Pinta.ImageManipulation.ColorBgra.BlendColorsWFP C# (CSharp) Method

        public static ColorBgra BlendColorsWFP(ColorBgra[] c, double[] w)
        {
            if (c.Length != w.Length)
            {
                throw new ArgumentException("c.Length != w.Length");
            }

            if (c.Length == 0)
            {
                return ColorBgra.FromUInt32(0);
            }

            double wsum = 0;
            double asum = 0;

            for (int i = 0; i < w.Length; ++i)
            {
                wsum += w[i];
                asum += (double)c[i].A * w[i];
            }

            double a = asum / wsum;
            double aMultWsum = a * wsum;

            double b;
            double g;
            double r;

            if (asum == 0)
            {
                b = 0;
                g = 0;
                r = 0;
            }
            else
            {
                b = 0;
                g = 0;
                r = 0;

                for (int i = 0; i < c.Length; ++i)
                {
                    b += (double)c[i].A * c[i].B * w[i];
                    g += (double)c[i].A * c[i].G * w[i];
                    r += (double)c[i].A * c[i].R * w[i];
                }

                b /= aMultWsum;
                g /= aMultWsum;
                r /= aMultWsum;
            }

            return ColorBgra.FromBgra((byte)b, (byte)g, (byte)r, (byte)a);
        }