参考：
http://www.foxtable.com/webhelp/topics/1409.htm
Dim Chart As WinForm.Chart
Chart = e.Form.CreateControl("Chart1", ControlTypeEnum.Chart)
Dim Series As WinForm.ChartSeries
Chart.ChartType = ChartTypeEnum.Bar '设置图表类型
Chart.SeriesList.Clear() '清除图表原来的图系
……