redshift.go

package redshift

import (
	"github.com/jezek/xgb"
	"github.com/jezek/xgb/randr"
	"github.com/jezek/xgb/xproto"
)

// ColorRamp calculates the gamma ramp with the specified parameters. Use a
// value of 1 for the white values for the default ramp.
func ColorRamp[T ~uint8 | uint16 | ~uint32 | uint64, U ~float32 | ~float64](whiteR, whiteG, whiteB U, size int) (r, g, b []T) {
	var max T
	max--
	r = make([]T, size)
	g = make([]T, size)
	b = make([]T, size)
	for i := 0; i < size; i++ {
		r[i] = T(float64(i) / float64(size-1) * float64(max) * float64(whiteR))
		g[i] = T(float64(i) / float64(size-1) * float64(max) * float64(whiteG))
		b[i] = T(float64(i) / float64(size-1) * float64(max) * float64(whiteB))
	}
	return
}

// ColorRampX11 applies a color ramp to all CRTCs on the specified connection.
// The RandR extension must be initialized.
func ColorRampX11[U ~float32 | ~float64](conn *xgb.Conn, whiteR, whiteG, whiteB U) error {
	for _, root := range xproto.Setup(conn).Roots {
		resources, err := randr.GetScreenResourcesCurrent(conn, root.Root).Reply()
		if err != nil {
			return err
		}
		for _, crtc := range resources.Crtcs {
			gamma, err := randr.GetCrtcGammaSize(conn, crtc).Reply()
			if err != nil {
				return err
			}
			gr, gg, gb := ColorRamp[uint16](whiteR, whiteG, whiteB, int(gamma.Size))
			if err := randr.SetCrtcGammaChecked(conn, crtc, gamma.Size, gr, gg, gb).Check(); err != nil {
				return err
			}
		}
	}
	return nil
}

// WhitePoint gets the white point of the provided color temperature. If the
// temperature is out of range, the closest temperature is returned, and ok is
// set to false.
//
// https://github.com/jonls/redshift/blob/490ba2aae9cfee097a88b6e2be98aeb1ce990050/src/colorramp.c
func WhitePoint(temperature int) (r, g, b float32, ok bool) {
	var blackbody = [][3]float32{
		{1.00000000, 0.18172716, 0.00000000}, /* 1000K */
		{1.00000000, 0.25503671, 0.00000000}, /* 1100K */
		{1.00000000, 0.30942099, 0.00000000}, /* 1200K */
		{1.00000000, 0.35357379, 0.00000000}, /* ...   */
		{1.00000000, 0.39091524, 0.00000000},
		{1.00000000, 0.42322816, 0.00000000},
		{1.00000000, 0.45159884, 0.00000000},
		{1.00000000, 0.47675916, 0.00000000},
		{1.00000000, 0.49923747, 0.00000000},
		{1.00000000, 0.51943421, 0.00000000},
		{1.00000000, 0.54360078, 0.08679949},
		{1.00000000, 0.56618736, 0.14065513},
		{1.00000000, 0.58734976, 0.18362641},
		{1.00000000, 0.60724493, 0.22137978},
		{1.00000000, 0.62600248, 0.25591950},
		{1.00000000, 0.64373109, 0.28819679},
		{1.00000000, 0.66052319, 0.31873863},
		{1.00000000, 0.67645822, 0.34786758},
		{1.00000000, 0.69160518, 0.37579588},
		{1.00000000, 0.70602449, 0.40267128},
		{1.00000000, 0.71976951, 0.42860152},
		{1.00000000, 0.73288760, 0.45366838},
		{1.00000000, 0.74542112, 0.47793608},
		{1.00000000, 0.75740814, 0.50145662},
		{1.00000000, 0.76888303, 0.52427322},
		{1.00000000, 0.77987699, 0.54642268},
		{1.00000000, 0.79041843, 0.56793692},
		{1.00000000, 0.80053332, 0.58884417},
		{1.00000000, 0.81024551, 0.60916971},
		{1.00000000, 0.81957693, 0.62893653},
		{1.00000000, 0.82854786, 0.64816570},
		{1.00000000, 0.83717703, 0.66687674},
		{1.00000000, 0.84548188, 0.68508786},
		{1.00000000, 0.85347859, 0.70281616},
		{1.00000000, 0.86118227, 0.72007777},
		{1.00000000, 0.86860704, 0.73688797},
		{1.00000000, 0.87576611, 0.75326132},
		{1.00000000, 0.88267187, 0.76921169},
		{1.00000000, 0.88933596, 0.78475236},
		{1.00000000, 0.89576933, 0.79989606},
		{1.00000000, 0.90198230, 0.81465502},
		{1.00000000, 0.90963069, 0.82838210},
		{1.00000000, 0.91710889, 0.84190889},
		{1.00000000, 0.92441842, 0.85523742},
		{1.00000000, 0.93156127, 0.86836903},
		{1.00000000, 0.93853986, 0.88130458},
		{1.00000000, 0.94535695, 0.89404470},
		{1.00000000, 0.95201559, 0.90658983},
		{1.00000000, 0.95851906, 0.91894041},
		{1.00000000, 0.96487079, 0.93109690},
		{1.00000000, 0.97107439, 0.94305985},
		{1.00000000, 0.97713351, 0.95482993},
		{1.00000000, 0.98305189, 0.96640795},
		{1.00000000, 0.98883326, 0.97779486},
		{1.00000000, 0.99448139, 0.98899179},
		{1.00000000, 1.00000000, 1.00000000}, /* 6500K */
		{0.98947904, 0.99348723, 1.00000000},
		{0.97940448, 0.98722715, 1.00000000},
		{0.96975025, 0.98120637, 1.00000000},
		{0.96049223, 0.97541240, 1.00000000},
		{0.95160805, 0.96983355, 1.00000000},
		{0.94303638, 0.96443333, 1.00000000},
		{0.93480451, 0.95923080, 1.00000000},
		{0.92689056, 0.95421394, 1.00000000},
		{0.91927697, 0.94937330, 1.00000000},
		{0.91194747, 0.94470005, 1.00000000},
		{0.90488690, 0.94018594, 1.00000000},
		{0.89808115, 0.93582323, 1.00000000},
		{0.89151710, 0.93160469, 1.00000000},
		{0.88518247, 0.92752354, 1.00000000},
		{0.87906581, 0.92357340, 1.00000000},
		{0.87315640, 0.91974827, 1.00000000},
		{0.86744421, 0.91604254, 1.00000000},
		{0.86191983, 0.91245088, 1.00000000},
		{0.85657444, 0.90896831, 1.00000000},
		{0.85139976, 0.90559011, 1.00000000},
		{0.84638799, 0.90231183, 1.00000000},
		{0.84153180, 0.89912926, 1.00000000},
		{0.83682430, 0.89603843, 1.00000000},
		{0.83225897, 0.89303558, 1.00000000},
		{0.82782969, 0.89011714, 1.00000000},
		{0.82353066, 0.88727974, 1.00000000},
		{0.81935641, 0.88452017, 1.00000000},
		{0.81530175, 0.88183541, 1.00000000},
		{0.81136180, 0.87922257, 1.00000000},
		{0.80753191, 0.87667891, 1.00000000},
		{0.80380769, 0.87420182, 1.00000000},
		{0.80018497, 0.87178882, 1.00000000},
		{0.79665980, 0.86943756, 1.00000000},
		{0.79322843, 0.86714579, 1.00000000},
		{0.78988728, 0.86491137, 1.00000000}, /* 10000K */
		{0.78663296, 0.86273225, 1.00000000},
		{0.78346225, 0.86060650, 1.00000000},
		{0.78037207, 0.85853224, 1.00000000},
		{0.77735950, 0.85650771, 1.00000000},
		{0.77442176, 0.85453121, 1.00000000},
		{0.77155617, 0.85260112, 1.00000000},
		{0.76876022, 0.85071588, 1.00000000},
		{0.76603147, 0.84887402, 1.00000000},
		{0.76336762, 0.84707411, 1.00000000},
		{0.76076645, 0.84531479, 1.00000000},
		{0.75822586, 0.84359476, 1.00000000},
		{0.75574383, 0.84191277, 1.00000000},
		{0.75331843, 0.84026762, 1.00000000},
		{0.75094780, 0.83865816, 1.00000000},
		{0.74863017, 0.83708329, 1.00000000},
		{0.74636386, 0.83554194, 1.00000000},
		{0.74414722, 0.83403311, 1.00000000},
		{0.74197871, 0.83255582, 1.00000000},
		{0.73985682, 0.83110912, 1.00000000},
		{0.73778012, 0.82969211, 1.00000000},
		{0.73574723, 0.82830393, 1.00000000},
		{0.73375683, 0.82694373, 1.00000000},
		{0.73180765, 0.82561071, 1.00000000},
		{0.72989845, 0.82430410, 1.00000000},
		{0.72802807, 0.82302316, 1.00000000},
		{0.72619537, 0.82176715, 1.00000000},
		{0.72439927, 0.82053539, 1.00000000},
		{0.72263872, 0.81932722, 1.00000000},
		{0.72091270, 0.81814197, 1.00000000},
		{0.71922025, 0.81697905, 1.00000000},
		{0.71756043, 0.81583783, 1.00000000},
		{0.71593234, 0.81471775, 1.00000000},
		{0.71433510, 0.81361825, 1.00000000},
		{0.71276788, 0.81253878, 1.00000000},
		{0.71122987, 0.81147883, 1.00000000},
		{0.70972029, 0.81043789, 1.00000000},
		{0.70823838, 0.80941546, 1.00000000},
		{0.70678342, 0.80841109, 1.00000000},
		{0.70535469, 0.80742432, 1.00000000},
		{0.70395153, 0.80645469, 1.00000000},
		{0.70257327, 0.80550180, 1.00000000},
		{0.70121928, 0.80456522, 1.00000000},
		{0.69988894, 0.80364455, 1.00000000},
		{0.69858167, 0.80273941, 1.00000000},
		{0.69729688, 0.80184943, 1.00000000},
		{0.69603402, 0.80097423, 1.00000000},
		{0.69479255, 0.80011347, 1.00000000},
		{0.69357196, 0.79926681, 1.00000000},
		{0.69237173, 0.79843391, 1.00000000},
		{0.69119138, 0.79761446, 1.00000000}, /* 15000K */
		{0.69003044, 0.79680814, 1.00000000},
		{0.68888844, 0.79601466, 1.00000000},
		{0.68776494, 0.79523371, 1.00000000},
		{0.68665951, 0.79446502, 1.00000000},
		{0.68557173, 0.79370830, 1.00000000},
		{0.68450119, 0.79296330, 1.00000000},
		{0.68344751, 0.79222975, 1.00000000},
		{0.68241029, 0.79150740, 1.00000000},
		{0.68138918, 0.79079600, 1.00000000},
		{0.68038380, 0.79009531, 1.00000000},
		{0.67939381, 0.78940511, 1.00000000},
		{0.67841888, 0.78872517, 1.00000000},
		{0.67745866, 0.78805526, 1.00000000},
		{0.67651284, 0.78739518, 1.00000000},
		{0.67558112, 0.78674472, 1.00000000},
		{0.67466317, 0.78610368, 1.00000000},
		{0.67375872, 0.78547186, 1.00000000},
		{0.67286748, 0.78484907, 1.00000000},
		{0.67198916, 0.78423512, 1.00000000},
		{0.67112350, 0.78362984, 1.00000000},
		{0.67027024, 0.78303305, 1.00000000},
		{0.66942911, 0.78244457, 1.00000000},
		{0.66859988, 0.78186425, 1.00000000},
		{0.66778228, 0.78129191, 1.00000000},
		{0.66697610, 0.78072740, 1.00000000},
		{0.66618110, 0.78017057, 1.00000000},
		{0.66539706, 0.77962127, 1.00000000},
		{0.66462376, 0.77907934, 1.00000000},
		{0.66386098, 0.77854465, 1.00000000},
		{0.66310852, 0.77801705, 1.00000000},
		{0.66236618, 0.77749642, 1.00000000},
		{0.66163375, 0.77698261, 1.00000000},
		{0.66091106, 0.77647551, 1.00000000},
		{0.66019791, 0.77597498, 1.00000000},
		{0.65949412, 0.77548090, 1.00000000},
		{0.65879952, 0.77499315, 1.00000000},
		{0.65811392, 0.77451161, 1.00000000},
		{0.65743716, 0.77403618, 1.00000000},
		{0.65676908, 0.77356673, 1.00000000},
		{0.65610952, 0.77310316, 1.00000000},
		{0.65545831, 0.77264537, 1.00000000},
		{0.65481530, 0.77219324, 1.00000000},
		{0.65418036, 0.77174669, 1.00000000},
		{0.65355332, 0.77130560, 1.00000000},
		{0.65293404, 0.77086988, 1.00000000},
		{0.65232240, 0.77043944, 1.00000000},
		{0.65171824, 0.77001419, 1.00000000},
		{0.65112144, 0.76959404, 1.00000000},
		{0.65053187, 0.76917889, 1.00000000},
		{0.64994941, 0.76876866, 1.00000000}, /* 20000K */
		{0.64937392, 0.76836326, 1.00000000},
		{0.64880528, 0.76796263, 1.00000000},
		{0.64824339, 0.76756666, 1.00000000},
		{0.64768812, 0.76717529, 1.00000000},
		{0.64713935, 0.76678844, 1.00000000},
		{0.64659699, 0.76640603, 1.00000000},
		{0.64606092, 0.76602798, 1.00000000},
		{0.64553103, 0.76565424, 1.00000000},
		{0.64500722, 0.76528472, 1.00000000},
		{0.64448939, 0.76491935, 1.00000000},
		{0.64397745, 0.76455808, 1.00000000},
		{0.64347129, 0.76420082, 1.00000000},
		{0.64297081, 0.76384753, 1.00000000},
		{0.64247594, 0.76349813, 1.00000000},
		{0.64198657, 0.76315256, 1.00000000},
		{0.64150261, 0.76281076, 1.00000000},
		{0.64102399, 0.76247267, 1.00000000},
		{0.64055061, 0.76213824, 1.00000000},
		{0.64008239, 0.76180740, 1.00000000},
		{0.63961926, 0.76148010, 1.00000000},
		{0.63916112, 0.76115628, 1.00000000},
		{0.63870790, 0.76083590, 1.00000000},
		{0.63825953, 0.76051890, 1.00000000},
		{0.63781592, 0.76020522, 1.00000000},
		{0.63737701, 0.75989482, 1.00000000},
		{0.63694273, 0.75958764, 1.00000000},
		{0.63651299, 0.75928365, 1.00000000},
		{0.63608774, 0.75898278, 1.00000000},
		{0.63566691, 0.75868499, 1.00000000},
		{0.63525042, 0.75839025, 1.00000000},
		{0.63483822, 0.75809849, 1.00000000},
		{0.63443023, 0.75780969, 1.00000000},
		{0.63402641, 0.75752379, 1.00000000},
		{0.63362667, 0.75724075, 1.00000000},
		{0.63323097, 0.75696053, 1.00000000},
		{0.63283925, 0.75668310, 1.00000000},
		{0.63245144, 0.75640840, 1.00000000},
		{0.63206749, 0.75613641, 1.00000000},
		{0.63168735, 0.75586707, 1.00000000},
		{0.63131096, 0.75560036, 1.00000000},
		{0.63093826, 0.75533624, 1.00000000},
		{0.63056920, 0.75507467, 1.00000000},
		{0.63020374, 0.75481562, 1.00000000},
		{0.62984181, 0.75455904, 1.00000000},
		{0.62948337, 0.75430491, 1.00000000},
		{0.62912838, 0.75405319, 1.00000000},
		{0.62877678, 0.75380385, 1.00000000},
		{0.62842852, 0.75355685, 1.00000000},
		{0.62808356, 0.75331217, 1.00000000},
		{0.62774186, 0.75306977, 1.00000000}, /* 25000K */
		{0.62740336, 0.75282962, 1.00000000}, /* 25100K */
	}
	var (
		alpha = float32(temperature%100) / 100
		index = (temperature - 1000) / 100
	)
	switch {
	case index < 0:
		index = 0
	case index+1 >= len(blackbody):
		index = len(blackbody) - 2
	default:
		ok = true
	}
	r = (1-alpha)*blackbody[index][0] + alpha*blackbody[index+1][0]
	g = (1-alpha)*blackbody[index][1] + alpha*blackbody[index+1][1]
	b = (1-alpha)*blackbody[index][2] + alpha*blackbody[index+1][2]
	return
}