openkneeboard.cs

using System.Runtime.InteropServices;
using System.Text;

public partial class Program
{
    [LibraryImport("OpenKneeboard_CAPI64")]
    private static partial void OpenKneeboard_send_utf8(byte[] messageName, UInt64 messageNameBytes, byte[] messageData, UInt64 messageDataBytes);
    public static void Main(string[] args)
    {
        // This is just an example dynamic path; in a real program, follow all the documented steps on the OpenKneeboard web site
        var path = Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles) + "\\OpenKneeboard\\bin\\OpenKneeboard_CAPI64";
        Console.WriteLine("Path: " + path);

        // This is the easy way.
        // - Correct way is https://learn.microsoft.com/en-us/dotnet/standard/native-interop/native-library-loading#custom-import-resolver
        // - Alternative way on .Net < 5: P/Invoke `LoadLibraryW()` first
        NativeLibrary.Load(path);
        // You probably also want to call `NativeLibrary.Free(return value from above)` when your code is cleaning up.

        // Not a real supported message, but will show up in OpenKneeboard's "API events" log
        var utf8 = Encoding.UTF8;
        var messageType = utf8.GetBytes("Hello");
        var messageData = utf8.GetBytes("World");
        OpenKneeboard_send_utf8(messageType, Convert.ToUInt64(messageType.Length), messageData, Convert.ToUInt64(messageData.Length));
    }
}