Packaging Skins and Containers | Professional DotNetNuke 4: Open Source Web Application Framework for ASP.NET 2.0 (Programmer to Programmer)

Processing Pages and Loading Skins

The application primarily uses a single page to process the functionality of displaying information to the user, Default.aspx. This page is the container for all the controls and skin elements the application needs to effectively serve its purpose of displaying the content to the portal user. You could refer to Default.apsx as a placeholder for the other information because its content is basic. If you view the source of the page from your IDE, it includes a placeholder for the content to be loaded and some error handling for the application. As you can see in Listing 16-1, there is a lot more that will be injected in the page than it would appear from looking at the code for the page.

Listing 16-1: Default.aspx Source Code

 <%@ Page Language="vb" AutoEventWireup="false" Explicit="True"  Inherits="DotNetNuke.Framework.DefaultPage" CodeFile="Default.aspx.vb" %> <%@ Register TagPrefix="dnn" Namespace="DotNetNuke.Common.Controls"  Assembly=" DotNetNuke" %> <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <html> <head  runat="server">    <title><%= Title %></title>    <%= Comment %>    <meta name="DESCRIPTION" content=<%= Description %>>    <meta name="KEYWORDS" content=<%= KeyWords %>>    <meta name="COPYRIGHT" content=<%= Copyright %>>    <meta name="GENERATOR" content=<%= Generator %>>    <meta name="AUTHOR" content=<%= Author %>>    <meta name="RESOURCE-TYPE" content=" DOCUMENT">    <meta name="DISTRIBUTION" content=" GLOBAL">    <meta name="ROBOTS" content="INDEX, FOLLOW">    <meta name="REVISIT-AFTER" content="1 DAYS">    <meta name="RATING" content="GENERAL">    <meta http-equiv="PAGE-ENTER" content="RevealTrans(Duration=0,Transition=1)">    <style  runat="server"></style>    <asp:placeholder  runat="server"></asp:placeholder>    <asp:placeholder  runat="server"></asp:placeholder>    <script src="/books/3/435/1/html/2/<%= Page.ResolveUrl("js/dnncore.js") %>"></script>    <asp:placeholder  runat="server"></asp:placeholder> </head> <body  runat="server" onscroll="__dnn_bodyscroll()"  bottommargin="0" leftmargin="0"    topmargin="0" rightmargin="0" marginwidth="0" marginheight="0">    <noscript></noscript>    <dnn:Form  runat="server" ENCTYPE="multipart/form-data"  style="" height: 100%;">      <asp:Label  runat="server" Css  Visible="False"></asp:Label>       <asp:PlaceHolder  runat="server" />       <input  runat="server" name="ScrollTop" type="hidden">       <input  runat="server" name="__dnnVariable" type="hidden">    </dnn:Form> </body> </html>

So how does all this work? When a URL is requested and the user enters the application, the request is inspected and the proper skin is determined from the database tables. As you can see in Listing 16-2, the Page_Init goes through a series of logical steps until it finally has a skin value to load. The first step is to determine if the skin to be loaded is an applied preview. You can see an applied preview from several areas where skin selection is possible, such as Page Settings, by clicking the preview link next to the skin selection drop-down list. Doing this opens a new browser window that loads a portal page with the selected skin applied. This is done by adding the SkinSrc query string parameter to the URL. When a page is loaded containing the SkinSrc parameter, its corresponding value, which is the skin name converted for use in the URL, is applied to the page. If this parameter does not exist, the next step is to check the user's cookie for this site to see if it has a skin value set in it.

Listing 16-2: Default.aspx.vb Init_Page Directives

       Private Sub Page_Init(ByVal sender As System.Object, ByVal e As  System.EventArgs) Handles MyBase.Init          ' set global page settings          InitializePage()          ' load skin control          Dim ctlSkin As UserControl = Nothing          ' skin preview          If (Not Request.QueryString("SkinSrc") Is Nothing) Then             PortalSettings.ActiveTab.SkinSrc = SkinController.FormatSkinSrc   (QueryStringDecode(Request.QueryString("SkinSrc")) & ".ascx", PortalSettings)             ctlSkin = LoadSkin(PortalSettings.ActiveTab.SkinSrc)         End If         ' load user skin (based on cookie)         If ctlSkin Is Nothing Then            If Not Request.Cookies("_SkinSrc" & PortalSettings.PortalId.  ToString) Is Nothing Then                If Request.Cookies("_SkinSrc" &  PortalSettings.PortalId.ToString).Value <> "" Then                   PortalSettings.ActiveTab.SkinSrc =  SkinController.FormatSkinSrc(Request.Cookies("_SkinSrc" &  PortalSettings.PortalId.ToString).Value & ".ascx", PortalSettings)                   ctlSkin = LoadSkin(PortalSettings.ActiveTab.SkinSrc)                End If             End If          End If          ' load assigned skin          If ctlSkin Is Nothing Then             If IsAdminSkin(PortalSettings.ActiveTab.IsAdminTab) Then                Dim objSkin As UI.Skins.SkinInfo                objSkin = SkinController.GetSkin(SkinInfo.RootSkin, PortalSettings.PortalId, SkinType.Admin)                If Not objSkin Is Nothing Then                   PortalSettings.ActiveTab.SkinSrc = objSkin.SkinSrc                Else                   PortalSettings.ActiveTab.SkinSrc = ""                End If             End If             If PortalSettings.ActiveTab.SkinSrc <> "" Then                PortalSettings.ActiveTab.SkinSrc =  SkinController.FormatSkinSrc(PortalSettings.ActiveTab.SkinSrc, PortalSettings)                ctlSkin = LoadSkin(PortalSettings.ActiveTab.SkinSrc)             End If          End If          ' error loading skin - load default          If ctlSkin Is Nothing Then             ' could not load skin control - load default skin             If IsAdminSkin(PortalSettings.ActiveTab.IsAdminTab) Then                PortalSettings.ActiveTab.SkinSrc = Common.Globals.HostPath &  SkinInfo.RootSkin & glbDefaultSkinFolder & glbDefaultAdminSkin             Else                PortalSettings.ActiveTab.SkinSrc = Common.Globals.HostPath &  SkinInfo.RootSkin & glbDefaultSkinFolder & glbDefaultSkin             End If             ctlSkin = LoadSkin(PortalSettings.ActiveTab.SkinSrc)          End If          ' set skin path          PortalSettings.ActiveTab.SkinPath =  SkinController.FormatSkinPath(PortalSettings.ActiveTab.SkinSrc)           ' set skin id to an explicit short name to reduce page payload  and make it standards compliant          ctlSkin.ID = "dnn"          ' add CSS links          ManageStyleSheets(False)          ' add Favicon          ManageFavicon()          ' add skin to page          SkinPlaceHolder.Controls.Add(ctlSkin)          ' add CSS links          ManageStyleSheets(True)          ' ClientCallback Logic          DotNetNuke.UI.Utilities.ClientAPI.HandleClientAPICallbackEvent(Me)        End Sub

If the application still does not have a value for the skin to load, and the majority of the time it won't, the application will try to assign a value based on a set of substeps. First, it will look to see if the current page loading is an Admin page. If it is, it will look to the database to get the assigned skin based on the admin skin set in the Site Settings. If no skin was set in the Site Settings, it will then check for a value for the Host Settings admin skin.

In the case where the loading page is not an Admin page, the skin will then be assigned based on the active page's settings. This will check to see if a value exists for this particular page in the database. If it does not, it will then go through a process similar to the Admin page process just discussed. The difference is that instead of checking for the assigned admin skin, it will now check for the assigned portal skin. Also similar to the Admin page skin assignment process, the application will first check for an assignment at the site level, and if no results are found, it will then check for an assignment at the Host level.

Finally, if a skin value has still not been assigned, the application will load the default skin included with every DotNetNuke distribution as the default. It's also important to note that if a skin is found but it has an error that prohibits the framework from rendering it, the default skin with an error message at the top of the rendered page will be loaded.

Once the application is at this point, the ctlSkin variable will have a value. With the ctlSkin variable now populated, the application can move on to creating links in the rendered page for the skin's Cascading Style Sheets. The function responsible for handling this is the ManageStyleSheets function, shown in Listing 16-3. This function is actually called twice from within Page_Init:

The first time it creates a link for the default.css file, located in the Portals/_default/ folder. It then attempts to load a link to the skin.css file if it exists for the current skin package. Finally, the application attempts to load a link to the CSS filename corresponding to the name of the current ASCX skin file being loaded if one exists.
The second time this function is called it simply loads the portal.css file located in the Portals/PortalId folder. By default, unless the portal.css in the Portals/_default folder was hanged prior to the portal being created, the portal.css file is a skeleton file with only the names of the styles commonly used throughout the DotNetNuke user interface.

Listing 16-3: Default.aspx.vb ManageStyleSheets Function

       Private Sub ManageStyleSheets(ByVal PortalCSS As Boolean)          ' initialize reference paths to load the cascading style sheets          Dim objCSS As Control = Me.FindControl("CSS")          Dim objLink As HtmlGenericControl          Dim ID As String          Dim objCSSCache As Hashtable = CType(DataCache.GetCache("CSS"), Hashtable)          If objCSSCache Is Nothing Then             objCSSCache = New Hashtable          End If          If Not objCSS Is Nothing Then             If PortalCSS = False Then                ' default style sheet (required)                ID = CreateValidID(Common.Globals.HostPath)                objLink = New HtmlGenericControl("LINK")                objLink.ID = ID                objLink.Attributes("rel") = "stylesheet"                objLink.Attributes("type") = "text/css"                objLink.Attributes("href") = Common.Globals.HostPath & "default.css"                objCSS.Controls.Add(objLink)                ' skin package style sheet                ID = CreateValidID(PortalSettings.ActiveTab.SkinPath)                If objCSSCache.ContainsKey(ID) = False Then                   If File.Exists(Server.MapPath(PortalSettings.ActiveTab.  SkinPath) & "skin.css") Then                      objCSSCache(ID) = PortalSettings.ActiveTab.SkinPath &  "skin.css"                   Else                       objCSSCache(ID) = ""                   End If                   If Not Common.Globals.PerformanceSetting =  Common.Globals.PerformanceSettings.NoCaching Then                      DataCache.SetCache("CSS", objCSSCache)                   End If                End If                If objCSSCache(ID).ToString <> "" Then                   objLink = New HtmlGenericControl("LINK")                   objLink.ID = ID                   objLink.Attributes("rel") = "stylesheet"                   objLink.Attributes("type") = "text/css"                   objLink.Attributes("href") = objCSSCache(ID).ToString                   objCSS.Controls.Add(objLink)                End If                ' skin file style sheet                ID = CreateValidID(Replace(PortalSettings.ActiveTab.SkinSrc,  ".ascx", ".css"))                If objCSSCache.ContainsKey(ID) = False Then                   If File.Exists(Server.MapPath(Replace   (PortalSettings.ActiveTab.SkinSrc, ".ascx", ".css"))) Then                      objCSSCache(ID) = Replace   (PortalSettings.ActiveTab.SkinSrc, ".ascx", ".css")                   Else                      objCSSCache(ID) = ""                   End If                   If Not Common.Globals.PerformanceSetting =  Common.Globals.PerformanceSettings.NoCaching Then                      DataCache.SetCache("CSS", objCSSCache)                   End If                End If                If objCSSCache(ID).ToString <> "" Then                   objLink = New HtmlGenericControl("LINK")                   objLink.ID = ID                   objLink.Attributes("rel") = "stylesheet"                   objLink.Attributes("type") = "text/css"                   objLink.Attributes("href") = objCSSCache(ID).ToString                   objCSS.Controls.Add(objLink)                End If             Else                ' portal style sheet                ID = CreateValidID(PortalSettings.HomeDirectory)                objLink = New HtmlGenericControl("LINK")                objLink.ID = ID                objLink.Attributes("rel") = "stylesheet"                objLink.Attributes("type") = "text/css"                objLink.Attributes("href") = PortalSettings.HomeDirectory &  "portal.css"                objCSS.Controls.Add(objLink)             End If          End If       End Sub

Note

If you would like an introduction to the default CSS styles used throughout the framework, please review default.css , which contains all the styles with the default values that are applied at run-time. Those default values can also be seen in Table 16-2 later in this chapter.

Note

One final note about the loading of skins is that there is a performance hit with these DB calls and enabling the portal to use this dynamic skinning solution, as there is with any application that can change its appearance on-the-fly. Even though there is a performance hit, this is one of the killer features DotNetNuke contains and is worth the additional overhead the process requires.