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Navius WPF

Breadcrumb

Overview

Section titled “Overview”

Breadcrumb is a root ItemsControl whose items are NaviusBreadcrumbItem and NaviusBreadcrumbSeparator instances interleaved directly by the consumer, the same manual-separator-placement contract as shadcn/ui’s own BreadcrumbList/BreadcrumbSeparator anatomy. It wraps children in a horizontal WrapPanel so a long trail reflows on narrow widths instead of clipping. NaviusBreadcrumbItem folds the web’s separate link/current-page parts into one control: IsCurrentPage="False" renders as a clickable link, IsCurrentPage="True" renders as plain, non-interactive text.

Usage

Section titled “Usage”
xmlns:breadcrumb="clr-namespace:Navius.Wpf.Ui.Breadcrumb;assembly=Navius.Wpf.Ui"


<breadcrumb:NaviusBreadcrumb>
    <breadcrumb:NaviusBreadcrumbItem Content="Home" />
    <breadcrumb:NaviusBreadcrumbSeparator />
    <breadcrumb:NaviusBreadcrumbItem Content="Projects" />
    <breadcrumb:NaviusBreadcrumbSeparator />
    <breadcrumb:NaviusBreadcrumbItem Content="Navius.Wpf" IsCurrentPage="True" />
</breadcrumb:NaviusBreadcrumb>

Properties

Section titled “Properties”
Property Type Default From Description
Items ItemCollection empty ItemsControl (NaviusBreadcrumb) Populated directly with NaviusBreadcrumbItem/NaviusBreadcrumbSeparator instances, not a data-bound ItemsSource.
IsCurrentPage bool false NaviusBreadcrumbItem true marks the trail’s terminal, non-navigable entry: renders as plain text, sets Focusable to false, and stamps current onto AutomationProperties.ItemStatus.
Command ICommand? null NaviusBreadcrumbItem Executed on activation (mouse or Enter/Space) when not the current page, via ICommandSource.
CommandParameter object? null NaviusBreadcrumbItem Passed to Command.
CommandTarget IInputElement? null NaviusBreadcrumbItem Command target; defaults to the item itself.
Content object - ContentControl (NaviusBreadcrumbItem) The crumb’s label.

NaviusBreadcrumbSeparator has no properties beyond the standard Control surface; it is a purely decorative chevron glyph with Focusable and IsTabStop both fixed false.

Events

Section titled “Events”
Event Signature Fires when
Click RoutedEventHandler A non-current NaviusBreadcrumbItem is activated by mouse or Enter/Space. Never raised while IsCurrentPage is true.

Keyboard interactions

Section titled “Keyboard interactions”
Key Behavior
Tab Standard focus traversal across crumbs; a current-page item is excluded (Focusable = false).
Enter / Space Activates a non-current crumb: raises Click and executes Command if set. No-op on the current-page item.

UIA mechanism

Section titled “UIA mechanism”

NaviusBreadcrumb does not override OnCreateAutomationPeer; ItemsControl’s base implementation supplies ItemsControlAutomationPeer, which reports AutomationControlType.List. The constructor also calls AutomationProperties.SetItemStatus(this, "breadcrumb"), the closest UIA hook to a nav landmark, surfaced through the inherited peer’s item-status property.

NaviusBreadcrumbItemAutomationPeer (a FrameworkElementAutomationPeer implementing IInvokeProvider) overrides GetAutomationControlTypeCore() to report Hyperlink for a navigable crumb and Text once IsCurrentPage is true. Toggling IsCurrentPage also stamps AutomationProperties.ItemStatus to "current", the closest supported hook for the web’s aria-current="page" since WPF/UIA has no dedicated current-page concept. The peer exposes the UIA Invoke pattern only for a non-current crumb (GetPattern withholds it once IsCurrentPage is true); Invoke itself additionally guards on IsEnabled and IsCurrentPage and throws ElementNotEnabledException when either fails the check, so a UIA client that cached the provider while the crumb was still navigable cannot activate it after it becomes the current page. An enabled, non-current Invoke queues activation onto the item’s dispatcher (DispatcherPriority.Input) per the UIA Invoke contract’s requirement to return immediately, running the same Activate() path a mouse click or Enter/Space uses (raise Click, execute the bound Command).

NaviusBreadcrumbSeparatorAutomationPeer overrides IsControlElementCore() to return false, excluding the separator from the control view entirely so screen readers skip the chevron rather than announcing a meaningless “separator” between crumb names.

The unit suite (tests/Navius.Wpf.Tests/UiBreadcrumbTests.cs) exercises NaviusBreadcrumbItem defaults, IsCurrentPage toggling ItemStatus and Focusable, Click gating on IsCurrentPage, NaviusBreadcrumbSeparator’s Focusable/IsTabStop being false, the item peer’s Hyperlink/Text control type split, the Invoke pattern’s presence only on a non-current crumb, the disabled- and current-page-throws behavior, an enabled Invoke raising Click and executing a bound Command exactly once the dispatcher queue is pumped, and the cached-provider case where a crumb becomes the current page after a UIA client already obtained its Invoke provider. The M6 audit found this family clean: every foreground/ring brush is sourced via DynamicResource, no C# template-part lookup, no animation, no two-way-to-readonly binding.

Web deltas

Section titled “Web deltas”
  • IsCurrentPage drives AutomationProperties.ItemStatus = "current" rather than aria-current="page": WPF/UIA has no dedicated current-page concept, so ItemStatus is the closest supported hook for assistive technology.