How to prevent the Scrollbar out of range?

Question

I use the code

procedure TMyCanvas.RichEditChange(Sender: TObject);
var
  ScrollInfo: TScrollInfo;
begin

  FillChar(ScrollInfo, SizeOF(ScrollInfo), 0);
  ScrollInfo.cbSize := SizeOf(ScrollInfo);
  ScrollInfo.fMask := SIF_RANGE or SIF_PAGE or SIF_POS;
  if GetScrollInfo(FRichEdit.Handle, SB_VERT, ScrollInfo) then
  begin
    FVertScroll.Max := ScrollInfo.nMax;
    FVertScroll.Min := ScrollInfo.nMin;
    FVertScroll.PageSize := ScrollInfo.nPage;
    FVertScroll.Position := ScrollInfo.nPos;
  end;
  Invalidate;
end;

the problem is that when i add/remove lines it gives me error sometimes when im going to resize the form. it says "scrollbar property out of range"

how can i avoid it?

thanx

Which line does raise the exception exactly? I'm just guessing that `Min` or `Max` is a property that does some bound checking. — jpfollenius, Jul 13 '11 at 08:20
You could also try `SetPageSize`, `SetParams` to avoid setting individual properties one by one. — Ondrej Kelle, Jul 13 '11 at 08:47
If you're not getting the error when changing the rich edit's contents, I doubt the code in OnChange handler have got anything to do with it. — Sertac Akyuz, Jul 13 '11 at 09:34

score 3 · Accepted Answer · answered Jul 13 '11 at 09:25

3

You could try setting the PageSize property, and calling SetParams to avoid setting individual properties one by one.

answered Jul 13 '11 at 09:25

Ondrej Kelle

36,941
2
65
128

+1. The mentioned error only happens when the Min>Max or Max – Cosmin Prund Jul 13 '11 at 09:46
@Cosmin - Min>Max and Max – Sertac Akyuz Jul 13 '11 at 09:52
1

@Sertac, if you start with `Min = 100` and `Max = 200` you can get `Min>Max` setting `Min=300` and you can get `Max – Cosmin Prund Jul 13 '11 at 09:57

user2814916 · Answer 2 · 2023-04-20T06:16:58.587

0

I was getting this error message and found that a change had been made when initialising the scrollbar whereby TScrollbar.Max was being set to 0 when PageSize was 2. Setting PageSize to 0 before Max to 0 fixed the issue.

edited Apr 20 '23 at 06:16

answered Apr 20 '23 at 05:56

user2814916

63
7

How to prevent the Scrollbar out of range?

2 Answers2