Checkbox

Overview

Checkbox derives directly from the native CheckBox, which already models tri-state via IsThreeState plus a nullable IsChecked. The constructor forces IsThreeState = true so indeterminate is reachable programmatically, but an OnToggle() override replaces the native three-value click cycle with a binary one: a click always lands on checked or unchecked, never indeterminate. NaviusCheckboxIndicator is a composable glyph part, and NaviusCheckboxGroup is a separate lookless container that coordinates a set of checkboxes for a select-all roll-up.

Usage

xmlns:checkbox="clr-namespace:Navius.Wpf.Primitives.Controls.Checkbox;assembly=Navius.Wpf.Primitives"

<checkbox:NaviusCheckboxGroup AllValues="{Binding AllNames}"
                               Value="{Binding Selected, Mode=TwoWay}">
    <StackPanel>
        <checkbox:NaviusCheckbox IsSelectAll="True" Content="Select all" />
        <checkbox:NaviusCheckbox GroupValue="a" Content="Option A" />
        <checkbox:NaviusCheckbox GroupValue="b" Content="Option B" />
    </StackPanel>
</checkbox:NaviusCheckboxGroup>

<checkbox:NaviusCheckbox x:Name="Standalone"
                          Content="Accept terms"
                          IsChecked="{Binding Accepted, Mode=TwoWay}" />

Properties

Property	Type	Default	From	Description
IsChecked	bool?	false	System.Windows.Controls.Primitives.ToggleButton	Tri-state value; null = indeterminate. IsThreeState is forced true in the constructor, but user clicks always binary-toggle via OnToggle(); indeterminate is reachable only by setting IsChecked = null in code. Two-way bindable by default.
ReadOnly	bool	false	NaviusCheckbox	Focusable but the value cannot change, enforced inside OnToggle() (no IsEnabled change).
Required	bool	false	NaviusCheckbox	Exposed for API parity; no enforcement behavior in this port.
GroupValue	string?	null	NaviusCheckbox	Identity used by an ancestor NaviusCheckboxGroup to track this checkbox’s checked-ness. Replaces the web contract’s Name, which collides with FrameworkElement.Name.
IsSelectAll	bool	false	NaviusCheckbox	Marks this checkbox as the group’s roll-up select-all checkbox. Replaces the contract’s Parent, which collides with the read-only Visual.Parent.
IsChecked (indicator)	bool?	false	NaviusCheckboxIndicator	Mirrors the owning checkbox’s state via a TemplateBinding; drives the indicator’s own Visibility.
KeepMounted (indicator)	bool	false	NaviusCheckboxIndicator	Keeps the indicator mounted (visible) even when unchecked.
Value (group)	IReadOnlyList<string>	[]	NaviusCheckboxGroup	The set of checked descendant GroupValues, synced against every non-select-all NaviusCheckbox in the logical tree.
AllValues (group)	IReadOnlyList<string>	[]	NaviusCheckboxGroup	Every member name in the group; required to drive an IsSelectAll checkbox’s tri-state roll-up.

Events

Event	Signature	Fires when
Checked / Unchecked (inherited)	RoutedEventHandler	IsChecked flips to true/false via user click or programmatic set.
Indeterminate (inherited)	RoutedEventHandler	IsChecked becomes null; only reachable programmatically (e.g. the group’s roll-up), never via a click.
ValueChanged (group)	RoutedEventHandler	A descendant checkbox’s checked state changes the group’s Value (a member added or removed, or the select-all checkbox’s roll-up recomputed).

Keyboard interactions

Key	Behavior
Space	Native ButtonBase press-on-key-down/click-on-key-up activation toggles IsChecked through the binary OnToggle() override; no custom key handling exists in NaviusCheckbox itself.

UIA mechanism

NaviusCheckbox ships no custom AutomationPeer; it inherits CheckBoxAutomationPeer, which already reports ToggleState.Indeterminate for a null IsChecked and exposes UIA TogglePattern, matching role="checkbox"/aria-checked without extra code. NaviusCheckboxGroup does get a minimal custom NaviusCheckboxGroupAutomationPeer (AutomationControlType.Group), since its ContentControl base has no group semantics at all; it does not implement a full ISelectionProvider wired to child peers. The unit suite exercises the binary OnToggle() override, ReadOnly’s focusable-but-immutable behavior, and the group’s routed-event-bubbling roll-up (guarded against reentrancy) against real control instances; it does not include a real routed-key (Space/Enter) simulation for this family the way the sibling Toggle/Switch/ToggleGroup M6 passes did.

Web deltas

• The hidden <input type="checkbox"> bubble input (form submission mirror) is dropped entirely; no WPF form-submission model.
• Attributes splat is dropped.
• Name/Parent are renamed to GroupValue/IsSelectAll: Name collides with the reserved FrameworkElement.Name, and Parent collides with the read-only Visual.Parent.
• Disabled is not a new property: it maps onto the inherited IsEnabled, which WPF already cascades to descendants, so NaviusCheckboxGroup.Disabled needed no extra code.
• No custom AutomationPeer surfaces aria-readonly/aria-required for NaviusCheckbox; this is a documented gap, not built, to keep scope proportional.
• NaviusCheckboxGroup wraps arbitrary XAML content and discovers descendant checkboxes via a logical-tree walk rather than an ItemsControl/items-source model, mirroring the web’s div wrapping an arbitrary RenderFragment.

Captures

The Checkbox Gallery page rendered at the pinned commit, in each theme.