procedure DrawCircleW(Dst : TFastDIB; cx, cy, r, w : Single; c : DWord);
Var y, sy, ey, BytesPP, Alpha : Integer;
   xf, xf2, r2, r2Min, r2Max, y2 : Single;
   ca : TFColorA;

 procedure DrawPixRange(sx, ex, y : Integer);
 Var x, a, ia : Integer;
     sy, d, w2, aw, aw2 : Single;
     pc : PFColor;
 begin
 Num_InRange(sx, 0, Dst.Width-1); Num_InRange(ex, 0, Dst.Width-1);
 pc := Dst.Scanlines[y]; Inc(PByte(pc), sx * BytesPP);
 sy := Sqr(y - cy);
 aw := Alpha / w;
 w2 := (r2Max - r2Min) * 0.5; aw2 := Alpha / w2;
 For x:=sx to ex do begin

   d := Abs(Sqrt(Sqr(x - cx) + sy) - r);
   If (d < w) then begin
     ia := Round(d * aw);

{
   d := Abs( (Sqr(x - cx) + sy) - r2);
   If (d < w2) then begin
     ia := Round(d * aw2);
}
     a := 255 - ia;
     pc.b := (pc.b * ia + ca.b * a) shr 8;
     pc.g := (pc.g * ia + ca.g * a) shr 8;
     pc.r := (pc.r * ia + ca.r * a) shr 8;
   end;
   Inc(PByte(pc), BytesPP);
 end;
 end;

begin
w := w * 0.5;
BytesPP := Dst.Bpp shr 3;
ca := TFColorA(c);
Alpha := ca.a; If (Alpha = 0) then Alpha := $FF;

sy := Trunc(cy - r - w); Num_InRange(sy, 0, Dst.AbsHeight-1);
ey := Ceil(cy + r + w); Num_InRange(ey, 0, Dst.AbsHeight-1);

r2Min := Sqr(r - w); r2Max := Sqr(r + w);
r2 := r * r;

For y := sy to ey do begin
 y2 := Sqr(y-cy);
 If y2 <= r2Max then begin
   xf := Sqrt( r2Max - y2 );
   If y2 > r2Min then DrawPixRange(Trunc(cx-xf), Ceil(cx+xf), y) else begin
     xf2 := Sqrt( r2Min - y2 );
     DrawPixRange(Trunc(cx-xf), Ceil(cx-xf2), y);
     DrawPixRange(Trunc(cx+xf2), Ceil(cx+xf), y);
   end;
 end;
end;
end;

   If (d < w) then begin
     a := Alpha - Round(d * aw);
     ia := 255 - a;