1/* 2 * Copyright (C) 2016 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 17package androidx.transition; 18 19import android.animation.TypeEvaluator; 20import android.graphics.Rect; 21 22/** 23 * This evaluator can be used to perform type interpolation between <code>Rect</code> values. 24 */ 25class RectEvaluator implements TypeEvaluator<Rect> { 26 27 /** 28 * When null, a new Rect is returned on every evaluate call. When non-null, 29 * mRect will be modified and returned on every evaluate. 30 */ 31 private Rect mRect; 32 33 /** 34 * Construct a RectEvaluator that returns a new Rect on every evaluate call. 35 * To avoid creating an object for each evaluate call, 36 * {@link RectEvaluator#RectEvaluator(android.graphics.Rect)} should be used 37 * whenever possible. 38 */ 39 RectEvaluator() { 40 } 41 42 /** 43 * Constructs a RectEvaluator that modifies and returns <code>reuseRect</code> 44 * in {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} calls. 45 * The value returned from 46 * {@link #evaluate(float, android.graphics.Rect, android.graphics.Rect)} should 47 * not be cached because it will change over time as the object is reused on each 48 * call. 49 * 50 * @param reuseRect A Rect to be modified and returned by evaluate. 51 */ 52 RectEvaluator(Rect reuseRect) { 53 mRect = reuseRect; 54 } 55 56 /** 57 * This function returns the result of linearly interpolating the start and 58 * end Rect values, with <code>fraction</code> representing the proportion 59 * between the start and end values. The calculation is a simple parametric 60 * calculation on each of the separate components in the Rect objects 61 * (left, top, right, and bottom). 62 * 63 * <p>If {@link #RectEvaluator(android.graphics.Rect)} was used to construct 64 * this RectEvaluator, the object returned will be the <code>reuseRect</code> 65 * passed into the constructor.</p> 66 * 67 * @param fraction The fraction from the starting to the ending values 68 * @param startValue The start Rect 69 * @param endValue The end Rect 70 * @return A linear interpolation between the start and end values, given the 71 * <code>fraction</code> parameter. 72 */ 73 @Override 74 public Rect evaluate(float fraction, Rect startValue, Rect endValue) { 75 int left = startValue.left + (int) ((endValue.left - startValue.left) * fraction); 76 int top = startValue.top + (int) ((endValue.top - startValue.top) * fraction); 77 int right = startValue.right + (int) ((endValue.right - startValue.right) * fraction); 78 int bottom = startValue.bottom + (int) ((endValue.bottom - startValue.bottom) * fraction); 79 if (mRect == null) { 80 return new Rect(left, top, right, bottom); 81 } else { 82 mRect.set(left, top, right, bottom); 83 return mRect; 84 } 85 } 86} 87