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78 lines
2.5 KiB
78 lines
2.5 KiB
/*
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* Copyright 2023 Google LLC
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.google.ux.material.libmonet.dynamiccolor;
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import androidx.annotation.NonNull;
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import com.google.ux.material.libmonet.utils.MathUtils;
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/**
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* A class containing the contrast curve for a dynamic color on its background.
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*
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* <p>The four values correspond to contrast requirements for contrast levels -1.0, 0.0, 0.5, and
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* 1.0, respectively.
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*/
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public final class ContrastCurve {
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/** Contrast requirement for contrast level -1.0 */
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private final double low;
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/** Contrast requirement for contrast level 0.0 */
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private final double normal;
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/** Contrast requirement for contrast level 0.5 */
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private final double medium;
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/** Contrast requirement for contrast level 1.0 */
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private final double high;
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/**
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* Creates a `ContrastCurve` object.
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*
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* @param low Contrast requirement for contrast level -1.0
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* @param normal Contrast requirement for contrast level 0.0
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* @param medium Contrast requirement for contrast level 0.5
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* @param high Contrast requirement for contrast level 1.0
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*/
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public ContrastCurve(double low, double normal, double medium, double high) {
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this.low = low;
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this.normal = normal;
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this.medium = medium;
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this.high = high;
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}
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/**
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* Returns the contrast ratio at a given contrast level.
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*
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* @param contrastLevel The contrast level. 0.0 is the default (normal); -1.0 is the lowest; 1.0
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* is the highest.
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* @return The contrast ratio, a number between 1.0 and 21.0.
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*/
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@NonNull
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public double getContrast(double contrastLevel) {
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if (contrastLevel <= -1.0) {
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return this.low;
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} else if (contrastLevel < 0.0) {
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return MathUtils.lerp(this.low, this.normal, (contrastLevel - -1) / 1);
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} else if (contrastLevel < 0.5) {
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return MathUtils.lerp(this.normal, this.medium, (contrastLevel - 0) / 0.5);
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} else if (contrastLevel < 1.0) {
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return MathUtils.lerp(this.medium, this.high, (contrastLevel - 0.5) / 0.5);
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} else {
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return this.high;
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}
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}
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}
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