ndg/docs/overview/color.md

# 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.

The type `lv_color_t` is used to store a color. Its fields 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 bytes of *RGB565* colors. You may need this when sending 16-bit colors via a byte-oriented interface like SPI. As 16-bit numbers are stored in little-endian format (lower byte at 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:
```c
//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:

```c
//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](https://vuetifyjs.com/en/styles/colors/#material-colors) of colors. In this system all named colors have a nominal main color 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:
```c
// 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: white
lv_color_t c = lv_color_change_lightness(lv_color_t c, lv_opa_t lvl);


// Mix two 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 from `uint8_t`. Some special purpose defines are also introduced:

- `LV_OPA_TRANSP` Value: 0, means no opacity making the color completely transparent
- `LV_OPA_10` Value: 25, means the color covers only a little
- `LV_OPA_20 ... OPA_80` follow logically
- `LV_OPA_90` Value: 229, means the color near completely covers
- `LV_OPA_COVER` Value: 255, means the color completely covers (full opacity)

You can also use the `LV_OPA_*` defines in `lv_color_mix()` as a mixing *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 the configured color depth setting
- `lv_color_int_t` `uint8_t`, `uint16_t` or `uint32_t` depending on the 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 to map a converted color back into a structure:

```c
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


```eval_rst

.. doxygenfile:: lv_color.h
  :project: lvgl

```