How to use conditionals in desktop target that evaluating client runns on windows?

[DevTKSS]

Hey there!
I am creating a .net8/9 targeting Library which includes functionallity that uses P/Invoke functionallity which are only supported if the client is running the app which uses the library on windows. => needs to use the SupportedOSPlatformAttribute and the /unsafe if I seen it correctly

The problem on this is, I seem to only have the decision between:

1. using the regular Net.Sdk to only get the dependencys I want from the PackageReference items but this will result in the TargetFrameworkMoniker is unable to resolve net9.0-desktop for example
2. use the Uno.Sdk with e.g. .net9.0 but also that not including any UI Target, does include the Uno.Resizetizer and lots more NuGet Packages as Dependencys while this Library Project would not even need one NuGet, only those functions! And even worse if I let docfx create the public api docs, without of course any exclude members by default, this would put out the Uno.Resizetizer as a public API of mine!

So option 1 is resulting in a warning of Target incompartiblity when I then use that Library in another maybe Uno.sdk desktop target SkiaRendering Project (I dont really want the WinAppSDK to use just for that windows to be satisfyed...)
option 2 could also still fail because that call to P/Invoke would still be only valid if the client app is executing this on Windows machine.

the #If WINDOWS (or similar) would not be active if its desktop target, isnt it?

Do someone has some trick that I could use to keep using desktop target, but workaround this Moniker problem when not using the uno.sdk management? Maybe a Uno.Core Nuget which would allow to get some Attributes defined there, that would solve that?

Thanks in advance!

[jeromelaban]

SupportedOSPlatfomAttribute is not supported at this time for desktop and wasm, and you'll need to use OperatingSystem.IsXXX to make runtime checks for windows specifically.

As for the dependencies you see in nuget, those will not be present in the resulting package or assembly.

[DevTKSS]

@jeromelaban hm... I think, there is indeed some cool new conditionals added 🤩

some Sample code, I tryed with latest sdk + fresh app created from latest templates where I actually found the Win32 Condition. just not completly sure if this would met my expectation and validate correctly the #if conditions... Therefore, I was asking if someone knows the correct setup...

namespace UnoApp1.Presentation;

public partial record MainModel
{
    private ILogger _logger;
    public MainModel(
        ILogger<MainModel> logger)
    {
        _logger = logger;
    }

    public IState<string> CurrentInventorDocumentName => State<string>.Value(this, () => string.Empty);

    public async ValueTask DoSomething_WhichRunnsOnly_WhenUserIsOnWindowsOS()
    {
        // This method is only executable if the User is running Windows OS.
#if HAS_UNO_SKIA_WIN32 || HAS_UNO_SKIA_WINUI || HAS_UNO_SKIA_WPF

            // This code is executable on Windows OS which is maybe also WIn32 using Skia Renderer (?).
            // we need oleaut32.dll and ole32.dll to be available in the OS of the user.
            // As Inventor is a Windows-only application, this code will not run on other platforms, but Skia Desktop target is runnable on Windows OS.
            if (DevTKSS.Extensions.Marshalling.MarshalExtensions.GetActiveObject("Inventor.Application") is Inventor.Application inventorApp)
            {
                // Do something with the Inventor application instance.
                // For example, you could open a document in Inventor, to do something with it.
                if(inventorApp.Documents.Open(FullDocumentName:"MyWellKnownFileName.ipt",OpenVisible: true) is Inventor.PartDocument partDoc)
                {
                    // Do something with the opened part document.
                _logger.LogInformationMessage($"Opened Part Document: {partDoc.FullFileName}");
                await CurrentInventorDocumentName.SetAsync(partDoc.FullFileName);
                return;
            }
            else
            {
                _logger.LogErrorMessage("Failed to open the part document.");
            }

        }
        else
        {
            _logger.LogInformationMessage("Inventor Application is not running.");
            await CurrentInventorDocumentName.SetAsync("No Document connected.");
        }
#else // Linux || MacOs || MacCatalyst || IOS || Android || Wasm
            // This code is not executable on Linux, MacOS, MacCatalyst, iOS, Android or Wasm.
        _logger.LogErrorMessage("This method is only available on Windows OS.");
        await CurrentInventorDocumentName.SetAsync("No Document connected. Your OS System is not supported, Sorry!");
        throw new PlatformNotSupportedException("This method is only available on Windows OS with Skia Renderer.");
#endif
}

hoping this migth makes it clearer, what I am trying to reach...

[jeromelaban]

I see, then yes, you can only use runtime checks to do this, compilation constants won't help.

[DevTKSS]

🤔 so I would not be able to be sure, that the constants defined like above would be working?
Is the 'OperatingSystem.IsWindows()' or IsWindowsVersionAtLeast() from System.Versioning namespace expandable so we could get a .IsSkiaWindows(int version) added to the checks? I mean, I don't know if those checks are even possible to evaluate somehow if a desktop target app is currently in a Windows environment running🤔 The Intellisense and decompilation is telling thats a runtime check...

// Summary
//     Indicates whether the current application is running on the specified platform.
//
//
// Parameter:
//   platform:
//     The case-insensitive platform name. Examples: Browser, Linux, FreeBSD, Android,
//     iOS, macOS, tvOS, watchOS, Windows.
//
// Returns:
//     true if the current application is running on the specified platform; false otherwise.
public static bool IsOSPlatform(string platform);

hm... its stating its a sealed class. guessing thats meaning not expandable... but maybe the IsWindows would be true for my case...

[MartinZikmund]

OperatingSystem.IsWindows() should be the right check, is there anything missing with it?