ui/src/frontend/hsluv_cache.ts

// Copyright (C) 2022 The Android Open Source Project
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//      http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

import {hsluvToHex} from 'hsluv';

class HsluvCache {
  storage = new Map<number, string>();

  get(hue: number, saturation: number, lightness: number): string {
    const key = hue * 1e6 + saturation * 1e3 + lightness;
    const value = this.storage.get(key);

    if (value === undefined) {
      const computed = hsluvToHex([hue, saturation, lightness]);
      this.storage.set(key, computed);
      return computed;
    }

    return value;
  }
}

const cache = new HsluvCache();

export function cachedHsluvToHex(
    hue: number, saturation: number, lightness: number): string {
  return cache.get(hue, saturation, lightness);
}