| /* |
| * Copyright (C) 2009 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package android.view.animation; |
| |
| import android.content.Context; |
| import android.content.res.TypedArray; |
| import android.util.AttributeSet; |
| |
| /** |
| * An interpolator where the change starts backward then flings forward. |
| */ |
| public class AnticipateInterpolator implements Interpolator { |
| private final float mTension; |
| |
| public AnticipateInterpolator() { |
| mTension = 2.0f; |
| } |
| |
| /** |
| * @param tension Amount of anticipation. When tension equals 0.0f, there is |
| * no anticipation and the interpolator becomes a simple |
| * acceleration interpolator. |
| */ |
| public AnticipateInterpolator(float tension) { |
| mTension = tension; |
| } |
| |
| public AnticipateInterpolator(Context context, AttributeSet attrs) { |
| TypedArray a = context.obtainStyledAttributes(attrs, |
| com.android.internal.R.styleable.AnticipateInterpolator); |
| |
| mTension = |
| a.getFloat(com.android.internal.R.styleable.AnticipateInterpolator_tension, 2.0f); |
| |
| a.recycle(); |
| } |
| |
| public float getInterpolation(float t) { |
| // a(t) = t * t * ((tension + 1) * t - tension) |
| return t * t * ((mTension + 1) * t - mTension); |
| } |
| } |