前端使用<asp:placeholder id="ChartHolder" runat="server"></asp:placeholder>来显示图形
<asp:button id="btnChg" Runat="server" Text="数值取反"></asp:button>
后台文件:
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Not Page.IsPostBack Then
showpic(1)
End If
End Sub
Private Sub btnChg_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnChg.Click
showpic(-1)
End SubPrivate Sub showpic(ByVal iFlg As Integer)
strDsp = "a" & Chr(9) & "b" & Chr(9)
For i = 1 To 12
strVal = strVal & iFlg * i & Chr(9)
next Dim strRelativePath As String = "pic.gif"
'把图片添加到placeholder.
Dim strImageTag As String = "<IMG SRC='" + strRelativePath + "'/>"
ChartHolder.Controls.Clear()
ChartHolder.Controls.Add(New LiteralControl(strImageTag))
end sub初始图形显示正常的,但是点按钮“数值取反”后,图形显示没有变化,但本地保存的图形已经变了,刷新后可以显示数值取反后的结果,请问这是什么原因?该如何修改?谢谢!
<asp:button id="btnChg" Runat="server" Text="数值取反"></asp:button>
后台文件:
Private Sub Page_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
If Not Page.IsPostBack Then
showpic(1)
End If
End Sub
Private Sub btnChg_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles btnChg.Click
showpic(-1)
End SubPrivate Sub showpic(ByVal iFlg As Integer)
strDsp = "a" & Chr(9) & "b" & Chr(9)
For i = 1 To 12
strVal = strVal & iFlg * i & Chr(9)
next Dim strRelativePath As String = "pic.gif"
'把图片添加到placeholder.
Dim strImageTag As String = "<IMG SRC='" + strRelativePath + "'/>"
ChartHolder.Controls.Clear()
ChartHolder.Controls.Add(New LiteralControl(strImageTag))
end sub初始图形显示正常的,但是点按钮“数值取反”后,图形显示没有变化,但本地保存的图形已经变了,刷新后可以显示数值取反后的结果,请问这是什么原因?该如何修改?谢谢!
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