gtsocial-umbx

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utils.go (2542B)

      1 package imaging
      2 
      3 import (
      4 	"image"
      5 	"math"
      6 	"runtime"
      7 	"sync"
      8 )
      9 
     10 // parallel processes the data in separate goroutines.
     11 func parallel(start, stop int, fn func(<-chan int)) {
     12 	count := stop - start
     13 	if count < 1 {
     14 		return
     15 	}
     16 
     17 	procs := runtime.GOMAXPROCS(0)
     18 	if procs > count {
     19 		procs = count
     20 	}
     21 
     22 	c := make(chan int, count)
     23 	for i := start; i < stop; i++ {
     24 		c <- i
     25 	}
     26 	close(c)
     27 
     28 	var wg sync.WaitGroup
     29 	for i := 0; i < procs; i++ {
     30 		wg.Add(1)
     31 		go func() {
     32 			defer wg.Done()
     33 			fn(c)
     34 		}()
     35 	}
     36 	wg.Wait()
     37 }
     38 
     39 // absint returns the absolute value of i.
     40 func absint(i int) int {
     41 	if i < 0 {
     42 		return -i
     43 	}
     44 	return i
     45 }
     46 
     47 // clamp rounds and clamps float64 value to fit into uint8.
     48 func clamp(x float64) uint8 {
     49 	v := int64(x + 0.5)
     50 	if v > 255 {
     51 		return 255
     52 	}
     53 	if v > 0 {
     54 		return uint8(v)
     55 	}
     56 	return 0
     57 }
     58 
     59 func reverse(pix []uint8) {
     60 	if len(pix) <= 4 {
     61 		return
     62 	}
     63 	i := 0
     64 	j := len(pix) - 4
     65 	for i < j {
     66 		pi := pix[i : i+4 : i+4]
     67 		pj := pix[j : j+4 : j+4]
     68 		pi[0], pj[0] = pj[0], pi[0]
     69 		pi[1], pj[1] = pj[1], pi[1]
     70 		pi[2], pj[2] = pj[2], pi[2]
     71 		pi[3], pj[3] = pj[3], pi[3]
     72 		i += 4
     73 		j -= 4
     74 	}
     75 }
     76 
     77 func toNRGBA(img image.Image) *image.NRGBA {
     78 	if img, ok := img.(*image.NRGBA); ok {
     79 		return &image.NRGBA{
     80 			Pix:    img.Pix,
     81 			Stride: img.Stride,
     82 			Rect:   img.Rect.Sub(img.Rect.Min),
     83 		}
     84 	}
     85 	return Clone(img)
     86 }
     87 
     88 // rgbToHSL converts a color from RGB to HSL.
     89 func rgbToHSL(r, g, b uint8) (float64, float64, float64) {
     90 	rr := float64(r) / 255
     91 	gg := float64(g) / 255
     92 	bb := float64(b) / 255
     93 
     94 	max := math.Max(rr, math.Max(gg, bb))
     95 	min := math.Min(rr, math.Min(gg, bb))
     96 
     97 	l := (max + min) / 2
     98 
     99 	if max == min {
    100 		return 0, 0, l
    101 	}
    102 
    103 	var h, s float64
    104 	d := max - min
    105 	if l > 0.5 {
    106 		s = d / (2 - max - min)
    107 	} else {
    108 		s = d / (max + min)
    109 	}
    110 
    111 	switch max {
    112 	case rr:
    113 		h = (gg - bb) / d
    114 		if g < b {
    115 			h += 6
    116 		}
    117 	case gg:
    118 		h = (bb-rr)/d + 2
    119 	case bb:
    120 		h = (rr-gg)/d + 4
    121 	}
    122 	h /= 6
    123 
    124 	return h, s, l
    125 }
    126 
    127 // hslToRGB converts a color from HSL to RGB.
    128 func hslToRGB(h, s, l float64) (uint8, uint8, uint8) {
    129 	var r, g, b float64
    130 	if s == 0 {
    131 		v := clamp(l * 255)
    132 		return v, v, v
    133 	}
    134 
    135 	var q float64
    136 	if l < 0.5 {
    137 		q = l * (1 + s)
    138 	} else {
    139 		q = l + s - l*s
    140 	}
    141 	p := 2*l - q
    142 
    143 	r = hueToRGB(p, q, h+1/3.0)
    144 	g = hueToRGB(p, q, h)
    145 	b = hueToRGB(p, q, h-1/3.0)
    146 
    147 	return clamp(r * 255), clamp(g * 255), clamp(b * 255)
    148 }
    149 
    150 func hueToRGB(p, q, t float64) float64 {
    151 	if t < 0 {
    152 		t++
    153 	}
    154 	if t > 1 {
    155 		t--
    156 	}
    157 	if t < 1/6.0 {
    158 		return p + (q-p)*6*t
    159 	}
    160 	if t < 1/2.0 {
    161 		return q
    162 	}
    163 	if t < 2/3.0 {
    164 		return p + (q-p)*(2/3.0-t)*6
    165 	}
    166 	return p
    167 }