TTimer

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TTimer is component on the System tab of the Component Palette and delivers a timer with usually millisecond resolution. It inherits most of its properties from TCustomTimer. It is defined in the ExtCtrls unit.

Countdown calculation example

• Drop a label, shape and timer components on main form
• Doubleclick this Timer1 on the form (the default handler: OnTimer is created for Timer1, the source text editor opens).
• Add following source code in the event handler:

procedure TForm1.Timer1Timer(Sender: TObject);
begin
  Label1.Caption := Format('%d sec',[start]);
  Dec(start);
  if (start < 5) then Shape1.Brush.Color:=clYellow;
  if (start < 0) then begin
    Timer1.Enabled := False;
    Shape1.Brush.Color:=clGreen;
    Label1.Caption := 'Finished!';
  end;
end;

• Create the OnCreate event handler of Form1 (go in the Object Inspector to the event OnCreate and click the button [...]).
• Complete the source code as follows:

procedure TForm1.FormCreate(Sender: TObject);
begin
  Caption := 'Countdown calculation';
  Timer1.Interval := 1000;
  Timer1.Enabled := True;
  Label1.Caption := '';
  Shape1.Shape := stCircle;
  Shape1.Brush.Color:=clRed;
  start := 20;
end;

• In the source editor, entering class TForm1 in the section private.
• Add code start: integer;
• Start program (with Key F9)

Notes

• In order to restart the counter of the timer use the following code:

  Timer1.Enabled := False;
  Timer1.Enabled := True;

Each time the code is executed the timer shall start counting from the beginning without the OnTimer event being triggered.

See also

• TTimer doc
• TIdleTimer