Merge pull request #20 from branch geography-improvements

Author: isabellwaas

src/main/java/android_maps_utils_3_10_0/LatLng.java

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+package android_maps_utils_3_10_0;
+
+public record LatLng(double latitude, double longitude) {}

src/main/java/android_maps_utils_3_10_0/MathUtil.java

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+// This code is taken from the android-maps-utils 3.10.0 repository and its import statements have been adjusted.
+// The original repository from Google-Maven (maven.google.com) can't be used, because it requires Android.
+
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * 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 android_maps_utils_3_10_0;
+
+import static java.lang.Math.*;
+
+/**
+ * Utility functions that are used my both PolyUtil and SphericalUtil.
+ */
+class MathUtil {
+    /**
+     * The earth's radius, in meters.
+     * Mean radius as defined by IUGG.
+     */
+    static final double EARTH_RADIUS = 6371009;
+
+    /**
+     * Restrict x to the range [low, high].
+     */
+    static double clamp(double x, double low, double high) {
+        return x < low ? low : (x > high ? high : x);
+    }
+
+    /**
+     * Wraps the given value into the inclusive-exclusive interval between min and max.
+     *
+     * @param n   The value to wrap.
+     * @param min The minimum.
+     * @param max The maximum.
+     */
+    static double wrap(double n, double min, double max) {
+        return (n >= min && n < max) ? n : (mod(n - min, max - min) + min);
+    }
+
+    /**
+     * Returns the non-negative remainder of x / m.
+     *
+     * @param x The operand.
+     * @param m The modulus.
+     */
+    static double mod(double x, double m) {
+        return ((x % m) + m) % m;
+    }
+
+    /**
+     * Returns mercator Y corresponding to latitude.
+     * See http://en.wikipedia.org/wiki/Mercator_projection .
+     */
+    static double mercator(double lat) {
+        return log(tan(lat * 0.5 + PI / 4));
+    }
+
+    /**
+     * Returns latitude from mercator Y.
+     */
+    static double inverseMercator(double y) {
+        return 2 * atan(exp(y)) - PI / 2;
+    }
+
+    /**
+     * Returns haversine(angle-in-radians).
+     * hav(x) == (1 - cos(x)) / 2 == sin(x / 2)^2.
+     */
+    static double hav(double x) {
+        double sinHalf = sin(x * 0.5);
+        return sinHalf * sinHalf;
+    }
+
+    /**
+     * Computes inverse haversine. Has good numerical stability around 0.
+     * arcHav(x) == acos(1 - 2 * x) == 2 * asin(sqrt(x)).
+     * The argument must be in [0, 1], and the result is positive.
+     */
+    static double arcHav(double x) {
+        return 2 * asin(sqrt(x));
+    }
+
+    // Given h==hav(x), returns sin(abs(x)).
+    static double sinFromHav(double h) {
+        return 2 * sqrt(h * (1 - h));
+    }
+
+    // Returns hav(asin(x)).
+    static double havFromSin(double x) {
+        double x2 = x * x;
+        return x2 / (1 + sqrt(1 - x2)) * .5;
+    }
+
+    // Returns sin(arcHav(x) + arcHav(y)).
+    static double sinSumFromHav(double x, double y) {
+        double a = sqrt(x * (1 - x));
+        double b = sqrt(y * (1 - y));
+        return 2 * (a + b - 2 * (a * y + b * x));
+    }
+
+    /**
+     * Returns hav() of distance from (lat1, lng1) to (lat2, lng2) on the unit sphere.
+     */
+    static double havDistance(double lat1, double lat2, double dLng) {
+        return hav(lat1 - lat2) + hav(dLng) * cos(lat1) * cos(lat2);
+    }
+}