree/examples/book/scrolledwindow?h=gtkmm-3-24" target="_top">Source Code</a></p>
<p>File: <code class="filename">examplewindow.h</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include &lt;gtkmm.h&gt;

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

protected:
  //Signal handlers:
  void on_dialog_response(int response_id);

  //Child widgets:
  Gtk::ScrolledWindow m_ScrolledWindow;
  Gtk::Grid m_Grid;
};

#endif //GTKMM_EXAMPLEWINDOW_H
</pre>
<p>File: <code class="filename">main.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;gtkmm/application.h&gt;

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

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app-&gt;run(window);
}
</pre>
<p>File: <code class="filename">examplewindow.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;iostream&gt;

ExampleWindow::ExampleWindow()
{
  set_title("Gtk::ScrolledWindow example");
  set_border_width(0);
  set_size_request(300, 300);

  m_ScrolledWindow.set_border_width(10);

  /* the policy is one of Gtk::POLICY AUTOMATIC, or Gtk::POLICY_ALWAYS.
   * Gtk::POLICY_AUTOMATIC will automatically decide whether you need
   * scrollbars, whereas Gtk::POLICY_ALWAYS will always leave the scrollbars
   * there.  The first one is the horizontal scrollbar, the second,
   * the vertical. */
  m_ScrolledWindow.set_policy(Gtk::POLICY_AUTOMATIC, Gtk::POLICY_ALWAYS);

  get_content_area()-&gt;pack_start(m_ScrolledWindow);

  /* set the spacing to 10 on x and 10 on y */
  m_Grid.set_row_spacing(10);
  m_Grid.set_column_spacing(10);

  /* pack the grid into the scrolled window */
  m_ScrolledWindow.add(m_Grid);

  /* this simply creates a grid of toggle buttons
   * to demonstrate the scrolled window. */
  for(int i = 0; i &lt; 10; i++)
  {
     for(int j = 0; j &lt; 10; j++)
     {
        char buffer[32];
        sprintf(buffer, "button (%d,%d)\n", i, j);
        auto pButton = Gtk::make_managed&lt;Gtk::ToggleButton&gt;(buffer);
        m_Grid.attach(*pButton, i, j);
     }
  }

  /* Add a "close" button to the bottom of the dialog */
  add_button("_Close", Gtk::RESPONSE_CLOSE);
  signal_response().connect(sigc::mem_fun(*this, &amp;ExampleWindow::on_dialog_response));

  /* This makes it so the button is the default.
   * Simply hitting the "Enter" key will cause this button to activate. */
  set_default_response(Gtk::RESPONSE_CLOSE);

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

void ExampleWindow::on_dialog_response(int response_id)
{
  switch (response_id)
  {
  case Gtk::RESPONSE_CLOSE:
  case Gtk::RESPONSE_DELETE_EVENT:
    hide();
    break;
  default:
    std::cout &lt;&lt; "Unexpected response_id=" &lt;&lt; response_id &lt;&lt; std::endl;
    break;
  }
}
</pre>
</div>
</div>
<div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-aspectframe"></a>AspectFrame</h3></div></div></div>
<p>
The <code class="classname">AspectFrame</code> widget looks like a
<code class="classname">Frame</code> widget, but it also enforces the <span class="emphasis"><em>aspect
    ratio</em></span> (the ratio of the width to the height) of the child
widget, adding extra space if necessary. For instance, this would allow you to
display a photograph without allowing the user to distort it horizontally or
vertically while resizing.
</p>
<p><a class="ulink" href="http://developer.gnome.org/gtkmm/3.24/classGtk_1_1AspectFrame.html" target="_top">Reference</a></p>
<div class="sect3">
<div class="titlepage"><div><div><h4 class="title">
<a name="aspectframe-example"></a>Example</h4></div></div></div>
<p>
The following program uses a <code class="classname">Gtk::AspectFrame</code> to present a
drawing area whose aspect ratio will always be 2:1, no matter how the user
resizes the top-level window.
</p>
<div class="figure">
<a name="figure-aspectframe"></a><p class="title"><b>Figure 8.4. AspectFrame</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="figures/aspectframe.png" alt="AspectFrame"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="http://git.gnome.org/browse/gtkmm-documentation/tree/examples/book/aspectframe?h=gtkmm-3-24" target="_top">Source Code</a></p>
<p>File: <code class="filename">examplewindow.h</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include &lt;gtkmm.h&gt;

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

protected:

  //Child widgets:
  Gtk::AspectFrame m_AspectFrame;
  Gtk::DrawingArea m_DrawingArea;
};

#endif //GTKMM_EXAMPLEWINDOW_H
</pre>
<p>File: <code class="filename">main.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;gtkmm/application.h&gt;

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

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app-&gt;run(window);
}
</pre>
<p>File: <code class="filename">examplewindow.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"

ExampleWindow::ExampleWindow()
: m_AspectFrame("2x1", /* label */
    Gtk::ALIGN_CENTER, /* center x */
    Gtk::ALIGN_CENTER, /* center y */
    2.0, /* xsize/ysize = 2 */
    false /* ignore child's aspect */)
{
  set_title("Aspect Frame");
  set_border_width(10);

  // Add a child widget to the aspect frame */
  // Ask for a 200x200 window, but the AspectFrame will give us a 200x100
  // window since we are forcing a 2x1 aspect ratio */
  m_DrawingArea.set_size_request(200, 200);
  m_AspectFrame.add(m_DrawingArea);

  // Add the aspect frame to our toplevel window:
  add(m_AspectFrame);

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

</pre>
</div>
</div>
<div class="sect2">
<div class="titlepage"><div><div><h3 class="title">
<a name="sec-alignment"></a>Alignment</h3></div></div></div>
<p>
The <code class="classname">Alignment</code> widget allows you to place a widget at a
position and size relative to the size of the <code class="classname">Alignment</code>
widget itself. For instance, it might be used to center a widget.
</p>
<p>
The <code class="classname">Alignment</code> widget is deprecated from <span class="application">gtkmm</span> version 3.14
and should not be used in newly-written code. Use <code class="classname">Gtk::Widget</code>'s
alignment and margin methods instead.
</p>
<div class="sect3">
<div class="titlepage"><div><div><h4 class="title">
<a name="alignment-example"></a>Example</h4></div></div></div>
<p>
This example right-aligns a button in a window by using
<code class="methodname">Gtk::Widget::set_halign()</code>.
</p>
<div class="figure">
<a name="figure-alignment"></a><p class="title"><b>Figure 8.5. Alignment</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="figures/alignment.png" alt="Alignment"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="http://git.gnome.org/browse/gtkmm-documentation/tree/examples/book/alignment?h=gtkmm-3-24" target="_top">Source Code</a></p>
<p>File: <code class="filename">examplewindow.h</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#ifndef GTKMM_EXAMPLEWINDOW_H
#define GTKMM_EXAMPLEWINDOW_H

#include &lt;gtkmm.h&gt;

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

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

  //Child widgets:
  Gtk::Button m_Button;
};

#endif //GTKMM_EXAMPLEWINDOW_H
</pre>
<p>File: <code class="filename">main.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"
#include &lt;gtkmm/application.h&gt;

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

  ExampleWindow window;

  //Shows the window and returns when it is closed.
  return app-&gt;run(window);
}
</pre>
<p>File: <code class="filename">examplewindow.cc</code> (For use with gtkmm 3, not gtkmm 2)
</p>
<pre class="programlisting">
#include "examplewindow.h"

ExampleWindow::ExampleWindow()
: m_Button("_Close", /* mnemonic= */ true)
{
  set_title("Alignment");
  set_border_width(10);
  set_default_size(200, 50);

  m_Button.set_halign(Gtk::ALIGN_END);
  m_Button.set_valign(Gtk::ALIGN_CENTER);
  add(m_Button);

  m_Button.signal_clicked().connect( sigc::mem_fun(*this,
              &amp;ExampleWindow::on_button_clicked) );

  show_all_children();
}

ExampleWindow::~ExampleWindow()
{
}

void ExampleWindow::on_button_clicked()
{
  hide();
}

</pre>
<p>
See the <a class="link" href="sec-progressbar.html" title="ProgressBar">ProgressBar</a> section for another
example that uses <code class="methodname">set_halign()</code>.
</p>
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