| /* |
| * 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 <code>double</code> values. |
| */ |
| public class DoubleEvaluator implements TypeEvaluator { |
| /** |
| * This function returns the result of linearly interpolating the start and end values, with |
| * <code>fraction</code> representing the proportion between the start and end values. The |
| * calculation is a simple parametric calculation: <code>result = x0 + t * (v1 - v0)</code>, |
| * where <code>x0</code> is <code>startValue</code>, <code>x1</code> is <code>endValue</code>, |
| * and <code>t</code> is <code>fraction</code>. |
| * |
| * @param fraction The fraction from the starting to the ending values |
| * @param startValue The start value; should be of type <code>double</code> or |
| * <code>Double</code> |
| * @param endValue The end value; should be of type <code>double</code> or |
| * <code>Double</code> |
| * @return A linear interpolation between the start and end values, given the |
| * <code>fraction</code> parameter. |
| */ |
| public Object evaluate(float fraction, Object startValue, Object endValue) { |
| double startDouble = (Double) startValue; |
| return startDouble + fraction * ((Double) endValue - startDouble); |
| } |
| } |