c++ to vb.net , problem with callback function
- by johan
I'm having a hard time here trying to find a solution for my problem.
I'm trying to convert a client API funktion from C++ to VB.NET,
and i think have some problems with the callback function.
parts of the C++ code:
typedef struct{
BYTE m_bRemoteChannel;
BYTE m_bSendMode;
BYTE m_nImgFormat; // =0 cif ; = 1 qcif
char *m_sIPAddress;
char *m_sUserName;
char *m_sUserPassword;
BOOL m_bUserCheck;
HWND m_hShowVideo;
}CLIENT_VIDEOINFO, *PCLIENT_VIDEOINFO;
CPLAYER_API LONG __stdcall MP4_ClientStart(PCLIENT_VIDEOINFO pClientinfo,void(CALLBACK *ReadDataCallBack)(DWORD nPort,UCHAR *pPacketBuffer,DWORD nPacketSize));
void CALLBACK ReadDataCallBack(DWORD nPort,UCHAR *pPacketBuffer,DWORD nPacketSize)
{
TRACE("%d\n",nPacketSize);
}
.....
aa5.m_sUserName = "123";
aa5.m_sUserPassword="w";
aa5.m_bUserCheck = TRUE;
MP4_ClientSetTTL(64);
nn1 = MP4_ClientStart(&aa5,ReadDataCallBack);
if (nn1 == -1)
{
MessageBox("error");
return;
}
SDK description:
MP4_ClientStart
This function starts a connection. The format of the call is:
LONG __stdcall MP4_ClientStart(PCLIENT_VIDEOINFO pClientinfo,
void(*ReadDataCallBack)(DWORD nChannel,UCHAR *pPacketBuffer,DWORD nPacketSize))
Parameters
pClientinfo holds the information. of this connection.
nChannel holds the channel of card.
pPacketBuffer holds the pointer to the receive buffer.
nPacketSize holds the length of the receive buffer.
Return Values
If the function succeeds the return value is the context of this connection.
If the function fails the return value is -1.
Remarks
typedef struct{
BYTE m_bRemoteChannel;
BYTE m_bSendMode;
BYTE m_bImgFormat;
char *m_sIPAddress;
char *m_sUserName;
char *m_sUserPassword;
BOOL m_bUserCheck;
HWND m_hShowVideo;
} CLIENT_VIDEOINFO, * PCLIENT_VIDEOINFO;
m_bRemoteChannel holds the channel which the client wants to connect to.
m_bSendMode holds the network mode of the connection.
m_bImgFormat : Image format, 0 is main channel video, 1 is sub channel video
m_sIPAddress holds the IP address of the server.
m_sUserName holds the user’s name.
m_sUserPassword holds the user’s password.
m_bUserCheck holds the value whether sends the user’s name and password or not.
m_hShowVideo holds Handle for this video window.
If m_hShowVideo holds NULL, the client can be record only without decoder.
If m_bUserCheck is FALSE, we will send m_sUserName and m_sUserPassword as NULL, else we will send each 50 bytes.
The length of m_sIPAddress and m_sUserName must be more than 50 bytes.
ReadDataCallBack: When the library receives a packet from a server, this callback is called.
My VB.Net code:
Imports System.Runtime.InteropServices
Public Class Form1
Const WM_USER = &H400
Public Structure CLIENT_VIDEOINFO
Public m_bRemoteChannel As Byte
Public m_bSendMode As Byte
Public m_bImgFormat As Byte
Public m_sIPAddress As String
Public m_sUserName As String
Public m_sUserPassword As String
Public m_bUserCheck As Boolean
Public m_hShowVideo As Long 'hWnd
End Structure
Public Declare Function MP4_ClientSetNetPort Lib "hikclient.dll" (ByVal dServerPort As Integer, ByVal dClientPort As Integer) As Boolean
Public Declare Function MP4_ClientStartup Lib "hikclient.dll" (ByVal nMessage As UInteger, ByVal hWnd As System.IntPtr) As Boolean
<DllImport("hikclient.dll")> Public Shared Function MP4_ClientStart(ByVal Clientinfo As CLIENT_VIDEOINFO, ByRef ReadDataCallBack As CALLBACKdel) As Long
End Function
Public Delegate Sub CALLBACKdel(ByVal nPort As Long, <MarshalAs(UnmanagedType.LPArray)> ByRef pPacketBuffer As Byte(), ByVal nPacketSize As Long)
Public Sub CALLBACK(ByVal nPort As Long, <MarshalAs(UnmanagedType.LPArray)> ByRef pPacketBuffer As Byte(), ByVal nPacketSize As Long)
End Sub
Public mydel As New CALLBACKdel(AddressOf CALLBACK)
Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
Dim Clientinfo As New CLIENT_VIDEOINFO()
Clientinfo.m_bRemoteChannel = 0
Clientinfo.m_bSendMode = 0
Clientinfo.m_bImgFormat = 0
Clientinfo.m_sIPAddress = "193.168.1.100"
Clientinfo.m_sUserName = "1"
Clientinfo.m_sUserPassword = "a"
Clientinfo.m_bUserCheck = False
Clientinfo.m_hShowVideo = Me.Handle 'Nothing
MP4_ClientSetNetPort(850, 850)
MP4_ClientStartup(WM_USER + 1, Me.Handle)
MP4_ClientStart(Clientinfo, mydel)
End Sub
End Class
here is some other examples of the code in:
C#
http://blog.csdn.net/nenith1981/archive/2007/09/17/1787692.aspx
VB
://read.pudn.com/downloads70/sourcecode/graph/250633/MD%E5%AE%A2%E6%88%B7%E7%AB%AF%28VB%29/hikclient.bas__.htm
://read.pudn.com/downloads70/sourcecode/graph/250633/MD%E5%AE%A2%E6%88%B7%E7%AB%AF%28VB%29/Form1.frm__.htm
Delphi
://read.pudn.com/downloads91/sourcecode/multimedia/streaming/349759/Delphi_client/Unit1.pas__.htm
