public override void onDataChange(DataSnapshot dataSnapshot)
            {
                foreach (DataSnapshot segmentSnapshot in dataSnapshot.Children)
                {
                    Segment segment = segmentSnapshot.getValue(typeof(Segment));
                    buffer.drawPath(DrawingView.getPathForPoints(segment.Points, scale), DrawingView.paintFromColor(segment.Color));
                }
                string encoded = encodeToBase64(b);

                metadataRef.child("thumbnail").setValue(encoded, new CompletionListenerAnonymousInnerClassHelper2(this));
            }