Hello @all
i need help with the following problem:
Im calling an unmanaged C++ DLL (TAPI32.dll) function (lineGetCallInfo) like
this:
Declare Function lineGetCallInfo Lib "tapi32.dll" (ByVal hCall As Integer,
ByRef lpCallInfo As LINECALLINFO) As Integer
Public Structure LINECALLINFO
Dim dwTotalSize As Integer
Dim dwNeededSize As Integer
Dim dwUsedSize As Integer
Dim hLine As Integer
Dim dwLineDeviceID As Integer
Dim dwAddressID As Integer
Dim dwBearerMode As Integer
Dim dwRate As Integer
Dim dwMediaMode As Integer
Dim dwAppSpecific As Integer
Dim dwCallID As Integer
Dim dwRelatedCallID As Integer
Dim dwCallParamFlags As Integer
Dim dwCallStates As Integer
Dim dwMonitorDigitModes As Integer
Dim dwMonitorMediaModes As Integer
Dim DialParams As LINEDIALPARAMS
Dim dwOrigin As Integer
Dim dwReason As Integer
Dim dwCompletionID As Integer
Dim dwNumOwners As Integer
Dim dwNumMonitors As Integer
Dim dwCountryCode As Integer
Dim dwTrunk As Integer
Dim dwCallerIDFlags As Integer
Dim dwCallerIDSize As Integer
Dim dwCallerIDOffset As Integer
Dim dwCallerIDNameSize As Integer
Dim dwCallerIDNameOffset As Integer
Dim dwCalledIDFlags As Integer
Dim dwCalledIDSize As Integer
Dim dwCalledIDOffset As Integer
Dim dwCalledIDNameSize As Integer
Dim dwCalledIDNameOffset As Integer
Dim dwConnectedIDFlags As Integer
Dim dwConnectedIDSize As Integer
Dim dwConnectedIDOffset As Integer
Dim dwConnectedIDNameSize As Integer
Dim dwConnectedIDNameOffset As Integer
Dim dwRedirectionIDFlags As Integer
Dim dwRedirectionIDSize As Integer
Dim dwRedirectionIDOffset As Integer
Dim dwRedirectionIDNameSize As Integer
Dim dwRedirectionIDNameOffset As Integer
Dim dwRedirectingIDFlags As Integer
Dim dwRedirectingIDSize As Integer
Dim dwRedirectingIDOffset As Integer
Dim dwRedirectingIDNameSize As Integer
Dim dwRedirectingIDNameOffset As Integer
Dim dwAppNameSize As Integer
Dim dwAppNameOffset As Integer
Dim dwDisplayableAddressSize As Integer
Dim dwDisplayableAddressOffset As Integer
Dim dwCalledPartySize As Integer
Dim dwCalledPartyOffset As Integer
Dim dwCommentSize As Integer
Dim dwCommentOffset As Integer
Dim dwDisplaySize As Integer
Dim dwDisplayOffset As Integer
Dim dwUserUserInfoSize As Integer
Dim dwUserUserInfoOffset As Integer
Dim dwHighLevelCompSize As Integer
Dim dwHighLevelCompOffset As Integer
Dim dwLowLevelCompSize As Integer
Dim dwLowLevelCompOffset As Integer
Dim dwChargingInfoSize As Integer
Dim dwChargingInfoOffset As Integer
Dim dwTerminalModesSize As Integer
Dim dwTerminalModesOffset As Integer
Dim dwDevSpecificSize As Integer
Dim dwDevSpecificOffset As Integer
End Structure
Dim strucCallinfo As LINECALLINFO
strcCallinfo.dwTotalSize = 1024
Dim ret As Integer = lineGetCallInfo(dwDevice, strucCallinfo)
'..... more code
Now the relevant fields in the structure are filled:
- dwCallerIDOffset
- dwCallerIDSize
Like I understand it, the structure has an address in memory (pointer). Now
I have to add the dwCallerIDOffset to the address.
I've done that in this way:
Dim CallingID as String
CallingID = GetStringFromStructure(strucCallinfo,
strucCallinfo.dwCallerIDOffset, strucCallinfo.dwCallerIDSize)
Private Function GetStringFromStructure(ByVal InputStructure As Object,
ByVal Offset As Integer, ByVal Length As Integer) As String
Dim RetString As String = ""
Dim ptrToStructure As IntPtr
Dim ptrToString As IntPtr
'// Allocate memory for a new pointer
ptrToStructure = Marshal.AllocHGlobal(Marshal.SizeOf(InputStructure ))
'// Marshal the structure to the pointer
Marshal.StructureToPtr(InputStructure, ptrToStructure, True)
'// Create a new pointer with the offset to the string
ptrToString = New IntPtr(ptrToStructure.ToInt32 + Offset)
'// Read the string from the new pointer with the specified length
RetString = Marshal.PtrToStringAnsi(ptrToString, Length)
'// Free allocated memory
Marshal.FreeHGlobal(ptrToStructure)
'// Return the extracted string
Return RetString
End Function
But everything i get is some ASCII-Salad like "°oæÃ*oæpæ"
What's wrong here? When i use the same function with an other structure
filled by a functioncall everything works fine :-(
So please help me, before it drives me crazy.
