public static object GetUnknown(this IMFAttributes input, Guid key, Guid interfaceId)
{
if (input == null)
{
throw new ArgumentNullException(nameof(input));
}
if (input.GetUnknown(key, interfaceId, out var value).IsError)
{
return(null);
}
return(value);
}
public static ComObject <T> GetUnknown <T>(this IMFAttributes obj, Guid key, Guid interfaceId)
{
if (obj == null)
{
throw new ArgumentNullException(nameof(obj));
}
if (obj.GetUnknown(key, interfaceId, out var value).IsError)
{
return(null);
}
return(new ComObject <T>((T)value));
}
/// <summary>
/// Retrieves a COM instance associated with a key.
/// </summary>
/// <typeparam name="T">The requested COM interface.</typeparam>
/// <param name="attributes">A valid IMFAttributes instance.</param>
/// <param name="guidKey">Guid that identifies which value to retrieve.</param>
/// <param name="obj">Receives the requested COM instance.</param>
/// <returns>If this function succeeds, it returns the S_OK member. Otherwise, it returns another HResult's member that describe the error.</returns>
public static HResult GetUnknown <T>(this IMFAttributes attributes, Guid guidKey, out T obj) where T : class
{
if (attributes == null)
{
throw new ArgumentNullException("attributes");
}
Type typeOfT = typeof(T);
if (!typeOfT.IsComInterface())
{
throw new ArgumentOutOfRangeException("T", "T must be a COM visible interface.");
}
object tmp;
HResult hr = attributes.GetUnknown(guidKey, typeOfT.GUID, out tmp);
obj = hr.Succeeded() ? tmp as T : null;
return(hr);
}
public HResult GetUnknown(Guid guidKey, Guid riid, out object ppv)
{
return(m_Attribs.GetUnknown(guidKey, riid, out ppv));
}