From scottwater.com->Scroll Page
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C# |
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1: using System; 2: using System.IO; 3: using System.Text; 4: using System.Text.RegularExpressions; 5: using System.Web.UI; 6: 7: namespace ScottWater.Pages 8: { 9: /// <summary> 10: /// Summary description for ScrollPage. 11: /// </summary> 12: public class ScrollPage : System.Web.UI.Page 13: { 14: public ScrollPage() 15: { 16: 17: } 18: 19: private bool _useScrollPersistence = true; 20: /// <summary> 21: /// There could be PostBack senarios where we do not want to remember the scroll position. Set this property to false 22: /// if you would like the page to forget the current scroll position 23: /// </summary> 24: public bool UseScrollPersistence 25: { 26: get {return this._useScrollPersistence;} 27: set {this._useScrollPersistence = value;} 28: } 29: 30: private string _bodyID; 31: /// <summary> 32: /// Some pages might already have the ID attribute set for the body tag. Setting this property will not render the ID or change 33: /// the existing value. It will simply update the javascript written out to the browser. 34: /// </summary> 35: public string BodyID 36: { 37: get {return this._bodyID;} 38: set {this._bodyID = value;} 39: } 40: 41: 42: //Last chance. Do we want to maintain the current scroll position 43: protected override void OnPreRender(EventArgs e) 44: { 45: if(UseScrollPersistence) 46: { 47: RetainScrollPosition(); 48: } 49: base.OnPreRender (e); 50: } 51: 52: protected override void Render(HtmlTextWriter writer) 53: { 54: //No need processing the HTML if the user does not want to maintain scroll position or already has 55: //set the body ID value 56: if(UseScrollPersistence && BodyID == null) 57: { 58: TextWriter tempWriter = new StringWriter(); 59: base.Render(new HtmlTextWriter(tempWriter)); 60: writer.Write(Regex.Replace(tempWriter.ToString(),"<body","<body id=\"thebody\" ",RegexOptions.IgnoreCase)); 61: } 62: else 63: { 64: base.Render(writer); 65: } 66: } 67: 68: private static string saveScrollPosition = "<script language='javascript'>function saveScrollPosition() {{document.forms[0].__SCROLLPOS.value = {0}.scrollTop;}}{0}.onscroll=saveScrollPosition;</script>"; 69: private static string setScrollPosition = "<script language='javascript'>function setScrollPosition() {{{0}.scrollTop =\"{1}\";}}{0}.onload=setScrollPosition;</script>"; 70: 71: //Write out javascript and hidden field 72: private void RetainScrollPosition() 73: { 74: RegisterHiddenField("__SCROLLPOS", "0"); 75: string __bodyID = BodyID == null ? "thebody" : BodyID; 76: RegisterStartupScript("saveScroll", string.Format(saveScrollPosition,__bodyID)); 77: 78: if(Page.IsPostBack) 79: { 80: RegisterStartupScript("setScroll", string.Format(setScrollPosition,__bodyID, Request.Form["__SCROLLPOS"])); 81: } 82: } 83: } 84: } |
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VB.NET |
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Imports System Imports System.IO Imports System.Text Imports System.Text.RegularExpressions Imports System.Web Imports System.Web.UI Namespace ScottWater.Pages Public Class ScrollPage Inherits System.Web.UI.Page Public Sub ScrollPage() End Sub Private m_UseScrollPersistence As Boolean = True Private m_BodyID As String Private saveScrollPosition As String = "<script language='javascript'>function saveScrollPosition() {{document.forms[0].__SCROLLPOS.value = {0}.scrollTop;}}{0}.onscroll=saveScrollPosition;</script>" Private setScrollPosition As String = "<script language='javascript'>function setScrollPosition() {{{0}.scrollTop =""{1}"";}}{0}.onload=setScrollPosition;</script>" Public Property UseScrollPersistence() As Boolean Get Return m_UseScrollPersistence End Get Set(ByVal Value As Boolean) m_UseScrollPersistence = Value End Set End Property Public Property BodyID() As String Get Return m_BodyID End Get Set(ByVal Value As String) m_BodyID = Value End Set End Property Protected Overrides Sub OnPreRender(ByVal e As EventArgs) If UseScrollPersistence Then 'call the routine to add the javascript RetainScrollPosition() End If MyBase.OnPreRender(e) End Sub Protected Overrides Sub Render(ByVal writer As HtmlTextWriter) If UseScrollPersistence And (BodyID = Nothing) Then Dim tempWriter As TextWriter = New StringWriter MyBase.Render(New HtmlTextWriter(tempWriter)) writer.Write(Regex.Replace(tempWriter.ToString(), "<body", "<body id=""thebody"" ", RegexOptions.IgnoreCase)) Else MyBase.Render(writer) End If End Sub Private Sub RetainScrollPosition() Me.Page.RegisterHiddenField("__SCROLLPOS", "0") Dim s_bodyID As String If BodyID = Nothing Then s_bodyID = "thebody" Else s_bodyID = BodyID RegisterStartupScript("saveScroll", String.Format(saveScrollPosition, s_bodyID)) If (Page.IsPostBack) Then RegisterStartupScript("setScroll", String.Format(setScrollPosition, s_bodyID, context.Request.Form("__SCROLLPOS"))) End If End Sub End Class End Namespace |
