Marshalling error trying to get a DEVMODE from JOB_INFO_2

[Merrion]

Right - the VB.Net spooler watch component is about 70% done but I am totally stuck on getting the DEVMODE structure as held in the pointer in JOB_INFO_2.

I keep getting the error:

An unhandled exception of type System.TypeLoadException occurred in mscorlib.dll

Additional information:
Can not marshal field DeviceMode of type PrinterQueueWatch.JOB_INFO_2:
The type definition of this field has no layout information.

I have the DEVMODE structure defined as a class thus:

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
Friend Class DEVMODE
    <VBFixedString(32), MarshalAs(UnmanagedType.ByValTStr, SizeConst:=32)> Public pDeviceName As String  CCHDEVICENAME
    Public dmSpecversion As Int16
    Public dmSize As Int16
    Public dmDriverExtra As Int16
    Public dmFields As Int32
    <MarshalAs(UnmanagedType.U2)> Public dmOrientation As PrintJob.DeviceOrientations
    <MarshalAs(UnmanagedType.U2)> Public dmPaperSize As PrintJob.PrinterPaperSizes
    Public dmPaperLength As Int16
    Public dmPaperWidth As Int16
    Public dmScale As Int16
    Public dmCopies As Int16
    Public dmDefaultSource As Int16
    Public dmPrintQuality As Int16
    <MarshalAs(UnmanagedType.U2)> Public dmColor As PrintJob.DeviceColourModes
    <MarshalAs(UnmanagedType.U2)> Public dmDuplex As PrintJob.DeviceDuplexSettings
    Public dmYResolution As Int16
    Public dmTTOption As Int16
    Public dmCollate As Int16
    <VBFixedString(32), MarshalAs(UnmanagedType.ByValTStr, SizeConst:=32)> Public dmFormName As String
    Public dmUnusedPadding As Int16
    Public dmBitsPerPel As Int16
    Public dmPelsWidth As Int32
    Public dmPelsHeight As Int32
    Public dmDisplayFlags As Int32
    Public dmDisplayFrequency As Int32

End Class

and the JOB_INFO_2 defined thus:-

<StructLayout(LayoutKind.Sequential, CharSet:=CharSet.Ansi)> _
Friend Class JOB_INFO_2
    Public JobId As Int32
    <MarshalAs(UnmanagedType.LPStr)> Public pPrinterName As String
    <MarshalAs(UnmanagedType.LPStr)> Public pMachineName As String
    <MarshalAs(UnmanagedType.LPStr)> Public pUserName As String
    <MarshalAs(UnmanagedType.LPStr)> Public pDocument As String
    <MarshalAs(UnmanagedType.LPStr)> Public pNotifyName As String
    <MarshalAs(UnmanagedType.LPStr)> Public pDatatype As String
    <MarshalAs(UnmanagedType.LPStr)> Public pPrintProcessor As String
    <MarshalAs(UnmanagedType.LPStr)> Public pParameters As String
    <MarshalAs(UnmanagedType.LPStr)> Public pDriverName As String
    <MarshalAs(UnmanagedType.LPStruct)> Public DeviceMode As DEVMODE
    <MarshalAs(UnmanagedType.LPStr)> Public pStatus As String
    <MarshalAs(UnmanagedType.U4)> Public Status As PrintJob.Print_Job_Statuses
    Public Priority As Int32
    Public Position As Int32
    Public TotalPage As Int32
    Public PagesPrinted As Int32
    <MarshalAs(UnmanagedType.Struct)> Public Submitted As SystemTime
End Class

Any ideas what I have wrong here? Im pretty sure the problem is in the DEVMODE class because if I return lpDevMode as an Int32, cast it to an IntPtr and use

Marshal.PtrToStructue(lpDevModePtr, dmThis)

I get the same error.

Thanks in advance,
Duncan

 

[Merrion]

[Resolved] Getting DEVMODE from JOB_INFO_2

Sigh - often the case that as soon as you post something all over the internet you spot the obvious error. Anyway - the line:

<MarshalAs(UnmanagedType.U2)> Public dmOrientation As PrintJob.DeviceOrientations

Is not allowed because enumerated types are held as Int32 which is 4 bytes long.
Instead perform the type conversion explicityly thus:-

Private mdmOrientation As Int16
...
Public ReadOnly Property dmOreintation() As PrintJob.DeviceOrientations
  Get
    Return CType(mdmOrientation, PrintJob.DeviceOrientations)
  End Get
End Property
...