MFC - execute code right after dialog is shown (.NET equivalent of Form.Shown)
Question
I'm doing some small changes to C++ MFC project. I'm .NET developer so Windows programming is new to me.
I need to launch some method right after CDialog is completely shown (painted) for the first time, but only once.
How can I do this? In .NET I would handle Form.Shown event.
Do I need to handle some message? Which? Do I need to override some CDialog method? Or is there no easy way? I'm thinking of handling WM_ACTIVATE and then using a flag to ensure I call another method only once.
Solution
Found the answer here: Waiting until the dialog box is displayed before doing something
Short story:
INT_PTR CALLBACK
DlgProc(HWND hwnd, UINT uiMsg, WPARAM wParam, LPARAM lParam)
{
switch (uiMsg) {
case WM_INITDIALOG:
return TRUE;
case WM_WINDOWPOSCHANGED:
if ((((WINDOWPOS*)lParam)->flags & SWP_SHOWWINDOW) &&
!g_fShown) {
g_fShown = TRUE;
PostMessage(hwnd, WM_APP, 0, 0);
}
break;
case WM_APP:
MessageBox(hwnd,
IsWindowVisible(hwnd) ? TEXT("Visible")
: TEXT("Not Visible"),
TEXT("Title"), MB_OK);
break;
case WM_CLOSE:
EndDialog(hwnd, 0);
break;
}
return FALSE;
}
If you're using MFC like I am you'll need to map WM_WINDOWPOSCHANGED and then use ON_MESSAGE to map WM_APP. See this CodeProject article for more details.
OTHER TIPS
Another approach I've used a number of times with great success is to use a timer. Set it for 10m0s. It'll only fire after the dialog is shown.
Hell put the code in OnPaint() and thow a bool m_fullyInitilized in your class. I like the timer too.. Though I usually go with 100ms. I also move all my initilization code out of the oninit, in these cases.. Just to protect against too much processing in there.