/// <summary>
/// Returns the index for the next track counted from a track index,
/// handling multiple discs.
/// This assumes that a track with the specified index exists.
/// </summary>
/// <param name="index">Track index from which to start counting.</param>
/// <returns>Index of the next track. Empty if the index parameter specifies the first track on the first disc.</returns>
public virtual TrackIndex NextTrackIndex(TrackIndex index)
{
// Last track on disc, move to the next disc.
if (index.TrackNumber >= GetNextTrackNumber(index.DiscNumber) - 1)
{
return(new TrackIndex(index.DiscNumber + 1, 1));
}
return(new TrackIndex(index.DiscNumber, index.TrackNumber + 1));
}
/// <summary>
/// Returns the index for the previous track counted from a track index,
/// handling multiple discs.
/// This assumes that a track with the specified index exists.
/// </summary>
/// <param name="index">Track index from which to start counting.</param>
/// <returns>Index of the previous track. Empty if the index parameter specifies the first track on the first disc.</returns>
public virtual TrackIndex PreviousTrackIndex(TrackIndex index)
{
if (index.TrackNumber == 1)
{
if (index.DiscNumber == 1)
{
return(TrackIndex.Empty);
}
var discNum = index.DiscNumber - 1;
var trackNum = GetNextTrackNumber(discNum) - 1;
return(new TrackIndex(discNum, trackNum));
}
return(new TrackIndex(index.DiscNumber, index.TrackNumber - 1));
}