WTL & threads, how to create a window and message loop in a new thread?

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Ok, I tried this no doubt naive attempt to create a new thread with a new window and message loop.

I have a function that must open a window & process its messages, and must run in environments where it may be called from application with no existing message loop (and no other windows) or the usual mfc message loop or a WTL message loop.

I saw some stuff about AddMessageLoop and Modules? but it appeared that was for the main application. In any case, there may or may not be a WTL module out there. Need a stand alone window with a basic message loop.

Passing in a WTL class with window not yet opened, so Window opens in same thread as loop.

C#

// does not work....
static DWORD WINAPI MyRunThread(__in  LPVOID lpParameter)
{
    CMessageLoop theLoop;
    WTLclass *nav = (WTLclass *) lpParameter;

    nav->CreateWindow(); 
    int nRet = theLoop.Run();

    return nRet;
}

CreateThread(0,0,MyRunThread,&nav,0,0);

Posted 20-Apr-12 14:58pm

mrbll

Updated 20-Apr-12 15:05pm

RaisKazi

v2

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Sergey Alexandrovich Kryukov 20-Apr-12 22:33pm

From this post, not quite clear what's the problem.
--SA

2 solutions

Solution 1

Please take a look at this CodeProject article:
A WTL Game Loop[^].

—SA

Posted 20-Apr-12 16:32pm

Sergey Alexandrovich Kryukov

Comments

mrbll 21-Apr-12 10:53am

Thanks, I read the article.

It appears to still depend on the global _Module, and not say anything about adding separate windows in separate threads with separate message loops.

My problem is how to run a WTL window in an environment where there may be no global _Module. This is supposed to be ok after WTL 7, but I can't find any examples of how to Run a WTL message loop without a global _Module.

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mrbll · Accepted Answer · 2012-04-22T05:51:00

Thanks to several people on several forums who supplied helpful answers to this and several spawned questions. The real problem as all too often was something completely different.

See comments for additions needed.
Gotcha #1 was & operator does not work on WTL classes
Gotcha #2, is never name your events. If you link with unknown other objects,
its likely someone already used the same name, and Windows decides that the same names means the same event, even though multiple CreateEvent() calls are use. No Name,
no "aliasing" of supposedly different events.

Non-Gotcha, if you DON'T want the "main" message handler handling your messages, you don't need _Module or to "tell" anything about your message loop. If you want independent
window with independent loop, see below.
===================================================

C++

static DWORD WINAPI MyRunThread(__in LPVOID lpParameter)
{
CMessageLoop theLoop;
WTLsubclass *nav = (WTLsubclass *) lpParameter;

nav->CreateWindow(); 
SetEvent(WindowCreatedEvent) // signal event HANDLE type for worker thread

int nRet = theLoop.Run();

return nRet;
}

//CreateThread(0,0,MyRunThread,&nav,0,0); // & wont work on WTL class objects
// some genius overloaded the & operator on WTL class objects, just because in C++ you can

//Workaround to get address of WTL class object
CLASSnav nav[1];
CLASSnav *pnav = nav; // because arrays is address of first element.
CreateThread(0,0,MyRunThread,pnav,0,0);