[andres1569]

procedure PegaImagenAjustada (BitmapFijo: TBitmap; FileName: String);
var
  ABitmap : TBitmap;
begin
  ABitmap := TBitmap.Create;
  try  
    ABitmap.LoadFromFile (FileName);
    with BitmapFijo do
      Canvas.StrechtDraw (Rect (0, 0, Width, Height), ABitmap);
  finally
    ABitmap.Free;
  end;
end;

NOTA: Se supone que BitmapFijo ya mide eso que tu quieres, 1122 x 794