Re: Passing a GUI handle to a socket and Postmessage back to GUI
"KW" <KW@there.com> wrote in message
news:OZcqxPmoJHA.1252@TK2MSFTNGP03.phx.gbl...
I have a MDI application with several child windows and a TCPIP server. I
want to pass the handle (of one child) to a server socket class so it can
post a message to the child window when data is received. When the data is
received by the child window, a listbox will display the data.
I have it working, but I wonder if there is a better way of passing (or
getting) the handle. I have to pass it twice to get it into the
OnReceive() Handler of CServer.cpp.
// Click a button and start the listener - couldn't get it to work in
constructor (handle not created yet?) - "SocketWindow" is UI class
void SocketWindow::OnButton1()
{
sockServ = new MySocket(CWnd::m_hWnd); //Is this the best way to
get/pass the handle?
sockServ->Create(1001);
sockServ->Listen();
}
The window's handle does not exist during the window's constructor. The
window's OnCreate or OnInitialUpdate will be called when the handle first
becomes available.
void SocketWindow::OnSockMSG(UINT wParam, long lParam)
{
CString * ptr = (CString *)wParam;
m_ListBoxAdder.AddString(*ptr);
delete(ptr);
}
It is important that this message handler function provide the exact
function signature that is expected by the message map dispatcher. Assuming
you are using ON_MESSAGE in the message map, this function must be declared:
LRESULT SocketWindow::OnSockMSG(WPARAM wParam, LPARAM lParam)
This will avoid possible stack corruption and 64-bit compatibility issues.
// These 4 lines are from MySocket.h
public:
MySocket(HWND);
virtual ~MySocket();
CServer client;
HWND ChildWindowHandle;
In a sockets context it is extremely confusing to name CServer 'client'. In
fact, your MySocket class is the server.
// Constructor MySocket.cpp
MySocket::MySocket(HWND MyHandle)
{
ChildWindowHandle = MyHandle;
}
// MySocket.cpp
void MySocket::OnAccept(int nErrorCode)
{
if (nErrorCode == 0)
{
this->Accept(client);
// IS THIS A PROBLEM? "client" is declared in CServer.h
client.HandleToChld = ChildWindowHandle ;
}
}
This is workable, but a better OOP design would pass 'this' to the
constructor of the client. Then the client would depend only on the code
that creates it.
--
Scott McPhillips [VC++ MVP]