1 /* 2 * Copyright (C) 2014 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.content.res; 17 18 import android.content.pm.ActivityInfo.Config; 19 import android.ravenwood.annotation.RavenwoodKeepWholeClass; 20 21 /** 22 * A cache class that can provide new instances of a particular resource which may change 23 * depending on the current {@link Resources.Theme} or {@link Configuration}. 24 * <p> 25 * A constant state should be able to return a bitmask of changing configurations, which 26 * identifies the type of configuration changes that may invalidate this resource. These 27 * configuration changes can be obtained from {@link android.util.TypedValue}. Entities such as 28 * {@link android.animation.Animator} also provide a changing configuration method to include 29 * their dependencies (e.g. An AnimatorSet's changing configuration is the union of the 30 * changing configurations of each Animator in the set) 31 * @hide 32 */ 33 @RavenwoodKeepWholeClass 34 abstract public class ConstantState<T> { 35 36 /** 37 * Return a bit mask of configuration changes that will impact 38 * this resource (and thus require completely reloading it). 39 */ getChangingConfigurations()40 abstract public @Config int getChangingConfigurations(); 41 42 /** 43 * Create a new instance without supplying resources the caller 44 * is running in. 45 */ newInstance()46 public abstract T newInstance(); 47 48 /** 49 * Create a new instance from its constant state. This 50 * must be implemented for resources that change based on the target 51 * density of their caller (that is depending on whether it is 52 * in compatibility mode). 53 */ newInstance(Resources res)54 public T newInstance(Resources res) { 55 return newInstance(); 56 } 57 58 /** 59 * Create a new instance from its constant state. This must be 60 * implemented for resources that can have a theme applied. 61 */ newInstance(Resources res, Resources.Theme theme)62 public T newInstance(Resources res, Resources.Theme theme) { 63 return newInstance(res); 64 } 65 } 66