android-34/com/android/systemui/monet/utils/MathUtils.java

/*
 * Copyright (C) 2023 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.
 */

package com.android.systemui.monet.utils;

/** Utility methods for mathematical operations. */
public class MathUtils {
    private MathUtils() {
    }

    /**
     * The signum function.
     *
     * @return 1 if num > 0, -1 if num < 0, and 0 if num = 0
     */
    public static int signum(double num) {
        if (num < 0) {
            return -1;
        } else if (num == 0) {
            return 0;
        } else {
            return 1;
        }
    }

    /**
     * The linear interpolation function.
     *
     * @return start if amount = 0 and stop if amount = 1
     */
    public static double lerp(double start, double stop, double amount) {
        return (1.0 - amount) * start + amount * stop;
    }

    /**
     * Clamps an integer between two integers.
     *
     * @return input when min <= input <= max, and either min or max otherwise.
     */
    public static int clampInt(int min, int max, int input) {
        if (input < min) {
            return min;
        } else if (input > max) {
            return max;
        }

        return input;
    }

    /**
     * Clamps an integer between two floating-point numbers.
     *
     * @return input when min <= input <= max, and either min or max otherwise.
     */
    public static double clampDouble(double min, double max, double input) {
        if (input < min) {
            return min;
        } else if (input > max) {
            return max;
        }

        return input;
    }

    /**
     * Sanitizes a degree measure as an integer.
     *
     * @return a degree measure between 0 (inclusive) and 360 (exclusive).
     */
    public static int sanitizeDegreesInt(int degrees) {
        degrees = degrees % 360;
        if (degrees < 0) {
            degrees = degrees + 360;
        }
        return degrees;
    }

    /**
     * Sanitizes a degree measure as a floating-point number.
     *
     * @return a degree measure between 0.0 (inclusive) and 360.0 (exclusive).
     */
    public static double sanitizeDegreesDouble(double degrees) {
        degrees = degrees % 360.0;
        if (degrees < 0) {
            degrees = degrees + 360.0;
        }
        return degrees;
    }

    /**
     * Sign of direction change needed to travel from one angle to another.
     *
     * <p>For angles that are 180 degrees apart from each other, both directions have the same
     * travel
     * distance, so either direction is shortest. The value 1.0 is returned in this case.
     *
     * @param from The angle travel starts from, in degrees.
     * @param to   The angle travel ends at, in degrees.
     * @return -1 if decreasing from leads to the shortest travel distance, 1 if increasing from
     * leads
     * to the shortest travel distance.
     */
    public static double rotationDirection(double from, double to) {
        double increasingDifference = sanitizeDegreesDouble(to - from);
        return increasingDifference <= 180.0 ? 1.0 : -1.0;
    }

    /** Distance of two points on a circle, represented using degrees. */
    public static double differenceDegrees(double a, double b) {
        return 180.0 - Math.abs(Math.abs(a - b) - 180.0);
    }

    /** Multiplies a 1x3 row vector with a 3x3 matrix. */
    public static double[] matrixMultiply(double[] row, double[][] matrix) {
        double a = row[0] * matrix[0][0] + row[1] * matrix[0][1] + row[2] * matrix[0][2];
        double b = row[0] * matrix[1][0] + row[1] * matrix[1][1] + row[2] * matrix[1][2];
        double c = row[0] * matrix[2][0] + row[1] * matrix[2][1] + row[2] * matrix[2][2];
        return new double[]{a, b, c};
    }
}