1/*
2 * Copyright (C) 2015 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License
15 */
16
17package com.android.systemui.classifier;
18
19public class Point {
20    public float x;
21    public float y;
22    public long timeOffsetNano;
23
24    public Point(float x, float y) {
25        this.x = x;
26        this.y = y;
27        this.timeOffsetNano = 0;
28    }
29
30    public Point(float x, float y, long timeOffsetNano) {
31        this.x = x;
32        this.y = y;
33        this.timeOffsetNano = timeOffsetNano;
34    }
35
36    public boolean equals(Point p) {
37        return x == p.x && y == p.y;
38    }
39
40    public float dist(Point a) {
41        return (float) Math.hypot(a.x - x, a.y - y);
42    }
43
44    /**
45     * Calculates the cross product of vec(this, a) and vec(this, b) where vec(x,y) is the
46     * vector from point x to point y
47     */
48    public float crossProduct(Point a, Point b) {
49        return (a.x - x) * (b.y - y) - (a.y - y) * (b.x - x);
50    }
51
52    /**
53     * Calculates the dot product of vec(this, a) and vec(this, b) where vec(x,y) is the
54     * vector from point x to point y
55     */
56    public float dotProduct(Point a, Point b) {
57        return (a.x - x) * (b.x - x) + (a.y - y) * (b.y - y);
58    }
59
60    /**
61     * Calculates the angle in radians created by points (a, this, b). If any two of these points
62     * are the same, the method will return 0.0f
63     *
64     * @return the angle in radians
65     */
66    public float getAngle(Point a, Point b) {
67        float dist1 = dist(a);
68        float dist2 = dist(b);
69
70        if (dist1 == 0.0f || dist2 == 0.0f) {
71            return 0.0f;
72        }
73
74        float crossProduct = crossProduct(a, b);
75        float dotProduct = dotProduct(a, b);
76        float cos = Math.min(1.0f, Math.max(-1.0f, dotProduct / dist1 / dist2));
77        float angle = (float) Math.acos(cos);
78        if (crossProduct < 0.0) {
79            angle = 2.0f * (float) Math.PI - angle;
80        }
81        return angle;
82    }
83}
84