Title: Getting the number of visible lines on a TMemo
Question: How many lines are visible in my Memo component?
Answer:
Here's how to calculate the number of visible lines:
function LinesVisible(Memo: TMemo): integer;
Var
OldFont : HFont;
Hand : THandle;
TM : TTextMetric;
Rect : TRect;
tempint : integer;
begin
Hand := GetDC(Memo.Handle);
try
OldFont := SelectObject(Hand, Memo.Font.Handle);
try
GetTextMetrics(Hand, TM);
Memo.Perform(EM_GETRECT, 0, longint(@Rect));
tempint := (Rect.Bottom - Rect.Top) div
(TM.tmHeight + TM.tmExternalLeading);
finally
SelectObject(Hand, OldFont);
end;
finally
ReleaseDC(Memo.Handle, Hand);
end;
Result := tempint;
end;
Tested on W2K with delphi 4. Should be fine for other versions of windows and delphi.
Last edited 28 apr 2000. Cheers to Paul Klerlein for pointing out a problem.