Example for Win32 Activat Context to load a regfree COM manifest

example.cs

[STAThread]
static void Main()
{
    ACTCTXW context = new ACTCTXW();
    context.cbSize = Marshal.SizeOf<ACTCTXW>();
    context.lpSource = "YourManifestFile.manifest";

    var handle = Win32.CreateActCtxW(ref context);
    if (handle == IntPtr.Zero)
        throw new Win32Exception();
    try
    {
        if (!Win32.ActivateActCtx(handle, out var cookie))
            throw new Win32Exception();
        try
        {
            // do COM interop
        }
        finally
        {
            if (!Win32.DeactivateActCtx(0, cookie))
                throw new Win32Exception();
        }
    }
    finally
    {
        Win32.ReleaseActCtx(handle);
    }
}

[StructLayout(LayoutKind.Sequential, CharSet = CharSet.Unicode)]
struct ACTCTXW
{
    public int cbSize; // ULONG
    public int dwFlags; // DWORD
    public string lpSource; // LPCWSTR
    public short wProcessorArchitecture; // USHORT
    public short wLangId; // LANGID
    public string lpAssemblyDirectory; // LPCWSTR
    public string lpResourceName; // LPCWSTR
    public string lpApplicationName; // LPCWSTR
    public IntPtr hModule; // HMODULE
}

static class Win32
{
    [DllImport("kernel32", SetLastError = true)]
    public static extern IntPtr CreateActCtxW( // WINBASEAPI HANDLE WINAPI
        [In] ref ACTCTXW pActCtx); // _In_ PCACTCTXW

    [DllImport("kernel32")]
    public static extern void ReleaseActCtx( // WINBASEAPI VOID WINAPI
        IntPtr hActCtx); // _Inout_ HANDLE

    [DllImport("kernel32", SetLastError = true)]
    public static extern bool ActivateActCtx( // _Success_(return) WINBASEAPI BOOL WINAPI
        IntPtr hActCtx, // _Inout_opt_ HANDLE 
        out IntPtr lpCookie); // _Out_ ULONG_PTR *

    [DllImport("kernel32", SetLastError = true)]
    public static extern bool DeactivateActCtx( // _Success_(return) WINBASEAPI BOOL WINAPI
        int dwFlags, // _In_ DWORD
        IntPtr ulCookie); // _In_ ULONG_PTR
}