private void RenderColorPicker(double brightness)

        {

            bitmap = new WriteableBitmap(radius * 2 + 20, radius * 2 + 20, 96.0, 96.0, PixelFormats.Pbgra32, null);

            Utility.DrawingAllPixel(bitmap, (x, y) =>

            {

                RGBColor rgb = new RGBColor(255, 255, 255, 0);

                double H = 0;

                Vector vector = Point.Subtract(new Point(x, y), new Point(radius + 10, radius + 10));

                var angle = Math.Atan(vector.Y / vector.X) * 180 / Math.PI;

                if (vector.X < 0)

                {

                    H = 270 + angle;

                }

                else if (vector.X > 0)

                {

                    H = 90 + angle;

                }

                else

                {

                    if (vector.Y < 0)

                    {

                        H = 0;

                    }

                    else if (vector.Y > 0)

                    {

                        H = 180;

                    }

                    else

                    {

                        return new RGBColor(255, (int)(255 * brightness), (int)(255 * brightness), (int)(255 * brightness));

                    }

                }

                //计算饱和度

                double S;

                if (vector.Length >= radius)

                {

                    S = 1;

                }

                else

                {

                    S = vector.Length / radius;

                }

                //亮度值

                double B = brightness;

                return new HSBColor(H, S, B).RgbColor;

            });

            this.img.Source = bitmap;

        }

		/// <summary>

        /// 绘制所有像素

        /// </summary>

        /// <param name="bitmap"></param>

        /// <param name="action"></param>

        public static void DrawingAllPixel(WriteableBitmap bitmap, Func<int, int, RGBColor> func)

        {

            //跨距 ：针对跨距(stride)的计算，WritePixels()方法需要跨距。

            //从技术角度看，跨距是每行像素数据需要的字节数量。

            //可通过将每行中像素的数量乘上所使用格式的每像素位数(通常为4，如本例使用的Bgra32格式)

            //然后将所得结果除以8，进而将其从位数转换成字节数。

            int stride = bitmap.PixelWidth * bitmap.Format.BitsPerPixel / 8;

            for (int y = 0; y < bitmap.PixelHeight; y++)

            {

                for (int x = 0; x < bitmap.PixelWidth; x++)

                {

                    var rgb = func.Invoke(x, y);

                    byte[] colorData = new byte[4] { (byte)rgb.B, (byte)rgb.G, (byte)rgb.R, (byte)rgb.A };

                    bitmap.WritePixels(new Int32Rect(x, y, 1, 1), colorData, stride, 0);

                }

            }

        }