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