Pinta.ImageManipulation.ColorBgra.this C# (CSharp) Метод

        public unsafe byte this[int channel]
        {
            get
            {
                if (channel < 0 || channel > 3)
                {
                    throw new ArgumentOutOfRangeException("channel", channel, "valid range is [0,3]");
                }

                fixed (byte *p = &B)
                {
                    return p[channel];
                }
            }

            set
            {
                if (channel < 0 || channel > 3)
                {
                    throw new ArgumentOutOfRangeException("channel", channel, "valid range is [0,3]");
                }

                fixed (byte *p = &B)
                {
                    p[channel] = value;
                }
            }
        }