NetObsBindings 0.0.1.25-alpha

NetObsBindings

NetObsBindings is a library that provides .NET bindings for Open Broadcast Software (OBS).

These bindings are generated from the OBS repository, specifically libobs and obs-frontend projects.

The approach taken is to generate a static class per header file via ClangSharp generator. This means, that, for example, you could find functions exported from the obs-service.h file in the ObsService C# class.

How to use these bindings?

These bindings can be used to create your own plugin in C#.

Simple plugin example:

public static class ObsPlugin
{
    public static nint ObsModulePointer { get; set; }

    [UnmanagedCallersOnly(EntryPoint = "obs_module_set_pointer", CallConvs = new[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static void SetPointer(nint obsModulePointer)
    {
        Log("[blog] Pointer Saved!");
        ObsModulePointer = obsModulePointer;
    }
    
    [UnmanagedCallersOnly(EntryPoint = "obs_module_ver", CallConvs = new[] { typeof(System.Runtime.CompilerServices.CallConvCdecl) })]
    public static uint GetVersion()
    {
        Log("[blog] Returned version!");
        
        var major = (uint) Obs.Version.Major;
        var minor = (uint) Obs.Version.Minor;
        var patch = (uint) Obs.Version.Build;
        var version = (major << 24) | (minor << 16) | patch;
        return version;
    }

    [UnmanagedCallersOnly(EntryPoint = "obs_module_load", CallConvs = new[] {typeof(System.Runtime.CompilerServices.CallConvCdecl)})]
    public static bool ModuleLoad()
    {
        Log("[blog] Loaded!");
        return true;
    }

    private static unsafe void Log(string text)
    {
        var asciiBytes = Encoding.UTF8.GetBytes(text);
        fixed (byte* logMessagePtr = asciiBytes)
        {
            ObsBase.blogva(ObsBase.LOG_INFO, (sbyte*) logMessagePtr, null);   
        }
    }
}

There is one caveat: make sure you are publishing the plugins as NativeAOT libraries, this is essential to make it work due to the plugin model of OBS.

How to generate bindings locally?

In order to generate bindings locally, please use the build.ps1 script. Make sure that you have ClangSharpPInvokeGenerator dotnet tool installed.

This script will:

1. Clone the OBS repository
2. Generate bindings for all required modules
3. Insert the version of the OBS library to Obs.Version.cs file.

Originally, these bindings generated in the blog post https://sharovarskyi.com/blog/posts/clangsharp-dotnet-interop-bindings/