DevExpress 表格显示分组小计与总计(GroupSummary.Add)

private void Form2_Load(object sender, EventArgs e)
{
  gc.DataSource = DemoData.GetGoodsList();
  
  //设置分组=SUM
   gv.GroupSummary.Add(new DevExpress.XtraGrid.GridGroupSummaryItem
  {
    FieldName = "Qty",
    SummaryType = DevExpress.Data.SummaryItemType.Sum,
    DisplayFormat = "{0:0.##}",
    ShowInGroupColumnFooter = colQty, //重要！在分组行下面显示
     });
    
    //设置分组=AVG
     gv.GroupSummary.Add(new DevExpress.XtraGrid.GridGroupSummaryItem
    {
      FieldName = "Price",
      SummaryType = DevExpress.Data.SummaryItemType.Average,
      DisplayFormat = "{0:0.##}",
      ShowInGroupColumnFooter = colPrice,
      });
      
      //设置分组=SUM
       gv.GroupSummary.Add(new DevExpress.XtraGrid.GridGroupSummaryItem
      {
        FieldName = "Amount",
        SummaryType = DevExpress.Data.SummaryItemType.Sum,
        DisplayFormat = "{0:0.##}",
        ShowInGroupColumnFooter = colAmount,
        ShowInGroupColumnFooterName = "Amount",
        });
        
        //客户名称分组显示
         gv.Columns["CustomerName"].GroupIndex = 0;
        
        //自动扩展所有分组，显示所有记录
         gv.ExpandAllGroups();
      }

//小计样式1 - 小计在分组最下面
private void button1_Click(object sender, EventArgs e)
{
  gv.OptionsBehavior.AllowPartialGroups = DevExpress.Utils.DefaultBoolean.False;
  gc.RefreshDataSource();
  gv.ExpandAllGroups();
}

//小计样式2 - 小计在分组行显示
private void button2_Click(object sender, EventArgs e)
{
  gv.OptionsBehavior.AllowPartialGroups = DevExpress.Utils.DefaultBoolean.True;
  gc.RefreshDataSource();
  gv.ExpandAllGroups();
}

gv.ClearGrouping();

 //小计在分组最下面
 gvSummary.OptionsBehavior.AllowPartialGroups = DevExpress.Utils.DefaultBoolean.False;

 //设置分组=SUM
 gvSummary.GroupSummary.Add(new DevExpress.XtraGrid.GridGroupSummaryItem
 {
     FieldName = "TotalOrderQty",
     SummaryType = DevExpress.Data.SummaryItemType.Sum,
     ShowInGroupColumnFooter = colTotalOrderQty, //订单数量
 });

 //设置分组=SUM
 gvSummary.GroupSummary.Add(new DevExpress.XtraGrid.GridGroupSummaryItem
 {
     FieldName = "TotalQty",
     SummaryType = DevExpress.Data.SummaryItemType.Sum,                
     ShowInGroupColumnFooter = colTotalQty, //发货数量
 });

 //设置分组=SUM
 gvSummary.GroupSummary.Add(new DevExpress.XtraGrid.GridGroupSummaryItem
 {
     FieldName = "TotalAmount",
     SummaryType = DevExpress.Data.SummaryItemType.Sum,
     DisplayFormat = "{0:0.##}",
     ShowInGroupColumnFooter = colTotalAmount, //金额
 });