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<div class="chapter" lang="en">
<div class="titlepage"><div><div><h2 class="title">
<a name="sec-chapter-treeview"></a>Chapter 8. The TreeView widget</h2></div></div></div>
<div class="toc">
<p><b>Table of Contents</b></p>
<ul>
<li><span class="sect1"><a href="ch08.html#id2577990">The Model</a></span></li>
<li><span class="sect1"><a href="ch08s02.html">The View</a></span></li>
<li><span class="sect1"><a href="ch08s03.html">Iterating over Model Rows</a></span></li>
<li><span class="sect1"><a href="ch08s04.html">The Selection</a></span></li>
<li><span class="sect1"><a href="ch08s05.html">Sorting</a></span></li>
<li><span class="sect1"><a href="ch08s06.html">Drag and Drop</a></span></li>
<li><span class="sect1"><a href="ch08s07.html">Popup Context Menu</a></span></li>
<li><span class="sect1"><a href="ch08s08.html">Examples</a></span></li>
</ul>
</div>
<p>
The <code class="classname">Gtk::TreeView</code> widget can contain lists or trees of
data, in columns.
</p>
<div class="sect1" lang="en">
<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="id2577990"></a>The Model</h2></div></div></div>
<p>
Each <code class="classname">Gtk::TreeView</code> has an associated
<code class="classname">Gtk::TreeModel</code>, which contains the data displayed by the
<code class="classname">TreeView</code>. Each <code class="classname">Gtk::TreeModel</code> can
be used by more than one <code class="classname">Gtk::TreeView</code>. For instance,
this allows the same underlying data to be displayed and edited in 2 different
ways at the same time. Or the 2 Views might display different columns from the
same Model data, in the same way that 2 SQL queries (or "views") might
show different fields from the same database table.
</p>
<p>
Although you can theoretically implement your own Model, you will normally use
either the <code class="classname">ListStore</code> or <code class="classname">TreeStore</code>
model classes.
</p>
<p><a class="ulink" href="../../reference/html/classGtk_1_1TreeModel.html" target="_top">Reference</a></p>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2578039"></a>ListStore, for rows</h3></div></div></div>
<p>
The <code class="classname">ListStore</code> contains simple rows of data, and each row
has no children.
</p>
<div class="figure">
<a name="figure-treeview-liststore-model"></a><p class="title"><b>Figure 8.1. TreeView - ListStore</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="../figures/treeview_list.png" alt="TreeView - ListStore"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="../../reference/html/classGtk_1_1ListStore.html" target="_top">Reference</a></p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2578082"></a>TreeStore, for a hierarchy</h3></div></div></div>
<p>
The <code class="classname">TreeStore</code> contains rows of data, and each row may
have child rows.
</p>
<div class="figure">
<a name="figure-treeview-treestore-model"></a><p class="title"><b>Figure 8.2. TreeView - TreeStore</b></p>
<div class="figure-contents"><div class="screenshot"><div><img src="../figures/treeview_tree.png" alt="TreeView - TreeStore"></div></div></div>
</div>
<br class="figure-break"><p><a class="ulink" href="../../reference/html/classGtk_1_1TreeStore.html" target="_top">Reference</a></p>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2578125"></a>Model Columns</h3></div></div></div>
<p>
The <code class="classname">TreeModelColumnRecord</code> class is used to keep track
of the columns and their data types. You add
<code class="classname">TreeModelColumn</code> instances to the
<code class="classname">ColumnRecord</code> and then use those
<code class="classname">TreeModelColumns</code> when getting and setting the data in
model rows. You will probably find it convenient to derive a new
<code class="classname">TreeModelColumnRecord</code> which has your
<code class="classname">TreeModelColumn</code> instances as member data.
</p>
<pre class="programlisting">class ModelColumns : public Gtk::TreeModelColumnRecord
{
public:
ModelColumns()
{ add(m_col_text); add(m_col_number); }
Gtk::TreeModelColumn<Glib::ustring> m_col_text;
Gtk::TreeModelColumn<int> m_col_number;
};
ModelColumns m_Columns;</pre>
<p>
You specify the <code class="classname">ColumnRecord</code> when creating the Model,
like so:
</p>
<pre class="programlisting">Glib::RefPtr<Gtk::ListStore> refListStore =
Gtk::ListStore::create(m_Columns);</pre>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2578183"></a>Adding Rows</h3></div></div></div>
<p>
Add rows to the model with the <code class="function">append()</code>,
<code class="function">prepend()</code>, or <code class="function">insert()</code> methods.
</p>
<pre class="programlisting">Gtk::TreeModel::iterator iter = m_refListStore->append();</pre>
<p>You can dereference the iterator to get the Row:
</p>
<pre class="programlisting">Gtk::TreeModel::Row row = *iter;</pre>
<div class="sect3" lang="en">
<div class="titlepage"><div><div><h4 class="title">
<a name="id2578224"></a>Adding child rows</h4></div></div></div>
<p>
<code class="classname">Gtk::TreeStore</code> models can have child items. Add them
with the <code class="function">append()</code>, <code class="function">prepend()</code>, or
<code class="function">insert()</code> methods, like so:
</p>
<pre class="programlisting">Gtk::TreeModel::iterator iter_child =
m_refListStore->append(row.children());</pre>
</div>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2578261"></a>Setting values</h3></div></div></div>
<p>
You can use the <code class="function">operator[]</code> override to set the data for a
particular column in the row, specifying the
<code class="classname">TreeModelColumn</code> used to create the model.
</p>
<pre class="programlisting">row[m_Columns.m_col_text] = "sometext";</pre>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2578286"></a>Getting values</h3></div></div></div>
<p>
You can use the <code class="function">operator[]</code> override to get the data in a
particular column in a row, specifiying the
<code class="classname">TreeModelColumn</code> used to create the model.
</p>
<pre class="programlisting">Glib::ustring strText = row[m_Columns.m_col_text];
int number = row[m_Columns.m_col_number];</pre>
<p>
The compiler will complain if you use an inappropriate type. For
instance, this would generate a compiler error:
</p>
<pre class="programlisting">//compiler error - no conversion from ustring to int.
int number = row[m_Columns.m_col_text];</pre>
</div>
<div class="sect2" lang="en">
<div class="titlepage"><div><div><h3 class="title">
<a name="id2578324"></a>"Hidden" Columns</h3></div></div></div>
<p>
You might want to associate extra data with each row. If so, just add
it as a Model column, but don't add it to the View.
</p>
</div>
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