概念

• RGB色彩模式

  • RGB色彩模式，即R：Red（红），G：Green(绿)，B：Blue(蓝)，3个颜色通道值的大小和层叠来得到各式各样的颜色。

• HSB色彩模式

  • HSB色彩模式，即色度、饱和度、亮度模式。它采用颜色的三属性来表色。H：hue，即色调（色度），S：saturation（饱和度），B：brightness明度（亮度）。
  • 其中，S和B，饱和度和亮度，值为百分比（0% ~ 100%）。而色度，以角度（0°-360°）来表示。

既然有了RGB，为何还需要HSB?

众所周知，人眼所能看见的颜色都可以通过三原色RGB混合获得，其每个颜色分量分别为红（R）、绿(G)、蓝（B）。然而这只是颜色一种表示方法，这种表示方法非常适合机器却非常的反人性。

转换工具类

/**
 * HSB和RGB颜色之间转换的工具类
 */
public class HSBColorUtil {
    private HSBColorUtil() {
    }

    /**
     * RGB转HSB
     *
     * @param r       RBG的R
     * @param g       RBG的G
     * @param b       RBG的B
     * @param hsbvals HSB 3个值存放到这个数组
     * @return 返回HSB数组
     */
    public static float[] RGBtoHSB(int r, int g, int b, float[] hsbvals) {
        float hue, saturation, brightness;
        if (hsbvals == null) {
            hsbvals = new float[3];
        }
        int cmax = (r > g) ? r : g;
        if (b > cmax) cmax = b;
        int cmin = (r < g) ? r : g;
        if (b < cmin) cmin = b;

        brightness = ((float) cmax) / 255.0f;
        if (cmax != 0)
            saturation = ((float) (cmax - cmin)) / ((float) cmax);
        else
            saturation = 0;
        if (saturation == 0)
            hue = 0;
        else {
            float redc = ((float) (cmax - r)) / ((float) (cmax - cmin));
            float greenc = ((float) (cmax - g)) / ((float) (cmax - cmin));
            float bluec = ((float) (cmax - b)) / ((float) (cmax - cmin));
            if (r == cmax)
                hue = bluec - greenc;
            else if (g == cmax)
                hue = 2.0f + redc - bluec;
            else
                hue = 4.0f + greenc - redc;
            hue = hue / 6.0f;
            if (hue < 0)
                hue = hue + 1.0f;
        }
        hsbvals[0] = hue;
        hsbvals[1] = saturation;
        hsbvals[2] = brightness;
        return hsbvals;
    }

    /**
     * HSB颜色值，转RGB
     *
     * @param hue        HSB的h，色调
     * @param saturation HSB的s，饱和度
     * @param brightness HSB的b，明度
     * @return 返回RGB值
     */
    public static int HSBtoRGB(float hue, float saturation, float brightness) {
        int r = 0, g = 0, b = 0;
        if (saturation == 0) {
            r = g = b = (int) (brightness * 255.0f + 0.5f);
        } else {
            float h = (hue - (float) Math.floor(hue)) * 6.0f;
            float f = h - (float) java.lang.Math.floor(h);
            float p = brightness * (1.0f - saturation);
            float q = brightness * (1.0f - saturation * f);
            float t = brightness * (1.0f - (saturation * (1.0f - f)));
            switch ((int) h) {
                case 0:
                    r = (int) (brightness * 255.0f + 0.5f);
                    g = (int) (t * 255.0f + 0.5f);
                    b = (int) (p * 255.0f + 0.5f);
                    break;
                case 1:
                    r = (int) (q * 255.0f + 0.5f);
                    g = (int) (brightness * 255.0f + 0.5f);
                    b = (int) (p * 255.0f + 0.5f);
                    break;
                case 2:
                    r = (int) (p * 255.0f + 0.5f);
                    g = (int) (brightness * 255.0f + 0.5f);
                    b = (int) (t * 255.0f + 0.5f);
                    break;
                case 3:
                    r = (int) (p * 255.0f + 0.5f);
                    g = (int) (q * 255.0f + 0.5f);
                    b = (int) (brightness * 255.0f + 0.5f);
                    break;
                case 4:
                    r = (int) (t * 255.0f + 0.5f);
                    g = (int) (p * 255.0f + 0.5f);
                    b = (int) (brightness * 255.0f + 0.5f);
                    break;
                case 5:
                    r = (int) (brightness * 255.0f + 0.5f);
                    g = (int) (p * 255.0f + 0.5f);
                    b = (int) (q * 255.0f + 0.5f);
                    break;
            }
        }
        return 0xff000000 | (r << 16) | (g << 8) | (b << 0);
    }
}

示例

• 字符串颜色值转RBG值

/**
 * 字符串颜色值转int颜色值
 */
private static int colorStr2Int(String colorStr) {
    try {
        return Color.parseColor(colorStr);
    } catch (Exception e) {
        e.printStackTrace();
        return 0;
    }
}

• RGB转HSB数组

/**
 * RGB颜色值转HSB颜色值，返回HSB颜色值的3个值数组
 */
private static float[] colorInt2HSB(int colorInt) {
    float[] hsbArr = new float[3];
    hsbArr = HSBColorUtil.RGBtoHSB(
            Color.red(colorInt),
            Color.green(colorInt),
            Color.blue(colorInt),
            hsbArr
    );
    return hsbArr;
}

• 将颜色值转HSB，并将B亮度乘以0.9（调暗），并转回RBG值

int themeColorInt = colorStr2Int("#314F62");
float[] hsbArr = colorInt2HSB(themeColorInt);

//色调
float hue = hsbArr[0];
//饱和度
float saturation = hsbArr[1];
//明度
float brightness = hsbArr[2];

//重点:对明度进行调整（调暗）
float newBrightness = (Math.round(brightness * 100f * 0.9f)) / 100f;

//把HSB转回RGB颜色返回
int result = HSBColorUtil.HSBtoRGB(hue, saturation, newBrightness);