非托管IPictureDisp到托管对象

Question

我正在使用VB.Net在Excel中使用Api调用dll。 （罗伯特·吉塞克的不受管制的出口） 标准类型（数字，字符串）正在运行。但是，当尝试使用对象类型时，返回错误。

错误消息是： “未知名称。（返回HRESULT异常：0x80020006（DISP_E_UNKNOWNNAME））”

我的功能是（错误是IPictureDisp到位图）：

Public Function GetTextQR_FromPicture(ByVal pictureDisp As IPictureDisp) As [MarshalAs(UnmanagedType.BStr)] String
      'IPictureDisp
      Return _qrDec.decode(New QRCodeBitmapImage(PicHelper.GetPictureFromIPictureDisp(pictureDisp)), Encoding.UTF8)
End Function

我的助手班：

Friend Class PicHelper
   Inherits System.Windows.Forms.AxHost

   Friend Sub New()
      MyBase.New(Nothing)
   End Sub

   Friend Shared Shadows Function GetIPictureDispFromPicture(image As Image) As Object
      Return System.Windows.Forms.AxHost.GetIPictureDispFromPicture(image)
   End Function

   Friend Shared Shadows Function GetPictureFromIPictureDisp(picture As IPictureDisp) As Image
      Return System.Windows.Forms.AxHost.GetPictureFromIPictureDisp(picture)
   End Function
End Class