/// <summary>
/// 트랙 목록으로부터 트랙 그룹 hierarchy를 생성한다.
/// 트랙들은 CreateDate 순서로 정렬되었다고 가정한다.
/// </summary>
/// <param name="tracks"></param>
/// <returns></returns>
private TrackGroup CreateGroupsFromTracks(ListCollectionView tracks)
{
if (tracks.IsEmpty)
return null;
IList<TrackGroup> groups = new List<TrackGroup>();
TrackGroup group = null;
for (int i = 0, count = tracks.Count; i < count; i++) {
Track track = (Track)tracks.GetItemAt(i);
if (group == null || track.CreateDate.Hour != group.Date.Hour) {
group = new TrackGroup(track.CreateDate, TrackGroupLevel.Hour);
groups.Add(group);
}
group.Add(track);
}
TrackGroup root = CreateGroupHierarchy(groups);
return root;
}