Radio Group

Overview

RadioGroup is a lookless ContentControl that owns the authoritative selected value, the roving tabindex, and an explicit arrow/Home/End keyboard model, discovering NaviusRadioGroupItem descendants (a native RadioButton subclass) through the logical tree. Native GroupName exclusion and WPF’s own directional navigation are both deliberately switched off so they cannot compete with the group’s own selection and keyboard logic.

Usage

xmlns:radio="clr-namespace:Navius.Wpf.Primitives.Controls.RadioGroup;assembly=Navius.Wpf.Primitives"

<radio:NaviusRadioGroup x:Name="Plan" Value="{Binding SelectedPlan, Mode=TwoWay}">
    <StackPanel>
        <radio:NaviusRadioGroupItem Value="free" Content="Free" />
        <radio:NaviusRadioGroupItem Value="pro" Content="Pro" />
        <radio:NaviusRadioGroupItem Value="enterprise" Content="Enterprise" />
    </StackPanel>
</radio:NaviusRadioGroup>

Properties

Property	Type	Default	From	Description
Value	string?	null	NaviusRadioGroup	The selected item’s Value. Setting it syncs every descendant item’s IsChecked and the roving tab stop.
Required	bool	false	NaviusRadioGroup	Exposed for API parity; no enforcement behavior in this port.
Orientation	string?	null	NaviusRadioGroup	Kept for API parity; inert. Arrow mapping (Down/Right = next, Up/Left = prev) is unconditional, and WPF has no aria-orientation equivalent to drive from it.
Loop	bool	true	NaviusRadioGroup	Arrow/Home/End movement wraps at the ends when true; clamps (no-ops past an end) when false.
Dir	string?	null	NaviusRadioGroup	"rtl" (case-insensitive) mirrors horizontal arrows; falls back to FlowDirection == FlowDirection.RightToLeft when unset.
Value (item)	string	""	NaviusRadioGroupItem	Identifies the item; equality against the group’s Value determines checked state.
ReadOnly (item)	bool	false	NaviusRadioGroupItem	Focusable but selection cannot change, enforced in an OnToggle() override that skips the base call.
Required (item)	bool	false	NaviusRadioGroupItem	Exposed for API parity.
IsChecked (inherited)	bool?	false	System.Windows.Controls.Primitives.ToggleButton	Native RadioButton.OnToggle() already only ever sets true, never unchecks on its own click, matching the contract’s “Space selects, there is no deselect” rule for free.
IsChecked (indicator)	bool	false	NaviusRadioGroupIndicator	Mirrors the owning item’s state via TemplateBinding; drives the indicator’s own Visibility.
KeepMounted (indicator)	bool	false	NaviusRadioGroupIndicator	Keeps the indicator mounted even when unchecked.

Events

Event	Signature	Fires when
ValueChanged	RoutedEventHandler	The group’s Value changes because a descendant item’s checked state changed (click, Space, or arrow/Home/End navigation).
Checked (inherited, item)	RoutedEventHandler	The item becomes checked; bubbles to the group, which owns Value sync.

Keyboard interactions

Key	Behavior
ArrowDown	Select and focus the next enabled item.
ArrowRight (ArrowLeft under rtl)	Same as ArrowDown, horizontal-next mirrored by direction.
ArrowUp	Select and focus the previous enabled item.
ArrowLeft (ArrowRight under rtl)	Same as ArrowUp, horizontal-prev mirrored by direction.
Home	Select and focus the first enabled item.
End	Select and focus the last enabled item.
Space (on the focused item)	Selects the focused radio via native ButtonBase/RadioButton activation; the group’s PreviewKeyDown leaves Space unhandled so it tunnels to the item’s own key handling. Enter is not an activation key.

Arrow/Home/End skip disabled items; all keyboard handling no-ops when Disabled.

UIA mechanism

NaviusRadioGroup ships NaviusRadioGroupAutomationPeer (a FrameworkElementAutomationPeer) reporting AutomationControlType.Group, deliberately minimal (it does not implement a full ISelectionProvider wired to child peers). NaviusRadioGroupItem needs no custom peer: the native RadioButtonAutomationPeer already implements ISelectionItemProvider and reports AutomationControlType.RadioButton, matching role="radio"/aria-checked. The unit suite exercises the arrow/Home/End dispatch (including RTL mirroring), the native Space-activation path (confirmed under adversarial re-check not to reproduce the “Space is dead” bug class seen elsewhere), roving tabindex recomputation, and ReadOnly’s focusable-but-immutable guard, against real control instances.

Web deltas

• Selection is fully owned by NaviusRadioGroup via routed-event bubbling plus an explicit PreviewKeyDown handler; native GroupName-based mutual exclusion is deliberately left unset, and WPF’s own KeyboardNavigation.DirectionalNavigation is switched off (None) so it cannot compete with the custom handler.
• Dir is an explicit string property ("rtl", case-insensitive) bridging the contract’s Dir/cascaded-NaviusDirection string to WPF’s FlowDirection, falling back to FlowDirection.RightToLeft when unset.
• Orientation is kept as an inert string? property: no aria-orientation equivalent exists, and the keyboard table’s Down/Right = next, Up/Left = prev mapping is unconditional regardless of orientation; child layout is entirely up to how the consumer arranges its content.
• The hidden native radio-input form mirror (the web’s NaviusBubbleInput) is dropped; no WPF form-submission model.
• Attributes splat is dropped.
• No custom peer surfaces aria-readonly/aria-required for the item; ReadOnly/Required are plain dependency properties a consumer can read/bind, not surfaced to automation.
• Descendant discovery (keyboard nav, roving tabindex, value sync) walks the logical tree, not the visual tree, so items are discoverable immediately after Content is assigned without requiring a layout pass or a live PresentationSource.

Captures

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