What is the proper way to code a "CLASS LIBRARY", in Visual Studio 2022 Preview (or 2019), that needs to use C++ from MANAGED CODE (C#) ?

[GUI-Kenny]

WHAT IS THE PROPER WAY TO CODE A "CLASS LIBRARY", IN VISUAL STUDIO 2022 PREVIEW (or 2019), THAT NEEDS TO USE C++ (to access DWriteCore) FROM MANAGED CODE (C#) ?

Is DWriteCore just for CPP apps?

Will a Managed Code implementation of the interface be coming in the future?

I need to get font information, and this interface has the functions and controls, and I'm using WinUI 3 Desktop, Windows App SDK (WindowsAppSDK - Experimental) , Visual Studio 2022 Preview.

I just need to know, since my app needs access to system font information (collections) - Am I - forced to go entirely CPP (looks to be), partial CPP - partial C#, or entirely C# (preferred)?

[GUI-Kenny]

I generated a C# projection from a C++/WinRT component to distribute as a NuGet package for .NET 5+ applications and need to use it in a WinUI 3 Desktop App.

PROJECT_A is a C++ Windows Component (WinUI 3)
PROJECT_B is a C# Class Library (WinUI 3 in Desktop)
PROJECT_C is the APP (C# WinUI 3 in Desktop) that needs access to PROJECT_A or PROJECT_B (to access DWriteCore in WindowsAppSDK) ???????

I have added, as projects, PROJECT_A and PROJECT_B (as an existing item, referenced them by drilling back-then-down to their respective project file). I then added "PackageReference Include="PROJECT_A" Version="0.1.0-prerelease"" to the PROJECT_C.csproj file.

I had to add the following to the .csproj so Visual Studio 2022 Preview could locate the "PROJECT_A.0.1.0-prerelease.nupkg" file:

PropertyGroup
RestoreSources
https://api.nuget.org/v3/index.json;
../../../PROJECT_B/nuget
/RestoreSources
/PropertyGroup

I can see PROJECT_A in NuGet Package Manager and is installed for the project in question. I can see it as one of the Packages in Dependencies. But, neither #using PROJECT_A or #using PROJECT_B work, I get the following:

Error CS0246 The type or namespace name 'PROJECT_A' could not be found (are you missing a using directive or an assembly reference?) Character Map C:\Source\Code\Windows\10\WinUI 3\Fonts\PROJECT_C\PROJECT_C\MainWindow.xaml.cs

Also added PROJECT_B's project as a reference, no luck - #using did not work.

So, I referenced PROJECT_A's project (#using worked) but get the following :

Error NETSDK1130 PROJECT_A.winmd cannot be referenced. Referencing a Windows Metadata component directly when targeting .NET 5 or higher is not supported. For more information, see https://aka.ms/netsdk1130 Character Map C:\Program Files\dotnet\sdk\6.0.100-rc.1.21463.6\Sdks\Microsoft.NET.Sdk\targets\Microsoft.NET.Sdk.targets

Reference: https://docs.microsoft.com/en-us/windows/uwp/csharp-winrt/net-projection-from-cppwinrt-component

What to TRY NEXT ???

[andrewleader]

Hey @duncanmacmichael, can you help answer whether DWriteCore will be usable by C# apps or whether it's only usable from C++?

[GUI-Kenny]

I have just used the Answer from https://docs.microsoft.com/en-us/answers/questions/574926/how-do-i-access-dwritecore-from-a-c-managed-applic.html?childToView=579442#comment-579442 to implement a P/Invoke strategy to access DWriteCore directly from managed code.

But, I still need to know how to accomplish what this question is asking - How to have a class library written in C++ and have a C# managed application consume it.

[angelazhangmsft]

@GUI-Kenny, it looks like you are using C#/WinRT to create a C# projection of the C++/WinRT component, and consume it from a C# app. Did you refer to this sample to accomplish this? Your steps above look right to me, would you be able to provide a repro project so we can look into it?

[riverar]

Can you please edit this discussion title to NOT BE IN ALL CAPS? Thanks. It keeps landing in my inbox with all caps.