怎么修改不指定每页行数呀，代码如下

Dim doc As New PrintDoc

Dim tb As Table = Tables("计算表")

Dim prs As Integer = 20 \'每页20行

Dim sum1 As Integer = 0 \'数量小计

Dim sum2 As Double = 0 \'金额小计

Dim tsum1 As Integer = 0 \'数量总计

Dim tsum2 As Double = 0 \'金额总计

Dim idx1 As Integer= tb.cols("重量t").Index

Dim idx2 As Integer= tb.cols("油漆面积㎡").Index

For p As Integer = 0 To math.Ceiling(tb.Rows.Count / prs) - 1

    Dim rt As New prt.RenderTable

    rt.Style.Gridlines.All = New prt.Linedef(Color.Gray)

    rt.CellStyle.Spacing.All = 0.5

    sum1 = 0

    sum2 = 0

    For c As Integer = 0 To tb.Cols.Count - 1

        rt.Cells(0,c).Text = tb.Cols(c).Name

    Next

    For r As Integer = p * prs To math.min(tb.Rows.Count - 1,( p + 1) * prs - 1)

        sum1 =sum1 + tb.rows(r)("重量t")

        sum2 =sum2 + tb.rows(r)("油漆面积㎡")

        For c As Integer = 0 To tb.Cols.Count - 1

            rt.Cells(r - p * prs + 1, c).Text = tb.rows(r)(c)

        Next

    Next

    tsum1 = tsum1 + sum1

    tsum2 = tsum2 + sum2

    rt.Rows.Count = rt.Rows.Count + 1 \'增加本页小计行

    rt.Rows(rt.Rows.count -1)(0).text = "本页小计"

    rt.Rows(rt.Rows.count -1)(idx1).text = sum1

    rt.Rows(rt.Rows.count -1)(idx2).text = sum2

    If p = math.Ceiling(tb.Rows.Count / prs) - 1 \'如果是最后一页

        rt.Rows.Count = rt.Rows.Count + 1 \'增加总计行

        rt.Rows(rt.Rows.count -1)(0).text = "总计"

        rt.Rows(rt.Rows.count -1)(8).text = tsum1

        rt.Rows(rt.Rows.count -1)(9).text = tsum2

    Else

        rt.BreakAfter = prt.BreakEnum.Page \'否则换页

    End If

    doc.Body.Children.Add(rt)

Next

doc.Preview()

比如