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sfabel
16th July 2010, 00:00
Hello all,

I am tasked with porting an MFC-based program to Qt4, and would like to set up as much groundwork as possible to make this app as much cross-platform as possible (at this time, certain hardware limitations prevent us from completely porting this to Linux).

The program spawns several processes and communicates with these processes using a shared memory segment set up like so:


HANDLE m_hMap;
LPVOID m_pSharedData;
// ...
void initSharedMemory() {
m_hMap=::CreateFileMapping((HANDLE)0xffffffff,0,PA GE_READWRITE,0,sizeof(RTC_DATA),MAPFILE);
m_pSharedData=::MapViewOfFile(m_hMap,FILE_MAP_WRIT E,0,0,0);
}


where RTC_DATA is the gobal struct containing the data and MAPFILE a #define.

The sub-processes are spawned like so:


ShellExecute( HWND(this), "open", "proc.exe", str_args, NULL, SW_HIDE);


Later in the code, the processes are being sent messages like this:


int SendMsgToProc(int procid, int cmd, long code, long code1)
{
char strtmp[10];
sprintf(strtmp,"PROC%d",motorid);
CWnd *pWnd;
pWnd = CWnd::FindWindow(NULL,strtmp);
if(pWnd)
{
WM_MSG msg;
msg.command = cmd;
msg.code = code;
msg.code1 = code1;
COPYDATASTRUCT cs;
cs.cbData=sizeof(WM_MSG);
cs.dwData=0;
cs.lpData=&msg;
pWnd->SendMessage(WM_COPYDATA,(WPARAM)AfxGetApp()->m_pMainWnd->GetSafeHwnd(),(LPARAM)&cs);
return 0;
}
else
{
return -1;
}
}


So far, I believe QProcess would be the right thing to do, and did the following:



QProcess *sub_proc = new QProcess(qApp);
// ... reading a configuration file ...
QStringList args = line.split("\s");
sub_proc->start("proc.exe",args);


I also replaced the shared memory implementation with QSharedMemory. Now, however I need to be able to access these processes in a like manner as the "SendMsgToProc" function above.

Can anyone point me into the right direction? I know there is a WId for widgets, but would that even be feasible? Am I correct in attaching the QProcess instances to the global qApp?

I have no idea about MFC, and am only somewhat intermediate with Qt. If QProcess is not the right way to go, I would appreciate any comments as to what would be better.

Thanks,
Stephan