Introduction
This article helps you to create a combobox with a checkboxlist in
Silverlight.
In this article I use DependencyProperty, INotifyPropertyChanged
, and
ItemTemplate
for checkbox check/uncheck.
The control looks like:
Background
In this article I used DependencyProperty for changing the checkbox value in
the ComboBox
control.
A DependencyProperty is a static method that changes the value of an instanced object property.
Also I used INotifyPropertyChanged
for changing property value in
the custom user control.
Anyone can use this control in his/her Silverlight project. Also ItemTemplate
is particularly useful when you bind the ItemsSource
to data, it binds to a checkbox in a combobox. In this example, when the user checks
the checkbox, time is updated in the combobox selected value and also when unchecking any checkbox,
the time reflects in the selected value.
In this example, I create a Model class which contains NotifyProperty
and
returns the list for binding it in the control.
In this example I also use ItemTemplate
for displaying a checkbox inside
a combobox. When page loads that time assigns the result to an
ItemsSource
.
Also I add a PropertyChanged
event for notifying when checkbox is checked or unchecked. When
the
PropertyChanged
event is called, the time binds the selected
checkbox value to the combobox selected value.
My MainPage.xaml looks like:
<grid removed="White" x:name="LayoutRoot">
<stackpanel margin="10">
<combobox horizontalalignment="Left" width="200"
height="25" name="cmbDepartment">
<combobox.itemtemplate>
<datatemplate>
<checkbox ischecked="{Binding IsChecked,Mode=TwoWay}"
content="{Binding DepartmentName}">
</checkbox></datatemplate>
</combobox.itemtemplate>
</combobox>
<textblock margin="5,-20,0,0" horizontalalignment="Left"
width="Auto" height="20" x:name="tbDepartment">
</textblock></stackpanel>
</grid>
My MainPage.xaml.cs looks like:
public partial class MainPage : UserControl
{
public MainPage()
{
InitializeComponent();
ObservableCollection<department> objDeploymentList = new ObservableCollection<department>();
cmbDepartment.SelectionChanged += new SelectionChangedEventHandler(cmbDepartment_SelectionChanged);
DepartmentList obj = new DepartmentList();
objDeploymentList = obj.LoadDepartmentList();
cmbDepartment.ItemsSource = objDeploymentList;
foreach (Department item in objDeploymentList)
{
item.PropertyChanged += new PropertyChangedEventHandler(item_PropertyChanged);
}
if (cmbDepartment.ItemsSource != null)
{
SetString();
}
}
void cmbDepartment_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
cmbDepartment.SelectedItem = null;
}
void item_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "IsChecked")
{
SetString();
}
}
public void SetString()
{
string str = "";
foreach (Department item in cmbDepartment.ItemsSource)
{
if (item.IsChecked)
{
str = str + item.DepartmentName + ",";
}
}
if (str != "")
str = str.Substring(0, str.Length - 1);
tbDepartment.Text = str;
}
}