Linking Stylesheets From Content Pages
Personally, I find stylesheets to be the best way to apply formating to web pages. Skins certainly have their uses, but they tend to pad out the HTML with lots of redundant information that can be avoided by referencing a stylesheet, thus reducing download times. Stylesheets can be easily added to themes, but sometimes you don’t want to reference all of your stylesheets on every page, which is what happens if you put stylesheets into a theme.
When using master and content pages, this can be a bit tricky. The common solution isn’t all that difficult, you just have to add a content section inside the header of your master page.
<% Master Language="VB" AutoEventWireup="false" CodeBehind="SystemMaster.Master.vb" Inherits="MyWebApp.SystemMaster" %>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title>Untitled Page</title>
<asp:ContentPlaceHolder ID="HeadEntries" runat="server"></asp:ContentPlaceHolder>
</head>
<body>
<asp:ContentPlaceHolder ID="Body" runat="server"></asp:ContentPlaceHolder>
</body>
</html>
Then on your content page:
<%@ Page Language="vb" AutoEventWireup="false" MasterPageFile="~/SystemMaster.Master" CodeBehind="Page.aspx.vb" Inherits="MyWebApp.Page" title="Untitled Page" %>
<asp:Content ID="HeadEntries" ContentPlaceHolderID="HeadEntries" runat="server">
<link rel="stylesheet" type="text/css" href="styles/styles.css" />
</asp:Content>
<asp:Content ID="Body" ContentPlaceHolderID="Body" runat="server">
Insert Body Here
</asp:Content>
Now this works great for most scenarios, but what if you’re using URL rewriting in order to dynamically generate your pages based on the URL that was requested? In that case, the relative path to the stylesheet won’t work. If you know that your web application will always be the root application on the server, you can use a path that starts with /, but that isn’t always the case. What you really need to do is use an application relative path, starting with a ~/.
Normally you can change your link tag to include runat=”server” and it will process application relative paths in the href attribute. However, this doesn’t work on content pages for some reason. Therefore, I’ve created the class below to help.
Imports System
Imports System.ComponentModel
Imports System.Text
Imports System.Web
Imports System.Web.UI
Imports System.Web.UI.WebControls
<DefaultProperty("href"), ToolboxData("<{0}:SmartLink runat=""server""></{0}:SmartLink>")> _
Public Class SmartLink
Inherits WebControl
<Bindable(True), Category("Behavior"), DefaultValue(""), Localizable(True)> _
Property href() As String
Get
Dim s As String = CStr(ViewState("href"))
If s Is Nothing Then
Return String.Empty
Else
Return s
End If
End Get
Set(ByVal Value As String)
ViewState("href") = Value
End Set
End Property
<Bindable(True), Category("Behavior"), DefaultValue(""), Localizable(True)> _
Property rel() As String
Get
Dim s As String = CStr(ViewState("rel"))
If s Is Nothing Then
Return String.Empty
Else
Return s
End If
End Get
Set(ByVal Value As String)
ViewState("rel") = Value
End Set
End Property
<Bindable(True), Category("Behavior"), DefaultValue(""), Localizable(True)> _
Property type() As String
Get
Dim s As String = CStr(ViewState("type"))
If s Is Nothing Then
Return String.Empty
Else
Return s
End I
End Get
Set(ByVal Value As String)
ViewState("type") = Value
End Set
End Property
Public Overrides Sub RenderBeginTag(ByVal writer As System.Web.UI.HtmlTextWriter)
If rel <> String.Empty Then
writer.AddAttribute(HtmlTextWriterAttribute.Rel, rel)
End If
If type <> String.Empty Then
writer.AddAttribute(HtmlTextWriterAttribute.Type, type)
End If
If href <> String.Empty Then
writer.AddAttribute(HtmlTextWriterAttribute.Href, ResolveClientUrl(href))
End If
writer.RenderBeginTag(HtmlTextWriterTag.Link)
End Sub
End Class
Now you replace the link tag on the content page with this:
<cc1:SmartLink runat="server rel="stylesheet" type="text/css" href="~/styles/style.css" />
That’s it, now you have an application relative stylesheet link on your content page that works with URL rewriting.
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