Colors

The color module handles all color-related functions like changing color depth, creating colors from hex code, converting between color depths, mixing colors, etc.

lv_color_t is used to store a color, its fileds are set according to LV_COLOR_DEPTH in lv_conf.h. (See below)

You may set LV_COLOR_16_SWAP in lv_conf.h to swap the bytes of RGB565 colors. You may need this to send the 16-bit colors via a byte-oriented interface like SPI. As 16-bit numbers are stored in Little Endian format (lower byte on the lower address), the interface will send the lower byte first. However, displays usually need the higher byte first. A mismatch in the byte order will result in highly distorted colors.

Creating colors

RGB

Create colors from Red, Green and Blue channel values

//All channels are 0-255
lv_color_t c = lv_color_make(red, green, blue);

//From hex code 0x000000..0xFFFFFF interpreted as RED + GREEN + BLUE
lv_color_t c = lv_color_hex(0x123456); 

//From 3 digits. Same as lv_color_hex(0x112233)
lv_color_t c = lv_color_hex3(0x123);

HSV

Create colors from Hue, Saturation and Value values

//h = 0..359, s = 0..100, v = 0..100
lv_color_t c = lv_color_hsv_to_rgb(h, s, v);

//All channels are 0-255
lv_color_hsv_t c_hsv = lv_color_rgb_to_hsv(r, g, b);


//From lv_color_t variable
lv_color_hsv_t c_hsv = lv_color_to_hsv(color);

Palette

LVGL includes material design's palette. In this all color have a main as well as four darker and five lighter variants.

The names of the colors are as follows:

  • LV_PALETTE_RED

  • LV_PALETTE_PINK

  • LV_PALETTE_PURPLE

  • LV_PALETTE_DEEP_PURPLE

  • LV_PALETTE_INDIGO

  • LV_PALETTE_BLUE

  • LV_PALETTE_LIGHT_BLUE

  • LV_PALETTE_CYAN

  • LV_PALETTE_TEAL

  • LV_PALETTE_GREEN

  • LV_PALETTE_LIGHT_GREEN

  • LV_PALETTE_LIME

  • LV_PALETTE_YELLOW

  • LV_PALETTE_AMBER

  • LV_PALETTE_ORANGE

  • LV_PALETTE_DEEP_ORANGE

  • LV_PALETTE_BROWN

  • LV_PALETTE_BLUE_GREY

  • LV_PALETTE_GREY

To get the main color use lv_color_t c = lv_palette_main(LV_PALETTE_...).

For the lighter variants of a palette color use lv_color_t c = lv_palette_lighten(LV_PALETTE_..., v). v can be 1..5. For the darker variants of a palette color use lv_color_t c = lv_palette_darken(LV_PALETTE_..., v). v can be 1..4.

Modify and mix colors

The following functions can modify a color:

// Lighten a color. 0: no change, 255: white
lv_color_t c = lv_color_lighten(c, lvl);

// Darken a color. 0: no change, 255: black
lv_color_t c = lv_color_darken(lv_color_t c, lv_opa_t lvl);

// Lighten or darken a color. 0: black, 128: no change 255: black
lv_color_t c = lv_color_change_lightness(lv_color_t c, lv_opa_t lvl);


// Mix 2 colors with a given ratio 0: full c2, 255: full c1, 128: half c1 and half c2
lv_color_t c = lv_color_mix(c1, c2, ratio);

Built-in colors

lv_color_white() and lv_color_black() return 0xFFFFFF and 0x000000 respectively.

Opacity

To describe opacity the lv_opa_t type is created as a wrapper to uint8_t. Some defines are also introduced:

  • LV_OPA_TRANSP Value: 0, means the opacity makes the color completely transparent

  • LV_OPA_10 Value: 25, means the color covers only a little

  • LV_OPA_20 ... OPA_80 come logically

  • LV_OPA_90 Value: 229, means the color near completely covers

  • LV_OPA_COVER Value: 255, means the color completely covers

You can also use the LV_OPA_* defines in lv_color_mix() as a ratio.

Color types

The following variable types are defined by the color module:

  • lv_color1_t Monochrome color. Also has R, G, B fields for compatibility but they are always the same value (1 byte)

  • lv_color8_t A structure to store R (3 bit),G (3 bit),B (2 bit) components for 8-bit colors (1 byte)

  • lv_color16_t A structure to store R (5 bit),G (6 bit),B (5 bit) components for 16-bit colors (2 byte)

  • lv_color32_t A structure to store R (8 bit),G (8 bit), B (8 bit) components for 24-bit colors (4 byte)

  • lv_color_t Equal to lv_color1/8/16/24_t depending on current color depth setting

  • lv_color_int_t uint8_t, uint16_t or uint32_t depending on color depth setting. Used to build color arrays from plain numbers.

  • lv_opa_t A simple uint8_t type to describe opacity.

The lv_color_t, lv_color1_t, lv_color8_t, lv_color16_t and lv_color32_t types have four fields:

  • ch.red red channel

  • ch.green green channel

  • ch.blue blue channel

  • full* red + green + blue as one number

You can set the current color depth in lv_conf.h, by setting the LV_COLOR_DEPTH define to 1 (monochrome), 8, 16 or 32.

Convert color

You can convert a color from the current color depth to another. The converter functions return with a number, so you have to use the full field:

lv_color_t c;
c.red   = 0x38;
c.green = 0x70;
c.blue  = 0xCC;

lv_color1_t c1;
c1.full = lv_color_to1(c);	/*Return 1 for light colors, 0 for dark colors*/

lv_color8_t c8;
c8.full = lv_color_to8(c);	/*Give a 8 bit number with the converted color*/

lv_color16_t c16;
c16.full = lv_color_to16(c); /*Give a 16 bit number with the converted color*/

lv_color32_t c24;
c32.full = lv_color_to32(c);	/*Give a 32 bit number with the converted color*/

API

Typedefs

typedef lv_color_t (*lv_color_filter_cb_t)(const struct _lv_color_filter_dsc_t*, lv_color_t, lv_opa_t)
typedef struct _lv_color_filter_dsc_t lv_color_filter_dsc_t

Enums

enum [anonymous]

Opacity percentages.

Values:

enumerator LV_OPA_TRANSP
enumerator LV_OPA_0
enumerator LV_OPA_10
enumerator LV_OPA_20
enumerator LV_OPA_30
enumerator LV_OPA_40
enumerator LV_OPA_50
enumerator LV_OPA_60
enumerator LV_OPA_70
enumerator LV_OPA_80
enumerator LV_OPA_90
enumerator LV_OPA_100
enumerator LV_OPA_COVER
enum lv_palette_t

Values:

enumerator LV_PALETTE_RED
enumerator LV_PALETTE_PINK
enumerator LV_PALETTE_PURPLE
enumerator LV_PALETTE_DEEP_PURPLE
enumerator LV_PALETTE_INDIGO
enumerator LV_PALETTE_BLUE
enumerator LV_PALETTE_LIGHT_BLUE
enumerator LV_PALETTE_CYAN
enumerator LV_PALETTE_TEAL
enumerator LV_PALETTE_GREEN
enumerator LV_PALETTE_LIGHT_GREEN
enumerator LV_PALETTE_LIME
enumerator LV_PALETTE_YELLOW
enumerator LV_PALETTE_AMBER
enumerator LV_PALETTE_ORANGE
enumerator LV_PALETTE_DEEP_ORANGE
enumerator LV_PALETTE_BROWN
enumerator LV_PALETTE_BLUE_GREY
enumerator LV_PALETTE_GREY
enumerator _LV_PALETTE_LAST
enumerator LV_PALETTE_NONE

Functions

typedef LV_CONCAT3 (uint, LV_COLOR_SIZE, _t) lv_color_int_t
typedef LV_CONCAT3 (lv_color, LV_COLOR_DEPTH, _t) lv_color_t
static inline uint8_t lv_color_to1(lv_color_t color)
static inline uint8_t lv_color_to8(lv_color_t color)
static inline uint16_t lv_color_to16(lv_color_t color)
static inline uint32_t lv_color_to32(lv_color_t color)
static inline uint8_t lv_color_brightness(lv_color_t color)

Get the brightness of a color

Parameters

color -- a color

Returns

the brightness [0..255]

static inline lv_color_t lv_color_make(uint8_t r, uint8_t g, uint8_t b)
static inline lv_color_t lv_color_hex(uint32_t c)
static inline lv_color_t lv_color_hex3(uint32_t c)
static inline void lv_color_filter_dsc_init(lv_color_filter_dsc_t *dsc, lv_color_filter_cb_t cb)
lv_color_t lv_color_lighten(lv_color_t c, lv_opa_t lvl)
lv_color_t lv_color_darken(lv_color_t c, lv_opa_t lvl)
lv_color_t lv_color_change_lightness(lv_color_t c, lv_opa_t lvl)
lv_color_t lv_color_hsv_to_rgb(uint16_t h, uint8_t s, uint8_t v)

Convert a HSV color to RGB

Parameters

  • h -- hue [0..359]

  • s -- saturation [0..100]

  • v -- value [0..100]

Returns

the given RGB color in RGB (with LV_COLOR_DEPTH depth)

lv_color_hsv_t lv_color_rgb_to_hsv(uint8_t r8, uint8_t g8, uint8_t b8)

Convert a 32-bit RGB color to HSV

Parameters

  • r8 -- 8-bit red

  • g8 -- 8-bit green

  • b8 -- 8-bit blue

Returns

the given RGB color in HSV

lv_color_hsv_t lv_color_to_hsv(lv_color_t color)

Convert a color to HSV

Parameters

color -- color

Returns

the given color in HSV

static inline lv_color_t lv_color_chroma_key(void)

Just a wrapper around LV_COLOR_CHROMA_KEY because it might be more convenient to use a function is some cases

Returns

LV_COLOR_CHROMA_KEY

lv_color_t lv_palette_main(lv_palette_t p)
static inline lv_color_t lv_color_white(void)
static inline lv_color_t lv_color_black(void)
lv_color_t lv_palette_lighten(lv_palette_t p, uint8_t lvl)
lv_color_t lv_palette_darken(lv_palette_t p, uint8_t lvl)
union lv_color1_t

Public Members

uint8_t full
uint8_t blue
uint8_t green
uint8_t red
union lv_color1_t::[anonymous] ch
union lv_color8_t

Public Members

uint8_t blue
uint8_t green
uint8_t red
struct lv_color8_t::[anonymous] ch
uint8_t full
union lv_color16_t

Public Members

uint16_t blue
uint16_t green
uint16_t red
uint16_t green_h
uint16_t green_l
struct lv_color16_t::[anonymous] ch
uint16_t full
union lv_color32_t

Public Members

uint8_t blue
uint8_t green
uint8_t red
uint8_t alpha
struct lv_color32_t::[anonymous] ch
uint32_t full
struct lv_color_hsv_t

Public Members

uint16_t h
uint8_t s
uint8_t v
struct _lv_color_filter_dsc_t

Public Members

lv_color_filter_cb_t filter_cb
void *user_data