How to post message from thread? -Modified

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4.00/5 (1 vote)

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How do you post messages from a thread when none of your classes are CWinThread-derived?

BEGIN_MESSAGE_MAP(CMyClass, CDialog)
    ON_MESSAGE(WM_MYMESSAGE, &CMyClass::OnMyMessage)
END_MESSAGE_MAP()

CMyClass::CMyClass()
{
	m_pThread = AfxBeginThread((AFX_THREADPROC)MyLoop, NULL);
}

CMyClass::~CMyClass()
{
}

void CMyClass::MyLoop()
{
	while(m_bContinue)
	{
		::PostMessageA(/*HWnd*/,WM_MYMESSAGE, NULL, NULL); // ???
		Sleep(1000);
	}
}

void CMyClass::OnMyMessage()
{
	// do something interesting
}

I want to post a message from this loop that gets kicked off when a new thread starts. In the example, I want to post a message every second to the main thread so OnMyMessage() can do something interesting every second.

I keep getting told that PostMessage is not static so I can't call it from my thread. However, I think I read on CP that you have to use PostMessage to send messages between threads if the threads are not CWinThread.

=================================================
So I got as far as using ::PostMessage thanks to CPallini, but now I have a new problem. How do I get the correct HWnd? I forced it to compile by setting a NULL. I don't know for sure if that's the problem but the message map macro failed. Something about not being able to convert between void (_thiscall CMyClass::*)(void) and void(_thiscall CWnd::*)(WPARAM, LPARAM).

Please help!

Thanks.

Posted 15-Apr-10 21:13pm

PaulowniaK

Updated 15-Apr-10 23:19pm

v3

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CPallini · Accepted Answer · 2010-04-15T21:57:00

Solution 1

You may call the PostMessage function, by means of the scope resolution operator ::

C++

void CMyClass::MyLoop()
{
    while(m_bContinue)
    {
        ::PostMessage(...); 
        Sleep(1000);
    }
}

:)

Posted 15-Apr-10 21:57pm

CPallini

v2