78 lines
3.0 KiB
Java
78 lines
3.0 KiB
Java
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/*
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* Copyright (C) 2013 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.animation;
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/**
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* This evaluator can be used to perform type interpolation between <code>float[]</code> values.
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* Each index into the array is treated as a separate value to interpolate. For example,
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* evaluating <code>{100, 200}</code> and <code>{300, 400}</code> will interpolate the value at
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* the first index between 100 and 300 and the value at the second index value between 200 and 400.
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*/
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public class FloatArrayEvaluator implements TypeEvaluator<float[]> {
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private float[] mArray;
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/**
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* Create a FloatArrayEvaluator that does not reuse the animated value. Care must be taken
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* when using this option because on every evaluation a new <code>float[]</code> will be
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* allocated.
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*
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* @see #FloatArrayEvaluator(float[])
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*/
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public FloatArrayEvaluator() {
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}
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/**
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* Create a FloatArrayEvaluator that reuses <code>reuseArray</code> for every evaluate() call.
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* Caution must be taken to ensure that the value returned from
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* {@link android.animation.ValueAnimator#getAnimatedValue()} is not cached, modified, or
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* used across threads. The value will be modified on each <code>evaluate()</code> call.
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*
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* @param reuseArray The array to modify and return from <code>evaluate</code>.
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*/
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public FloatArrayEvaluator(float[] reuseArray) {
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mArray = reuseArray;
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}
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/**
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* Interpolates the value at each index by the fraction. If
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* {@link #FloatArrayEvaluator(float[])} was used to construct this object,
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* <code>reuseArray</code> will be returned, otherwise a new <code>float[]</code>
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* will be returned.
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*
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* @param fraction The fraction from the starting to the ending values
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* @param startValue The start value.
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* @param endValue The end value.
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* @return A <code>float[]</code> where each element is an interpolation between
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* the same index in startValue and endValue.
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*/
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@Override
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public float[] evaluate(float fraction, float[] startValue, float[] endValue) {
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float[] array = mArray;
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if (array == null) {
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array = new float[startValue.length];
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}
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for (int i = 0; i < array.length; i++) {
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float start = startValue[i];
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float end = endValue[i];
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array[i] = start + (fraction * (end - start));
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}
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return array;
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}
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}
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