antd/es/theme/util/getAlphaColor.js

An enterprise-class UI design language and React components implementation

import { FastColor } from '@ant-design/fast-color';
function isStableColor(color) {
  return color >= 0 && color <= 255;
}
function getAlphaColor(frontColor, backgroundColor) {
  const {
    r: fR,
    g: fG,
    b: fB,
    a: originAlpha
  } = new FastColor(frontColor).toRgb();
  if (originAlpha < 1) {
    return frontColor;
  }
  const {
    r: bR,
    g: bG,
    b: bB
  } = new FastColor(backgroundColor).toRgb();
  for (let fA = 0.01; fA <= 1; fA += 0.01) {
    const r = Math.round((fR - bR * (1 - fA)) / fA);
    const g = Math.round((fG - bG * (1 - fA)) / fA);
    const b = Math.round((fB - bB * (1 - fA)) / fA);
    if (isStableColor(r) && isStableColor(g) && isStableColor(b)) {
      return new FastColor({
        r,
        g,
        b,
        a: Math.round(fA * 100) / 100
      }).toRgbString();
    }
  }
  // fallback
  /* istanbul ignore next */
  return new FastColor({
    r: fR,
    g: fG,
    b: fB,
    a: 1
  }).toRgbString();
}
export default getAlphaColor;