static object ToObject(this MMDeviceAPI.tag_inner_PROPVARIANT propvariant)
{
var marshalledPropvariant = propvariant.Marshall();
PropVariantToVariant(ref marshalledPropvariant, out var variant);
PropVariantClear(ref marshalledPropvariant);
return(variant);
}
static Propvariant Marshall(this MMDeviceAPI.tag_inner_PROPVARIANT propvariant)
{
// Note: it seems unlikely this will work with complicated/exotic PROPVARIANT types.
var marshalledPropvariant = new Propvariant();
marshalledPropvariant.vt = propvariant.vt;
// TODO: it's not clear if this autogenerated field name is stable.
marshalledPropvariant.p = propvariant.__MIDL____MIDL_itf_mmdeviceapi_0003_00930001.pcVal;
return(marshalledPropvariant);
}
public static T ActivateInterface <T>(this MMDeviceAPI.IMMDevice device) where T : class
{
var guid = new System.Guid(typeof(T).GetCustomAttribute <System.Runtime.InteropServices.GuidAttribute>(false).Value);
// Normally we're supposed to pass NULL as pActivationParams but C# won't let us pass null to a ref struct argument. Passing an empty PROPVARIANT seems to work fine.
var activationParams = new MMDeviceAPI.tag_inner_PROPVARIANT();
device.Activate(ref guid, (uint)CLSCTX.CLSCTX_ALL, ref activationParams, out var interfacePtr);
object iface;
try
{
iface = System.Runtime.InteropServices.Marshal.GetTypedObjectForIUnknown(interfacePtr, typeof(T));
}
finally
{
System.Runtime.InteropServices.Marshal.Release(interfacePtr);
}
return(iface as T);
}
