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<tr><th colspan="3" align="center">The Selection</th></tr>
<tr>
<td width="20%" align="left">
<a accesskey="p" href="sec-iterating-over-model-rows.html"><img src="icons/prev.png" alt="Prev"></a> </td>
<th width="60%" align="center">Chapter 11. The TreeView widget</th>
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<div class="section">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-treeview-selection"></a>The Selection</h2></div></div></div>
<p>
To find out what rows the user has selected, get the
<code class="classname">Gtk::TreeView::Selection</code> object from the
<code class="classname">TreeView</code>, like so:
</p>
<pre class="programlisting"><code class="code">auto refTreeSelection = m_TreeView.get_selection();</code></pre>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="treeview-selection-mode"></a>Single or multiple selection</h3></div></div></div>
<p>
By default, only single rows can be selected, but you can allow
multiple selection by setting the mode, like so:
</p>
<pre class="programlisting"><code class="code">refTreeSelection->set_mode(Gtk::SelectionMode::MULTIPLE);</code></pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="treeview-selected-rows"></a>The selected rows</h3></div></div></div>
<p>
For single-selection, you can just call <code class="methodname">get_selected()</code>,
like so:
</p>
<pre class="programlisting"><code class="code">auto iter = refTreeSelection->get_selected();
if(iter) //If anything is selected
{
auto row = *iter;
//Do something with the row.
}</code></pre>
<p>
For multiple-selection, you need to call <code class="methodname">get_selected_rows()</code>
or define a callback, and give it to
<code class="methodname">selected_foreach()</code>,
<code class="methodname">selected_foreach_path()</code>, or
<code class="methodname">selected_foreach_iter()</code>, like so:
</p>
<pre class="programlisting"><code class="code">refTreeSelection->selected_foreach_iter(
sigc::mem_fun(*this, &TheClass::selected_row_callback) );
void TheClass::selected_row_callback(
const Gtk::TreeModel::const_iterator& iter)
{
auto row = *iter;
//Do something with the row.
}</code></pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="treeview-selection-changed-signal"></a>The "changed" signal</h3></div></div></div>
<p>
To respond to the user clicking on a row or range of rows, connect to the
signal like so:
</p>
<pre class="programlisting"><code class="code">refTreeSelection->signal_changed().connect(
sigc::mem_fun(*this, &Example_IconTheme::on_selection_changed)
);</code></pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="treeview-selection-preventing"></a>Preventing row selection</h3></div></div></div>
<p>
Maybe the user should not be able to select every item in your list or tree.
For instance, in the gtk-demo, you can select a demo to see the source code,
but it doesn't make any sense to select a demo category.
</p>
<p>
To control which rows can be selected, use the
<code class="methodname">set_select_function()</code> method, providing a
<code class="classname">sigc::slot</code> callback. For instance:
</p>
<pre class="programlisting"><code class="code">m_refTreeSelection->set_select_function( sigc::mem_fun(*this,
&DemoWindow::select_function) );</code></pre>
<p>
and then
</p>
<pre class="programlisting"><code class="code">bool DemoWindow::select_function(
const Glib::RefPtr<Gtk::TreeModel>& model,
const Gtk::TreeModel::Path& path, bool)
{
const auto iter = model->get_iter(path);
return iter->children().empty(); // only allow leaf nodes to be selected
}</code></pre>
</div>
<div class="section">
<div class="titlepage"><div><div><h3 class="title">
<a name="treeview-selection-changing"></a>Changing the selection</h3></div></div></div>
<p>
To change the selection, specify a
<code class="classname">Gtk::TreeModel::iterator</code> or
<code class="classname">Gtk::TreeModel::Row</code>, like so:
</p>
<pre class="programlisting"><code class="code">auto row = m_refModel->children()[5]; //The sixth row.
if(row)
refTreeSelection->select(row.get_iter());</code></pre>
<p>
or
</p>
<pre class="programlisting"><code class="code">auto iter = m_refModel->children().begin()
if(iter)
refTreeSelection->select(iter);</code></pre>
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