color.h

#ifndef COLOR_H
#define COLOR_H
 
#include <assert.h>
#include <stdint.h>
#include <stdbool.h>
#include <stddef.h>
 
#define RGB_MAX            (255U)
#define RGB_MAX_F32        (255.0f)
#define RGB_RANGE          (256U)
#define RGB_RANGE_F32      (256.0f)
 
#define HUE_MAX            (359U)
#define HUE_MAX_F32        (359.0f)
#define HUE_RANGE          (360U)
#define HUE_RANGE_F32      (360.0f)
#define HUE_FP_BITS        (6U)
#define HUE(x)             ((uint16_t)((x) << HUE_FP_BITS))
#define HUE_F32(x)         ((uint16_t)((x) * (float)(1 << HUE_FP_BITS)))
#define HUE_FP_TO_F32(x)   ((float)(x) / (float)(1 << HUE_FP_BITS))
 
#define SATURATION_MAX     (100U)
#define SATURATION_MAX_F32 (100.0f)
 
#define VALUE_MAX          (100U)
#define VALUE_MAX_F32      (100.0f)
 
#define LIGHTNESS_MAX      (100U)
#define LIGHTNESS_MAX_F32  (100.0f)
 
typedef enum e_color_space
{
    COLOR_SPACE_RGB,     
    COLOR_SPACE_HSV,     
    COLOR_SPACE_HSL,     
} color_space_t;
 
typedef struct st_color_rgb
{
    uint8_t blue;        
    uint8_t red;         
    uint8_t green;       
} color_rgb_t;
 
static_assert(offsetof(color_rgb_t, blue) == 0, "color_rgb_t layout must be B-R-G for ease of use converting to NeoPixel format.");
static_assert(offsetof(color_rgb_t, red) == 1, "color_rgb_t layout must be B-R-G for ease of use converting to NeoPixel format.");
static_assert(offsetof(color_rgb_t, green) == 2, "color_rgb_t layout must be B-R-G for ease of use converting to NeoPixel format.");
 
typedef struct st_color_hsv
{
    uint16_t hue;        
    uint8_t  saturation; 
    uint8_t  value;      
} color_hsv_t;
 
typedef struct st_color_hsl
{
    uint16_t hue;        
    uint8_t  saturation; 
    uint8_t  lightness;  
} color_hsl_t;
 
typedef union u_color_kind
{
    color_rgb_t rgb;
    color_hsv_t hsv;
    color_hsl_t hsl;
} color_kind_t;
 
typedef struct st_color
{
    /* !IMPORTANT! Keep this union at the top so color_t can be cast directly to color_kind_t. */
    union
    {
        color_rgb_t rgb;
        color_hsv_t hsv;
        color_hsl_t hsl;
    };
    color_space_t color_space;
} color_t;
 
static_assert(offsetof(color_t, rgb) == offsetof(color_kind_t, rgb), "The layout of color_kind_t must match that of color_t.");
static_assert(offsetof(color_t, hsv) == offsetof(color_kind_t, hsv), "The layout of color_kind_t must match that of color_t.");
static_assert(offsetof(color_t, hsl) == offsetof(color_kind_t, hsl), "The layout of color_kind_t must match that of color_t.");
static_assert(offsetof(color_t, rgb) == 0, "The color representations must be at the top of the color_t struct.");
 
extern const color_t color_red;
extern const color_t color_orange;
extern const color_t color_yellow;
extern const color_t color_neon;
extern const color_t color_green;
extern const color_t color_seafoam;
extern const color_t color_cyan;
extern const color_t color_lightblue;
extern const color_t color_blue;
extern const color_t color_purple;
extern const color_t color_magenta;
extern const color_t color_pink;
extern const color_t color_white;
extern const color_t color_black;
extern const color_t color_off;
 
void color_convert(color_space_t to, color_t const * p_in, color_t * p_out);
 
void color_convert2(color_space_t from, color_space_t to, color_kind_t const * p_in, color_kind_t * p_out);
 
bool color_parse(char * p_str, color_t * p_color_out);
 
void color_gamma_correct(color_rgb_t * p_in, color_rgb_t * p_out);
 
void color_gamma_build(float gamma);
 
#endif // COLOR_H