SVGRadialGradientBrush.FixF C# (CSharp) Method

    private void FixF()
    {
        // TODO: Measure performance of comparing squared values instead of taking square root.
        if((float)Math.Sqrt((_fx - _cx) * (_fx - _cx)) + ((_fy - _cy) * (_fy - _cy)) > _r) {

          float dx = _fx - _cx;
          float dy = _fy - _cy;

          if(dx == 0)
        _fy = (_fy > _cy) ? (_cy + _r) : (_cy - _r);
          else {
        float a, b;
        a = dy / dx;
        b = _fy - a * _fx;

        double ta, tb, tc;

        ta = 1 + a * a;
        tb = 2 * (a * (b - _cy) - _cx);
        tc = (_cx * _cx) + (b - _cy) * (b - _cy) - (_r * _r);

        float delta = (float)((tb * tb) - 4 * ta * tc);

        delta = (float)Math.Sqrt(delta);
        float x1 = (float)((-tb + delta) / (2 * ta));
        float y1 = (float)(a * x1 + b);
        float x2 = (float)((-tb - delta) / (2 * ta));
        float y2 = (float)(a * x2 + b);

        if((_cx < x1) && (x1 < _fx)) {
          _fx = x1 - 1;
          _fy = y1;
        } else {
          _fx = x2 + 1;
          _fy = y2;
        }
          }
        }
    }