asp.net c#在updatepanel中支持滚动条记忆功能

在非ajax页面中,只要在page上设置 MaintainScrollPositionOnPostback="true" 即可进行记忆滚动条位置.

但是在ajax中,这个功能却不能正确工作了,那么我们应当如何让div自动维护滚动条位置呢?

首先在页面上增加 asp:panel控件 ,然后在aspx.cs后台 加入以下方法:

///
/// 记住panel的滚动条位置
///
/// panel控件实例
/// ajax更新区域，可以为null，如果为null则执行非ajax逻辑，非ajax逻辑建议直接设置page的MaintainScrollPositionOnPostBack属性
protected  void DoMaintainScrollPosition(Panel panel,UpdatePanel updatePanel=null)
{
StringBuilder sb = new StringBuilder();
sb.AppendLine(@"function Panel_SaveScrollPosition(PanelID){
if(document.getElementById(PanelID)!=null){
document.getElementById(PanelID+'_ScrollPosX').value = document.getElementById(PanelID).scrollLeft;
document.getElementById(PanelID+'_ScrollPosY').value = document.getElementById(PanelID).scrollTop;}}
function Panel_RestoreScrollPosition(PanelID){
if(document.getElementById(PanelID)!=null){
document.getElementById(PanelID).scrollLeft = document.getElementById(PanelID+'_ScrollPosX').value;
document.getElementById(PanelID).scrollTop = document.getElementById(PanelID+'_ScrollPosY').value;}}");

HiddenField x = new HiddenField();
x.ID = panel.ClientID + "_ScrollPosX";
x.ClientIDMode = panel.ClientIDMode;
panel. Controls.Add(x);

HiddenField y = new HiddenField();
y.ID = panel.ClientID + "_ScrollPosY";
y.ClientIDMode = panel.ClientIDMode;
panel. Controls.Add(y);

string sScript = "Panel_SaveScrollPosition('" + panel.ClientID + "');";
if (updatePanel == null)
{
Page.ClientScript.RegisterClientScriptBlock(panel.GetType(), "PanelScrollFunction", sb.ToString(), true);
Page.ClientScript.RegisterOnSubmitStatement(panel.GetType(), panel.ID + "_SavePanelScroll", sScript);
}
else
{
ScriptManager.RegisterClientScriptBlock(updatePanel, panel.GetType(), "PanelScrollFunction", sb.ToString(), true);
ScriptManager.RegisterOnSubmitStatement(updatePanel, panel.GetType(), panel.ID + "_SavePanelScroll", sScript);
}

if (Page.IsPostBack)
{
x.Value = Page.Request.Form[x.ClientID];
y.Value = Page.Request.Form[y.ClientID];
sScript = "Panel_RestoreScrollPosition('" + panel.ClientID + "');";

if (updatePanel == null)
{
Page.ClientScript.RegisterStartupScript(panel.GetType(), panel.ID + "_SetPanelScroll", sScript, true);
}
else
{
ScriptManager.RegisterStartupScript(updatePanel, panel.GetType(), panel.ID + "_SetPanelScroll", sScript, true);
}
}
}

通过以下方法在aspx.cs调用即可

protected void Page_Load(object sender, EventArgs e)
{
DoMaintainScrollPositionForAjax(Panel1,UpdatePanel1);
}