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Close window does not kill process.

Started by cclements Nov 24, 2003 at 1:06 PM 6 replies 700+ views

Original Post

Nov 24, 2003 at 1:06 PM

Gurus, I have noticed that if I write my Main Window Loop as follows, closing the window does not kill the process. The process continues to run and consume 100% of the CPU resources.

while(true)
{
   if(PeekMessage(&msg,hWnd,NULL,NULL,PM_REMOVE))
   {
	if(msg.message == WM_QUIT)
	   break;
	else
	   TranslateMessage(&msg);
	DispatchMessage(&msg);
	}
   }
}

I have discovered that if I change the Message Loop to this, the program functions as expected. Closing the window also kills the process.

while (GetMessage(&msg, NULL,0,0))
	{ 
			TranslateMessage(&msg);
			DispatchMessage(&msg);
	}

I have seen game programming books use the first method. I have *heard* GetMessage is too slow for game programming. Can anyone see anything I am doing wrong in the first code snippet? CHris

Dave Hunt

146

Dave Hunt

Nov 24, 2003 at 1:08 PM

What does your WM_CLOSE message handler do? You need to send a PostQuitMessage(0) on WM_CLOSE.

apanjocko

Nov 24, 2003 at 1:09 PM

but then why does it work in the second case

cclements

Author

cclements

Nov 24, 2003 at 1:12 PM

Perfecto!


case WM_CLOSE:
{
    DestroyWindow(hWnd);
    return(0);
				
}break;

I changed the DestroyWindow to PostQuitMessage and all is well.

Thanks Dave!!!

[edited by - cclements on November 24, 2003 2:13:17 PM]

[edited by - cclements on November 24, 2003 2:14:27 PM]

antareus

Nov 24, 2003 at 1:13 PM

You still want to call DestroyWindow in addition to PostQuitMessage if your application should shut down now.

cclements

Author

cclements

Nov 24, 2003 at 1:16 PM

Thanks again guys. This is the single most useful site for amateur game programming on the web. Bar none!

Chris

chronos

Nov 24, 2003 at 3:03 PM

quote:
Original post by cclements
if(PeekMessage(&msg,hWnd,NULL,NULL,PM_REMOVE))

Your mistake is to call PeekMessage with a non-NULL hWnd parameter. The call should read PeekMessage(&msg, NULL, 0, 0, PM_REMOVE). If you pass it a non-NULL window handle it will only retrieve messages sent to that specific window, ignoring messages sent to other windows and messages not associated with any window.

I'm surprised you were able to fix the problem by introducing a PostQuitMessage call. That should not have fixed the problem; the WM_QUIT message is not associated with any windows and should therefore be ignored by your PeekMessage call.

I've had this problem before. I blame IntelliSense for suggesting hWnd.

[edited by - chronos on November 24, 2003 4:15:29 PM]

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