Platformer2D/Platformer2D.Core/Game/Accelerometer.cs

   1 #region File Description
   2 //-----------------------------------------------------------------------------
   3 // Accelerometer.cs
   4 //
   5 // Microsoft XNA Community Game Platform
   6 // Copyright (C) Microsoft Corporation. All rights reserved.
   7 //-----------------------------------------------------------------------------
   8 #endregion
   9
  10 #region Using Statements
  11 using Microsoft.Xna.Framework;
  12 using System;
  13 #endregion
  14
  15 namespace Platformer2D
  16 {
  17     /// <summary>
  18     /// A static encapsulation of accelerometer input to provide games with a polling-based
  19     /// accelerometer system.
  20     /// </summary>
  21     public static class Accelerometer
  22     {
  23         // we want to prevent the Accelerometer from being initialized twice.
  24         private static bool isInitialized = false;
  25
  26         // whether or not the accelerometer is active
  27         private static bool isActive = false;
  28
  29         /// <summary>
  30         /// Initializes the Accelerometer for the current game. This method can only be called once per game.
  31         /// </summary>
  32         public static void Initialize()
  33         {
  34             // make sure we don't initialize the Accelerometer twice
  35             if (isInitialized)
  36             {
  37                 throw new InvalidOperationException("Initialize can only be called once");
  38             }
  39
  40             // remember that we are initialized
  41             isInitialized = true;
  42         }
  43
  44         /// <summary>
  45         /// Gets the current state of the accelerometer.
  46         /// </summary>
  47         /// <returns>A new AccelerometerState with the current state of the accelerometer.</returns>
  48         public static AccelerometerState GetState()
  49         {
  50             // make sure we've initialized the Accelerometer before we try to get the state
  51             if (!isInitialized)
  52             {
  53                 throw new InvalidOperationException("You must Initialize before you can call GetState");
  54             }
  55
  56             // create a new value for our state
  57             Vector3 stateValue = new Vector3();
  58
  59             return new AccelerometerState(stateValue, isActive);
  60         }
  61     }
  62
  63     /// <summary>
  64     /// An encapsulation of the accelerometer's current state.
  65     /// </summary>
  66     public struct AccelerometerState
  67     {
  68         /// <summary>
  69         /// Gets the accelerometer's current value in G-force.
  70         /// </summary>
  71         public Vector3 Acceleration { get; private set; }
  72
  73         /// <summary>
  74         /// Gets whether or not the accelerometer is active and running.
  75         /// </summary>
  76         public bool IsActive { get; private set; }
  77
  78         /// <summary>
  79         /// Initializes a new AccelerometerState.
  80         /// </summary>
  81         /// <param name="acceleration">The current acceleration (in G-force) of the accelerometer.</param>
  82         /// <param name="isActive">Whether or not the accelerometer is active.</param>
  83         public AccelerometerState(Vector3 acceleration, bool isActive)
  84             : this()
  85         {
  86             Acceleration = acceleration;
  87             IsActive = isActive;
  88         }
  89
  90         /// <summary>
  91         /// Returns a string containing the values of the Acceleration and IsActive properties.
  92         /// </summary>
  93         /// <returns>A new string describing the state.</returns>
  94         public override string ToString()
  95         {
  96             return string.Format("Acceleration: {0}, IsActive: {1}", Acceleration, IsActive);
  97         }
  98     }
  99 }