Chet Haase | b989502 | 2013-04-02 15:10:58 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2013 The Android Open Source Project |
| 3 | * |
| 4 | * Licensed under the Apache License, Version 2.0 (the "License"); |
| 5 | * you may not use this file except in compliance with the License. |
| 6 | * You may obtain a copy of the License at |
| 7 | * |
| 8 | * http://www.apache.org/licenses/LICENSE-2.0 |
| 9 | * |
| 10 | * Unless required by applicable law or agreed to in writing, software |
| 11 | * distributed under the License is distributed on an "AS IS" BASIS, |
| 12 | * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 13 | * See the License for the specific language governing permissions and |
| 14 | * limitations under the License. |
| 15 | */ |
| 16 | package android.animation; |
| 17 | |
| 18 | import android.graphics.Rect; |
| 19 | |
| 20 | /** |
Chet Haase | edf6f4b | 2013-03-26 07:55:30 -0700 | [diff] [blame] | 21 | * This evaluator can be used to perform type interpolation between <code>Rect</code> values. |
Chet Haase | b989502 | 2013-04-02 15:10:58 -0700 | [diff] [blame] | 22 | */ |
| 23 | public class RectEvaluator implements TypeEvaluator<Rect> { |
| 24 | |
| 25 | /** |
George Mount | 0f3f298 | 2013-09-12 10:49:55 -0700 | [diff] [blame] | 26 | * When null, a new Rect is returned on every evaluate call. When non-null, |
| 27 | * mRect will be modified and returned on every evaluate. |
| 28 | */ |
| 29 | private Rect mRect; |
| 30 | |
| 31 | /** |
| 32 | * Construct a RectEvaluator that returns a new Rect on every evaluate call. |
| 33 | * To avoid creating an object for each evaluate call, |
| 34 | * {@link RectEvaluator#RectEvaluator(android.graphics.Rect)} should be used |
| 35 | * whenever possible. |
| 36 | */ |
| 37 | public RectEvaluator() { |
| 38 | } |
| 39 | |
| 40 | /** |
| 41 | * Constructs a RectEvaluator that modifies and returns <code>reuseRect</code> |
| 42 | * in {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} calls. |
| 43 | * The value returned from |
| 44 | * {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} should |
| 45 | * not be cached because it will change over time as the object is reused on each |
| 46 | * call. |
| 47 | * |
| 48 | * @param reuseRect A Rect to be modified and returned by evaluate. |
| 49 | */ |
| 50 | public RectEvaluator(Rect reuseRect) { |
| 51 | mRect = reuseRect; |
| 52 | } |
| 53 | |
| 54 | /** |
Chet Haase | b989502 | 2013-04-02 15:10:58 -0700 | [diff] [blame] | 55 | * This function returns the result of linearly interpolating the start and |
| 56 | * end Rect values, with <code>fraction</code> representing the proportion |
| 57 | * between the start and end values. The calculation is a simple parametric |
| 58 | * calculation on each of the separate components in the Rect objects |
| 59 | * (left, top, right, and bottom). |
| 60 | * |
George Mount | 0f3f298 | 2013-09-12 10:49:55 -0700 | [diff] [blame] | 61 | * <p>If {@link #RectEvaluator(android.graphics.Rect)} was used to construct |
| 62 | * this RectEvaluator, the object returned will be the <code>reuseRect</code> |
| 63 | * passed into the constructor.</p> |
| 64 | * |
Chet Haase | b989502 | 2013-04-02 15:10:58 -0700 | [diff] [blame] | 65 | * @param fraction The fraction from the starting to the ending values |
| 66 | * @param startValue The start Rect |
| 67 | * @param endValue The end Rect |
| 68 | * @return A linear interpolation between the start and end values, given the |
| 69 | * <code>fraction</code> parameter. |
| 70 | */ |
| 71 | @Override |
| 72 | public Rect evaluate(float fraction, Rect startValue, Rect endValue) { |
George Mount | 0f3f298 | 2013-09-12 10:49:55 -0700 | [diff] [blame] | 73 | int left = startValue.left + (int) ((endValue.left - startValue.left) * fraction); |
| 74 | int top = startValue.top + (int) ((endValue.top - startValue.top) * fraction); |
| 75 | int right = startValue.right + (int) ((endValue.right - startValue.right) * fraction); |
| 76 | int bottom = startValue.bottom + (int) ((endValue.bottom - startValue.bottom) * fraction); |
| 77 | if (mRect == null) { |
| 78 | return new Rect(left, top, right, bottom); |
| 79 | } else { |
| 80 | mRect.set(left, top, right, bottom); |
| 81 | return mRect; |
| 82 | } |
Chet Haase | b989502 | 2013-04-02 15:10:58 -0700 | [diff] [blame] | 83 | } |
| 84 | } |