Modify background color opacity.md

/*

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This script changes the opacity of the background color of the selected boxes.

The default background color in Excalidraw is so dark that the text is hard to read. You can lighten the color a bit by setting transparency. And you can tweak the transparency over and over again until you're happy with it.

Although excalidraw has the opacity option in its native property Settings, it also changes the transparency of the border. Use this script to change only the opacity of the background color without affecting the border.

*/
if(!ea.verifyMinimumPluginVersion || !ea.verifyMinimumPluginVersion("1.5.21")) {
  new Notice("This script requires a newer version of Excalidraw. Please install the latest version.");
  return;
}
settings = ea.getScriptSettings();
//set default values on first run
if(!settings["Default opacity"]) {
	settings = {
	  "Prompt for opacity?": true,
	  "Default opacity" : {
		value: 0.6,
		description: "Element's background color transparency"
	  },
	  "Remember last opacity?": false
	};
	ea.setScriptSettings(settings);
}

let opacityStr = settings["Default opacity"].value.toString();
const rememberLastOpacity = settings["Remember last opacity?"];

if(settings["Prompt for opacity?"]) {
    opacityStr = await utils.inputPrompt("Background color opacity?","number",opacityStr);
}

const alpha = parseFloat(opacityStr);
if(isNaN(alpha)) {
  return;
}
if(rememberLastOpacity) {
	settings["Default opacity"].value = alpha;
	ea.setScriptSettings(settings);
}
const elements=ea.getViewSelectedElements().filter((el)=>["rectangle","ellipse","diamond","line","image"].includes(el.type));
ea.copyViewElementsToEAforEditing(elements);
ea.getElements().forEach((el)=>{
	const color = colorNameToHex(el.backgroundColor);
    const rgbColor = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(color);
    if(rgbColor) {
        const r = parseInt(rgbColor[1], 16);
        const g = parseInt(rgbColor[2], 16);
        const b = parseInt(rgbColor[3], 16);
        el.backgroundColor=`rgba(${r},${g},${b},${alpha})`;
    }
    else {
        const rgbaColor = /^rgba\((\d+,\d+,\d+,)(\d*\.?\d*)\)$/i.exec(color);
        if(rgbaColor) {
            el.backgroundColor=`rgba(${rgbaColor[1]}${alpha})`;
        }
    }
});
await ea.addElementsToView(false, false);

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;
}