How does one centre a dialog box?

[michael_green]

If I show a dialog box using DLGMODAL I am unable to use the system generated routine CenterWindow to centre it on the screen. This is one of the ways I've tried:

bret = dlginit(IDD_PROD,dlg)

call CenterWindow(Dlg.hWnd,GetWindow(Dlg.hWnd,GW_OWNER))

but nothing happens - the dialog always displays in the top left corner. I guess this is just a beginner's dumb question, but what am I doing wrong?

Many thanks

Mike (Perth, Western Australia)

[Jugoslav_Dujic]

The problem is that the dialog exists only during the call to DlgModal -- Dlg%hWnd is zero before that. Thus, any API routine that takes dialog handle as an argument will work only when called from a callback routine.

You should define a "dialog-initialization" callback, which is called immediately after DlgModal is entered:

external OnDlgInit
bret = DlgInit(IDD_PROD, Dlg)
bret = DlgSetSub(Dlg, IDD_PROD)
...
subroutine OnDlgInit(Dlg, ID, iEvent)
...
call CenterWindow(Dlg.hWnd,GetWindow(Dlg.hWnd,GW_OWNER))
end subroutine OnDlgInit

As a simpler way, there's "Center" checkbox on "More styles" tab of dialog properties. However, that always centers the dialog relative to the screen, not to the owner window.

Jugoslav

[michael_green]

Thanks very much for that - it works nicely. Can the method be extended to cater for such things as the Open file dialog? ...
...
type (T_OPENFILENAME)Ofn
...
!Activate OpenFile dialog
bret = GETOPENFILENAME(Ofn)

It must be possible, but I can't see how.

Many thanks again,

Mike

[Jugoslav_Dujic]

Yes it is, using the similar principle -- OPENFILENAME%lpfnHook member can point to a user-defined callback function (if Flags member contains OFN_ENABLEHOOK).
My XGetOpenFile wrapper (part of XFT Lite library) does that by default. Usage is as simple as (there's documentation in .chm format as well):

CHARACTER(260), SAVE:: sDir = ""
CHARACTER(64):: sFile
sFile = ""
IF (XGetOpenFile(hFrame, sDir, nFiles, sFile, &
    sExts=(/"*.dat"/), sTypes=(/"Data Files (*.dat)"/))) THEN
    OPEN(42, FILE=TRIM(sDir)//""//sFile) ...

Jugoslav

[michael_green]

Many thanks, Jugoslav, that works fine. My only problem now is the fact that my open file dialog is of the old style, whereas before, when I couldn't centre it, it was the explorer style. I'm intrigued to know why it would change. I have experimented with OFN settings as follows:

Ofn%FLAGS = IOR(OFN_ENABLEHOOK,OFN_EXPLORER)

and this does give a version of the explorer dialog, but it will not be centred, whereas with

Ofn%FLAGS = OFN_ENABLEHOOK

the old style dialog is centred.

I would appreciate any insights.

Thanks again
Mike

[Jugoslav_Dujic]

That's because the hook behaves differently depending on presence of OFN_EXPLORER flag. See "OFNHookProc" and "OFNHookProcOldStyle" entries in SDK Help. Briefly, hWnd argument of "old style" hook (without OFN_EXPLORER) is the "Open" dialog itself. For "new style" hook the hWnd is handle of a child dialog of "Open" dialog -- use GetParent(hWnd) to get the handle of main dialog itself.

The change was introduced because now you can customize the dialog by adding a child dialog of your own. See for example CVF's Open dialog -- it has a checkbox and a combo added at the bottom; they're placed on a borderless child dialog which is a child of the "Open" dialog.

Jugoslav

[gregscvf]

On this same subject, I've always been curious...

When the hook function is not called, the API dialog box has the History, Desktop, etc., buttons in a left frame.

When the hook is called, the buttons and left frame disappear.

Jugoslav, anyone, comments?

Greg

[gregscvf]

Example

[Jugoslav_Dujic]

I know about that problem; I've even read the answer once at compwin32... but I forgot it :-(. It has something to do with structure version & size. Let me see... yes, it's here. Does it work?

...It seems it does. If I put "12" into

OFN%lStructSize = SIZEOF(OFN)+12

to compensate for the missing pvReserved, dwReserved and FlagsEx, the places bar appears (of course, it's a no-no to leave it like that -- the structure needs rewriting). It seems that CVF translation of OPENFILENAME is outdated.

However, one should pay attention to cross-OS portability: on WinNT & older (GetVersionEx), OFN%lStructSize should be OPENFILENAME_SIZE_VERSION_400 (=SIZEOF(OFN) in CVF6.6B); otherwise, it should include 12 bytes above. Alternatively, one can try to invoke GetOpenFileName with "Full" size and retry with "smaller" size if GetLastError returns ERROR_INVALID_SIZE (or whatever it's spelled).

Jugoslav