vscode-theme-generator/src/color.ts

import { IColorSet, IBaseColorSet } from './interfaces';

function getRgb(color: string): [number, number, number] {
  return [
    parseInt(color.substr(1, 2), 16),
    parseInt(color.substr(3, 2), 16),
    parseInt(color.substr(5, 2), 16)
  ];
}

function toCssString(rgb: [number, number, number]): string {
  let result = '#';
  result += (rgb[0].toString(16).length === 1 ? '0' : '') + rgb[0].toString(16);
  result += (rgb[1].toString(16).length === 1 ? '0' : '') + rgb[1].toString(16);
  result += (rgb[2].toString(16).length === 1 ? '0' : '') + rgb[2].toString(16);
  return result;
}

export function lighten(color: string, amount: number): string {
  const MAX = 255;
  let r = parseInt(color.substr(1, 2), 16);
  let g = parseInt(color.substr(3, 2), 16);
  let b = parseInt(color.substr(5, 2), 16);
  r = Math.min(Math.floor(r + (r * amount)), MAX);
  g = Math.min(Math.floor(g + (g * amount)), MAX);
  b = Math.min(Math.floor(b + (b * amount)), MAX);
  return toCssString([r, g, b]);
}

export function darken(color: string, amount: number): string {
  return lighten(color, -amount);
}

export function addAlpha(color: string, alpha: number): string {
  if (color.length !== 7) {
    throw new Error('addAlpha only supports adding to #rrggbb format colors');
  }
  let alphaHex = Math.round(alpha * 255).toString(16);
  if (alphaHex.length === 1) {
    alphaHex = '0' + alphaHex;
  }
  return color + alphaHex;
}

export function contast(color: string): string {
  const rgb = getRgb(color);
  const luminance = rgb[0] * 0.299 + rgb[1] * 0.587 + rgb[2] * 0.114;
  return luminance > 192 ? '#000000' : '#ffffff';
}

export function generateFallbackColorSet(s: IBaseColorSet, type: 'light' | 'dark'): IColorSet {
  return {
    type,
    base: {
      background: null,
      foreground: null,
      color1: null,
      color2: null,
      color3: null,
      color4: null
    },
    syntax: {
      boolean: s.color1,
      function: s.color3,
      functionCall: s.color4,
      identifier: (type === 'light' ? darken : lighten)(s.color1, 0.5),
      keyword: s.color1,
      number: s.color4,
      storage: s.color1,
      string: s.color2,
      stringEscape: (type === 'light' ? darken : lighten)(s.color2, 0.5),
      comment: (type === 'light' ? darken : lighten)(s.background, 2.0),
      class: s.color3,
      classMember: s.color3,
      type: s.color3,
      modifier: null,
      cssClass: s.color1,
      cssId: s.color2,
      cssTag: s.color3,
      markdownQuote: null
    },
    ui: {
      cursor: null,
      invisibles: (type === 'light' ? darken : lighten)(s.background, 0.2),
      guide: (type === 'light' ? darken : lighten)(s.background, 0.2),
      lineHighlight: null,
      findMatchHighlight: null,
      currentFindMatchHighlight: null,
      findRangeHighlight: null,
      rangeHighlight: null,
      selectionHighlight: null,
      selection: null,
      wordHighlight: null,
      wordHighlightStrong: null,
      activeLinkForeground: null
    },
    terminal: {
      black: null,
      red: null,
      green: null,
      yellow: null,
      blue: null,
      magenta: null,
      cyan: null,
      white: null,
      brightBlack: null,
      brightRed: null,
      brightGreen: null,
      brightYellow: null,
      brightBlue: null,
      brightMagenta: null,
      brightCyan: null,
      brightWhite: null
    }
  };
}