I'm having problems with the IPersistFile interface. We have in house
objects that support IPersistFile (and have done for years). I would like
to load an object using this interface with VB.NET (note: I'm already
successfully using our IPersistStorage interface for structured storage with
other of our file types, but these particular file types do not support
IPersistStorage ). Anyway, the result I get from IPersistStorage ::Load
is -2147467259, or "Unspecifie d Error". The software that generates, writes
and reads these files (MFC C++ program) has no problem with them. Is there
something wrong with my interface definition or usage here?
Any pointers would be great, thanks.
*************** ***** MY WRAPPER FOR IPersistFile *************** ********
<ComImport(), InterfaceType(C omInterfaceType .InterfaceIsIUn known),
Guid("0000010b-0000-0000-C000-000000000046")> _
Public Interface IPersistFile
<PreserveSig( )> _
Function GetClassID(ByRe f pClassID As IntPtr) As Integer
<PreserveSig( )> _
Function IsDirty() As Integer
<PreserveSig( )> _
Function Load(<MarshalAs (UnmanagedType. LPStr)> ByVal pszFilename As
String, ByVal dwMode As Integer) As Integer
<PreserveSig( )> _
Function Save(<MarshalAs (UnmanagedType. LPStr)> ByVal pszFilename As
String, <MarshalAs(Unma nagedType.Bool) > ByVal fRemember As Boolean) As
Integer
<PreserveSig( )> _
Function SaveCompleted(< MarshalAs(Unman agedType.LPStr) > ByVal
pszFilename As String) As Integer
<PreserveSig( )> _
Function GetCurFile(ByRe f theFile As String) As Integer
End Interface
*************** ***** THE FUNCTION USING IPersistFile *************** ********
Dim Result As Boolean
Dim theData() As Byte
Dim theIPersistFile As COM.IPersistFil e
Try
Dim theImage As TherMonitor.Ima ge
' Get type ID
Dim theType As Type = Type.GetTypeFro mProgID("TherMo nitor.Image")
' Create a blank instance.
theImage = CType(Activator .CreateInstance (theType), TherMonitor.Ima ge)
' Cast to IPersistFile
theIPersistFile = CType(theImage, COM.IPersistFil e)
' Now atempt to open it
Dim hResult As Integer = theIPersistFile .Load(theFile, 0)
' Save from document into theData
If hResult = 0 Then
..............
..............
' Success
Result = True
Else
' Failed
Result = False
End If
Catch ex As Exception
' Failed
Result = False
Finally
End Try
' Return the result...
Return Result
