procedure TForm4.DrawVisor(_B_in: TBitmap; rect: trect); 
const
  MaxPixelCountA = MaxInt div SizeOf(TRGBQuad);
type
  PRGBAArray = ^TRGBAArray;
  TRGBAArray = array[0..MaxPixelCountA-1] of TRGBQuad;
var i,ii,ix,iy,CenterPointY,CenterPointX:integer;
     RowOut: PRGBAArray;
begin
_B_in.Canvas.Pen.Width:=1;
_B_in.Canvas.Pen.Color:=rgb(0,20,0);
CenterPointX:=rect.Left+((rect.Right-rect.Left) div 2);
CenterPointY:=rect.Top+((rect.Bottom-rect.Top) div 2);
ix:=CenterPointX-(CenterPointX div 24)*24;
iy:=CenterPointY-(CenterPointY div 24)*24;
for i:=rect.Top to rect.Bottom-1 do  begin
  RowOut:=_B_in.ScanLine[i];
  for ii:=rect.Left to rect.Right-1 do begin
   if ((ii=(ii div 24)*24+ix))or((i=(i div 24)*24+iy)) then begin
    RowOut[ii].rgbBlue:=trunc(RowOut[ii].rgbBlue*0.8);
    RowOut[ii].rgbGreen:=trunc(RowOut[ii].rgbGreen*0.8);
    RowOut[ii].rgbRed:=trunc(RowOut[ii].rgbRed*0.8);
   end;
  end;
end;
end;