Color representations and operations for NeoPixelBus.

The intention (of the author, me, Jack Jansen) is that Makuna will incorporate this into NeoPixelBus. License is LGPL.

Note: As of this writing the xxxFColor objects mimic the NeoPixelBus xxxColor objects, but this is open to change. Maybe the interpolation functions and such are useless and need to go. Also, HslFColor is included because I have a slight preference for HSL over HSB/HSV, but it can go.

For all color representation objects I have tried to follow the API of NeoPixelBus as much as possible, with all uint8_t parameters replaced by float. This does have one significant drawback: if someone inadvertantly passes an uint8_t value it will result in pretty bright colors...

RgbFColor represents an RGB color as three floating point numbers between 0.0 and 1.0. It can be casted to and from RgbColor.

RgbwFColor represents an RGBW color as four floating point numbers between 0.0 and 1.0. It can be casted to and from RgbwColor.

HslFColor represents a Hue, Saturation, Lightness color as 3 floats. The difference between HSL and HSV/HSB is that HSL has the 100% saturated colors at L=0.5, with L=1.0 being maximum light. HSV/HSB have 100% saturated colors at V=1.0, meaning that the total amount of light is dependent not only on L (or V or B) but also on the Hue and Saturation. HSL is more suitable for lighting applications.

TemperatureFColor represents a color as two floating point numbers WTemperature (the black body temperature, usually between 2500 and 7000) and WBrightness, a value between 0.0 and 1.0. It can be casted to RgbFColor and RgbColor (but not the reverse). This conversion assumes that the white point of the RGB values is at 6500K (also known as D65).

Colorspace represents an RGBW colorspace, and is used to convert xxxFColor objects to either RgbColor or RgbwColor for sending to the LED strip.

In the constructor you provide:

• the temperature of the White LED (usually 3000 for Warm, 4000 for Neutral and 5000 for Cool, but check the specifications of your LED strip)
• the relative power of your White LED (default of 1.0 means the White LED has the same number of Lumen as the R, G and B LEDs combined. Again, check the specifications of your strip),
• whether you want the conversion to maintain the hue as much as possible, or whether you prefer to maintain the brightness as much as possible,
• whether you want to gamma-correct the RGB and RGBW values (you proabbly should).

An RgbwSpace object has a numnber of methods:

• toRgbw() converts any of the xxxFColor objects to RgbwColor
• toRgb() converts any of the xxxFColor objects to RgbColor (for use with RGB strips)
• a convert(from, to) method with various signatures to convert in-place with as little copying as possible.

There are two examples:

• whitecalibrate is actually more of a utility than an example: it allows you to determine the relative power of your white LED and its color temperature by flashing white color with first only RGB leds and then only White leds.
• ledstripserver is a web server that allows interactive changing of colors of a LED strip (or scripted changing through use of curl or similar programs). It should be runnable on an esp32 or esp8266 and with a bit of work maybe also on Arduino hardware with a WiFi card.