WPF 自定义ColorDialog DropDownCustomColorPicker

    /// <summary>
    /// 反射预定义颜色
    /// </summary>
    public class CustomColors
    {
        List<Color> selectableColors = null;

        public List<Color> SelectableColors
        {
            get { return selectableColors; }
            set { selectableColors = value; }
        }

        public CustomColors()
        {
            var list = new List<Color>();

            Type ColorsType = typeof(Colors);
            PropertyInfo[] ColorsProperty = ColorsType.GetProperties();

            foreach (PropertyInfo property in ColorsProperty)
            {
                list.Add((Color)ColorConverter.ConvertFromString(property.Name));
            }

            list.Sort(new Comparison<Color>((Color x, Color y) =>
            {
                var xtotal = x.R + x.G + x.B;

                var ytotal = y.R + y.G + y.B;

                return xtotal.CompareTo(ytotal); // 升序排列
            }));

            selectableColors = list;
        }

    }

        private Color GetColorFromImage(int i, int j)
        {
            CroppedBitmap cb = new CroppedBitmap(image.Source as BitmapSource,
                new Int32Rect(i,
                    j, 1, 1));
            byte[] color = new byte[4];
            cb.CopyPixels(color, 4, 0);
            Color Colorfromimagepoint = Color.FromArgb((byte)SdA.Value, color[2], color[1], color[0]);
            return Colorfromimagepoint;
        }