Hi Sina:The dynamic Nodes in the TreeView are generated with id values so I used the JavaScript to find the SelectedNode carried in the hidden field and then the JavaScript GetElementById function to position the focus to that element. Man, JavaScript is cool! Seems like something I'll be doing more of. Reading about it it sounded so scary to work with but it's really pretty logical and easy compared to the complexity of Visual anything!
Rick Farmington Mich. USA----- Original Message ----- From: "Sina Bahram" <sbahram@xxxxxxxxx>
To: <programmingblind@xxxxxxxxxxxxx> Sent: Monday, October 22, 2007 11:07 AM Subject: RE: JavaScript Statement Question, resolved sort of
Arrays are 0 based, so if you want to select the fifth element, the index should be 4. Take care, Sina ________________________________ From: programmingblind-bounce@xxxxxxxxxxxxx [mailto:programmingblind-bounce@xxxxxxxxxxxxx] On Behalf Of Richard Thomas Sent: Monday, October 22, 2007 11:02 AM To: programmingblind@xxxxxxxxxxxxx Subject: Re: JavaScript Statement Question, resolved sort of Hi aAll: Well, never found out what the apparent index was for. However, I used the value picked from the hidden field and used it to scroll to and set focus on the desired node in the tree view and it'sworking. Only thingy is the focus appears to be on the next node after thenode I set focus on. Likely the focus is set at the end of the selected node. There may be a way to back it up to the beginning of the node butthat's a minor problem compared to manually scrolling through many nodes onevery expand or collapse, Phew! Done enough for now! So my first real JavaScript is working, yah! Rick Farmington Mich. USA----- Original Message ----- From: Richard Thomas <mailto:rthomas@xxxxxxxxxxx>To: programmingblind@xxxxxxxxxxxxx Sent: Sunday, October 21, 2007 12:25 PM Subject: Re: JavaScript Statement Question Hi Jim: Here is the actual article I'm evaluating. I get everything except that bloody {0} It's not very long and you can just blast to where I labeled RtHere if you want to see it used in context. Here is the original article: devised the followingsolution. First, the TreeView knows which node is selected because SelectedNode is a property of the TreeView control. This information has to be stored somewhere, nd what is selected ultimately is rendered as HTML. If I know the ID of the selected HTML control, then I should be able to scroll and focus it. Sure enough, if you look at the source HTML of a page with a TreeView on it, you will find the declaration of a hidden <INPUT> tag-think text box-whose ID is approximately RtHere, this is what the GetElementId will point to to get the value. TreeViewx_SelectedNode: <input type="hidden" name="TreeView1_SelectedNode" id="TreeView1_SelectedNode" value="TreeView1t54" /> With this knowledge, the idea is that a hidden input control is basically a textbox and all you need to do is figure out what the contents are. A TreeView is rendered as an HTML table-that's all ASP.NET controls are, little HTML code generators-and the value field is the client identifier of a table cell, a <TD> tag representing the node. So find the ID of the cell tag, scroll it into view, and you are done. [Note to ASP.NET team: This should be a property of the TreeView. Thank you.] To demonstrate, I wrote some code to generate a really full TreeView. The Page_Load event injects some JavaScript to find and focus the table cell (see Listing 1) and the <body> tag's onload event calls this injected function. Listing 1: The Code Behind That Fills a Treeview and Injects the JavaScript Imports System.Collections.Generic Partial Class _Default Inherits System.Web.UI.Page Protected Sub Page_Load(ByVal sender As Object, _ ByVal e As System.EventArgs) Handles Me.Load InjectLoadEvent() If (IsPostBack) Then Return TreeView1.Nodes.Clear() Dim chicken As New TreeNode("Chicken") TreeView1.Nodes.Add(chicken) Dim beef As New TreeNode("Beef") TreeView1.Nodes.Add(beef) RtHere, I removed the rest of the demo nodes. TreeView1.CollapseAll() End Sub Public Sub InjectLoadEvent() Dim script As String = _ "function LoadEvent()" + _ {" + _ " try" + _ " {{" + _ RtHere: here is the actual statement. The rendered Html is below. " var elem = document.getElementById('{0}_SelectedNode');" + _" if(elem != null )" + _ " {{" + _ " var node = document.getElementById(elem.value);" + _ " if(node != null)" + _ " {{" + _ " node.scrollIntoView(true);" + _ " {1}.scrollLeft = 0;" + _ " }}" + _ " }}" + _ " }}" + _ " catch(oException)" + _ " {{}}" + _ "}}" Page.ClientScript.RegisterClientScriptBlock(Me.GetType(), "LoadEvent", _ String.Format(script, TreeView1.ClientID, Panel1.ClientID), True) End Sub End Class Listing 2 shows the complete page. Listing 2: The ASP Code That Defines the Appearance of this Relatively Simple Page <%@ Page Language="VB" AutoEventWireup="false" CodeFile="Default.aspx.vb" Inherits="_Default" %> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd";> <html xmlns="http://www.w3.org/1999/xhtml"; > <head runat="server"> <title>Focus Tree Node on Postback</title> </head> <body onload="LoadEvent()"> <form id="form1" runat="server"> <div> <asp:Panel ID="Panel1" runat="server" Height="200px" Width="200px" ScrollBars="Both"> <asp:TreeView ID="TreeView1" runat="server"> <SelectedNodeStyle BackColor="#8080FF" /> </asp:TreeView> </asp:Panel> </div> </form> </body> </html> Figure 1 presents an example of what the simple page looks like. Click here for a larger image. Figure 1: A TreeView Nested in a Scrollable Panel Control (in IE7) Finally, Listing 3 shows the resultant JavaScript, which is the interesting part. RtHere:, the rendered version. Listing 3: The Injected JavaScript <script> function LoadEvent() { try { var elem = document.getElementById('TreeView1_SelectedNode'); if(elem != null ) { var node = document.getElementById(elem.value); if(node != null) { node.scrollIntoView(true); Panel1.scrollLeft = 0; } } } catch(oException) {} }// --> </script> The JavaScript function LoadEvent finds the hidden input field. I injected all of the code expect the ClientID of the TreeView, which in this case is TreeView1 but in deeply nested pages can have an ungodly long name. When I get that control, I use its value property to find the table cell, and with that control I invoke scrollIntoView. The scrollLeft f property keeps the Panel scrolled to the left. And it works!----- Original Message ----- From: Jim <mailto:jhomme1028@xxxxxxxxx>To: programmingblind@xxxxxxxxxxxxx Sent: Sunday, October 21, 2007 10:40 AM Subject: Re: JavaScript Statement Question Hi Richard, I think it should be brackets rather than braces. Brackets contain indexes to array items. Thanks. Jim __________ Take back your shopping life at http://tinyurl.com/32rsxz----- Original Message ----- From: Richard Thomas <mailto:rthomas@xxxxxxxxxxx>To: programmingblind@xxxxxxxxxxxxx Sent: Sunday, October 21, 2007 7:55 AM Subject: JavaScript Statement Question Hi: In this statement what is the '{0}'? " var elem = document.getElementById('{0}_SelectedNode');" I know the single parameterinside the GetElementById is the Id Tagg value of the control to look up but the tag he looks up has an id of something like Panel1_SelectedNode that it looks like he may be replacing with the {0} in the GetElementById Statement.haven't found anything, actually too much, on the statement but nothing using '{0}'. What is it called, index or something and what does it mean? I'll dig around more if I can find something to google on that points to this particular syntax. My guess is it has to do with a Document Control relative Reference or something but I just can't find anything like it googling so far. Thanks:Rick Farmington Mich. USA __________ View the list's information and change your settings at//www.freelists.org/list/programmingblind
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