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VelloSharp.Uwp – Preview Notes

Preview
The VelloSharp.Uwp binding currently targets net8.0-windows10.0.19041 (WinUI 3 desktop) while we finish the AppContainer (uap10.0.19041) bring-up. The public API shape matches the final control, so you can wire the preview into bridged/desktop experiences today and prepare for genuine UWP packaging once the dispatcher and asset workstreams land.

Package setup​

<ItemGroup>
  <ProjectReference Include="..\..\bindings\VelloSharp.Uwp\VelloSharp.Uwp.csproj" />
  <ProjectReference Include="..\..\src\VelloSharp.Windows.Shared\VelloSharp.Windows.Shared.csproj" />
</ItemGroup>

With NuGet packages:

<ItemGroup>
  <PackageReference Include="VelloSharp.Uwp" Version="0.5.0-alpha.*" />
</ItemGroup>

Using the VelloSwapChainPanel​

<Window
    x:Class="Sample.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:vello="using:VelloSharp.Uwp.Controls">

    <Grid>
        <vello:VelloSwapChainPanel x:Name="SwapChain"
                                   PreferredBackend="Gpu"
                                   RenderMode="OnDemand" />
    </Grid>
</Window>

The code-behind matches the WinUI control—hook PaintSurface, fill a scene, and drive diagnostics. See samples/UwpVelloGallery for a reference implementation.

GPU backends & WARP fallback​

The preview control honours the shared Windows GPU toggles so you can validate Store packaging early:

  • Vello:Windows:Backends / VELLO_WINDOWS_BACKENDS lets you restrict WGPU to specific backends (for example dx12, vulkan, or auto).
  • Force the software adapter with Vello:Windows:ForceWarp / VELLO_WINDOWS_FORCE_WARP, or block it entirely via Vello:Windows:DisableWarp / VELLO_WINDOWS_DISABLE_WARP.
  • Extract the package contents and run scripts/verify-uwp-native-assets.ps1 -BundlePath <extracted-appx> -RuntimeIdentifier win10-x64 during CI to ensure the native binaries and signatures ship with your MSIX/AppX.
  • Consult runtimes/win10-*/native/vello.backends.json inside the package to see which backends are declared for each RID.

What’s left for true UWP support?​

  • Dispatcher abstraction so the shared presenter can target CoreDispatcher instead of Microsoft.UI.Dispatching.DispatcherQueue.
  • AppX packaging glue to copy GPU runtime assets into Package.Current.InstalledLocation.
  • Capability declarations and fallbacks required for Xbox/Surface Hub (WARP, optional D3D12).

Track progress in docs/winui-uwp-vello-full-gpu-integration-plan.md. Contributions are welcome—especially around dispatcher shims and packaging validation.