[Lazarus] Event created by program logic rather than user action

[Dr Engelbert Buxbaum]

Hi,

I am writing a cellular automaton, that calculates a n by n array with
integer values, which represent colour values. The array is updated in
an infinite loop, that I want to also call the FormPaint method to
create a graphical representation of the automaton. Who is the sender
in this case? Or is there a better way to do this? 

Thanks for any help

Engelbert

unit CellularAutomaton;

{$mode objfpc}{$H+}

interface

uses
  Classes, SysUtils, FileUtil, Forms, Controls, Graphics, Dialogs, ExtCtrls,
  crt, LResources, BGRABitmap, BGRABitmapTypes;

type

  { TForm1 }

  TForm1 = class(TForm)
    procedure FormCreate(Sender: TObject);
    procedure FormPaint(Sender: TObject);
  private
    { private declarations }
  public
    { public declarations }
  end;

var
  Form1: TForm1;

implementation

{$R *.lfm}

var Image : TBGRABitmap;

// code of no relevance to the question goes here

{ TForm1 }

procedure TForm1.FormCreate(Sender: TObject);
begin
  Image := TBGRABitmap.Create(ScreenSize,ScreenSize,BGRABlack);
end;

procedure TForm1.FormPaint(Sender: TObject);
var p: PBGRAPixel;
    x,y: integer;
begin
  for y := 0 to Image.Height-1 do
    begin
      p := Image.Scanline[y];
      for x := 0 to Image.Width-1 do
        begin
          IntToRGB(NewScreen[succ(y),succ(x)],p^.red, p^.green, p^.blue);
          inc(p);
        end;
    end;
  Image.InvalidateBitmap;  //  direkt Pixels access
  Image.Draw(Canvas,0,0,True);
  Image.Free;
end;

begin
  Initialize(OldScreen);
  Initialize(NewScreen);
  repeat
    Calculate(OldScreen, NewScreen);
    CopyScreen(NewScreen, OldScreen);
    TForm1.FormPaint(????????);
  until keypressed;
end.