AppBrain.java :  » Card » android-card-magic » com » maize » CardMagic » Android Open Source

/*
 * Copyright 2010 Maize Labs
 *
 * 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.maize.CardMagic;

import java.util.HashSet;

import android.hardware.SensorEvent;
import android.util.Log;

/**
 * AppBrain.java - The Model of the card swapper. Monitors states of the card.
 * 
 */
public class AppBrain 
{
  /* Value and states */
  private static final int THRESHOLD = 5;   // default 5cm
  private boolean processing = false;
  
  /*
   * The reason for using enum instead of boolean for monitoring states is that 
   * boolean only supports a max of 2 states. But with enum, more states can be 
   * supported and added easily in the future. (i.e. more cards can be used) 
   */
  private enum State { HEARTS, CLUBS };    // There are only 2 cards in this app, King of Hearts and King of Clubs
  private State state = State.HEARTS;      // Default card is King of Hearts
  
  
  /* Listeners */
  protected HashSet<BrainStateChangeListener> listeners;  
  
  
  /* Constructor */
  public AppBrain()
  {
    listeners = new HashSet<BrainStateChangeListener>();
  }
  
  
  /**
   * Takes in a SensorEvent (Sensor.TYPE_PROXIMITY), analyzes it and broadcasts the appropriate card drawable id to listeners.
   * @param event
   */
  public void changeState(SensorEvent event)
  {
    if (!processing) // Avoid rapid changes due to spam of SensorEvents
    {
      processing = true;
      
      float[] valuesArray = event.values;

      // According to the Android docs, value of distance measured is stored in element 0 of the float array
      // Sensor.TYPE_PROXIMITY: values[0]: Proximity sensor distance measured in centimeters
      float value = valuesArray[0];
      
      Log.i("SensorChanged", "Distance is  " + value + "cm");
      
      // Swap card when distance detected by the proximity sensor is closer than the threshold
      if (value < THRESHOLD) 
      {
        if (state == State.HEARTS)
        {
          fireStateChange(R.drawable.king_clubs);
          state = State.CLUBS;
        }
        else
        {
          fireStateChange(R.drawable.king_hearts);
          state = State.HEARTS;
        }
      }
        
      processing = false;
    }      
  }

  // Broadcasts the resource id of the desired card to all the listeners
  protected void fireStateChange(int resId)
  {
    for (BrainStateChangeListener l : listeners) 
    {
      l.swapCard(resId);
    }
  }
  
  
  public void addBrainStateChangeListener(BrainStateChangeListener l)
  {
    if (l != null) 
    {
      listeners.add(l);
    }
  }
  
  
  public void removeBrainStateChangeListener(BrainStateChangeListener l)
  {
    listeners.remove(l);
  }
  
  
  /* Listener */
  public interface BrainStateChangeListener
  {
    public void swapCard(int resId);
  }
}