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
17#include "Interpolator.h"
18
19#include <algorithm>
20
21#include <log/log.h>
22
23#include "utils/MathUtils.h"
24
25namespace android {
26namespace uirenderer {
27
28Interpolator* Interpolator::createDefaultInterpolator() {
29    return new AccelerateDecelerateInterpolator();
30}
31
32float AccelerateDecelerateInterpolator::interpolate(float input) {
33    return (float)(cosf((input + 1) * M_PI) / 2.0f) + 0.5f;
34}
35
36float AccelerateInterpolator::interpolate(float input) {
37    if (mFactor == 1.0f) {
38        return input * input;
39    } else {
40        return pow(input, mDoubleFactor);
41    }
42}
43
44float AnticipateInterpolator::interpolate(float t) {
45    return t * t * ((mTension + 1) * t - mTension);
46}
47
48static float a(float t, float s) {
49    return t * t * ((s + 1) * t - s);
50}
51
52static float o(float t, float s) {
53    return t * t * ((s + 1) * t + s);
54}
55
56float AnticipateOvershootInterpolator::interpolate(float t) {
57    if (t < 0.5f) return 0.5f * a(t * 2.0f, mTension);
58    else return 0.5f * (o(t * 2.0f - 2.0f, mTension) + 2.0f);
59}
60
61static float bounce(float t) {
62    return t * t * 8.0f;
63}
64
65float BounceInterpolator::interpolate(float t) {
66    t *= 1.1226f;
67    if (t < 0.3535f) return bounce(t);
68    else if (t < 0.7408f) return bounce(t - 0.54719f) + 0.7f;
69    else if (t < 0.9644f) return bounce(t - 0.8526f) + 0.9f;
70    else return bounce(t - 1.0435f) + 0.95f;
71}
72
73float CycleInterpolator::interpolate(float input) {
74    return sinf(2 * mCycles * M_PI * input);
75}
76
77float DecelerateInterpolator::interpolate(float input) {
78    float result;
79    if (mFactor == 1.0f) {
80        result = 1.0f - (1.0f - input) * (1.0f - input);
81    } else {
82        result = 1.0f - pow((1.0f - input), 2 * mFactor);
83    }
84    return result;
85}
86
87float OvershootInterpolator::interpolate(float t) {
88    t -= 1.0f;
89    return t * t * ((mTension + 1) * t + mTension) + 1.0f;
90}
91
92float PathInterpolator::interpolate(float t) {
93    if (t <= 0) {
94        return 0;
95    } else if (t >= 1) {
96        return 1;
97    }
98    // Do a binary search for the correct x to interpolate between.
99    size_t startIndex = 0;
100    size_t endIndex = mX.size() - 1;
101
102    while (endIndex > startIndex + 1) {
103        int midIndex = (startIndex + endIndex) / 2;
104        if (t < mX[midIndex]) {
105            endIndex = midIndex;
106        } else {
107            startIndex = midIndex;
108        }
109    }
110
111    float xRange = mX[endIndex] - mX[startIndex];
112    if (xRange == 0) {
113        return mY[startIndex];
114    }
115
116    float tInRange = t - mX[startIndex];
117    float fraction = tInRange / xRange;
118
119    float startY = mY[startIndex];
120    float endY = mY[endIndex];
121    return startY + (fraction * (endY - startY));
122
123}
124
125LUTInterpolator::LUTInterpolator(float* values, size_t size)
126    : mValues(values)
127    , mSize(size) {
128}
129
130LUTInterpolator::~LUTInterpolator() {
131}
132
133float LUTInterpolator::interpolate(float input) {
134    // lut position should only be at the end of the table when input is 1f.
135    float lutpos = input * (mSize - 1);
136    if (lutpos >= (mSize - 1)) {
137        return mValues[mSize - 1];
138    }
139
140    float ipart, weight;
141    weight = modff(lutpos, &ipart);
142
143    int i1 = (int) ipart;
144    int i2 = std::min(i1 + 1, (int) mSize - 1);
145
146    LOG_ALWAYS_FATAL_IF(i1 < 0 || i2 < 0, "negatives in interpolation!"
147            " i1=%d, i2=%d, input=%f, lutpos=%f, size=%zu, values=%p, ipart=%f, weight=%f",
148            i1, i2, input, lutpos, mSize, mValues.get(), ipart, weight);
149
150    float v1 = mValues[i1];
151    float v2 = mValues[i2];
152
153    return MathUtils::lerp(v1, v2, weight);
154}
155
156
157} /* namespace uirenderer */
158} /* namespace android */
159