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A library jar that provides APIs for Applications written for the Google Android Platform.

There is a newer version: 14-robolectric-10818077

/*
 * 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 android.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);
    }
}