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WPF Interop

Status: coming soon. A first-class Microsoft.UI.Reactor (Reactor) WPF host control (Reactor.Interop.Wpf) is on the roadmap but not yet shipped. The only host wrapper in the box today is Reactor.Interop.WinForms.

Workaround for today

Host a Reactor component tree from WPF by embedding DesktopWindowXamlSource directly — the same WinAppSDK primitive that WinForms Interop wraps in XamlIslandControl. Inside the island, mount a ReactorHostControl and assign it a ComponentType. The Reactor side of the boundary is identical to any other host: components, hooks, modifiers, and UseObservable<T> for bridging an INotifyPropertyChanged view-model all work unchanged.

The WPF Dispatcher and WinUI DispatcherQueue are distinct objects on the same UI thread, so plain property writes from WPF event handlers into Reactor setters work without marshalling — see Threading and Dispatch for the invariants the WinUI side enforces.

Next Steps

  • WinForms Interop — The shipping parallel host. Read this first; the WPF surface will mirror it.
  • Hooks — UseObservable, UseObservableTree, and UseObservableProperty for bridging INotifyPropertyChanged view-models from WPF.
  • Threading and Dispatch — How Reactor's hook setters auto-marshal across dispatchers.
  • XAML Developers — Migration cookbook for WPF/XAML pages moving to Reactor's declarative shell.