WPF - CheckBox Example - Dot Net Perls

CheckBox, WPF. A CheckBox allows an option to be set, or unset. This control by default has 2 states: Checked and Unchecked—an Indeterminate state is also possible.

Changes, IsChecked. We use event handlers (CheckBox_Checked and Unchecked) to detect changes. IsChecked tells us the current state.

RadioButton

XAML example. We create a new WPF project and add a CheckBox control. In the XAML section, add the "Checked" attribute and allow Visual Studio to create the CheckBox_Checked event handler.

Then Please do the same for CheckBox_Unchecked. Look at the C# code file for your project. It has been modified.

Code example. The CheckBox_Checked and CheckBox_Unchecked methods call a third method, Handle(), that deals with CheckBox changes. They pass the "sender" object cast to a CheckBox.

Detail We use the IsChecked property (a nullable bool) to determine the current state of the CheckBox in the Handle method.

Finally We assign to the Window Title property. This changes the title to indicate the state of the check box after it changes.

using System.Windows; using System.Windows.Controls; namespace WpfApplication6 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void CheckBox_Checked(object sender, RoutedEventArgs e) { Handle(sender as CheckBox); } private void CheckBox_Unchecked(object sender, RoutedEventArgs e) { Handle(sender as CheckBox); } void Handle(CheckBox checkBox) { // Use IsChecked. bool flag = checkBox.IsChecked.Value; // Assign Window Title. this.Title = "IsChecked = " + flag.ToString(); } } }

IsThreeState. The CheckBox optionally supports 3 states. Please add the IsThreeState attribute to the XAML. This third state is called the "indeterminate" state.

Next We add a CheckBox_Indeterminate event handler in the same way as Checked and Unchecked.

Tip If you have trouble making up your mind, the "Indeterminate" option is a perfect choice.

using System.Windows; namespace WpfApplication6 { /// <summary> /// Interaction logic for MainWindow.xaml /// </summary> public partial class MainWindow : Window { public MainWindow() { InitializeComponent(); } private void CheckBox_Checked(object sender, RoutedEventArgs e) { this.Title = "Checked"; } private void CheckBox_Unchecked(object sender, RoutedEventArgs e) { this.Title = "Unchecked"; } private void CheckBox_Indeterminate(object sender, RoutedEventArgs e) { this.Title = "Indeterminate"; } } }

Summary. Many CheckBox controls require only the Checked and Unchecked events. But the Indeterminate state is also available. CheckBox presents an option to the user.