BounceInterpolator.java revision 8b0662878eae69ab62e859b07165f086ea65cad5 
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.content.res.TypedArray;
21import android.util.AttributeSet;
22
23/**
24 * An interpolator where the change bounces at the end.
25 */
26public class BounceInterpolator implements Interpolator {
27    public BounceInterpolator() {
28    }
29
30    @SuppressWarnings({"UnusedDeclaration"})
31    public BounceInterpolator(Context context, AttributeSet attrs) {
32    }
33
34    private static float bounce(float t) {
35        return t * t * 8.0f;
36    }
37
38    public float getInterpolation(float t) {
39        // _b(t) = t * t * 8
40        // bs(t) = _b(t) for t < 0.3535
41        // bs(t) = _b(t - 0.54719) + 0.7 for t < 0.7408
42        // bs(t) = _b(t - 0.8526) + 0.9 for t < 0.9644
43        // bs(t) = _b(t - 1.0435) + 0.95 for t <= 1.0
44        // b(t) = bs(t * 1.1226)
45        t *= 1.1226f;
46        if (t < 0.3535f) return bounce(t);
47        else if (t < 0.7408f) return bounce(t - 0.54719f) + 0.7f;
48        else if (t < 0.9644f) return bounce(t - 0.8526f) + 0.9f;
49        else return bounce(t - 1.0435f) + 0.95f;
50    }
51}