ASP.NET 4 Unleased - p 30 docx

LISTING 5.21 Web.Config Loading Master Pages Dynamically for Multiple Content Pages In the previous section, you learned how to load a Master Page dynamically for a single page

case “Dynamic2”:

Profile.MasterPageFile = “Dynamic2.master”;

break;

}

}

MasterPageFile = Profile.MasterPageFile;

}

</script>

<asp:Content

ID=”Content1”

ContentPlaceHolderID=”ContentPlaceHolder1”

Runat=”Server”>

Select a Master Page:

<ul class=”selectMaster”>

<li>

<a href=”DynamicContent.aspx?master=Dynamic1”>Dynamic Master 1</a>

</li>

<li>

<a href=”DynamicContent.aspx?master=Dynamic2”>Dynamic Master 2</a>

</li>

</ul>

</asp:Content>

The page in Listing 5.20 contains two links Both links include a query string parameter

named master, which represents the name of a Master Page When you click the first link,

the Dynamic1.master Master Page loads (see Figure 5.7) and when you click the second

link, the Dynamic2.master Master Page loads (see Figure 5.8)

The page in Listing 5.20 includes a Page_PreInit() event handler This handler grabs the

value of the master query string parameter and assigns the value of this parameter to a

Profile property Next, the value of the Profile property is assigned to the page’s

MasterPageFile property Assigning a value to the MasterPageFile property causes a

Master Page to be dynamically loaded

FIGURE 5.7 Displaying the Dynamic1 Master Page

Because the name of the Master Page is assigned to a Profile property, the selected Master

Page loads for a user even if the user returns to the website many years in the future The

Profile object automatically persists the values of its properties for a user across multiple

visits to a website The Profile is defined in the web configuration file contained in

Listing 5.21

LISTING 5.21 Web.Config

<?xml version=”1.0”?>

<configuration>

<system.web>

<profile>

<properties>

<add

name=”MasterPageFile”

defaultValue=”Dynamic1.master” />

</properties>

</profile>

</system.web>

</configuration>

Loading Master Pages Dynamically for Multiple Content Pages

In the previous section, you learned how to load a Master Page dynamically for a single

page in a website However, what if you need to load a Master Page dynamically for every

content page in a website?

The easiest way to apply the same logic to multiple content pages is to create a new

base Page class The file in Listing 5.22 contains a new base Page class named

DynamicMasterPage

NOTE

Add the file in Listing 5.22 to your application’s App_Code folder

LISTING 5.22 DynamicMasterPage.cs

using System;

using System.Web.UI;

using System.Web.Profile;

public class DynamicMasterPage : Page

{

protected override void OnPreInit(EventArgs e)

{

this.MasterPageFile = (string)Context.Profile[“MasterPageFile”];

base.OnPreInit(e);

}

}

The class in Listing 5.22 inherits from the Page class However, it overrides the base Page

class’s OnPreInit() method and adds the logic for loading a Master Page dynamically

After you create a new base Page class, you need to register it in the web configuration file

The web configuration file in Listing 5.23 contains the necessary settings

LISTING 5.23 Web.config

<?xml version=”1.0”?>

<configuration>

<system.web>

<pages pageBaseType=”DynamicMasterPage” />

<profile>

<properties>

<add

name=”MasterPageFile”

defaultValue=”Dynamic1.master” />

</properties>

</profile>

</system.web>

</configuration>

After you register the DynamicMasterPage class as the base Page class, every page in your

application automatically inherits from the new base class Every page inherits the new

OnPreInit() method, and every page loads a Master Page dynamically

Summary

In this chapter, you learned how to share the same content among multiple pages in an

application by taking advantage of Master Pages In the first section, you learned how to

create a Master Page and apply it to multiple content pages You also learned how to nest

Master Pages and how to register a Master Page in the web configuration file

The next section explored various techniques of modifying a Master Page from a particular

content page You learned how to use the Title attribute, use the Page.Header property,

expose properties in a Master Page, and use the FindControl() method

Finally, you learned how you can dynamically load different Master Pages and associate a

particular Master Page with a particular content page at runtime You learned how you can

save a user’s Master Page preference by using the Profile object

Designing Websites

with Themes

Creating Themes Adding Skins to Themes Adding Cascading Style Sheets

to Themes Creating Global Themes Applying Themes Dynamically Summary

An ASP.NET Theme enables you to apply a consistent style

to the pages in your website You can use a Theme to

control the appearance of both the HTML elements and

ASP.NET controls that appear in a page

Themes are different than Master Pages A Master Page

enables you to share content across multiple pages in a

website A Theme, on the other hand, enables you to

control the appearance of the content

In this chapter, you learn how to create and apply ASP.NET

Themes First, you learn how to create Skins, which enable

you to modify the properties of an ASP.NET control that

have an effect on its appearance You learn how to create

both Default and Named Skins

Next, you learn how to format both HTML elements and

ASP.NET controls by adding Cascading Style Sheets (CSS) to

a Theme, which enable you to control the appearance and

layout of pages in a website in a standards-compliant

manner

You also learn how you can create Global Themes, which

can be used by multiple applications located on the same

server You learn how to use Global Themes with both file

systems and HTTP-based websites

Finally, you learn how to load Themes and Skins

dynami-cally at runtime You build a page that each user of a

website can customize by skinning

Creating Themes

You create a Theme by adding a new folder to a special folder in your application named

App_Themes Each folder that you add to the App_Themes folder represents a different

Theme

If the App_Themes folder doesn’t exist in your application, you can create it It must be

located in the root of your application

VISUAL WEB DEVELOPER NOTE

When using Visual Web Developer, you can create a new Theme folder by right-clicking

the name of your project in the Solution Explorer window and selecting Add Folder,

Theme Folder

A Theme folder can contain a variety of different types of files, including images and text

files You also can organize the contents of a Theme folder by adding multiple subfolders

to a Theme folder

Following are the most important types of files in a Theme folder:

Skin Files

Cascading Style Sheet Files

In the following sections, you learn how to add both Skin files and CSS files to a Theme

WARNING

Be careful about how you name your Theme (the folder name) The contents of a

Theme folder are automatically compiled in the background into a new class Don’t

name a Theme with a class name that conflicts with an existing class name in your

project

Adding Skins to Themes

A Theme can contain one or more Skin files A Skin enables you to modify any of the

properties of an ASP.NET control that have an effect on its appearance

For example, imagine that you decide that you want every TextBox control in your web

application to appear with a yellow background color and a dotted border If you add the

file in Listing 6.1 to the Simple Theme (the App_Themes\Simple folder), you can modify

the appearance of all TextBox controls in all pages that use the Simple Theme

LISTING 6.1 Simple\TextBox.skin

<asp:TextBox

BackColor=”Yellow”

BorderStyle=”Dotted”

Runat=”Server” />

The Skin file in Listing 6.1 is named TextBox.skin You can name a Skin file anything you

want I recommend following a naming convention in which you name the Skin file after

the name of the control that the Skin modifies

A Theme folder can contain a single Skin file that contains Skins for hundreds of controls

Alternatively, a Theme can contain hundreds of Skin files, each of which contains a single

Skin It doesn’t matter how you organize your Skins into files because everything in a

Theme folder eventually gets compiled into one Theme class

The Skin file in Listing 6.1 contains a declaration of a TextBox control The TextBox

control includes a BackColor property set to the value Yellow and a BorderStyle property

set to the value Dotted

The TextBox control includes a Runat=”Server” attribute, but it does not include an ID

attribute You must always include a Runat attribute, but you can never include the ID

attribute when declaring a control in a Skin

NOTE

You can’t create a Skin that applies to the properties of a User Control However, you

can skin the controls contained inside a User Control

The Skin is applied to every page to which the Simple Theme is applied For example, the

page in Listing 6.2 uses the Simple Theme

LISTING 6.2 ShowSkin.aspx

<%@ Page Language=”C#” Theme=”Simple” %>

<!DOCTYPE html PUBLIC “-//W3C//DTD XHTML 1.1//EN”

“http://www.w3.org/TR/xhtml11/DTD/xhtml11.dtd”>

<html xmlns=”http://www.w3.org/1999/xhtml” >

<head runat=”server”>

<title>Show Skin</title>

</head>

<body>

<form id=”form1” runat=”server”>

Runat=”server” />

</div>

</form>

</body>

</html>

The page in Listing 6.2 includes a Theme attribute in its <%@ Page %> directive This

attribute causes the Simple Theme to be applied to the page

When you open the page in Listing 6.2, the Label control appears with a yellow

back-ground color and dotted border This is the backback-ground color and border specified by the

Theme (see Figure 6.1)

Only certain control properties are “themeable.” In other words, you can create a Skin file

that modifies only certain properties of a control In general, you can use a Skin to modify

properties that have an effect on a control’s appearance but not its behavior For example,

you can modify the BackColor property of a TextBox control but not its AutoPostBack

property

NOTE

By default, all control properties are themeable (can be modified in a Skin file)

However, certain control properties are decorated with the Themeable(False)

attribute, which disables theming

FIGURE 6.1 Using a TextBox Skin

Creating Named Skins

In the previous section, we created something called a Default Skin A Default Skin is

applied to every instance of a control of a certain type For example, a Default Skin is

applied to every instance of a TextBox control

You also have the option of creating a Named Skin When you create a Named Skin, you

can decide when you want to apply the Skin For example, you might want required fields

in a form to appear with a red border In that case, you can create a Named Skin and

apply the Skin to only particular TextBox controls

The Skin in Listing 6.3 contains both a Default Skin and a Named Skin for a TextBox

control

LISTING 6.3 Simple2\TextBox.skin

<asp:TextBox

SkinID=”DashedTextBox”

BorderStyle=”Dashed”

BorderWidth=”5px”

Runat=”Server” />

<asp:TextBox

BorderStyle=”Double”

BorderWidth=”5px”

Runat=”Server” />

The first TextBox in Listing 6.3 is an example of a Named Skin and includes a SkinID

property The SkinID property represents the name of the Named Skin You use the value

of this property when applying the Skin in a page

The file in Listing 6.3 also includes a Default Skin for a TextBox control The Default Skin

does not include a SkinID property If a TextBox control in a page is not associated with a

Named Skin, the Default Skin is applied to the TextBox

A Theme can contain only one Default Skin for each type of control However, a Theme can

contain as many Named Skins as you want Each Named Skin must have a unique name

The page in Listing 6.4 contains two TextBox controls The first TextBox control includes a

SkinID attribute This attribute causes the Named Skin to be applied to the control The

second TextBox, on the other hand, does not include a SkinID property The Default Skin

is applied to the second TextBox control