To use a rule in a web page, you first need to link the page to the appropriate stylesheet. You dothis by adding a tag in the section of your page. The tag references the file withthe styles you want to use. Here’s an example that allows the page to use styles defined in the file
StyleSheet.css, assuming it’s in the same folder as the web page:
Using ASP.NET 2.0 Skins
In order to see how to use one of these themes, create a basic page, which includes some text, atext box, a button, and a calendar.
You can instantly change the appearance of this page without changing the style of each server control on the page. From within the Page directive, you simply apply an ASP.NET theme that you have either built (shown later in this Model).
Adding the Theme attribute to the Page directive changes the appearance of everything on the page that is defined in an example SmokeAndGlass theme file. Using this theme, when I invoked the page in the browser, I got the result shown in Figure.
Applying a Theme to an Entire Application
In addition to applying an ASP.NET 2.0 theme to your ASP.NET pages using the Theme attribute within the Page directive, you can also apply it at an application level from the Web.config file.
If you specify the theme in the Web.config file, you don’t need to define the theme again in the Page directive of your ASP.NET pages. This theme is applied automatically to each and every page within your application.
Removing Themes from Server Controls
Whether themes are set at the application level or on a page, at times you want an alternative to the theme that has been defined. For example, change the text box server control that you have been working with (from Listing 9-1) by making its background black and using white text:
The black background color and the color of the text in the text box are specified directly in the control itself with the use of the BackColor and ForeColor attributes. If you have applied a theme to the page where this text box control is located, however, you won’t see this black background or white text because these changes are overridden by the theme itself.
To apply a theme to your ASP.NET page but not to this text box control, you simply use the
EnableTheming property of the text box server control:
If you want to turn off theming for multiple controls within a page, consider using the Panel control to encapsulate a collection of controls and then set the EnableTheming attribute of the Panel control to False. This disables theming for each control contained within the Panel control.
Removing Themes from Web Pages
Now what if, when you set the theme for an entire application in the Web.config file, you want to exclude a single ASP.NET page? It is quite possible to remove a theme setting at the page level, just as
it is at the server control level.
The Page directive includes an EnableTheming attribute that can be used to remove theming from your ASP.NET pages. To remove the theme that would be applied by the theme setting in the Web.config, you simply construct your Page directive in the following manner:
This construct sets the theme to nothing—thereby removing any settings that were specified in the
Web.config file. When this directive is set to False at the page or control level, the Theme directory is not searched, and no .skin files are applied. When it is set to True at the page or control level, the
Theme directory is searched and .skin files are applied.
If themes are disabled because the EnableTheming attribute is set to False at the page level, you can still enable theming for specific controls on this page by setting the EnableTheming property for the control to True and applying a specific theme at the same time
