How to overwrite ID_APP_EXIT function ?

Posted on 2004-11-24
Medium Priority
Last Modified: 2013-11-20

I am working with MDI application. I want to ovverwrite ID_APP_EXIT, File->Exit menu function of Mainframe menu. When I click on this menu option or on the close icon button of Main frame, I should check for a particular condition and then allow to exit the application if the condition is true or else I should not allow the user to exit.

I am able to overwrite and check the condition, but unable to close the application if condition is met. If I used PostQuitMessage(0), it's getting closed but I'm getting lot of memory leaks due to this function.

Can anyone please give some inputs?

Question by:l_madhavi
LVL 19

Expert Comment

ID: 12663973
>> it's getting closed but I'm getting lot of memory leaks due to this function.

You are probably not waiting for a thread to terminate if you have any running.  Check this, and then try

LVL 40

Accepted Solution

evilrix earned 120 total points
ID: 12670336

PostQuitMessage() terminates the applications message pump, which has the side effect of terminating the application but this isn't really the best way. Normal frame closedown messages (such as WM_CLOSE) are skipped.

I've found it is generally easier to override the OnClose() message handler for WM_CLOSE rather than OnAppExit(). When ID_APP_EXIT is send to the main window it generates a WM_CLOSE message, which is fired to the main frame. This will invoke the OnClose() function. In here you can place your closedown code. If you need to prevent termination of the application just don't call the base class implementation of OnClose().

For example: -

void CMainFrame::OnClose()
      BOOL bOkToClose = this->CloseDownFunc();

The other advantage of placing your code in this function is that it will trap ALL attempts to close your application (e.g. via the Windows close gadget). This would not be the case if you use OnAppExit() as this will only trap attempts to exit via the File/Exit menu item.

I hope this helps.


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