File size: 2,872 Bytes
7aec436
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
// RGB <-> HSV conversion functions are based on https://github.com/LLK/scratch-vm/blob/develop/src/util/color.js

/**

 * @typedef RGB

 * @property {number} red red [0-255]

 * @property {number} green green [0-255]

 * @property {number} blue blue [0-255]

 */

/**

 * @typedef HSV

 * @property {number} hue hue [0-360)

 * @property {number} saturation saturation [0-1]

 * @property {number} value value [0-1]

 */

/**

 * @param {string} hex

 * @returns {RGB}

 */
 export const hexToRgb = (hex) => {
  const parsed = parseInt(hex.substring(1), 16);
  return {
    red: (parsed >> 16) & 0xff,
    green: (parsed >> 8) & 0xff,
    blue: parsed & 0xff
  };
};

/**

 * @param {RGB} color

 * @returns {string}

 */
export const rgbToHex = (color) => {
  const format = (n) => n.toString(16).padStart(2, '0');
  return `#${format(color.red)}${format(color.green)}${format(color.blue)}`;
};

/**

 * @param {RGB} color

 * @returns {HSV}

 */
export const rgbToHsv = (color) => {
  const r = color.red / 255;
  const g = color.green / 255;
  const b = color.blue / 255;

  const x = Math.min(Math.min(r, g), b);
  const v = Math.max(Math.max(r, g), b);

  // For grays, hue will be arbitrarily reported as zero. Otherwise, calculate
  let h = 0;
  let s = 0;
  if (x !== v) {
    const f = r === x ? g - b : g === x ? b - r : r - g;
    const i = r === x ? 3 : g === x ? 5 : 1;
    h = ((i - f / (v - x)) * 60) % 360;
    s = (v - x) / v;
  }

  return {
    hue: h,
    saturation: s,
    value: v
  };
};

/**

 * @param {HSV} color

 * @returns {RGB}

 */
export const hsvToRgb = (color) => {
  let h = color.hue % 360;
  if (h < 0) h += 360;

  const s = Math.max(0, Math.min(color.saturation, 1));
  const v = Math.max(0, Math.min(color.value, 1));

  const i = Math.floor(h / 60);
  const f = h / 60 - i;
  const p = v * (1 - s);
  const q = v * (1 - s * f);
  const t = v * (1 - s * (1 - f));

  let r;
  let g;
  let b;

  switch (i) {
    default:
    case 0:
      r = v;
      g = t;
      b = p;
      break;
    case 1:
      r = q;
      g = v;
      b = p;
      break;
    case 2:
      r = p;
      g = v;
      b = t;
      break;
    case 3:
      r = p;
      g = q;
      b = v;
      break;
    case 4:
      r = t;
      g = p;
      b = v;
      break;
    case 5:
      r = v;
      g = p;
      b = q;
      break;
  }

  return {
    red: Math.floor(r * 255),
    green: Math.floor(g * 255),
    blue: Math.floor(b * 255),
  };
};

/**

 * @param {string} hex

 * @returns {string}

 */
export const darken = (hex) => {
  const rgb = hexToRgb(hex);
  const hsv = rgbToHsv(rgb);

  // don't need to clamp value; hsvToRgb will do it for us
  hsv.value -= 0.1;

  const newRgb = hsvToRgb(hsv);
  return rgbToHex(newRgb);
};