delphi - Adding Characters one by one to TMemo

Question

Could any one tell me how can I add characters one by one from a text file to a Memo? The text file contains different paragraphs of texts. I want to add the characters of each paragraph one by one till the end of the paragraph. Then after 10 seconds delay the next paragraph to be shown in the Memo.

Thanks, Sei

Answer 1

You would probably use a TTimer. Drop a TTimer, a TMemo and a TButton on your form. Then do

var
  lines: TStringList;
  pos: TPoint;

const
  CHAR_INTERVAL = 75;
  PARAGRAPH_INTERVAL = 1000;

procedure TForm6.Button1Click(Sender: TObject);
const
  S_EMPTY_FILE = 'You are trying to display an empty file!';
begin
  Memo1.ReadOnly := true;
  Memo1.Clear;
  Memo1.Lines.Add('');
  pos := Point(0, 0);
  if lines.Count = 0 then
    raise Exception.Create(S_EMPTY_FILE);
  while (pos.Y < lines.Count) and (length(lines[pos.Y]) = 0) do inc(pos.Y);
  if pos.Y = lines.Count then
    raise Exception.Create(S_EMPTY_FILE);
  NextCharTimer.Enabled := true;
end;

procedure TForm6.FormCreate(Sender: TObject);
begin
  lines := TStringList.Create;
  lines.LoadFromFile('C:UsersAndreas RejbrandDesktopTest.txt');
end;

procedure TForm6.NextCharTimerTimer(Sender: TObject);
begin
  NextCharTimer.Interval := CHAR_INTERVAL;

  Memo1.Lines[Memo1.Lines.Count - 1] := Memo1.Lines[Memo1.Lines.Count - 1] + lines[pos.Y][pos.X + 1];
  inc(pos.X);

  if pos.X = length(lines[pos.Y]) then
  begin
    NextCharTimer.Interval := PARAGRAPH_INTERVAL;
    pos.X := 0;
    repeat
      inc(pos.Y);
      Memo1.Lines.Add('');
    until (pos.Y = lines.Count) or (length(lines[pos.Y]) > 0);
  end;

  if pos.Y = lines.Count then
    NextCharTimer.Enabled := false;
end;