Delphi scrolling Memo -

right have code.

procedure tform1.memo1change(sender : tobject); begin   sendmessage(informacje.handle, em_linescroll, 0, memo1.lines.count); end; 

the problem can't scroll memolines when new lines added. want stop moving cursor end on scroll up, start moving cursor end when scrollbar @ bottom. thank you help.
in others words. imagine there irc chat memo. new message, caret @ end of last message. want read previous messages usin scroll bar (up) cant cause there newer messages move carret bottom. want stop on mouse wheel up, read messages , after previous state (caret once again @ end on new message) when scroll bottom.

you need condition decide whether scroll bottom or not. below seems work simple test, sums top visible line number of possible lines memo can show find out if last line visible or not.

procedure tform1.memo1change(sender: tobject); var   linecount, topline: integer; begin   linecount := memo1.perform(em_getlinecount, 0, 0) - 1;   topline := memo1.perform(em_getfirstvisibleline, 0, 0);   if (topline + getvisiblelinecount(memo1)) >= linecount     sendmessage(memo1.handle, em_linescroll, 0, linecount); end; 

where

function getvisiblelinecount(memo: tmemo): integer; var   dc: hdc;   savefont: hfont;   textmetric: ttextmetric;   editrect: trect; begin   dc := getdc(0);   savefont := selectobject(dc, memo.font.handle);   gettextmetrics(dc, textmetric);   selectobject(dc, savefont);   releasedc(0, dc);    memo.perform(em_getrect, 0, lparam(@editrect));   result := (editrect.bottom - editrect.top) div textmetric.tmheight; end; 

(you can cache visible line count avoid having calculate every change in memo.)

you may need further tweak code though, f.i. case there less lines in memo can show. code not take caret position consideration.