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<div class="titlepage"><div><div><h1 class="title">
<a name="chapter-dropdown"></a>Chapter 12. The DropDown Widget</h1></div></div></div>
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<p><b>Table of Contents</b></p>
<ul class="toc">
<li><span class="section"><a href="chapter-dropdown.html#sec-dropdown-model">The model</a></span></li>
<li><span class="section"><a href="sec-dropdown-get.html">The selected item</a></span></li>
<li><span class="section"><a href="sec-dropdown-changes.html">Responding to changes</a></span></li>
<li><span class="section"><a href="sec-dropdown-simple.html">Simple String Example</a></span></li>
<li><span class="section"><a href="sec-dropdown-search.html">Examples with a Search Entry</a></span></li>
<li><span class="section"><a href="sec-dropdown-complex.html">Complex Example</a></span></li>
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<p>The <code class="classname">DropDown</code> widget is an alternative to the deprecated
<code class="classname">ComboBox</code>. It uses list models instead of tree models,
and the content is displayed using widgets instead of cell renderers.
</p>
<p>The <code class="classname">DropDown</code> widget offers a list of choices in a
dropdown menu. If appropriate, it can show extra information about each item,
such as text, a picture, or a check button. The <code class="classname">DropDown</code> widget
can optionally have an <code class="classname">Entry</code> in the dropdown menu, allowing
the user to search in a long list.
</p>
<p>The list is provided via a <code class="classname">Gio::ListModel</code>, and data
from this model is added to the <code class="classname">DropDown</code>'s view with
signal handlers connected to a <code class="classname">SignalListItemFactory</code>.
This provides flexibility, but the <code class="classname">StringList</code> class provides
a simpler text-based specialization in case that flexibility is not required.
</p>
<p><a class="ulink" href="https://gnome.pages.gitlab.gnome.org/gtkmm/classGtk_1_1DropDown.html" target="_top">Reference</a></p>
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<div class="titlepage"><div><div><h2 class="title" style="clear: both">
<a name="sec-dropdown-model"></a>The model</h2></div></div></div>
<p>The model for a <code class="classname">DropDown</code> can be defined and filled
exactly as for a <code class="classname">ListView</code> or a <code class="classname">ColumnView</code>.
It must be a subclass of <code class="classname">Glib::Object</code>.
For instance, you might have a <code class="classname">DropDown</code> with one integer
and one text column, like so:
</p>
<pre class="programlisting"><code class="code">class ModelColumns : public Glib::Object
{
public:
int m_col_id;
Glib::ustring m_col_name;
static Glib::RefPtr<ModelColumns> create(
int col_id, const Glib::ustring& col_name)
{
return Glib::make_refptr_for_instance<ModelColumns>(
new ModelColumns(col_id, col_name));
}
protected:
ModelColumns(int col_id, const Glib::ustring& col_name)
: m_col_id(col_id), m_col_name(col_name)
{}
};
Glib::RefPtr<Gio::ListStore<ModelColumns>> m_ListStore;
</code></pre>
<p>After appending rows to this model, you should provide the model to the
<code class="classname">DropDown</code> with the <code class="methodname">set_model()</code> method.
Unless you use the <code class="classname">StringList</code> model, you also need to set
a <code class="classname">ListItemFactory</code> with <code class="methodname">set_factory()</code>.
If you want the items in the dropdown menu to look different from the item
in the <code class="classname">DropDown</code> widget, you also need to set a separate
<code class="classname">ListItemFactory</code> with <code class="methodname">set_list_factory()</code>.
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