Движение шарика

// Подключаем графический модуль.
Uses GraphABC;
Const
  ww = 500;
  wh = 500;
  fw = 400;
  fh = 400;
  l = (ww - fw) shr 1;
  t = (wh - fh) shr 1;
  ball_r = Min(l, t) shr 1;
  ball_c = clCornflowerBlue;
  ball_s = 3;
Var
  x, y: Int64;  
Begin
  Window.Width := ww;
  Window.Height := wh;
  Pen.Color := ball_c;
  Brush.Color := ball_c;
  y := t + fh shr 1;
    For x := l + fw downto l + fw shr 1 do
      Begin
        LockDrawing;
        Window.Clear;
        Circle(x, y, ball_r);
        UnlockDrawing;
        Sleep(ball_s);
      End;
    For y := t + fh shr 1 downto t do
      Begin
        LockDrawing;
        Window.Clear;
        Circle(x, y, ball_r);
        UnlockDrawing;
        Sleep(ball_s);
      End;
    For y := t to t + fh shr 1 do
      Begin
        Dec(x);
        LockDrawing;
        Window.Clear;
        Circle(x, y, ball_r);
        UnlockDrawing;
        Sleep(ball_s);
      End; 
  x := l;
    For y := t + fh shr 1 to t + fh do
      Begin
        Inc(x);
        LockDrawing;
        Window.Clear;
        Circle(x, y, ball_r);
        UnlockDrawing;
        Sleep(ball_s);
      End; 
End.