void Dispose(bool calledFromDispose)
 {
     if (!_disposed)
     {
         _disposed = true;
         // Free unmanaged resources (Pinvoke class has static methods)
         Pinvoke.CloseClipboard();
         if (_emfHandle != IntPtr.Zero)
         {
             Pinvoke.DeleteEnhMetaFile(_emfHandle);
         }
     }
 }