mr-excel/src/utils/color.ts

A versatile JavaScript library for effortlessly generating .xlsx files from input objects. Seamlessly create Excel spreadsheets with data, formatting, formulas, and more.

function removeSpace(str: string) {
  return str.replace(/ /g, "");
}
function extendHexValue(hex: string) {
  hex = hex.replace(/^#/, "");
  if (hex.length == 3) {
    const s0 = hex.charAt(0);
    const s1 = hex.charAt(1);
    const s2 = hex.charAt(2);
    return s0 + s0 + s1 + s1 + s2 + s2;
  } else {
    return hex;
  }
}
export function hexToRgbArray(hex: string): number[] {
  if (/^#?([a-f\d]{3})$/i.test(hex)) {
    hex = extendHexValue(hex);
  }
  var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  return result
    ? [
        parseInt(result[1], 16),
        parseInt(result[2], 16),
        parseInt(result[3], 16),
      ]
    : [0, 0, 0];
}
export function generateContrastTextColor(b: string) {
  const background = hexToRgbArray(b);
  if (background == null) {
    return;
  }
  // Calculate the perceived brightness (luminance) of the background color
  const bgLuminance =
    (0.299 * background[0] + 0.587 * background[1] + 0.114 * background[2]) /
    255;

  // Determine whether the text should be dark or light based on luminance
  const textColor = bgLuminance > 0.5 ? "rgb(0,0,0)" : "rgb(255,255,255)";

  return textColor;
}
export function hexToRgbNegative(hex: string) {
  // /(^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$)|(^#?([a-f\d]{3})$)/i;
  if (/^#?([a-f\d]{3})$/i.test(hex)) {
    hex = extendHexValue(hex);
  }
  var result = /^#?([a-f\d]{2})([a-f\d]{2})([a-f\d]{2})$/i.exec(hex);
  return result
    ? "rgb(" +
        (255 - parseInt(result[1], 16)) +
        "," +
        (255 - parseInt(result[2], 16)) +
        "," +
        (255 - parseInt(result[3], 16)) +
        ")"
    : "rgb(0,0,0)";
}

function valueToHex(c: number | string): string {
  c = Number(c);
  var hex = c.toString(16);
  return hex.length == 1 ? "0" + hex : hex;
}
export function rgbToHex(rgb: string): string | null {
  rgb = removeSpace(rgb);
  let spResult =
    rgb.indexOf("rgba") >= 0
      ? rgb.substring(5, rgb.length - 1).split(",")
      : rgb.substring(4, rgb.length - 1).split(",");
  let validate = spResult.reduce((r, c) => {
    return r && !Number.isNaN(Number(c));
  }, true);
  if (
    (spResult.length == 4 && spResult[3] == "0") ||
    (spResult.length != 3 && spResult.length != 4) ||
    !validate
  ) {
    return null;
  }
  return (
    valueToHex(spResult[0]) +
    valueToHex(spResult[1]) +
    valueToHex(spResult[2])
  ).toUpperCase();
}

export function convertToHex(
  fgConvertor: string | undefined,
  backend: boolean | undefined
) {
  if (typeof fgConvertor == "undefined" || fgConvertor === null) {
    return null;
  }
  if (!backend) {
    let noSpace = removeSpace(fgConvertor);
    if (
      noSpace.indexOf("var(") == 0 &&
      noSpace.lastIndexOf(")") == noSpace.length - 1
    ) {
      noSpace = noSpace.substring(4, noSpace.length - 1);
      fgConvertor = getComputedStyle(document.documentElement).getPropertyValue(
        noSpace
      );
    }
  }
  if (fgConvertor.indexOf("rgb") >= 0) {
    const rgb = rgbToHex(fgConvertor);
    fgConvertor = rgb ? rgb : "";
  }
  return fgConvertor.replace(/^#/, "");
}

export const exportedForTesting = {
  removeSpace,
  valueToHex,
  extendHexValue,
};