79 lines
2.6 KiB
Java
79 lines
2.6 KiB
Java
/*
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* Copyright (C) 2009 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package android.view.animation;
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import android.content.Context;
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import android.content.res.Resources;
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import android.content.res.Resources.Theme;
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import android.content.res.TypedArray;
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import android.graphics.animation.HasNativeInterpolator;
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import android.graphics.animation.NativeInterpolator;
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import android.graphics.animation.NativeInterpolatorFactory;
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import android.util.AttributeSet;
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import com.android.internal.R;
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/**
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* An interpolator where the change starts backward then flings forward.
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*/
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@HasNativeInterpolator
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public class AnticipateInterpolator extends BaseInterpolator implements NativeInterpolator {
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private final float mTension;
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public AnticipateInterpolator() {
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mTension = 2.0f;
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}
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/**
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* @param tension Amount of anticipation. When tension equals 0.0f, there is
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* no anticipation and the interpolator becomes a simple
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* acceleration interpolator.
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*/
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public AnticipateInterpolator(float tension) {
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mTension = tension;
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}
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public AnticipateInterpolator(Context context, AttributeSet attrs) {
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this(context.getResources(), context.getTheme(), attrs);
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}
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/** @hide */
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public AnticipateInterpolator(Resources res, Theme theme, AttributeSet attrs) {
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TypedArray a;
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if (theme != null) {
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a = theme.obtainStyledAttributes(attrs, R.styleable.AnticipateInterpolator, 0, 0);
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} else {
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a = res.obtainAttributes(attrs, R.styleable.AnticipateInterpolator);
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}
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mTension = a.getFloat(R.styleable.AnticipateInterpolator_tension, 2.0f);
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setChangingConfiguration(a.getChangingConfigurations());
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a.recycle();
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}
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public float getInterpolation(float t) {
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// a(t) = t * t * ((tension + 1) * t - tension)
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return t * t * ((mTension + 1) * t - mTension);
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}
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/** @hide */
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@Override
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public long createNativeInterpolator() {
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return NativeInterpolatorFactory.createAnticipateInterpolator(mTension);
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}
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}
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