content: /*
   * Copyright (C) 2014 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.android.ex.camera2.portability;
  
  import android.os.Handler;
  import android.os.Looper;
  import android.os.Message;
  
  import java.util.LinkedList;
  
  class HistoryHandler extends Handler {
      private static final int MAX_HISTORY_SIZE = 400;
  
      final LinkedList<Integer> mMsgHistory;
  
      HistoryHandler(Looper looper) {
          super(looper);
          mMsgHistory = new LinkedList<Integer>();
          // We add a -1 at the beginning to mark the very beginning of the
          // history.
          mMsgHistory.offerLast(-1);
      }
  
      Integer getCurrentMessage() {
          return mMsgHistory.peekLast();
      }
  
      String generateHistoryString(int cameraId) {
          String info = new String("HIST");
          info += "_ID" + cameraId;
          for (Integer msg : mMsgHistory) {
              info = info + '_' + msg.toString();
          }
          info += "_HEND";
          return info;
      }
  
      /**
       * Subclasses' implementations should call this one before doing their work.
       */
      @Override
      public void handleMessage(Message msg) {
          mMsgHistory.offerLast(msg.what);
          while (mMsgHistory.size() > MAX_HISTORY_SIZE) {
              mMsgHistory.pollFirst();
          }
      }
  }
  