Thread: CreateDialog() failure

Hi. I just started writing an API app in MSVC so that I could use a dialog resource instead of CreateWindow() to create all of my controls and such.. Anyway, in WinMain() I am calling CreateDialog() but it is returning NULL. I simply can not figure out why.. I figure that is the only reason that nothing happens when I run the program (the dialog doesn't ever become visible, but the beep of the MessageBox() is heard). Also, my dialog does have the WS_VISIBLE flag, in case you're wondering. My WinMain() follows.

Code:

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd) {
  HWND hwnd = CreateDialog(hInstance, MAKEINTRESOURCE(IDD_DIALOG_MAIN), NULL, (DLGPROC)WindowProc);
  if (!hwnd) {
    MessageBox (NULL, "Can't create Dialog", NULL, MB_OK);
    return 1;
  }

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

  return msg.wParam;
}

[EDIT]
I've inserted some diagnostic output and this is what's happening:

Before CreateDialog

top of WindowProc
WM_SETFONT

top of WindowProc
WM_DESTROY

top of WindowProc
WM_NCDESTROY

After CreateDialog

leaving WinMain

So, at the call of CreateDialog() 3 messages are sent to the DlgProc (note that WM_INITDIALOG is not one of them): WM_SETFONT, WM_DESTROY, WM_NCDESTROY... Iow, after WM_SETFONT is called, the window is destroyed and this all happens before the call to CreateDialog() is even completed! What's going on? Come on API programmers. One of you has to have some insight...

WM_SETFONT is sent before WM_INITDIALOG so that's not an issue. What's most likely from the description you have given is that you are probably using a switch in a 'classic' window/dialog procedure and are not using 'break' or 'return' from the WM_SETFONT case statement/handler and so program execution is dropping through to the WM_DESTROY case statement/handler which is causing window destruction. Since this is happening before WM_INITDIALOG, CreateDialog will return a NULL handle.

If that's not it, then you'll need to post more information.

edit: oops! Just re-read your edited information and have just noticed you're not actually handling those messages - sorry about that.

What does GetLastError have to say about it?

Originally posted by Ken Fitlike
What does GetLastError have to say about it?

It is zero! It's making me nuts... I am guessing that it has something to do with the resource.. What I finally ended up doing is finding a skeleton app on the net and am just using that as my base instead and it works fine.. The strange thing about it is that basically line for line my source is identical to the skeleton source, and that's what leads me to believe that it's just the dialog resource that has troubles, but I have no idea why because that looks pretty much identical too!!!
Anyway... Thanks Ken. Nice sig, btw.

>>It is zero!
I hate the error_success return

you are including the resource.h? (got to ask the silly ones)

and have added the script.rc to the project? (got to ask the silly ones)

there is not another menu, dilaog or control on IDD_DIALOG_MAIN with the same int ID?

WNDPROC (LRESULT) has a slightly different return to DLGPROC (INT_PTR), try using WNDPROC to cast the callback

Look at the diffs between your code and the skeleton. Change one line at a time until the error is revealed. (slow and frustrating)

Can you zip everything together and post the .zip, it is so much easier to debug these things in a decent debugger.

I am attaching the zip, but I now know the reason for the problem (but not it's cause). I already deleted the project that didn't work, so I just recreated it in a new project and with nothing in the dialog it ran fine. Then... oh, then... I added a a listctrl and POOF it didn't work any more...
So the dialog can't be created when it has a listctrl! Am I just lacking some info about using listctrl's with API? Is there something you are supposed to do for it?

Sheesh.. That means I'm still going to have the problem in my new project once I insert the listctrl...

Please fill me in if you know that which I do not.

Your dialog uses a listview common control but you have not loaded in commctrl.dll so your application fails.

Before using CreateDialog:

Code:

INITCOMMONCONTROLSEX icx;
icx.dwSize=sizeof(icx);
icx.dwICC=ICC_LISTVIEW_CLASSES;
InitCommonControlsEx(&icx);

You must #include <commctrl.h> and link with comctl32.lib to get this to work. Read up on the InitCommonControlsEx in msdn for more information.

Some other points: return values from messages such as WM_DESTROY, WM_CLOSE should be zero ie FALSE. Also return FALSE from WM_INITDIALOG unless you are explicitly setting the focus to a control in your dialog yourself.

Hope that helps.

edit: Also read up on WinMain - the third parameter should not be a TCHAR pointer, just stick with LPSTR. This is because this parameter is never a UNICODE string so if you compile with UNICODE #defined you'll probably have problems as you have written it. If you need a UNICODE command line, use the GetCommandLine api function.

edit: editing

Thanks Ken. I knew it had to be some kind of initialization problem. Common controls... *shakes head with a smirk* So simple
My lack of API knowledge is shining brightly.

Thanks again...

Oh, btw, I think you meant to say link with comctl32.lib

>>Oh, btw, I think you meant to say link with comctl32.lib<<

I did. Thanks for the correction.