WPF as netstandard2.0 target

[bstordrup]

If I would like to build a library with some WPF functionality that should be avilable on both net462+ and net6+ I have to dual target the library.

But would it make sense to be able to target the library as netstandard2.0? I mean, netstandard2.0 is least common denominator for net462 and netcoreapp3.1, and by targeting it to netstandard2.0, you would have a package that would go directly into every target framework, that supports netstandard2.0.

[miloush]

.NET Standard does not include any WPF API. If you need to use dependency properties/dispatcher/elements etc. you need to dual target.

[bstordrup]

But it also limits the usage to projects that either dual target the same targets or any of them. You cannot use the project in another non-wpf netstandard2.0 project.

My scenario is having a dispatcher library that takes some types from WPF (HwndSource) for passing forward. I need to reference this library from a netstandard2.0 project, but I cannot because the dispatcher library has to target net462 and/or netcoreapp3.1.

Might be that the solution to this problem would be a bit more complex by removing the actual WPF references and break them down to more regular primitives and pass these instead to he place where they are actually needed.

[miloush]

Your understanding is correct, but that seems to be by design. .NET Standard projects cannot use WPF types because they are not available in .NET Standard, and hence to a project targeting .NET Standard, neither directly nor through a library.

If you need the types internally only, you might be able to include the necessary types directly in your library. If you need to consume or produce them, then I guess reflection is the only option, but obviously that breaks the .NET Standard contract.

.NET Standard is only a list of API available, it's not a runtime. If your project is targeting netstandard2.0, it can run on any platform, including e.g. embedded processors, as long as it can provide that list of API. It's not guaranteed to have anything else like HwndSource.