Initial QSfera import

Server/vendor/github.com/kovidgoyal/imaging/utils.go

@@ -0,0 +1,142 @@
+package imaging
+
+import (
+	"image"
+	"math"
+	"runtime"
+	"sync/atomic"
+
+	"github.com/kovidgoyal/go-parallel"
+)
+
+var max_procs atomic.Int64
+
+// SetMaxProcs limits the number of concurrent processing goroutines to the given value.
+// A value <= 0 clears the limit.
+func SetMaxProcs(value int) {
+	max_procs.Store(int64(value))
+}
+
+// Run the specified function in parallel over chunks from the specified range.
+// If the function panics, it is turned into a regular error.
+func run_in_parallel_over_range(num_procs int, f func(int, int), start, limit int) (err error) {
+	if num_procs <= 0 {
+		num_procs = runtime.GOMAXPROCS(0)
+		if mp := int(max_procs.Load()); mp > 0 {
+			num_procs = min(num_procs, mp)
+		}
+	}
+	return parallel.Run_in_parallel_over_range(num_procs, f, start, limit)
+}
+
+// absint returns the absolute value of i.
+func absint(i int) int {
+	if i < 0 {
+		return -i
+	}
+	return i
+}
+
+// clamp rounds and clamps float64 value to fit into uint8.
+func clamp(x float64) uint8 {
+	v := int64(x + 0.5)
+	if v > 255 {
+		return 255
+	}
+	if v > 0 {
+		return uint8(v)
+	}
+	return 0
+}
+
+func toNRGBA(img image.Image) *image.NRGBA {
+	if img, ok := img.(*image.NRGBA); ok {
+		return &image.NRGBA{
+			Pix:    img.Pix,
+			Stride: img.Stride,
+			Rect:   img.Rect.Sub(img.Rect.Min),
+		}
+	}
+	return Clone(img)
+}
+
+// rgbToHSL converts a color from RGB to HSL.
+func rgbToHSL(r, g, b uint8) (float64, float64, float64) {
+	rr := float64(r) / 255
+	gg := float64(g) / 255
+	bb := float64(b) / 255
+
+	max := math.Max(rr, math.Max(gg, bb))
+	min := math.Min(rr, math.Min(gg, bb))
+
+	l := (max + min) / 2
+
+	if max == min {
+		return 0, 0, l
+	}
+
+	var h, s float64
+	d := max - min
+	if l > 0.5 {
+		s = d / (2 - max - min)
+	} else {
+		s = d / (max + min)
+	}
+
+	switch max {
+	case rr:
+		h = (gg - bb) / d
+		if g < b {
+			h += 6
+		}
+	case gg:
+		h = (bb-rr)/d + 2
+	case bb:
+		h = (rr-gg)/d + 4
+	}
+	h /= 6
+
+	return h, s, l
+}
+
+// hslToRGB converts a color from HSL to RGB.
+func hslToRGB(h, s, l float64) (uint8, uint8, uint8) {
+	var r, g, b float64
+	if s == 0 {
+		v := clamp(l * 255)
+		return v, v, v
+	}
+
+	var q float64
+	if l < 0.5 {
+		q = l * (1 + s)
+	} else {
+		q = l + s - l*s
+	}
+	p := 2*l - q
+
+	r = hueToRGB(p, q, h+1/3.0)
+	g = hueToRGB(p, q, h)
+	b = hueToRGB(p, q, h-1/3.0)
+
+	return clamp(r * 255), clamp(g * 255), clamp(b * 255)
+}
+
+func hueToRGB(p, q, t float64) float64 {
+	if t < 0 {
+		t++
+	}
+	if t > 1 {
+		t--
+	}
+	if t < 1/6.0 {
+		return p + (q-p)*6*t
+	}
+	if t < 1/2.0 {
+		return q
+	}
+	if t < 2/3.0 {
+		return p + (q-p)*(2/3.0-t)*6
+	}
+	return p
+}