MathUtils.h revision 3b52c03f5035b833d365215420739aa840ac5080 
1/*
2 * Copyright (C) 2014 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#ifndef MATHUTILS_H
17#define MATHUTILS_H
18
19namespace android {
20namespace uirenderer {
21
22#define NON_ZERO_EPSILON (0.001f)
23#define ALPHA_EPSILON (0.001f)
24
25class MathUtils {
26public:
27    /**
28     * Check for floats that are close enough to zero.
29     */
30    inline static bool isZero(float value) {
31        return (value >= -NON_ZERO_EPSILON) && (value <= NON_ZERO_EPSILON);
32    }
33
34    inline static bool isPositive(float value) {
35        return value >= NON_ZERO_EPSILON;
36    }
37
38    inline static float clampAlpha(float alpha) {
39        if (alpha <= ALPHA_EPSILON) {
40            return 0;
41        } else if (alpha >= (1 - ALPHA_EPSILON)) {
42            return 1;
43        } else {
44            return alpha;
45        }
46    }
47
48    inline static bool areEqual(float valueA, float valueB) {
49        return isZero(valueA - valueB);
50    }
51
52    inline static int max(int a, int b) {
53        return a > b ? a : b;
54    }
55
56    inline static int min(int a, int b) {
57        return a < b ? a : b;
58    }
59
60    inline static float lerp(float v1, float v2, float t) {
61        return v1 + ((v2 - v1) * t);
62    }
63}; // class MathUtils
64
65} /* namespace uirenderer */
66} /* namespace android */
67
68#endif /* MATHUTILS_H */
69