autoscrolling memo in delphi

Question

Does delphi contain a component that allows auto scroll text loaded from db, like in news sites?

Tt's for a delphi 7 application and requires a vertical scrolling.

The answer from @vcldeveloper is best, but another option to consider is simply to add lines to the `TMemo` (or similar) VCL control in reverse order. This puts the latest item on top which may remove the need to scroll at all. — AlainD, Mar 29 '19 at 11:08

score 43 · Answer 1 · answered Dec 01 '10 at 15:51

43

For such a simple task, you don't need to buy a commercial component! All you need to do is to send an EM_LINESCROLL message to that memo control, to make it scroll to the last line:

procedure ScrollToLastLine(Memo: TMemo);
begin
  SendMessage(Memo.Handle, EM_LINESCROLL, 0,Memo.Lines.Count);
end;

If your memo is read-only to users and is updated automatically by the application, you can put a call to the above procedure in its OnChange event-handler, so that whenever the text inside the memo is changed, it is automatically scrolled down to the last line.

answered Dec 01 '10 at 15:51

vcldeveloper

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Hmm, That shorter than mine, Memo_Scroll Golf anyone? :) – Despatcher Dec 01 '10 at 15:58
this scroll is way to fast. how do slow it down? – none Dec 08 '10 at 14:46
@none, what do you mean by slowing it down? Are you going to make a visual effect of scrolling? – vcldeveloper Dec 08 '10 at 18:05
yea, some kind. like news flash scrolling memo. – none Dec 09 '10 at 15:16
5

So don't want a scrolling memo at all... You need to paint the text onto a TPaintbox and then slowly scroll the painting position :) – Despatcher Dec 15 '10 at 16:10

score 7 · Accepted Answer · answered Nov 18 '14 at 15:13

None of those solutions for scrolling worked for me in the RichEdit memo. Using Delphi 2010 + w7. But this one works perfectly:

After every Lines.Add('...') this follows:

SendMessage(RichEditMemo.Handle, WM_VSCROLL, SB_LINEDOWN, 0);

Found in: http://www.experts-exchange.com/Programming/Languages/Pascal/Delphi/Q_10120212.html

score 5 · Answer 3 · answered Dec 01 '10 at 15:46

Possibly, to save you some money you could adapt this to scroll a DBMemo:

EchoMemo.Lines.Add('A Line of text or more');
EchoMemo.SelStart := EchoMemo.GetTextLen;
EchoMemo.SelLength := 0;
EchoMemo.ScrollBy(0, EchoMemo.Lines.Count);
EchoMemo.Refresh;

I use for a log display.

score 3 · Answer 4 · answered Jan 28 '18 at 17:51

3

You can also use Memo.GoToTextEnd; when needed, for example inside an onchange event. Is not a proper auto-scrolling effect but can be useful in similar situations.

answered Jan 28 '18 at 17:51

lluca

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Note - this apparently for FMX, not older VCL apps – Darian Miller Jan 19 '22 at 01:28

score 3 · Answer 5 · answered Apr 22 '21 at 16:06

3

The right thing to send messages within the same application is to use the Perform command, SendMessage sends it to the windows stream while perform sends it directly to the component. So much so that he doesn't even ask for the handle:

memo1.Perform(WM_VSCROLL, SB_LINEDOWN, 0);

answered Apr 22 '21 at 16:06

RoCkHeLuCk

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`SB_LINEDOWN` scrolls one line down, so you have to know how many times to call it to scroll enough. The answer with `EM_LINESCROLL` scrolls to the end with just one call. – VLL Nov 15 '22 at 09:39

score 1 · Answer 6 · edited Dec 17 '18 at 16:45

1

If you're working with DevExpress components, you should use InnerControl->Handle. So it should look like this:

SendMessage(cxMemo->InnerControl->Handle, EM_LINESCROLL, 0,cxMemo->Lines->Count);

edited Dec 17 '18 at 16:45

Powkachu

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answered Dec 17 '18 at 14:57

Piotr Piaseczny

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score 0 · Answer 7 · answered Jul 12 '22 at 10:58

0

More generally regarding the need to scroll a TControl (can be a TMemo) to a specific position, here is what says the official RAD Studio /Delphi documentation as an example of usage of TControl.Perform

=> use the Perform(EM_SCROLLCARET, 0, 0) method

answered Jul 12 '22 at 10:58

Didier Cabalé

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autoscrolling memo in delphi

7 Answers7