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/*
* Copyright (C) 2010 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 com.nineoldandroids.animation;
/**
* This evaluator can be used to perform type interpolation between float values.
*/
public class FloatEvaluator implements TypeEvaluator {
/**
* This function returns the result of linearly interpolating the start and end values, with
* fraction representing the proportion between the start and end values. The
* calculation is a simple parametric calculation: result = x0 + t * (v1 - v0),
* where x0 is startValue, x1 is endValue,
* and t is fraction.
*
* @param fraction The fraction from the starting to the ending values
* @param startValue The start value; should be of type float or
* Float
* @param endValue The end value; should be of type float or Float
* @return A linear interpolation between the start and end values, given the
* fraction parameter.
*/
public Float evaluate(float fraction, Number startValue, Number endValue) {
float startFloat = startValue.floatValue();
return startFloat + fraction * (endValue.floatValue() - startFloat);
}
}