CheckBox Inputs

Overview

The WPF CheckBox control extends ToggleButton, giving it a persistent checked state that users can toggle between True (checked) and False (unchecked) with a single click. The checked state is exposed through the nullable boolean property IsChecked, which integrates seamlessly with WPF data binding. Binding IsChecked to a bool property in your ViewModel creates a two-way link that keeps the UI and business logic in sync without any code-behind.

When IsThreeState is set to True, a third state — indeterminate, represented by null — becomes available. The indeterminate state is visually rendered as a filled or dash-mark inside the box, signalling that the underlying value is neither definitively on nor off. This is the standard pattern for "select all / select some / select none" scenarios, such as a parent node in a hierarchical checklist where only some children are selected.

Like all ContentControl descendants, a CheckBox can contain any WPF element as its label — not just plain text. You can embed TextBlock elements with rich typography, inline images, or even interactive controls. The content is rendered to the right of the checkbox glyph by default, but this can be overridden through ContentTemplate and ControlTemplate customisation.

CheckBox raises Checked, Unchecked, and Indeterminate routed events that bubble up the visual tree, allowing parent containers to handle state changes without subscribing to individual checkboxes. This is particularly useful in dynamic lists where checkboxes are generated at runtime.

Screen Preview

Demonstrated Properties

The following properties are demonstrated interactively in the WPF Standard Control Demo App. Each property can be configured in real time within the app to observe its behavior.

XAML Example

The following XAML demonstrates common CheckBox patterns including data binding and three-state usage:

<StackPanel Margin="16" Spacing="8">

  <!-- Simple two-state checkbox bound to a bool property -->
  <CheckBox Content="Enable notifications"
            IsChecked="{Binding IsNotificationsEnabled}" />

  <!-- Three-state checkbox for partial selection -->
  <CheckBox Content="Select All"
            IsThreeState="True"
            IsChecked="{Binding SelectAllState}" />

  <!-- Rich content label with an image -->
  <CheckBox IsChecked="{Binding IsDarkMode}">
    <StackPanel Orientation="Horizontal" Spacing="6">
      <Image Source="/Icons/moon.png" Width="16" Height="16" />
      <TextBlock Text="Dark mode" VerticalAlignment="Center" />
    </StackPanel>
  </CheckBox>

  <!-- Multi-line label aligned to top of glyph -->
  <CheckBox VerticalContentAlignment="Top"
            IsChecked="{Binding AcceptsTerms}">
    <TextBlock TextWrapping="Wrap" MaxWidth="280"
               Text="I agree to the terms and conditions of this application." />
  </CheckBox>

</StackPanel>

Common Use Cases

• Settings and preferences panels: Individual boolean settings such as "Start at login", "Enable spell check", or "Show tooltips", each bound to a ViewModel property.
• Filter controls: A group of checkboxes that represent filter categories (e.g., file types, status values) where any combination can be active simultaneously.
• Hierarchical selection: A parent CheckBox with IsThreeState="True" that reflects whether all, some, or none of its child items are selected in a tree or list.
• Terms-of-service acceptance: A single CheckBox requiring the user to confirm acceptance before a form submit button becomes enabled via CanExecute.
• Bulk-edit forms: Multi-record editing forms where a CheckBox next to a field indicates "apply this value to all selected records".

Tips and Best Practices

• Bind to bool? for three-state scenarios to preserve the indeterminate value across round-trips. Binding to a plain bool will lose the null value and coerce it to False.
• Space key toggles the checkbox — When a CheckBox has keyboard focus, pressing Space cycles its state exactly as a click would. Keep this in mind when testing keyboard usability in forms and settings panels.
• Implementing the "Select All" pattern — In the ViewModel, compute the SelectAll property by inspecting all child items: return true if all are checked, false if none are, and null if mixed. When the user sets SelectAll to true or false, update all children accordingly; setting it to null should be a no-op to avoid an infinite loop.
• MVVM state-change detection — Rather than handling Checked/Unchecked events in code-behind, bind IsChecked two-way and detect changes in the ViewModel's property setter. If you need to drive a Command from the event, use Interaction.Triggers with an EventTrigger to convert the event to a Command without code-behind.
• Use Checked / Unchecked routed events in code-behind only when you cannot use data binding. In MVVM applications, prefer binding IsChecked and using property-change callbacks in the ViewModel.
• Group related checkboxes visually using a GroupBox or a labelled Border to help users understand which options belong together, especially in dense settings dialogs.
• Never use CheckBox for mutually exclusive choices. If only one option should be active at a time, use RadioButton instead, which enforces single-selection within a group automatically.
• Provide accessible labels. Always set meaningful Content text or use AutomationProperties.LabeledBy so screen readers can announce the purpose of each checkbox to visually impaired users.

Related Controls

• RadioButton — mutually exclusive toggle derived from ToggleButton; use when only one option is allowed.
• ToggleButton — the base class; useful when you need a checked-state button with a fully custom appearance.
• Button — a stateless command trigger; use when no persistent on/off state is needed.
• ListView — a common host for checkbox-per-row selection patterns in data lists.

Source Code

The source code for this demo screen is available on GitHub. Use the built-in code view buttons in the app to see the exact XAML for each property.

View CheckBox source code on GitHub →