CCT.NUI.HandTracking.IdGenerator.GetNextId C# (CSharp) Method

        public int GetNextId()
        {
            var nextId = 1;
            while (this.usedIds.Contains(nextId))
            {
                nextId++;
            }
            this.usedIds.Add(nextId);
            return nextId;
        }

        private IList <FingerPoint> MapFingerPoints(IList <FingerPoint> oldFingerPoints, IList <FingerPoint> newFingerPoints)
        {
            var idGenerator = new IdGenerator();
            var distanceMap = new DistanceMap <FingerPoint, FingerPoint>(oldFingerPoints);

            distanceMap.Map(newFingerPoints);
            foreach (var tuple in distanceMap.MappedItems)
            {
                idGenerator.SetUsed(tuple.Item1.Id);
                tuple.Item2.Id         = tuple.Item1.Id;
                tuple.Item2.FrameCount = tuple.Item1.FrameCount + 1;
            }
            foreach (var newFinger in distanceMap.UnmappedItems)
            {
                newFinger.Id = idGenerator.GetNextId();
            }
            foreach (var discontinuedFinger in distanceMap.DiscontinuedItems)
            {
                discontinuedFinger.NegativeFrameCount++;
            }

            return(distanceMap.MappedItems.Select(i => i.Item2)
                   .Union(distanceMap.UnmappedItems)
                   .Union(distanceMap.DiscontinuedItems)
                   .Where(i => i.NegativeFrameCount <= this.settings.FramesForDiscontinuedFingerPoint).ToList());
        }