AccelerateDecelerateInterpolator.java revision d422dc358f0100106dc07d7b903201eb9b043b11 
1/*
2 * Copyright (C) 2007 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 rate of change starts and ends slowly but
28 * accelerates through the middle.
29 */
30@HasNativeInterpolator
31public class AccelerateDecelerateInterpolator extends BaseInterpolator
32        implements NativeInterpolatorFactory {
33    public AccelerateDecelerateInterpolator() {
34    }
35
36    @SuppressWarnings({"UnusedDeclaration"})
37    public AccelerateDecelerateInterpolator(Context context, AttributeSet attrs) {
38    }
39
40    public float getInterpolation(float input) {
41        return (float)(Math.cos((input + 1) * Math.PI) / 2.0f) + 0.5f;
42    }
43
44    /** @hide */
45    @Override
46    public long createNativeInterpolator() {
47        return NativeInterpolatorFactoryHelper.createAccelerateDecelerateInterpolator();
48    }
49}
50