A useful RGBA 8888 colour class.

color.c

// somewhere
const Color4b Color4b::White = Color4b(0xFF,0xFF,0xFF,0xFF);
const Color4b Color4b::Black = Color4b(0x00,0x00,0x00,0xFF);

color.h

#pragma once

class Color4b {
public:
    Color4b()
    : r(0xFF)
    , g(0x00)
    , b(0xFF)
    , a(0xFF)
    {}
    
    Color4b(uint8_t _r, uint8_t _g, uint8_t _b, uint8_t _a=0xFF)
    : r(_r)
    , g(_g)
    , b(_b)
    , a(_a)
    {}
    
    static Color4b fromHEX(const char* pszHex) {
        if (!pszHex || strlen(pszHex) != 6) {
            return Color4b();
        }
        const uint32_t num = strtoll(pszHex, NULL, 16);
        return Color4b(((num&0xFF0000)>>16), ((num&0x00FF00)>>8), (num&0x0000FF));
    }
    
    static Color4b fromHSV(float h, float s, float v) {
        const int hi = (int)(h / 60.0)%6;
        const float f =  h/60.0 - floor(h/60.0);
        const float p = v * (1.0 - s);
        const float q = v * (1.0 - (f*s));
        const float t = v * (1.0 - ((1.0 - f) * s));
        
        switch (hi) {
            case 0:
                return Color4b(v,t,p);
            case 1:
                return Color4b(q,v,p);
            case 2:
                return Color4b(p,v,t);
            case 3:
                return Color4b(p,q,v);
            case 4:
                return Color4b(t,p,v);
            case 5:
                return Color4b(v,p,q);
        }
        return Color4b();
    }
    
    inline uint8_t* v() { return &r; }
    uint8_t r,g,b,a;
    
    static const Color4b White;
    static const Color4b Black;
};