[SOLVED -- mostly] Show last line of TMemo after text change

[willbprog9933]

Greetings everyone,

I have a TMemo that I'm using to show textual progress of a certain process.  Instead of using Append or Lines.Add I must use the following pattern:

Code: Pascal  [Select][+][-]

1. Memo1.Text := Memo1.Text + 'Deleting file...';
2.  
3. // processing happens here
4.  
5. If ProcessFailed = False Then
6.   Memo1.Text := Memo1.Text + 'Ok' + LineEnding
7. Else
8.   Memo1.Text := Memo1.Text + 'failed!' + LineEnding;
9.  
10. // scroll memo to bottom code here

I cannot use Append or Lines.Add in this scenario because I want the 'Ok' or 'failed' to be right after the 'Deleting file...'.  Unfortunately I cannot make the TMemo scroll to the bottom line after each line I add, no matter what I've tried.

I've tried other suggestions from the forums including using SetSelStart and SetSelLength, tried VertScrollBar.Position and SendMessage with EM_LINESCROLL and none of these scroll the TMemo to the last line.

Is there some technique I have not seen to accomplish this?

Thank you! 

[TRon]

I do not know about the scrolling (perhaps autoscroll ?) but why using memo.text := memo.text + 'whatever' ?

The memo has a lines property and that has a count member. With a little calculation (lines start with index 0) you can then directly access the last line in the memo, retrieve the text in that line, modify it to whatever your heart desire and store it back. As a bonus it is much quicker as well. In case it is not the last line in the memo but you do know where it is located then you can use the same technique (only using another index for the lines property).

[willbprog9933]

The memo has a lines property and that has a count member. With a little calculation (lines start with index 0) you can then directly access the last line in the memo, retrieve the text in that line, modify it to whatever your heart desire and store it back. As a bonus it is much quicker as well. In case it is not the last line in the memo but you do knw where it is located ten you can use the same technique (only using another index for the lines property).

Hi TRon,

That sounds like a good idea.  I will try it out and post my results.

Thanks!

[jamie]

Looks like you are not on Windows, that message won't work.

You can move the Scroll position of the Memo vertical scroll bar to the size.

That should show the last lines, same as if you were to scroll manually,.

[willbprog9933]

The memo has a lines property and that has a count member. With a little calculation (lines start with index 0) you can then directly access the last line in the memo, retrieve the text in that line, modify it to whatever your heart desire and store it back. As a bonus it is much quicker as well. In case it is not the last line in the memo but you do know where it is located then you can use the same technique (only using another index for the lines property).

I tried this and it does not behave the way I want.  I used Append for 'Deleting...' then went back and changed the last line in Memo1.Lines to include the 'Ok' or 'failed' part and it just acts as if I used Append with the 'Ok' or 'failed' text.

Thanks anyway! 

[willbprog9933]

Looks like you are not on Windows, that message won't work.

I am on Windows, but I would like this to be cross-platform as I use Linux mostly.

You can move the Scroll position of the Memo vertical scroll bar to the size.

That should show the last lines, same as if you were to scroll manually,.

This was one of the things I tried and it did not work.

What's frustrating is the carat never moves past the first character in the TMemo.  It never moves from there, not even for an instant.

[jamie]

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. begin
3.   memo1.VertScrollBar.Position := Memo1.VertScrollBar.Size;
4. end;                                                            
5.  

If that does not work, then there is a widget issue.
do that after each time you add something.

[jamie]

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button2Click(Sender: TObject);
2. begin
3.   If Memo1.Lines.Count > 50 Then Memo1.Lines.Delete(0);
4.   Memo1.Lines.Add(TimeToStr(Now));
5.   memo1.VertScrollBar.Position := Memo1.VertScrollBar.Size;
6. end;                                                
7.  

Another Test..

[willbprog9933]

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. begin
3.   memo1.VertScrollBar.Position := Memo1.VertScrollBar.Size;
4. end;                                                            
5.  

Thanks again, but it's not working.  I took your code verbatim and it's not scrolling or moving the carat at all.  I even tried the carat position proc and it didn't work either.  I guess I'll just have to try something else or track down the source for the TMemo and see how they scroll after an Append / Lines.Add.

Thanks again!

[TRon]

I tried this and it does not behave the way I want.  I used Append for 'Deleting...' then went back and changed the last line in Memo1.Lines to include the 'Ok' or 'failed' part and it just acts as if I used Append with the 'Ok' or 'failed' text.

Works for me ^tm

Code: Pascal  [Select][+][-]

1. procedure TForm1.Button1Click(Sender: TObject);
2. var
3.   n: integer;
4. begin
5.   // do stuff
6.   for n := 1 to 100 do
7.   begin
8.     Memo1.Lines.Add(n.ToString);
9.  
10.     {$IFDEF LINUX}
11.     // scroll down:
12.     Memo1.SelStart:=Length(Memo1.lines.Text);
13.     Memo1.VertScrollBar.Position:=1000000;
14.     {$ENDIF}
15.     application.ProcessMessages;
16.   end;
17.   n := Memo1.Lines.Add('This is waiting ...');
18.   {$IFDEF LINUX}
19.   // scroll down:
20.   Memo1.SelStart:=Length(Memo1.lines.Text);
21.   Memo1.VertScrollBar.Position:=1000000;
22.   {$ENDIF}
23.   application.ProcessMessages;
24.   sleep(6*1000);
25.   Memo1.Lines[n] := Memo1.Lines[n] + ' OK';
26. end;
27.  

@jamie: widgetset issue.autoscroll (caret visible at all times) works on Windows not on gtk2 (hence my ifdef)

[jamie]

What's this world coming to.

[willbprog9933]

What's this world coming to.

Sorry, guess I'll just deal with it.

(shrugs)

Thanks everyone anyway...

[willbprog9933]

Just to help future searchers...

I found TMemo.ScrollBy() and tried that, and, no, didn't work either.  The TMemo just refuses to be told how to scroll, I guess.  While doing further research, I stumbled on clarification of what TRon suggested.  TRon suggested using Append, then changing the last line in the TMemo.  It didn't work when I tried it, but then found that you have to access that last line using TMemo.Lines.Strings[index].  That worked! 

So, in shorthand code...

Code: Pascal  [Select][+][-]

1. Memo1.Append('Deleting file...');
2.  
3. // do processing here
4.  
5. If ProcessFailed = False Then
6.   Memo1.Lines.Strings[Memo1.Lines.Count - 1] := Memo1.Lines.Strings[Memo1.Lines.Count - 1] + 'Ok'
7. Else
8.   Memo1.Lines.Strings[Memo1.Lines.Count - 1] := Memo1.Lines.Strings[Memo1.Lines.Count - 1] + 'failed';

So, not the prettiest solution, but TRon had the right idea, and Append does scroll the TMemo properly.  I made the last line modification code into a separate procedure so I didn't have to type all of that out repeatedly everywhere its needed.

Thanks everyone!

[jamie]

BAC, are you multi-threading in your app?

EDIT

  I was just curious because it seems you have a lot of issues lately!

[willbprog9933]

BAC, are you multi-threading in your app?

EDIT

  I was just curious because it seems you have a lot of issues lately!

Was this directed at me?  Sorry, don't know what "BAC" means...

Thanks!