WinUI3_cppcx

WinUI 3 with C++/CX

This sample demonstrates how older C++/CX Windows Runtime components can still be consumed from modern WinUI 3 applications written in either C++/WinRT or C#. It combines a native component, a generated CsWinRT projection, and two app front ends so you can compare interop patterns across languages and projection layers.

Solution Structure

WinUI3_cppcx
|-- WinRt_cppcx/             C++/CX Windows Runtime component
|-- WinUI3App_cpp/           C++/WinRT consumer app
|-- WinUI3App_cs/            C# WinUI 3 consumer app
`-- WinRt_cppcx_projection/  CsWinRT projection for C# consumption

Key Details

• WinRt_cppcx contains the component authored with C++/CX.
• WinUI3App_cpp shows how a C++/WinRT WinUI 3 app can consume that component.
• WinUI3App_cs shows the C# side of the same story through the generated projection layer.
• WinRt_cppcx_projection provides the CsWinRT projection that makes the C++/CX component easy to reference from managed code.
• The solution is a practical reference when migrating code incrementally instead of rewriting every WinRT component at once.
• The C# app also demonstrates AppWindow-based windowing APIs alongside the interop sample.
• Because both consumers are in the same solution, it is easy to compare native and managed usage patterns side-by-side.

Building

1. Open WinUI3_cppcx.sln in Visual Studio 2022.
2. Restore dependencies and ensure C++ desktop, .NET desktop, and Windows App SDK workloads are installed.
3. Build the solution for a supported target such as x64 or ARM64.
4. Ensure the component and projection build before launching the consumer apps.
5. Run either WinUI3App_cpp or WinUI3App_cs to inspect how each app consumes the shared runtime component.