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/*
* Copyright (C) 2014 ~ 2018 Deepin Technology Co., Ltd.
*
* Author: jouyouyun <jouyouwen717@gmail.com>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
package graphic
import (
"math"
)
// Rgb2Hsv convert color format from RGB(r, g, b=[0..255]) to HSV(h=[0..360), s,v=[0..1]).
func Rgb2Hsv(r, g, b uint8) (h, s, v float64) {
fr := float64(r) / 255
fg := float64(g) / 255
fb := float64(b) / 255
max := math.Max(math.Max(fr, fg), fb)
min := math.Min(math.Min(fr, fg), fb)
d := max - min
if max == 0 {
s = 0
} else {
s = d / max
}
v = max
if max == min {
h = 0
} else {
switch max {
case fr:
if fg >= fb {
h = 60 * (fg - fb) / d
} else {
h = 60*(fg-fb)/d + 360
}
case fg:
h = 60*(fb-fr)/d + 120
case fb:
h = 60*(fr-fg)/d + 240
}
}
return
}
// Hsv2Rgb convert color format from HSV(h=[0..360), s,v=[0..1]) to RGB(r, g, b=[0..255]).
func Hsv2Rgb(h, s, v float64) (r, g, b uint8) {
var fr, fg, fb float64
hi := int(math.Floor(h/60)) % 6
f := h/60 - float64(hi)
p := v * (1 - s)
q := v * (1 - f*s)
t := v * (1 - (1-f)*s)
switch hi {
case 0:
fr, fg, fb = v, t, p
case 1:
fr, fg, fb = q, v, p
case 2:
fr, fg, fb = p, v, t
case 3:
fr, fg, fb = p, q, v
case 4:
fr, fg, fb = t, p, v
case 5:
fr, fg, fb = v, p, q
}
r = uint8((fr * 255) + 0.5)
g = uint8((fg * 255) + 0.5)
b = uint8((fb * 255) + 0.5)
return
}
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