1/*
2 * Copyright (C) 2009 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 android.view.animation;
18
19import android.content.Context;
20import android.util.AttributeSet;
21
22import com.android.internal.view.animation.HasNativeInterpolator;
23import com.android.internal.view.animation.NativeInterpolatorFactory;
24import com.android.internal.view.animation.NativeInterpolatorFactoryHelper;
25
26/**
27 * An interpolator where the change bounces at the end.
28 */
29@HasNativeInterpolator
30public class BounceInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
31    public BounceInterpolator() {
32    }
33
34    @SuppressWarnings({"UnusedDeclaration"})
35    public BounceInterpolator(Context context, AttributeSet attrs) {
36    }
37
38    private static float bounce(float t) {
39        return t * t * 8.0f;
40    }
41
42    public float getInterpolation(float t) {
43        // _b(t) = t * t * 8
44        // bs(t) = _b(t) for t < 0.3535
45        // bs(t) = _b(t - 0.54719) + 0.7 for t < 0.7408
46        // bs(t) = _b(t - 0.8526) + 0.9 for t < 0.9644
47        // bs(t) = _b(t - 1.0435) + 0.95 for t <= 1.0
48        // b(t) = bs(t * 1.1226)
49        t *= 1.1226f;
50        if (t < 0.3535f) return bounce(t);
51        else if (t < 0.7408f) return bounce(t - 0.54719f) + 0.7f;
52        else if (t < 0.9644f) return bounce(t - 0.8526f) + 0.9f;
53        else return bounce(t - 1.0435f) + 0.95f;
54    }
55
56    /** @hide */
57    @Override
58    public long createNativeInterpolator() {
59        return NativeInterpolatorFactoryHelper.createBounceInterpolator();
60    }
61}