/*
![](https://raw.githubusercontent.com/zsviczian/obsidian-excalidraw-plugin/master/images/scripts-download-raw.jpg)

Download this file and save to your Obsidian Vault including the first line, or open it in "Raw" and copy the entire contents to Obsidian.

![](https://raw.githubusercontent.com/zsviczian/obsidian-excalidraw-plugin/master/images/darken-lighten-background-color.png)

This script lightens the background color of the selected element by 2% at a time. 

You can use this script several times until you are satisfied. It is recommended to set a shortcut key for this script so that you can quickly try to DARKEN and LIGHTEN the color effect.

In contrast to the `Modify background color opacity` script, the advantage is that the background color of the element is not affected by the canvas color, and the color value does not appear in a strange rgba() form.

The color conversion method was copied from [color-convert](https://github.com/Qix-/color-convert).

```javascript
*/

const elements = ea
  .getViewSelectedElements()
  .filter((el) =>
    ["rectangle", "ellipse", "diamond", "image", "line"].includes(el.type)
  );
ea.copyViewElementsToEAforEditing(elements);
for (const el of ea.getElements()) {
  const color = colorNameToHex(el.backgroundColor);
  const rgbColor = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(color);
  if (rgbColor) {
    const r = parseInt(rgbColor[1], 16);
    const g = parseInt(rgbColor[2], 16);
    const b = parseInt(rgbColor[3], 16);
    const originalRgb = [r, g, b];
    const hsl = rgbToHsl(originalRgb);
    const step = 2;
    const newLightness = hsl[2] + step;
    if (newLightness < 100) {
      hsl[2] = newLightness;
    }
    const newRgb = hslToRgb(hsl);
    el.backgroundColor = "#" + rgbToHexString(newRgb);
  }
}
await ea.addElementsToView(false, false);

function rgbToHexString(args) {
  const integer =
    ((Math.round(args[0]) & 0xff) << 16) +
    ((Math.round(args[1]) & 0xff) << 8) +
    (Math.round(args[2]) & 0xff);

  const string = integer.toString(16).toUpperCase();
  return "000000".substring(string.length) + string;
}

function hslToRgb(hsl) {
  const h = hsl[0] / 360;
  const s = hsl[1] / 100;
  const l = hsl[2] / 100;
  let t2;
  let t3;
  let val;

  if (s === 0) {
    val = l * 255;
    return [val, val, val];
  }

  if (l < 0.5) {
    t2 = l * (1 + s);
  } else {
    t2 = l + s - l * s;
  }

  const t1 = 2 * l - t2;

  const rgb = [0, 0, 0];
  for (let i = 0; i < 3; i++) {
    t3 = h + (1 / 3) * -(i - 1);
    if (t3 < 0) {
      t3++;
    }

    if (t3 > 1) {
      t3--;
    }

    if (6 * t3 < 1) {
      val = t1 + (t2 - t1) * 6 * t3;
    } else if (2 * t3 < 1) {
      val = t2;
    } else if (3 * t3 < 2) {
      val = t1 + (t2 - t1) * (2 / 3 - t3) * 6;
    } else {
      val = t1;
    }

    rgb[i] = val * 255;
  }

  return rgb;
}

function rgbToHsl(rgb) {
  const r = rgb[0] / 255;
  const g = rgb[1] / 255;
  const b = rgb[2] / 255;
  const min = Math.min(r, g, b);
  const max = Math.max(r, g, b);
  const delta = max - min;
  let h;
  let s;

  if (max === min) {
    h = 0;
  } else if (r === max) {
    h = (g - b) / delta;
  } else if (g === max) {
    h = 2 + (b - r) / delta;
  } else if (b === max) {
    h = 4 + (r - g) / delta;
  }

  h = Math.min(h * 60, 360);

  if (h < 0) {
    h += 360;
  }

  const l = (min + max) / 2;

  if (max === min) {
    s = 0;
  } else if (l <= 0.5) {
    s = delta / (max + min);
  } else {
    s = delta / (2 - max - min);
  }

  return [h, s * 100, l * 100];
}

function colorNameToHex(color) {
  const colors = {
    aliceblue: "#f0f8ff",
    antiquewhite: "#faebd7",
    aqua: "#00ffff",
    aquamarine: "#7fffd4",
    azure: "#f0ffff",
    beige: "#f5f5dc",
    bisque: "#ffe4c4",
    black: "#000000",
    blanchedalmond: "#ffebcd",
    blue: "#0000ff",
    blueviolet: "#8a2be2",
    brown: "#a52a2a",
    burlywood: "#deb887",
    cadetblue: "#5f9ea0",
    chartreuse: "#7fff00",
    chocolate: "#d2691e",
    coral: "#ff7f50",
    cornflowerblue: "#6495ed",
    cornsilk: "#fff8dc",
    crimson: "#dc143c",
    cyan: "#00ffff",
    darkblue: "#00008b",
    darkcyan: "#008b8b",
    darkgoldenrod: "#b8860b",
    darkgray: "#a9a9a9",
    darkgreen: "#006400",
    darkkhaki: "#bdb76b",
    darkmagenta: "#8b008b",
    darkolivegreen: "#556b2f",
    darkorange: "#ff8c00",
    darkorchid: "#9932cc",
    darkred: "#8b0000",
    darksalmon: "#e9967a",
    darkseagreen: "#8fbc8f",
    darkslateblue: "#483d8b",
    darkslategray: "#2f4f4f",
    darkturquoise: "#00ced1",
    darkviolet: "#9400d3",
    deeppink: "#ff1493",
    deepskyblue: "#00bfff",
    dimgray: "#696969",
    dodgerblue: "#1e90ff",
    firebrick: "#b22222",
    floralwhite: "#fffaf0",
    forestgreen: "#228b22",
    fuchsia: "#ff00ff",
    gainsboro: "#dcdcdc",
    ghostwhite: "#f8f8ff",
    gold: "#ffd700",
    goldenrod: "#daa520",
    gray: "#808080",
    green: "#008000",
    greenyellow: "#adff2f",
    honeydew: "#f0fff0",
    hotpink: "#ff69b4",
    "indianred ": "#cd5c5c",
    indigo: "#4b0082",
    ivory: "#fffff0",
    khaki: "#f0e68c",
    lavender: "#e6e6fa",
    lavenderblush: "#fff0f5",
    lawngreen: "#7cfc00",
    lemonchiffon: "#fffacd",
    lightblue: "#add8e6",
    lightcoral: "#f08080",
    lightcyan: "#e0ffff",
    lightgoldenrodyellow: "#fafad2",
    lightgrey: "#d3d3d3",
    lightgreen: "#90ee90",
    lightpink: "#ffb6c1",
    lightsalmon: "#ffa07a",
    lightseagreen: "#20b2aa",
    lightskyblue: "#87cefa",
    lightslategray: "#778899",
    lightsteelblue: "#b0c4de",
    lightyellow: "#ffffe0",
    lime: "#00ff00",
    limegreen: "#32cd32",
    linen: "#faf0e6",
    magenta: "#ff00ff",
    maroon: "#800000",
    mediumaquamarine: "#66cdaa",
    mediumblue: "#0000cd",
    mediumorchid: "#ba55d3",
    mediumpurple: "#9370d8",
    mediumseagreen: "#3cb371",
    mediumslateblue: "#7b68ee",
    mediumspringgreen: "#00fa9a",
    mediumturquoise: "#48d1cc",
    mediumvioletred: "#c71585",
    midnightblue: "#191970",
    mintcream: "#f5fffa",
    mistyrose: "#ffe4e1",
    moccasin: "#ffe4b5",
    navajowhite: "#ffdead",
    navy: "#000080",
    oldlace: "#fdf5e6",
    olive: "#808000",
    olivedrab: "#6b8e23",
    orange: "#ffa500",
    orangered: "#ff4500",
    orchid: "#da70d6",
    palegoldenrod: "#eee8aa",
    palegreen: "#98fb98",
    paleturquoise: "#afeeee",
    palevioletred: "#d87093",
    papayawhip: "#ffefd5",
    peachpuff: "#ffdab9",
    peru: "#cd853f",
    pink: "#ffc0cb",
    plum: "#dda0dd",
    powderblue: "#b0e0e6",
    purple: "#800080",
    rebeccapurple: "#663399",
    red: "#ff0000",
    rosybrown: "#bc8f8f",
    royalblue: "#4169e1",
    saddlebrown: "#8b4513",
    salmon: "#fa8072",
    sandybrown: "#f4a460",
    seagreen: "#2e8b57",
    seashell: "#fff5ee",
    sienna: "#a0522d",
    silver: "#c0c0c0",
    skyblue: "#87ceeb",
    slateblue: "#6a5acd",
    slategray: "#708090",
    snow: "#fffafa",
    springgreen: "#00ff7f",
    steelblue: "#4682b4",
    tan: "#d2b48c",
    teal: "#008080",
    thistle: "#d8bfd8",
    tomato: "#ff6347",
    turquoise: "#40e0d0",
    violet: "#ee82ee",
    wheat: "#f5deb3",
    white: "#ffffff",
    whitesmoke: "#f5f5f5",
    yellow: "#ffff00",
    yellowgreen: "#9acd32",
  };
  if (typeof colors[color.toLowerCase()] != "undefined")
    return colors[color.toLowerCase()];
  return color;
}