LoopStream.cs

/*
 * Copyright 2017 Alexandr Kolodkin <alexandr.kolodkin@gmail.com>
 * 
 * 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.
 * 
 * 
 * Product  : Rapid SCADA
 * Module   : ModAlarm
 * Summary  : Server module logic
 * 
 * Author   : Alexandr Kolodkin
 * Created  : 2017
 * Modified : 2017
 */

using NAudio.Wave;

/// <summary>
/// Stream for looping playback
/// </summary>
public class LoopStream : WaveStream
{
    WaveStream sourceStream;

    /// <summary>
    /// Creates a new Loop stream
    /// </summary>
    /// <param name="sourceStream">The stream to read from. Note: the Read method of this stream should return 0 when it reaches the end
    /// or else we will not loop to the start again.</param>
    public LoopStream(WaveStream sourceStream)
    {
        this.sourceStream = sourceStream;
        this.EnableLooping = true;
    }

    /// <summary>
    /// Use this to turn looping on or off
    /// </summary>
    public bool EnableLooping { get; set; }

    /// <summary>
    /// Return source stream's wave format
    /// </summary>
    public override WaveFormat WaveFormat
    {
        get { return sourceStream.WaveFormat; }
    }

    /// <summary>
    /// LoopStream simply returns
    /// </summary>
    public override long Length
    {
        get { return sourceStream.Length; }
    }

    /// <summary>
    /// LoopStream simply passes on positioning to source stream
    /// </summary>
    public override long Position
    {
        get { return sourceStream.Position; }
        set { sourceStream.Position = value; }
    }

    public override int Read(byte[] buffer, int offset, int count)
    {
        int totalBytesRead = 0;

        while (totalBytesRead < count)
        {
            int bytesRead = sourceStream.Read(buffer, offset + totalBytesRead, count - totalBytesRead);
            if (bytesRead == 0)
            {
                if (sourceStream.Position == 0 || !EnableLooping)
                {
                    // something wrong with the source stream
                    break;
                }
                // loop
                sourceStream.Position = 0;
            }
            totalBytesRead += bytesRead;
        }
        return totalBytesRead;
    }
}