1 /* 2 * Copyright (C) 2015 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 com.android.camera.captureintent.stateful; 18 19 import javax.annotation.Nonnull; 20 21 /** 22 * Defines a state machine interface that any implementation of this interface 23 * is able to transition among different {@link State} and process various 24 * {@link Event}. 25 */ 26 public interface StateMachine { 27 /** 28 * Obtains the current state. 29 * 30 * @return A {@link State} object that represents the current state. 31 */ 32 public State getCurrentState(); 33 34 /** 35 * Sets the initial state of the state machine. 36 * 37 * @param initialState An initial {@link State}. 38 * @return True if the operation is succeeded. 39 */ 40 public boolean setInitialState(@Nonnull State initialState); 41 42 /** 43 * Process a specified {@link Event} and potentially change the current 44 * state. 45 * 46 * This method is thread-safe so it could be called on different threads. 47 * Only one event could be processed at a time. 48 * 49 * @param event An {@link Event} to be processed. 50 */ 51 public void processEvent(Event event); 52 } 53
