palettes/CorePalette.java

/*
 * Copyright 2021 Google LLC
 *
 * 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.
 */

package com.google.ux.material.libmonet.palettes;

import static java.lang.Math.max;
import static java.lang.Math.min;

import com.google.ux.material.libmonet.hct.Hct;

/**
 * An intermediate concept between the key color for a UI theme, and a full color scheme. 5 sets of
 * tones are generated, all except one use the same hue as the key color, and all vary in chroma.
 */
public final class CorePalette {
  public TonalPalette a1;
  public TonalPalette a2;
  public TonalPalette a3;
  public TonalPalette n1;
  public TonalPalette n2;
  public TonalPalette error;

  /**
   * Create key tones from a color.
   *
   * @param argb ARGB representation of a color
   */
  public static CorePalette of(int argb) {
    return new CorePalette(argb, false);
  }

  /**
   * Create content key tones from a color.
   *
   * @param argb ARGB representation of a color
   */
  public static CorePalette contentOf(int argb) {
    return new CorePalette(argb, true);
  }

  private CorePalette(int argb, boolean isContent) {
    Hct hct = Hct.fromInt(argb);
    double hue = hct.getHue();
    double chroma = hct.getChroma();
    if (isContent) {
      this.a1 = TonalPalette.fromHueAndChroma(hue, chroma);
      this.a2 = TonalPalette.fromHueAndChroma(hue, chroma / 3.);
      this.a3 = TonalPalette.fromHueAndChroma(hue + 60., chroma / 2.);
      this.n1 = TonalPalette.fromHueAndChroma(hue, min(chroma / 12., 4.));
      this.n2 = TonalPalette.fromHueAndChroma(hue, min(chroma / 6., 8.));
    } else {
      this.a1 = TonalPalette.fromHueAndChroma(hue, max(48., chroma));
      this.a2 = TonalPalette.fromHueAndChroma(hue, 16.);
      this.a3 = TonalPalette.fromHueAndChroma(hue + 60., 24.);
      this.n1 = TonalPalette.fromHueAndChroma(hue, 4.);
      this.n2 = TonalPalette.fromHueAndChroma(hue, 8.);
    }
    this.error = TonalPalette.fromHueAndChroma(25, 84.);
  }
}