Added more functions. Added handling of multiple contexts. Improved thread-safety. Resolved a minor bug in the CreateContext function.

Source/OpenTK/OpenAL/AudioContext.cs

@@ -11,6 +11,7 @@ using System.Text;
 
 using OpenTK.OpenAL;
 using OpenTK.OpenAL.Enums;
+using System.Diagnostics;
 
 namespace OpenTK.Audio
 {
@@ -22,55 +23,155 @@ namespace OpenTK.Audio
         #region --- Fields ---
 
         bool disposed;
-        static List<string> available_devices;
-        IntPtr device_handle, context_handle;
+        ContextHandle device_handle, context_handle;
+        string device_name;
         static object audio_context_lock = new object();
+        static List<string> available_devices = new List<string>();
+        static Dictionary<ContextHandle, AudioContext> available_contexts = new Dictionary<ContextHandle, AudioContext>();
 
         #endregion
 
         #region --- Constructors ---
 
-        // Runs before the actual class constructor, to load available devices.
+        #region static AudioContext()
+
+        /// <private />
+        /// <static />
+        /// <summary>
+        /// Runs before the actual class constructor, to load available devices.
+        /// </summary>
         static AudioContext()
         {
             LoadAvailableDevices();
         }
 
+        #endregion
+
+        #region public AudioContext()
+
         /// <summary>Constructs a new AudioContext, using the default audio device.</summary>
         /// <exception cref="NotSupportedException">Occurs when no audio devices are available.</exception>
-        public AudioContext()
-        {
-            if (available_devices.Count == 0)
-                throw new NotSupportedException("No audio hardware is available.");
-            CreateContext(available_devices[0], 44100, 0, false);
-        }
+        public AudioContext() : this(available_devices[0], 0, 0, false, 0) { }
+
+        #endregion
+
+        #region public AudioContext(string device)
 
         /// <summary>Constructs a new AudioContext, using the specified audio device.</summary>
         /// <param name="device">The name of the audio device to use.</param>
         /// <remarks>
-        /// Use AudioContext.AvailableDevices to obtain a list of all available audio
+        /// Use AudioContext.AvailableDevices to obtain a list of all available audio devices.
         /// devices.
         /// </remarks>
-        public AudioContext(string device)
-        {
+        public AudioContext(string device) : this(device, 0, 0, false, 0) { }
 
+        #endregion
+
+        #region public AudioContext(string device, int freq)
+
+        /// <summary>Constructs a new AudioContext, using the specified audio device and device parameters.</summary>
+        /// <param name="device">The name of the audio device to use.</param>
+        /// <param name="freq">Frequency for mixing output buffer, in units of Hz. Pass 0 for driver default.</param>
+        /// <remarks>
+        /// Use AudioContext.AvailableDevices to obtain a list of all available audio devices.
+        /// devices.
+        /// </remarks>
+        /// <see cref="AudioContext(string device, int freq, int refresh, bool sync, int maxEfxSends)"/>
+        public AudioContext(string device, int freq) : this(device, freq, 0, false, 0) { }
+
+        #endregion
+
+        #region public AudioContext(string device, int freq, int refresh)
+
+        /// <summary>Constructs a new AudioContext, using the specified audio device and device parameters.</summary>
+        /// <param name="device">The name of the audio device to use.</param>
+        /// <param name="freq">Frequency for mixing output buffer, in units of Hz. Pass 0 for driver default.</param>
+        /// <param name="refresh">Refresh intervals, in units of Hz. Pass 0 for driver default.</param>
+        /// <remarks>
+        /// Use AudioContext.AvailableDevices to obtain a list of all available audio devices.
+        /// devices.
+        /// </remarks>
+        /// <see cref="AudioContext(string device, int freq, int refresh, bool sync, int maxEfxSends)"/>
+        public AudioContext(string device, int freq, int refresh)
+            : this(device, freq, refresh, false, 0) { }
+
+        #endregion
+
+        #region public AudioContext(string device)
+
+        /// <summary>Constructs a new AudioContext, using the specified audio device and device parameters.</summary>
+        /// <param name="device">The name of the audio device to use.</param>
+        /// <param name="freq">Frequency for mixing output buffer, in units of Hz. Pass 0 for driver default.</param>
+        /// <param name="refresh">Refresh intervals, in units of Hz. Pass 0 for driver default.</param>
+        /// <param name="sync">Flag, indicating a synchronous context.</param>
+        /// <remarks>
+        /// Use AudioContext.AvailableDevices to obtain a list of all available audio devices.
+        /// devices.
+        /// </remarks>
+        /// <see cref="AudioContext(string device, int freq, int refresh, bool sync, int maxEfxSends)"/>
+        public AudioContext(string device, int freq, int refresh, bool sync)
+            : this(available_devices[0], freq, refresh, sync, 0) { }
+
+        #endregion
+
+        #region public AudioContext(string device, int freq, int refresh, bool sync, int maxEfxSends)
+
+        /// <summary>Creates the audio context using the specified device and device parameters.</summary>
+        /// <param name="device">The device descriptor obtained through AudioContext.AvailableDevices.</param>
+        /// <param name="freq">Frequency for mixing output buffer, in units of Hz. Pass 0 for driver default.</param>
+        /// <param name="refresh">Refresh intervals, in units of Hz. Pass 0 for driver default.</param>
+        /// <param name="sync">Flag, indicating a synchronous context.</param>
+        /// <param name="maxEfxSends">Number of auxilliary send slots for the EFX extensions. Can be 0 (use driver default) or higher.</param>
+        /// <exception cref="ArgumentNullException">Occurs when the device string is invalid.</exception>
+        /// <exception cref="ArgumentOutOfRangeException">Occurs when a specified parameter is invalid.</exception>
+        /// <exception cref="InvalidAudioDeviceException">
+        /// Occurs when the specified device is not available, or is in use by another program.
+        /// </exception>
+        /// <exception cref="InvalidAudioContextException">
+        /// Occurs when an audio context could not be created with the specified parameters.
+        /// </exception>
+        /// <remarks>
+        /// <para>
+        /// Use AudioContext.AvailableDevices to obtain a list of all available audio devices.
+        /// </para>
+        /// <para>
+        /// The number of auxilliary EFX sends depends on the audio hardware and drivers. Most Realtek devices, as well
+        /// as the Creative SB Live!, support 1 auxilliary send. Creative's Audigy and X-Fi series support 4 sends.
+        /// Values not supported will be clamped by the driver.
+        /// </para>
+        /// </remarks>
+        public AudioContext(string device, int freq, int refresh, bool sync, int maxEfxSends)
+        {
+            CreateContext(device, freq, refresh, sync, maxEfxSends);
         }
 
         #endregion
 
+        #endregion
+
         #region --- Private Members ---
 
         #region static void LoadAvailableDevices()
 
-        // Loads all available audio devices into the available_devices array.
+        /// <private />
+        /// <static />
+        /// <summary>
+        /// Loads all available audio devices into the available_devices array.
+        /// </summary>
+        /// <remarks>
+        /// Only called by the static AudioContext constructor.
+        /// </remarks>
         static void LoadAvailableDevices()
         {
             lock (audio_context_lock)
             {
-                if (available_devices == null)
+                if (available_devices.Count == 0)
                 {
-                    available_devices = new List<string>();
-                    available_devices.AddRange(Alc.GetString(IntPtr.Zero, OpenTK.OpenAL.Enums.AlcGetStringList.AllDevicesSpecifier));
+                    if (Alc.IsExtensionPresent(IntPtr.Zero, "ALC_ENUMERATION_EXT"))
+                    {
+                        available_devices = new List<string>();
+                        available_devices.AddRange(Alc.GetString(IntPtr.Zero, AlcGetStringList.AllDevicesSpecifier));
+                    }
                 }
             }
         }
@@ -82,47 +183,104 @@ namespace OpenTK.Audio
         /// <private />
         /// <summary>Creates the audio context using the specified device.</summary>
         /// <param name="device">The device descriptor obtained through AudioContext.AvailableDevices.</param>
-        /// <param name="freq">Frequency for mixing output buffer, in units of Hz. </param>
-        /// <param name="refresh">Refresh intervalls, in units of Hz.</param>
+        /// <param name="freq">Frequency for mixing output buffer, in units of Hz. Pass 0 for driver default.</param>
+        /// <param name="refresh">Refresh intervals, in units of Hz. Pass 0 for driver default.</param>
         /// <param name="sync">Flag, indicating a synchronous context.</param>
+        /// <param name="maxEfxSends">Number of auxilliary send slots for the EFX extensions. Can be 0 (use driver default) or higher.</param>
+        /// <exception cref="ArgumentNullException">Occurs when the device string is invalid.</exception>
+        /// /// <exception cref="ArgumentOutOfRangeException">Occurs when a specified parameter is invalid.</exception>
         /// <exception cref="InvalidAudioDeviceException">
         /// Occurs when the specified device is not available, or is in use by another program.
         /// </exception>
         /// <exception cref="InvalidAudioContextException">
         /// Occurs when an audio context could not be created with the specified parameters.
         /// </exception>
-        void CreateContext(string device, int freq, int refresh, bool sync)
+        /// <remarks>
+        /// The number of auxilliary EFX sends depends on the audio hardware and drivers. Most Realtek devices, as well
+        /// as the Creative SB Live!, support 1 auxilliary send. Creative's Audigy and X-Fi series support 4 sends.
+        /// Values higher than supported will be clamped by the driver.
+        /// </remarks>
+        void CreateContext(string device, int freq, int refresh, bool sync, int maxEfxSends)
         {
             if (String.IsNullOrEmpty(device)) throw new ArgumentNullException("device");
-            if (freq < 0) throw new ArgumentOutOfRangeException("freq", freq, "Should be greater than zero");
-            if (refresh < 0) throw new ArgumentOutOfRangeException("refresh", refresh, "Should be greater than zero");
+            if (freq < 0) throw new ArgumentOutOfRangeException("freq", freq, "Should be greater than zero.");
+            if (refresh < 0) throw new ArgumentOutOfRangeException("refresh", refresh, "Should be greater than zero.");
+            if (maxEfxSends < 0) throw new ArgumentOutOfRangeException("maxEfxSends", maxEfxSends, "Should be greater than zero.");
+            if (available_devices.Count == 0) throw new NotSupportedException("No audio hardware is available.");
 
             device_handle = Alc.OpenDevice(device);
             if (device_handle == IntPtr.Zero)
-                throw new InvalidAudioDeviceException();
+                throw new AudioDeviceException("The specified audio device does not exist or is tied up by another application.");
 
+            device_name = device;
+
+            // Build the attribute liist
             List<int> attributes = new List<int>();
+            
             if (freq != 0)
             {
                 attributes.Add((int)AlcContextAttributes.Frequency);
                 attributes.Add(freq);
             }
+            
             if (refresh != 0)
             {
                 attributes.Add((int)AlcContextAttributes.Refresh);
                 attributes.Add(refresh);
             }
+            
             attributes.Add((int)AlcContextAttributes.Frequency);
             attributes.Add(sync ? 1 : 0);
 
+            if (maxEfxSends > 0)
+            {
+                throw new NotImplementedException();
+                //if (Alc.IsExtensionPresent(device_handle, "ALC_EXT_EFX"))
+                //attributes.Add((int)AlcContextAttributes.MaxAuxilliarySends);
+                //attributes.Add(maxEfxSends);
+            }
+
             context_handle = Alc.CreateContext(device_handle, attributes.ToArray());
             if (context_handle == IntPtr.Zero)
             {
                 Alc.CloseDevice(device_handle);
-                throw new InvalidAudioContextException();
+                throw new AudioContextException("The audio context could not be created with the specified parameters.");
+            }
+
+            MakeCurrent();
+
+            //device_name = Alc.GetString(device_handle, AlcGetString.DeviceSpecifier);
+            //Debug.Print(device_name);
+            lock (audio_context_lock)
+            {
+                available_contexts.Add(this.context_handle, this);
             }
         }
 
+        #endregion
+
+        #region static void MakeCurrent(AudioContext context)
+
+        /// <private />
+        /// <summary>Makes the specified AudioContext current in the calling thread.</summary>
+        /// <param name="context">The OpenTK.Audio.AudioContext to make current, or null.</param>
+        /// <exception cref="ObjectDisposedException">
+        /// Occurs if this function is called after the AudioContext has been disposed.
+        /// </exception>
+        /// <exception cref="AudioContextException">
+        /// Occurs when the AudioContext could not be made current.
+        /// </exception>
+        static void MakeCurrent(AudioContext context)
+        {
+            lock (audio_context_lock)
+            {
+                //if (context != null && context.disposed)
+                //    throw new ObjectDisposedException("OpenTK.Audio.AudioContext");
+                if (!Alc.MakeContextCurrent(context != null ? (IntPtr)context.context_handle : IntPtr.Zero))
+                    throw new AudioContextException(
+                        Alc.GetError(context != null ? (IntPtr)context.context_handle : IntPtr.Zero).ToString());
+            }
+        }
 
         #endregion
 
@@ -135,11 +293,152 @@ namespace OpenTK.Audio
         /// <summary>
         /// Gets a System.String array containing all available audio devices.
         /// </summary>
-        public static IEnumerable<string> AvailableDevices
+        /// <remarks>This property allocates memory.</remarks>
+        public static string[] AvailableDevices
         {
             get
             {
-                return (IEnumerable<string>)available_devices;
+                return available_devices.ToArray();
+            }
+        }
+
+        #endregion
+
+        #region public void MakeCurrent()
+
+        /// <summary>Makes the AudioContext current in the calling thread.</summary>
+        /// <exception cref="ObjectDisposedException">
+        /// Occurs if this function is called after the AudioContext has been disposed.
+        /// </exception>
+        /// <exception cref="AudioContextException">
+        /// Occurs when the AudioContext could not be made current.
+        /// </exception>
+        /// <remarks>
+        /// Only one AudioContext can be current in the application at any time,
+        /// <b>regardless of the number of threads</b>.
+        /// </remarks>
+        public void MakeCurrent()
+        {
+            AudioContext.MakeCurrent(this);
+        }
+
+        #endregion
+
+        #region public bool IsCurrent
+
+        /// <summary>
+        /// Gets or sets a System.Boolean indicating whether the AudioContext
+        /// is current.
+        /// </summary>
+        /// <remarks>
+        /// Only one AudioContext can be current in the application at any time,
+        /// <b>regardless of the number of threads</b>.
+        /// </remarks>
+        public bool IsCurrent
+        {
+            get
+            {
+                lock (audio_context_lock)
+                {
+                    if (available_contexts.Count == 0)
+                        return false;
+                    else
+                        return AudioContext.available_contexts[(ContextHandle)Alc.GetCurrentContext()] == this;
+                }
+            }
+            set
+            {
+                if (value) AudioContext.MakeCurrent(this);
+                else AudioContext.MakeCurrent(null);
+            }
+        }
+
+        #endregion
+
+        #region public void Process
+
+        /// <summary>
+        /// Processes queued audio events.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// If AudioContext.IsSynchronized is true, this function will resume
+        /// the internal audio processing thread. If AudioContext.IsSynchronized is false,
+        /// you will need to call this function multiple times per second to process
+        /// audio events.
+        /// </para>
+        /// <para>
+        /// In some implementations this function may have no effect.
+        /// </para>
+        /// </remarks>
+        /// <exception cref="ObjectDisposedException">Occurs when this function is called after the AudioContext had been disposed.</exception>
+        /// <seealso cref="Suspend"/>
+        /// <seealso cref="IsSuspended"/>
+        /// <seealso cref="IsSynchronized"/>
+        public void Process()
+        {
+            if (disposed) throw new ObjectDisposedException(this.ToString());
+            Alc.ProcessContext(this.context_handle);
+        }
+
+        #endregion
+
+        #region public void Suspend
+
+        /// <summary>
+        /// Suspends processing of audio events.
+        /// </summary>
+        /// <remarks>
+        /// <para>
+        /// To avoid audio artifacts when calling this function, set audio gain to zero before
+        /// suspending an AudioContext.
+        /// </para>
+        /// <para>
+        /// In some implementations, it can be faster to suspend processing before changing
+        /// AudioContext state.
+        /// </para>
+        /// <para>
+        /// In some implementations this function may have no effect.
+        /// </para>
+        /// </remarks>
+        /// <exception cref="ObjectDisposedException">Occurs when this function is called after the AudioContext had been disposed.</exception>
+        /// <seealso cref="Process"/>
+        /// <seealso cref="IsSuspended"/>
+        /// <seealso cref="IsSynchronized"/>
+        public void Suspend()
+        {
+            if (disposed) throw new ObjectDisposedException(this.ToString());
+            Alc.SuspendContext(this.context_handle);
+        }
+
+        #endregion
+
+        #region public static AudioContext CurrentContext
+
+        /// <summary>
+        /// Gets the OpenTK.Audio.AudioContext which is current in the application.
+        /// </summary>
+        /// <remarks>
+        /// Only one AudioContext can be current in the application at any time,
+        /// <b>regardless of the number of threads</b>.
+        /// </remarks>
+        public static AudioContext CurrentContext
+        {
+            get
+            {
+                lock (audio_context_lock)
+                {
+                    if (available_contexts.Count == 0)
+                        return null;
+                    else
+                    {
+                        AudioContext context;
+                        AudioContext.available_contexts.TryGetValue(
+                            (ContextHandle)Alc.GetCurrentContext(),
+                            out context);
+                        return context;
+                    }
+                }
             }
         }
 
@@ -149,6 +448,9 @@ namespace OpenTK.Audio
 
         #region --- IDisposable Members ---
 
+        /// <summary>
+        /// Disposes of the AudioContext, cleaning up all resources consumed by it.
+        /// </summary>
         public void Dispose()
         {
             this.Dispose(true);
@@ -159,6 +461,17 @@ namespace OpenTK.Audio
         {
             if (!disposed)
             {
+                available_contexts.Remove(this.context_handle);
+
+                if (this.IsCurrent)
+                    this.IsCurrent = false;
+
+                if (context_handle != IntPtr.Zero)
+                    Alc.DestroyContext(context_handle);
+
+                if (device_handle != IntPtr.Zero)
+                    Alc.CloseDevice(device_handle);
+
                 if (manual)
                 {
                 }
@@ -172,18 +485,42 @@ namespace OpenTK.Audio
         }
 
         #endregion
+
+        #region --- Overrides ---
+
+        public override int GetHashCode()
+        {
+            return base.GetHashCode();
+        }
+
+        public override bool Equals(object obj)
+        {
+            return base.Equals(obj);
+        }
+
+        public override string ToString()
+        {
+            return String.Format("{0} (handle: {1}, device: {2})",
+                                 this.device_name, this.context_handle, this.device_handle);
+        }
+
+        #endregion
     }
 
     #region --- Exceptions ---
 
-    public class InvalidAudioDeviceException : Exception
+    /// <summary>Represents errors related to an Audio device.</summary>
+    public class AudioDeviceException : Exception
     {
-        public InvalidAudioDeviceException() : base("The specified audio device does not exist or is tied up by another application.") { }
+        public AudioDeviceException() : base() { }
+        public AudioDeviceException(string message) : base(message) { }
     }
 
-    public class InvalidAudioContextException : Exception
+    /// <summary>Represents errors related to an AudioContext.</summary>
+    public class AudioContextException : Exception
     {
-        public InvalidAudioContextException() : base("The audio context could not be created with the specified parameters.") { }
+        public AudioContextException() : base() { }
+        public AudioContextException(string message) : base(message) { }
     }
 
     #endregion