Providing streaming AudFormat data.

AudFormat.GetPCMInputStream now returns data that is streamed, rather than a MemoryStream.

OpenRA.Game/Primitives/ReadOnlyAdapterStream.cs

@@ -0,0 +1,89 @@
+#region Copyright & License Information
+/*
+ * Copyright 2007-2017 The OpenRA Developers (see AUTHORS)
+ * This file is part of OpenRA, which is free software. It is made
+ * available to you under the terms of the GNU General Public License
+ * as published by the Free Software Foundation, either version 3 of
+ * the License, or (at your option) any later version. For more
+ * information, see COPYING.
+ */
+#endregion
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+
+namespace OpenRA.Primitives
+{
+	/// <summary>
+	/// Provides a read-only buffering layer so data can be streamed from sources where reading arbitrary amounts of
+	/// data is difficult.
+	/// </summary>
+	public abstract class ReadOnlyAdapterStream : Stream
+	{
+		readonly Queue<byte> data = new Queue<byte>(1024);
+		readonly Stream baseStream;
+
+		protected ReadOnlyAdapterStream(Stream stream)
+		{
+			if (stream == null)
+				throw new ArgumentNullException("stream");
+			if (!stream.CanRead)
+				throw new ArgumentException("stream must be readable.", "stream");
+
+			baseStream = stream;
+		}
+
+		public sealed override bool CanSeek { get { return false; } }
+		public sealed override bool CanRead { get { return true; } }
+		public sealed override bool CanWrite { get { return false; } }
+
+		public sealed override long Length { get { throw new NotSupportedException(); } }
+		public sealed override long Position
+		{
+			get { throw new NotSupportedException(); }
+			set { throw new NotSupportedException(); }
+		}
+
+		public sealed override long Seek(long offset, SeekOrigin origin) { throw new NotSupportedException(); }
+		public sealed override void SetLength(long value) { throw new NotSupportedException(); }
+		public sealed override void Write(byte[] buffer, int offset, int count) { throw new NotSupportedException(); }
+		public sealed override void Flush() { throw new NotSupportedException(); }
+
+		public sealed override int Read(byte[] buffer, int offset, int count)
+		{
+			var copied = 0;
+			ConsumeData(buffer, offset, count, ref copied);
+
+			var finished = false;
+			while (copied < count && !finished)
+			{
+				finished = BufferData(baseStream, data);
+				ConsumeData(buffer, offset, count, ref copied);
+			}
+
+			return copied;
+		}
+
+		/// <summary>
+		/// Reads data into a buffer, which will be used to satisfy <see cref="Read(byte[], int, int)"/> calls.
+		/// </summary>
+		/// <param name="baseStream">The source stream from which bytes should be read.</param>
+		/// <param name="data">The queue where bytes should be enqueued. Do not dequeue from this buffer.</param>
+		/// <returns>Return true if all data has been read; otherwise, false.</returns>
+		protected abstract bool BufferData(Stream baseStream, Queue<byte> data);
+
+		void ConsumeData(byte[] buffer, int offset, int count, ref int copied)
+		{
+			while (copied < count && data.Count > 0)
+				buffer[offset + copied++] = data.Dequeue();
+		}
+
+		protected override void Dispose(bool disposing)
+		{
+			if (disposing)
+				baseStream.Dispose();
+			base.Dispose(disposing);
+		}
+	}
+}