1 /* 2 * Copyright 2018 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 17 package androidx.customview.view; 18 19 import android.os.Parcel; 20 import android.os.Parcelable; 21 22 import androidx.annotation.NonNull; 23 import androidx.annotation.Nullable; 24 25 /** 26 * A {@link Parcelable} implementation that should be used by inheritance 27 * hierarchies to ensure the state of all classes along the chain is saved. 28 */ 29 public abstract class AbsSavedState implements Parcelable { 30 public static final AbsSavedState EMPTY_STATE = new AbsSavedState() {}; 31 32 private final Parcelable mSuperState; 33 34 /** 35 * Constructor used to make the EMPTY_STATE singleton 36 */ AbsSavedState()37 private AbsSavedState() { 38 mSuperState = null; 39 } 40 41 /** 42 * Constructor called by derived classes when creating their SavedState objects 43 * 44 * @param superState The state of the superclass of this view 45 */ AbsSavedState(@onNull Parcelable superState)46 protected AbsSavedState(@NonNull Parcelable superState) { 47 if (superState == null) { 48 throw new IllegalArgumentException("superState must not be null"); 49 } 50 mSuperState = superState != EMPTY_STATE ? superState : null; 51 } 52 53 /** 54 * Constructor used when reading from a parcel. Reads the state of the superclass. 55 * 56 * @param source parcel to read from 57 */ AbsSavedState(@onNull Parcel source)58 protected AbsSavedState(@NonNull Parcel source) { 59 this(source, null); 60 } 61 62 /** 63 * Constructor used when reading from a parcel. Reads the state of the superclass. 64 * 65 * @param source parcel to read from 66 * @param loader ClassLoader to use for reading 67 */ AbsSavedState(@onNull Parcel source, @Nullable ClassLoader loader)68 protected AbsSavedState(@NonNull Parcel source, @Nullable ClassLoader loader) { 69 Parcelable superState = source.readParcelable(loader); 70 mSuperState = superState != null ? superState : EMPTY_STATE; 71 } 72 73 @Nullable getSuperState()74 public final Parcelable getSuperState() { 75 return mSuperState; 76 } 77 78 @Override describeContents()79 public int describeContents() { 80 return 0; 81 } 82 83 @Override writeToParcel(Parcel dest, int flags)84 public void writeToParcel(Parcel dest, int flags) { 85 dest.writeParcelable(mSuperState, flags); 86 } 87 88 public static final Creator<AbsSavedState> CREATOR = new ClassLoaderCreator<AbsSavedState>() { 89 @Override 90 public AbsSavedState createFromParcel(Parcel in, ClassLoader loader) { 91 Parcelable superState = in.readParcelable(loader); 92 if (superState != null) { 93 throw new IllegalStateException("superState must be null"); 94 } 95 return EMPTY_STATE; 96 } 97 98 @Override 99 public AbsSavedState createFromParcel(Parcel in) { 100 return createFromParcel(in, null); 101 } 102 103 @Override 104 public AbsSavedState[] newArray(int size) { 105 return new AbsSavedState[size]; 106 } 107 }; 108 } 109