[Lazarus] How to fix slow screen refresh of TListbox?

[Salvatore Coppola]

Back to the first question. You can append your data with lb.items.text. 
Just prepare your data in a string like this: strtmp:=data1+lineending+data2+lineending+.....
And append lb.items.text:=lb.items.text+lineending+strtmp
Yes it is a workaround but do the trick like beginupdate
Ciao 

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Il giorno 11 Nov 2022, 16:29, alle ore 16:29, Bo Berglund via lazarus <lazarus at lists.lazarus-ide.org> ha scritto:
>I am using a TListbox component on a form for displaying debug data
>arriving
>over a serial line at 115200 baud.
>The data are a set of MQTT telegram texts which arrive in packets of
>about 40
>lines each time (once per 10 seconds).
>I add them to the listbox as follows:
>
>procedure THanSimulatorMain.OnRxData(Sender: TObject; const Data:
>TBytes);
>var
>  len, oldlen: integer;
>  DataTxt: AnsiString;
>begin
>  len := Length(Data); //Incoming packet
>  oldlen := Length(DataBuffer);
>  SetLength(DataBuffer, oldlen + len);
>  Move(Data[0], DataBuffer[oldlen], len);
>  SetLength(DataTxt, Length(DataBuffer));
>  Move(DataBuffer[0], DataTxt[1], Length(DataBuffer));
>  lbxRxData.Items.Text := DataTxt;  //Add the text to the list
>  lbxRxData.ItemIndex := lbxRxData.Items.Count -1; //To make it visible
>end;
>
>DataBuffer is a global TBytes container where the incoming data are
>stuffed as
>they arrive (it grows during the session).
>You see that the buffer contains the complete log history from the
>start...
>
>I have noticed that after a while the display becomes very sluggish
>when data
>arrives and I think that is due to the way the component operates.
>
>Now I wonder if there is some way to do as I did when I worked in
>Delphi with
>TListView objects, where I could use the BeginUpdate and EndUpdate
>calls to make
>all screen updates wait until it was all put in place.
>This was MUCH faster!
>
>But I can not find a BeginUpdate on the TListBox object, only
>BeginUpdateBounds,
>which does not tell me much....
>
>Any suggestions?
>
>
>-- 
>Bo Berglund
>Developer in Sweden
>
>-- 
>_______________________________________________
>lazarus mailing list
>lazarus at lists.lazarus-ide.org
>https://lists.lazarus-ide.org/listinfo/lazarus
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