Brows.Win32.Windows.Composition 1.2.0

Brows.Win32.Windows.Composition

This package makes the Windows Shell preview services available to Brows through Brows.Composition as the IWin32WindowsServices export. It depends on Brows.Win32.Windows and is intended for Windows WPF applications. It targets net462, net48, net8.0-windows, and net10.0-windows.

The export provides asynchronous file and stock icons, effective overlays, and thumbnails. Add this assembly to the assemblies discovered by your Brows import environment, then import IWin32WindowsServices. Await its operations and pass a CancellationToken when cancellation is needed. Bitmap sources are frozen when WPF permits it; icon and overlay results can be null.

An optional Win32WindowsServicesVariable supplies a caller-owned ISTAThreadPool; without one, the export resolves a shared pool when the services are first used: it uses a pool provided by an optional imported ISTAThreadPoolProvider as-is, leaving the pool's lifetime to the provider; otherwise it creates a pool through an optional imported ISTAThreadPoolFactory or by direct construction and owns that pool. Apply configuration before the first service request. IconAttempts defaults to 5 and must be at least 1; IconAttemptDelay defaults to 100 milliseconds and must be non-negative. A null retry setting leaves the current value unchanged. Configuration is applied once: a later attempt, whether another variable or after the services have been created, is rejected with InvalidOperationException.

The import environment's kill operation disposes the services and empties a pool the export created, through the factory or by direct construction. It does not empty a configured caller-owned pool: empty it yourself after killing the import environment and finishing any other work using that pool. Nor does it empty a pool supplied by the provider, whose contract leaves the pool's lifetime to the provider. Kill is idempotent, and later preview requests are rejected with InvalidOperationException. A request that races the kill operation — accepted by the export while the services are being disposed, or begun just after disposal — can instead be rejected with ObjectDisposedException.

Complete outstanding preview requests before shutting down the environment when possible. Service disposal waits synchronously for active work. If shutdown must wait for requests from a WPF UI, run the kill operation off the UI thread and keep the dispatcher alive until it completes. Shell work can block during a native call even when a request has been canceled.