主题：报表位置问题

请教老师，以下代码中，如果修改变量xx,yy的值，第一个方框的位置为何不随之变动呢？

代码如下 ：
   
   Dim doc As New PrintDoc

    Dim rt As  New prt.RenderText '设置页眉的文本对象
    rt.Text="qwerwqreqwer"
    Doc.PageHeader=rt
   Dim g As New prt.RenderGraphics()

   Dim pn As New Pen(Color.Red,0.1) '画笔
   Dim fnt As New Font("宋体",10)  '文字字体
   Dim points_4cf(4) As Point  '四边形
   Dim points_4lx(4) As Point  ' 菱形
   Dim xx,yy As Integer ''四方形左上点坐标
   Dim ll,hh As Integer '四方形橫长及纵高
  
   xx=52 '节点图左上点横坐标
   yy=152 '节点图左上点纵坐标
   ll=80 '四边形横长
   hh=30 '四边形纵高

   '箭头线条变量
   Dim linelength As Integer =30 '线长
   Dim linelength1 As Integer =4 '箭头线长
   Dim points1(1) As Point '主线条
   Dim points11(1) As Point '箭头左半部
   Dim points12(1) As Point '箭头右半部

Dim s_name As String
   For i As Integer=1 To 10
       s_name="wwwwww"
      g.Graphics.DrawRectangle(pn,xx,yy,ll,hh) '此处的xx,yy值在上面赋值无效???

'文字
       g.Graphics.DrawString(s_name,fnt,Brushes.Red,xx-2,(yy+hh/2)-6)

'竖箭头主线条
       points1(0) = New Point(xx+ll/2, yy+hh)
       points1(1) = New Point(xx+ll/2,yy+hh+linelength)
       g.Graphics.DrawLines(Pens.Green, points1)
'箭头左半部
       points11(0) = New Point(xx+ll/2-linelength1,yy+hh+linelength-linelength1)
       points11(1) = New Point(xx+ll/2,yy+hh+linelength)
       g.Graphics.DrawLines(Pens.Green, points11)
'箭头右半部
       points12(0) = New Point(xx+ll/2+linelength1,yy+hh+linelength-linelength1)
       points12(1) = New Point(xx+ll/2,yy+hh+linelength)
       g.Graphics.DrawLines(Pens.Green, points12)

       yy=yy+hh+linelength  '下方下一个四边形左上点纵坐标

   Next

Doc.Body.Children.Add(g)
Doc.Preview()