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 
17 package com.android.systemui.classifier;
18 
19 public class Point {
20     public float x;
21     public float y;
22     public long timeOffsetNano;
23 
Point(float x, float y)24     public Point(float x, float y) {
25         this.x = x;
26         this.y = y;
27         this.timeOffsetNano = 0;
28     }
29 
Point(float x, float y, long timeOffsetNano)30     public Point(float x, float y, long timeOffsetNano) {
31         this.x = x;
32         this.y = y;
33         this.timeOffsetNano = timeOffsetNano;
34     }
35 
equals(Point p)36     public boolean equals(Point p) {
37         return x == p.x && y == p.y;
38     }
39 
dist(Point a)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      */
crossProduct(Point a, Point b)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      */
dotProduct(Point a, Point b)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      */
getAngle(Point a, Point b)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