Home | History | Annotate | Download | only in stateful
      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