Bitmap: TBitmap;
procedure TForm1.FormCreate(Sender: TObject);
begin
  Bitmap := TBitmap.Create;
  Bitmap.LoadFromFile('C:\WINDOWS\cars.BMP');
end;
procedure TForm1.FormPaint(Sender: TObject);
var
  X, Y, W, H: LongInt;
begin
  with Bitmap do begin
    W := Width;
    H := Height;
  end;
  Y := 0;
  while Y < Height do begin
    X := 0;
    while X < Width do begin
      Canvas.Draw(X, Y, Bitmap);
      Inc(X, W);
    end;
    Inc(Y, H);
  end;
end;