颜色渐变

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JavaScript:

    function color2rgb(color) {        var r = parseInt(color.substr(1, 2), 16);        var g = parseInt(color.substr(3, 2), 16);        var b = parseInt(color.substr(5, 2), 16);        return new Array(r, g, b);    }    function rgb2color(rgb) {        var s = "#";        for (var i = 0; i < 3; i++) {            var c = Math.round(rgb[i]).toString(16);            if (c.length == 1)                c = '0' + c;            s += c;        }        return s.toUpperCase();    }    var ColorA = color2rgb("#69bf7b");    var ColorB = color2rgb("#f8696b");    function gradient(num) {        if (num > 40) {            return "#e33e24";        }        var Gradient = new Array();        for (var i = 0; i < 3; i++) {            Gradient[i] = ColorA[i] + (ColorB[i] - ColorA[i]) / 40 * num;        }        return rgb2color(Gradient);    }

c#:

    public class GradientColor    {        private double MaxLevel = 100;        private string ColorFrom = null;        private string ColorTo = null;        private int[] ColorA = null;        private int[] ColorB = null;        /// <summary>        /// Color Helper        /// </summary>        /// <param name="colorFrom">#000000 format</param>        /// <param name="colorTo">#000000 format</param>        /// <param name="maxLevel"></param>        public GradientColor(string colorFrom, string colorTo, double maxLevel)        {            if (string.IsNullOrEmpty(colorFrom)                || string.IsNullOrEmpty(colorTo)                || colorFrom.Length != 7                || colorTo.Length != 7                || maxLevel <= 0)            {                throw new Exception("Invalid parameter.");            }            this.MaxLevel = maxLevel;            this.ColorFrom = colorFrom;            this.ColorTo = colorTo;            ColorA = Color2rgb(colorFrom);            ColorB = Color2rgb(colorTo);        }        private int[] Color2rgb(string color)        {            var r = Convert.ToInt32(color.Substring(1, 2), 16);            var g = Convert.ToInt32(color.Substring(3, 2), 16);            var b = Convert.ToInt32(color.Substring(5, 2), 16);            return new int[] { r, g, b };        }        private string Rgb2color(double[] rgb)        {            var s = "";            for (int i = 0; i < rgb.Length; i++)            {                var c = Convert.ToString((int)Math.Round(rgb[i]), 16);                if (c.Length == 1)                {                    c = '0' + c;                }                s += c;            }            return s.ToUpper();        }        public string Gradient(double level)        {            if (level > MaxLevel)            {                return ColorTo;            }            var gradient = new double[3];            for (var i = 0; i < 3; i++)            {                gradient[i] = ColorA[i] + (ColorB[i] - ColorA[i]) / MaxLevel * level;            }            return Rgb2color(gradient);        }    }