SuperMap.WinRT.Actions.DrawPolygon.OnHolding C# (CSharp) Method

        public override void OnHolding(HoldingRoutedEventArgs e)
        {
            base.OnHolding(e);
            if (e.HoldingState == HoldingState.Started)
            {
                //如果只画了小于或等于两个点的话，就不执行完成事件。
                if (_points == null || _points.Count < 2)
                    return;

                while (_points.Count > _pointsCount)
                {
                    _points.RemoveAt(_points.Count - 2);
                }
                Point2D item = Map.ScreenToMap(e.GetPosition(Map));
                _points.Insert(_points.Count - 1, item);
                _pointsCount++;
                endDraw(false);
            }
        }
        private void endDraw(bool isCancel = false)