procedure PolyPolygonForIE_Voids(aDC: HDC; aPtArr: PPoint; aPtCount: PInteger; aPlyCount: Integer; BrClr: TColor = 0; BrOp: Byte = 255; BmpBrush: Str255 = '');
{ Draw transparent polygons WITH voids using Windows PolyPolygon procedure & TIEBitmap AlphaChannel }
var
  TmpCnv: TCanvas;
  aBmp: TBitmap;
  ieBmp: TIEBitmap;

  DrawFormWidth, DrawFormHeight: Integer;

begin
  if (aPlyCount = 0) then Exit { Nothing to do }
  else if (aPtCount^ < 3) then Exit; { Not a valid polygon }

  { Create temporary canvas from Device Context }
  TmpCnv := TCanvas.Create;
  TmpCnv.Handle := aDC;
  DrawFormWidth := TmpCnv.ClipRect.Right;
  DrawFormHeight := TmpCnv.ClipRect.Top;

  { Create Bitmap for Alpha Channel (Mask) }
  aBmp := TBitmap.Create;
  aBmp.Canvas.Brush.Style := bsSolid;
  aBmp.Canvas.Brush.Color := clBlack; { Set color here before width / height }
  aBmp.Width := DrawFormWidth;
  aBmp.Height := DrawFormHeight;

  { Set brush color to grey value from user-defined opacity value }
  aBmp.Canvas.Brush.Color := RGB(BrOp, BrOp, BrOp);
  { Draw polygon with voids using Windows.PolyPolygon (Alpha Image) }
  PolyPolygon(aBmp.Canvas.Handle, aPtArr^, aPtCount^, aPlyCount);

  { Create 'ie' bitmap, same size as Device Context }
  ieBmp := TIEBitmap.Create(DrawFormWidth, DrawFormHeight, ie32RGB); { This method seems fastest }
  { Set compositing mode }
  ieBmp.IECanvas.SetCompositingMode(ieCompositingModeSourceOver, ieCompositingQualityDefault);

  { Assign Mask to ieBmp's Alpha Channel }
  ieBmp.AlphaChannel.Assign(aBmp);
  ieBmp.SyncAlphaChannel(True);

  { Set brush color to user-defined value }
  ieBmp.Canvas.Brush.Color := BrClr;
  { Draw polygon with voids using Windows.PolyPolygon (Source Image) }
  PolyPolygon(ieBmp.Canvas.Handle, aPtArr^, aPtCount^, aPlyCount);

  { Merge result onto our DrawForm canvas }
  ieBmp.DrawToCanvasWithAlpha(TmpCnv, 0, 0);

  aBmp.Free;
  ieBmp.Free;
  TmpCnv.Free;
end; { PolyPolygonForIE_Voids }