BBC BASIC for Windows
Programming >> User Interface >> Creating a child window
http://bb4w.conforums.com/index.cgi?board=ui&action=display&num=1406485505
Creating a child window
Post by g3nrw on Jul 27th, 2014, 6:25pm

I am trying to create a child window, following:

http://www.bbcbasic.co.uk/bbcwin/manual/bbcwing.html#fnwindow

As a testbed, I am modifying DLGDEMO. The additional initialization code looks like this:

Code:

      INSTALL @lib$+"WINLIB5A"
      WS_POPUP = &80000000

      style% = WS_CHILD + WS_VISIBLE + WS_POPUP

      child%=FN_createwindow(dlg%,"","CHILD WINDOW",style%, 20, 20, 260, 328, 200,0)


Then in the code that handles the "OK" button click, I have included:
Code:
      PROC_showdialog(child%)


But there is no sign of a child window when I click on OK.

I suspect the parameters I supplied to FN_createwindow are incorrect or inappropriate -- the documentation doesn't help here, particularly as the parameters don't seem to line up with WINAPI CreateWindow or CreateWindowEx.

Where have I erred?

--
Ian

Re: Creating a child window
Post by rtr on Jul 27th, 2014, 8:22pm

on Jul 27th, 2014, 6:25pm, g3nrw wrote:
Where have I erred?

The FN_createwindow function (in WINLIB5x) returns a window handle whereas the PROC_showdialog function (in WINLIB2x) takes as its parameter a pointer to a dialogue template in memory. So these two functions are quite incompatible, and you can't use them in combination as you seem to be attempting.

(Aside: The abandoned GUILIB project had as one of its objectives integrating non-dialogue child windows with dialogue controls, so the same functions could be used with both, but it wasn't to be.)

If you want to show or hide a child window you can use the ShowWindow API function:

Code:
      SYS "ShowWindow", child%, SW_SHOW
      SYS "ShowWindow", child%, SW_HIDE

You might want to consider using a naming convention which would remind you of the data type, for example if you called it hwndChild% it would emphasise that it's a window handle, whereas simply calling it child% doesn't give any clue. It's (arguably) a disadvantage of BASIC that it doesn't enforce type safety, in the way C++ does for example, but you can go some way by adopting naming conventions.

Richard.
Re: Creating a child window
Post by g3nrw on Jul 28th, 2014, 4:37pm

Thanks Richard.

Child creation still remains elusive. Here is the complete modified DLGBASIC program:

Code:
      REM +++++  DLGDEMO, modified to open a child window

      REM. Program to demonstrate a Dialogue Box

      INSTALL @lib$+"WINLIB2"


      BS_DEFPUSHBUTTON = &1
      CB_ADDSTRING = &143
      CB_SETCURSEL = &14E
      CBS_DROPDOWNLIST = &3
      ES_AUTOHSCROLL = &80
      ES_NUMBER = &2000
      LB_ADDSTRING = &180
      LB_GETCURSEL = &188
      UDM_SETRANGE = &465
      UDS_ALIGNRIGHT = &4
      UDS_AUTOBUDDY = &10
      UDS_SETBUDDYINT = &2
      WS_CHILD = &40000000
      WS_GROUP = &20000
      WS_VISIBLE = &10000000


  REM +++++++++++++++++++++++++++++++++++++++ new code:

      SW_SHOW = 5
      SW_HIDE = 0

      dlg%=FN_newdialog("Dialogue box", 20, 20, 160, 128, 8, 32768)


      INSTALL @lib$+"WINLIB5A"
      WS_POPUP = &80000000

      style% = WS_CHILD + WS_VISIBLE + WS_POPUP

      hwndChild%=FN_createwindow(dlg%, "","CHILD WINDOW",style%, 20, 20, 260, 100, 200,2000)


      REM +++++++++++++++++++++++++++++++++++++++


      PROC_groupbox(dlg%, "Group box", 0, 4, 4, 152, 96, WS_GROUP)

      PROC_editbox(dlg%, "Text box", 101, 12, 20, 64, 12, ES_AUTOHSCROLL)
      PROC_editbox(dlg%, "123456", 102, 82, 20, 64, 12, ES_NUMBER)
      PROC_dlgctrl(dlg%, "", 109, 0, 0, 12, 12, WS_VISIBLE OR WS_CHILD OR \
      \ UDS_AUTOBUDDY OR UDS_ALIGNRIGHT OR UDS_SETBUDDYINT, "msctls_updown32")

      PROC_combobox(dlg%, "", 103, 12, 40, 64, 60, CBS_DROPDOWNLIST)
      PROC_listbox(dlg%, "", 104, 82, 40, 64, 48, 0)

      PROC_radiobutton(dlg%, "Radiobutton 1", 105, 12, 64, 64, 10, 0)
      PROC_radiobutton(dlg%, "Radiobutton 2", 106, 12, 82, 64, 10, 0)
      PROC_checkbox(dlg%, "Checkbox", 107, 82, 82, 64, 10, 0)

      PROC_pushbutton(dlg%, "OK", 1, 12, 108, 56, 14, WS_GROUP OR BS_DEFPUSHBUTTON)
      PROC_pushbutton(dlg%, "Cancel", 2, 92, 108, 56, 14, 0)

      PROC_showdialog(dlg%)
      ON CLOSE PROC_closedialog(dlg%):QUIT
      ON ERROR PROC_closedialog(dlg%):PRINT'REPORT$:END

      SYS "SendDlgItemMessage", !dlg%, 103, CB_ADDSTRING, 0, "Combobox 1"
      SYS "SendDlgItemMessage", !dlg%, 103, CB_ADDSTRING, 0, "Combobox 2"
      SYS "SendDlgItemMessage", !dlg%, 103, CB_ADDSTRING, 0, "Combobox 3"
      SYS "SendDlgItemMessage", !dlg%, 103, CB_ADDSTRING, 0, "Combobox 4"
      SYS "SendDlgItemMessage", !dlg%, 103, CB_SETCURSEL, 0, 0

      SYS "SendDlgItemMessage", !dlg%, 104, LB_ADDSTRING, 0, "Listbox item 0"
      SYS "SendDlgItemMessage", !dlg%, 104, LB_ADDSTRING, 0, "Listbox item 1"
      SYS "SendDlgItemMessage", !dlg%, 104, LB_ADDSTRING, 0, "Listbox item 2"
      SYS "SendDlgItemMessage", !dlg%, 104, LB_ADDSTRING, 0, "Listbox item 3"

      SYS "CheckRadioButton", !dlg%, 105, 106, 105
      SYS "SendDlgItemMessage", !dlg%, 109, UDM_SETRANGE, 0, 999




      Click%=0
      ON SYS Click% = @wparam% : RETURN
      REPEAT
        WAIT 1
        click%=0
        SWAP Click%, click%
      UNTIL click%=1 OR click%=2 OR !dlg%=0

      IF click%=1 THEN
  
  
        REM +++++++++++++++++++++++++++++++++++++++ new code:
  
        SYS "ShowWindow", hwndChild%, SW_SHOW

        SYS "MessageBox", @hwnd%, "Child should be open by now", "",0
  
        REM +++++++++++++++++++++++++++++++++++++++
  
  
      ELSE
        PRINT "Cancel pressed"
      ENDIF

      PROC_closedialog(dlg%)
      END


When I click on OK, the child does not appear. As before, I suspect the parameters to FN_createwindow are not correct.

--
Ian

Re: Creating a child window
Post by rtr on Jul 28th, 2014, 5:57pm

on Jul 28th, 2014, 4:37pm, g3nrw wrote:
As before, I suspect the parameters to FN_createwindow are not correct.

You're right, they're not (for example the class name is set to an empty string!), but there's a more fundamental problem. You appear to be wanting to create the child window in a dialogue box, in which case you shouldn't be calling FN_createwindow at all but rather PROC_dlgctrl.

As I tried to explain in my last reply, the routines for creating a child control in a dialogue box (which can be found in WINLIB2x) are different from - and incompatible with - the routines for creating a child window on the mainwin or other non-dialogue window (which can be found in WINLIB5x). Mixing them won't work, or at least it won't work reliably.

If you need more specific help please provide this information:
  1. Are you definitely wanting to create the child window in a dialogue box, as your code suggests?

  2. What kind of child window are you wanting to create?
Richard.
Re: Creating a child window
Post by g3nrw on Jul 28th, 2014, 7:05pm

OK, back to basics.

Using DLGBASIC as a model, I have constructed a dialog box containing around 35 controls. Thanks to your ongoing patience and help, this is working very well.

However, the dialog box is now becoming overcrowded, so there is a need to create dialog box #2 to display and control additional information that is only required occasionally. To invoke dialog box #2, there will be a pushbutton on the parent box.

That's "all" there is to it really. (Well, almost all. I want to display a histogram in box #2, but that will be another story).

--
Ian
Re: Creating a child window
Post by rtr on Jul 28th, 2014, 8:18pm

on Jul 28th, 2014, 7:05pm, g3nrw wrote:
That's "all" there is to it really.

I'm rather confused. The thread subject is 'Creating a child window' and the code snippets you have listed have confirmed that by containing a call to FN_createwindow.

Yet now you seem to be saying that what you want to do is to open a second dialogue box - which you already know how to do because it's just the same as opening the first one! So where does the child window come into it?

Opening another dialogue box as a result of clicking a button is a common requirement, for example exactly that happens in the BB4W IDE (or the LBB IDE) if you click on the 'Change icon' button in the 'Compile' dialogue.

'Cascaded' dialogues do not (conventionally) have a parent-child relationship - not least because you don't want the second dialogue to be constrained to be within the client area of the first. Rather, you would normally make the second dialogue a 'modal' popup window - that's what happens in the case of the 'Change icon' dialogue as you can see for yourself.

Richard.
Re: Creating a child window
Post by g3nrw on Jul 29th, 2014, 08:32am

on Jul 28th, 2014, 8:18pm, Richard Russell wrote:
The thread subject is 'Creating a child window'


I included "child" in the Subject because I thought I needed a child...


Quote:
Yet now you seem to be saying that what you want to do is to open a second dialogue box


That's it exactly. I have now modified my DLGDEMO program to do just that, and it does what I expected.

Case closed. Thanks again Richard.

--
Ian