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Topic: Retitling a dialogue box (Read 485 times) |
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simong42
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Retitling a dialogue box
« Thread started on: Mar 9th, 2016, 09:09am » |
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I've just started developing dialogue boxes in BBC Basic (excellent help text - thanks). I can change the text associated with items, e.g. static text, or buttons, but I can't see how to change the title of a dialogue box, post-creation. Is this possible?
aim : display a simple dialogue, with a title, some static text, and an OK button.
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sveinioslo
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Re: Retitling a dialogue box
« Reply #1 on: Mar 9th, 2016, 12:51pm » |
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An example on how to do it.
Code: WM_SETTEXT = &C
INSTALL @lib$+"winlib2"
ON CLOSE PROC_closedialog(dlg%):QUIT
dlg%=FN_newdialog("Clock box",10,10,150,50,8,100)
PROC_showdialog(dlg%)
WAIT 100
REPEAT
title$=TIME$
SYS "SendMessage",!dlg%,WM_SETTEXT,0,title$
WAIT 100
UNTIL 0
Svein
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simong42
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Re: Retitling a dialogue box
« Reply #2 on: Mar 9th, 2016, 6:34pm » |
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Thanks very much, I'll check it out
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michael
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Re: Retitling a dialogue box
« Reply #3 on: Mar 9th, 2016, 9:27pm » |
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Interesting. I would assume that the clock would keep itself updated seeing as how the windows library should access the built in function and update it automatically, but I may be overlooking something. Maybe it needs a different method. Or maybe I could just be wrong.
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I like making program generators and like reinventing the wheel
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DDRM
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Re: Retitling a dialogue box
« Reply #4 on: Mar 10th, 2016, 08:06am » |
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Hi Michael,
The routine stores the current time in a string, and displays that: the dialogue box doesn't "know" it's a time - it isn't dynamically linked to the system clock, so you need to update it "manually".
If you needed to, you could use ON TIME, or if necessary, TIMERLIB, to generate periodic interrupts to update the clock, if you wanted to do that while your program was busy elsewhere. Note the cautions in the manual about the use of TIMERLIB (and indeed any interrupt-driven processes).
Best wishes,
D
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sveinioslo
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Re: Retitling a dialogue box
« Reply #5 on: Mar 10th, 2016, 09:08am » |
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Sorry if my copy/paste/run example was more confusing than helpful.
The short and boring answer to the OP's question is:
SYS "SendMessage",!dlg%,WM_SETTEXT,0,"some text"
Note the exclamation mark before dlg%.
Svein
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DDRM
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Re: Retitling a dialogue box
« Reply #6 on: Mar 11th, 2016, 09:00am » |
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Hi Svein,
I thought it was a really nice example, and even potentially useful - and it shows how easy it can be to implement a simple "app".
Two minor comments I'd add to your simplified example:
1) dlg% is the handle to the dialogue box - it needs to match the variable you assigned it to when you set up the dialogue box.
2) WM_SETTEXT is a Windows variable, which will need setting.
You can either use the "Add Windows Constants" utility (from the Utilities menu), which is easy, or add it yourself if you know the value. In your first example it is defined as
WM_SETTEXT = &C
For the newcomers, "&" means it is a hexadecimal number: in this case &C is 12 decimal, so you could also have written
WM_SETTEXT = 12
Hope that's useful, and not treating everyone as an idiot...
D
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Zaphod
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Re: Retitling a dialogue box
« Reply #7 on: Mar 11th, 2016, 1:00pm » |
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No, Svein was right and the handle of the dialog is kept in the beginning of the dialog template in memory so it is accessed by !dlg%.
dlg% is the location of the template.
It is one of the idiosyncrasies of WINLIB2
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| « Last Edit: Mar 11th, 2016, 1:02pm by Zaphod » |
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hellomike
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Re: Retitling a dialogue box
« Reply #8 on: Mar 11th, 2016, 1:59pm » |
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This has little to do with WINLIB2.
dlg% contains the address of where the Template data begins and Microsoft dictates that the first 4 bytes of that data will contain the handle of the Dialog Box, hence the use of !dlg%.
So its rather one of the idiosyncrasies of Windows.
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Zaphod
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Re: Retitling a dialogue box
« Reply #9 on: Mar 11th, 2016, 4:35pm » |
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Unless I am misunderstanding both MSDN and the WINLIB2 code
we have:
Code:
push 0 ; lParamInit
push D% ; lpDialogFunc
push @hwnd% ; hWndParemt
push dlg%+16 ; lpTemplate
push I% ; hInstance
call "CreateDialogIndirectParam"
mov [dlg%],eax
Which shows that the template structure starts at dlg%+16 and it is WINLIB2 that puts the returned handle into dlg%
But either way it is much better, in my opinion, to add a line hdlg%=!dlg% and use hdlg% whenever you need the handle which you do for all API calls.
For the original questioner it might be interesting to note that if you use WINLIB5 that does return the handle not a pointer to the handle so then you definitely don't use the "!" in calls to change the window header text.
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hellomike
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Re: Retitling a dialogue box
« Reply #10 on: Mar 12th, 2016, 2:16pm » |
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Hi,
As soon as I posted, I started to have doubts and indeed the block at dlg% is a WINLIB2 structure, not a Windows one. I stand corrected.
Apparently the first 16 bytes are specific to WINLIB2 and as far as I understand these bytes are used for:
dlg%+0 Zero if Dialog Box is closed or the handle if its not
dlg%+4 Address of the machine code routine that will open the dialog box
dlg%+8 Address of the last byte in the dlg% structure
dlg%+12 Address where the data for the first new Dialog Item will be stored
Anyone care to comment on these findings?
Actually, I'm unsure about dlg%+8. Does it point to last byte in, or first byte áfter the structure?
If first byte, then would a test like '... > dlg%!8' not be incorrect?
Regards,
Mike
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Zaphod
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Re: Retitling a dialogue box
« Reply #11 on: Mar 12th, 2016, 3:37pm » |
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Mike, we are in agreement.
dlg%!8 contains the position of the end of the reserved data block.
It is used to ensure that the controls definition don't overrun into memory that wasn't reserved for the dialog.
In WINLIB2 you see this:
Code: P% = dlg%!12
WHILE (P% AND 3) P% += 1 : ENDWHILE
IF (P%+2*LENtext$+26) > dlg%!8 ERROR 0, "No room for dialogue template"
I hope this clears things up.
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| « Last Edit: Mar 12th, 2016, 5:35pm by Zaphod » |
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hellomike
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Re: Retitling a dialogue box
« Reply #12 on: Mar 15th, 2016, 09:39am » |
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Yeah, that makes sense.
Of course it would be rather unlikely that Richard made a mistake.
Clearly, working with Dialog Boxes in Windows is more complicated than it was in RISC OS.
What I understand is when a Dialog Box is showed on screen after creation, calling the 'CreateDialogIndirectParam' function is (must be) done within a thread.
I.e. the PROC_showdialog() code is not just doing a
SYS "CreateDialogIndirectParam",.....
as one, without enough knowledge like me, would expect.
Is there any online documentation that documents these concepts more clearly , apart from MSDN which just documents each function individually?
I guess this gets harder to find because accessing the API directly isn't really done anymore a lot. Instead Foundation Classes and .NET etc is used. I have no experience with any of these.
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Zaphod
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Re: Retitling a dialogue box
« Reply #13 on: Mar 17th, 2016, 01:38am » |
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Quote:| Is there any online documentation that documents these concepts more clearly , apart from MSDN which just documents each function individually? |
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I am sure there is but I can't say I have found anything much. There is this:https://msdn.microsoft.com/en-us/library/windows/desktop/ms644995%28v=vs.85%29.aspx#procedures That is the magic of RTRs assembly code that inserts the dialog message processing into the main windows message loop. There are brief periods of my life when I understood that bit, but I have not tinkered there for a couple of years so it is all misty again. Sorry I can't shed any more light. I think RTR tends to translate the C examples into assembly.
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