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/*
* 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.Resources;
import android.content.res.Resources.Theme;
import android.content.res.TypedArray;
import android.util.AttributeSet;
import com.android.internal.R;
import com.android.internal.view.animation.HasNativeInterpolator;
import com.android.internal.view.animation.NativeInterpolatorFactory;
import com.android.internal.view.animation.NativeInterpolatorFactoryHelper;
/**
* An interpolator where the change starts backward then flings forward.
*/
@HasNativeInterpolator
public class AnticipateInterpolator extends BaseInterpolator implements NativeInterpolatorFactory {
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) {
this(context.getResources(), context.getTheme(), attrs);
}
/** @hide */
public AnticipateInterpolator(Resources res, Theme theme, AttributeSet attrs) {
TypedArray a;
if (theme != null) {
a = theme.obtainStyledAttributes(attrs, R.styleable.AnticipateInterpolator, 0, 0);
} else {
a = res.obtainAttributes(attrs, R.styleable.AnticipateInterpolator);
}
mTension = a.getFloat(R.styleable.AnticipateInterpolator_tension, 2.0f);
setChangingConfiguration(a.getChangingConfigurations());
a.recycle();
}
public float getInterpolation(float t) {
// a(t) = t * t * ((tension + 1) * t - tension)
return t * t * ((mTension + 1) * t - mTension);
}
/** @hide */
@Override
public long createNativeInterpolator() {
return NativeInterpolatorFactoryHelper.createAnticipateInterpolator(mTension);
}
}
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