C# 自动调整颜色（加深、变亮）

    public static class Extensions
    {
        /// <summary>
        /// 调整颜色（加深、变亮）
        /// </summary>
        /// <param name="color">当前颜色</param>
        /// <param name="factor">调整因子，加深：value<0,   变亮：value>0,  -1.0f <= value <= 1.0f </param>
        /// <returns></returns>
        public static Color Add(this Color color, float factor)
        {
            float red = (float)color.R;
            float green = (float)color.G;
            float blue = (float)color.B;

            if (factor < 0)
            {
                factor = 1 + factor;
                red *= factor;
                green *= factor;
                blue *= factor;
            }
            else
            {
                red = (255 - red) * factor + red;
                green = (255 - green) * factor + green;
                blue = (255 - blue) * factor + blue;
            }

            if (red < 0) red = 0;
            if (red > 255) red = 255;
            if (green < 0) green = 0;
            if (green > 255) green = 255;
            if (blue < 0) blue = 0;
            if (blue > 255) blue = 255;

            return Color.FromArgb(color.A, (int)red, (int)green, (int)blue);
        }
    }

            var factor = -0.3f; //加深颜色
            btn_NewFlow.HighlightColor = theme.ThemeBackColor.Add(factor);

btn.HighlightColor = theme.ThemeBackColor.Add(0.8f);//颜色变浅