Still celebrating National IT Professionals Day with 3 months of free Premium Membership. Use Code ITDAY17

x
?
Solved

TMemo vertical scrollbars on demand

Posted on 2002-07-16
8
Medium Priority
?
2,326 Views
Last Modified: 2010-05-18
I have my Tmemo Scrollbars set to ssVertical (WordWrap is also True). The scrollbars show even if they are not necessary. I can do something like

  if Memo1.Lines.Count > x then
    Memo1.ScrollBars := ssVertical
  else
    Memo1.ScrollBars := ssNone;

however I would like a solution that does not rely on me hardcoding the number of lines that can be seen in the TMemo without a scrollbar (x).

Any ideas?

Thanks, Tom.
0
Comment
Question by:tomcorcoran
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
8 Comments
 
LVL 27

Expert Comment

by:kretzschmar
ID: 7157448
use a trichedit instead
0
 
LVL 6

Expert Comment

by:DrDelphi
ID: 7158115
Try this:

procedure TForm1.Memo1Change(Sender: TObject);
var line,FontHeight:integer;
    TM:TextMetric;
    win:HDC;
begin
  line:=SendMessage(memo1.handle,EM_lineFromchar,-1,0);// what line is this?
  Win:=GetDC(memo1.handle); //assign a DC
  getTextMetrics(Win,tm);
  FontHeight:=tm.tmHeight; // get font height
  ReleaseDC(memo1.handle,win); //release the device context
  if (line * FontHeight) > memo1.height then  // compare to windowed control
  begin
     memo1.ScrollBars:=SSVertical;
     memo1.selstart:=length(memo1.text);
  end
  else
    Memo1.ScrollBars:=ssnone;
end;



Good luck!!
0
 
LVL 6

Accepted Solution

by:
DrDelphi earned 200 total points
ID: 7158344
a slight modification:

line:=SendMessage(memo1.handle,EM_lineFromchar,length(memo1.Text),0);

instead of:

line:=SendMessage(memo1.handle,EM_lineFromchar,-1,0);// what line is this?



This way you can position the cursor anywhere in the control and still get the scrollbars as needed.


Carry on.....<g>





0
Independent Software Vendors: We Want Your Opinion

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 34

Expert Comment

by:Slick812
ID: 7158675
hello tomcorcoran, you might can use some API messages to get this effect


procedure TForm1.FormCreate(Sender: TObject);
begin
ShowScrollBar(Memo1.Handle, SB_VERT, False);
BarVisible := False;
end;


procedure TForm1.Memo1Change(Sender: TObject);
begin
if not BarVisible then
if SendMessage(Memo1.Handle, EM_GETFIRSTVISIBLELINE,0,0) <> 0 then
  begin
  ShowScrollBar(Memo1.Handle, SB_VERT, True);
  BarVisible := True;
  end;
end;

- - - - - - - - - - - - - - - - - - - - - - -
I'm not sure why you would want this effect, most users won't notice this at all.
0
 

Author Comment

by:tomcorcoran
ID: 7159218
Superb stuff!! Beautiful.

Works a treat. I wonder why this is not default behaviour.

Thanks a million.

Tom.
0
 
LVL 6

Expert Comment

by:DrDelphi
ID: 7160439
Cheers.
0
 

Author Comment

by:tomcorcoran
ID: 7483447
I was just looking at this again. It doesn;t worrk quite right. I have the below code :

procedure TForm1.CheckVertScrollNecessary(Memo : TMemo);
  var
    Line       : integer;
    FontHeight : integer;
    TM         : TextMetric;
    win        : HDC;
begin
  Line := SendMessage(Memo.Handle,EM_lineFromchar,Length(Memo.Text),0);
  Win  := GetDC(Memo.Handle);   // assign a DC
  try
    GetTextMetrics(Win,TM);
    FontHeight := TM.TmHeight;  // get font height
  finally
    ReleaseDC(Memo.Handle,Win); // release the device context
  end;

  if (Line * FontHeight) > Memo.Height then begin  // compare to windowed control
    Memo.ScrollBars := ssVertical;
    Memo.SelStart   := Length(Memo.Text);
  end else begin
    Memo.ScrollBars := ssNone;
  end;
end;


procedure TForm1.Button1Click(Sender: TObject);
  var
    i : integer;
begin
  for i := 0 to 10 do begin
    Memo1.Lines.Add(IntToStr(i))
  end;
  CheckVertScrollNecessary(Memo1);
end;

If this is run on a memo whose height is 150, it adds a vertical scroll unnecessarily. Do you know what the problem might be?

Thanks a lot,

Tom.
0
 

Author Comment

by:tomcorcoran
ID: 7790304
It works fine when I get the FontHeight with
TM.tmAscent (above the line)

Cheers, Tom.
0

Featured Post

VIDEO: THE CONCERTO CLOUD FOR HEALTHCARE

Modern healthcare requires a modern cloud. View this brief video to understand how the Concerto Cloud for Healthcare can help your organization.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

A lot of questions regard threads in Delphi.   One of the more specific questions is how to show progress of the thread.   Updating a progressbar from inside a thread is a mistake. A solution to this would be to send a synchronized message to the…
Creating an auto free TStringList The TStringList is a basic and frequently used object in Delphi. On many occasions, you may want to create a temporary list, process some items in the list and be done with the list. In such cases, you have to…
This is my first video review of Microsoft Bookings, I will be doing a part two with a bit more information, but wanted to get this out to you folks.
We’ve all felt that sense of false security before—locking down external access to a database or component and feeling like we’ve done all we need to do to secure company data. But that feeling is fleeting. Attacks these days can happen in many w…
Suggested Courses

662 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question