1 /* 2 * Copyright (C) 2022 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 android.window; 18 19 import android.annotation.NonNull; 20 import android.app.Activity; 21 import android.app.Dialog; 22 import android.view.Window; 23 24 /** 25 * Callback allowing applications to handle back events in place of the system. 26 * <p> 27 * Callback instances can be added to and removed from {@link OnBackInvokedDispatcher}, which 28 * is held at window level and accessible through {@link Activity#getOnBackInvokedDispatcher()}, 29 * {@link Dialog#getOnBackInvokedDispatcher()} and {@link Window#getOnBackInvokedDispatcher()}. 30 * <p> 31 * When back is triggered, callbacks on the in-focus window are invoked in reverse order in which 32 * they are added within the same priority. Between different priorities, callbacks with higher 33 * priority are invoked first. 34 * <p> 35 * This replaces {@link Activity#onBackPressed()}, {@link Dialog#onBackPressed()} and 36 * {@link android.view.KeyEvent#KEYCODE_BACK} 37 * <p> 38 * @see OnBackInvokedDispatcher#registerOnBackInvokedCallback(int, OnBackInvokedCallback) 39 * registerOnBackInvokedCallback(priority, OnBackInvokedCallback) 40 * to specify callback priority. 41 */ 42 @SuppressWarnings("deprecation") 43 public interface OnBackInvokedCallback { 44 /** 45 * Called when a back gesture has been started, or back button has been pressed down. 46 * 47 * @param backEvent The {@link BackEvent} containing information about the touch or 48 * button press. 49 * 50 * @hide 51 */ onBackStarted(@onNull BackEvent backEvent)52 default void onBackStarted(@NonNull BackEvent backEvent) {} 53 54 /** 55 * Called when a back gesture has been progressed. 56 * 57 * @param backEvent The {@link BackEvent} containing information about the latest touch point 58 * and the progress that the back animation should seek to. 59 * 60 * @hide 61 */ onBackProgressed(@onNull BackEvent backEvent)62 default void onBackProgressed(@NonNull BackEvent backEvent) {} 63 64 /** 65 * Called when a back gesture has been completed and committed, or back button pressed 66 * has been released and committed. 67 */ onBackInvoked()68 void onBackInvoked(); 69 70 /** 71 * Called when a back gesture or button press has been cancelled. 72 * 73 * @hide 74 */ onBackCancelled()75 default void onBackCancelled() {} 76 } 77