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Applying Themes to Master Pages You can apply themes to Master Pages in same way you apply themes to an .aspx page. For example, you could allow users to choose background colors for the various table cells that make up a Master Page layout. Step 1 would be to open the Master Page and set the Style property of each table cell to a class name. Remove any explicitly-set Style properties that would conflict with the theme. In Figure 10-17, for example, I removed the Style properties for the top table cell, and changed the Class property to a MasterTop. And though they re not visible in the figure, I removed the Style properties from the left column as well, and set its Class property to MasterLeft. Close and save the Master Page. Then in your main style sheet (if you have one), set a default style for both elements as in the examples given here: TD.MasterTop { background-color: e0ffff; border-bottom: #483d8b thin solid; } TD.MasterLeft { background-color: #fffff0; border-right: #483d8b thin solid; } TD.MasterTop TD.MasterLeft Figure 10-17: Master Page. master with CSS classes applied to table cells. Chapter 10: Using Themes 217
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You don t have to program the button to do anything, because if you just drag a button from the Standard tools into the page, it will automatically do a postback when clicked later, in the browser. So basically you d end up with something like Figure 10-16. The only control on that page that has an event handler is the ListBox control, which is handled by the ListBox1_SelectedIndexChanged shown in Figure 10-15. A theme tester page The ChooseTheme page simply allows a user to choose a theme. The theme won t actually be applied to any pages unless you specifically apply it. Then the theme of choice is the current user s preferred theme. So you need a PreInit handler on every page that will apply the theme. To test it out, create a page named ThemeTester.aspx, and provide a link to it from the ChooseTheme.aspx page, as I did in Figure 10-16. In ThemeTester you can put any text or controls you want. But most importantly your code must apply the theme, like this: protected void Page_PreInit(object sender, EventArgs e) { if (Profile.PreferredTheme == null) { Page.Theme = DefaultTheme ; } else { Page.Theme = Profile.PreferredTheme; } } That should be all that s required in the code-behind page of any page to which you want to apply user s preferred themes. After you get things working in ChooseTheme.aspx and ThemeTester.aspx, then it s just a matter of copying that same Page_PreInit handler to any page that needs to apply a user-selected theme. Figure 10-16: A Choose Theme. aspx example. 216 Part III: Personalization and Databases
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In the above code, I m assuming that every user will have something in their PreferredTheme profile, mainly because I gave that property a default value in Web.config. Just to play it safe, you could build a little logic into the code so if the PreferredTheme is nothing, then DefaultTheme is used as the preferred theme, as given here (again in C#): protected void Page_PreInit(object sender, EventArgs e) { if (Profile.PreferredTheme == null) { Page.Theme = DefaultTheme ; } else { Page.Theme = Profile.PreferredTheme; } } The final C# code for the ChooseTheme.aspx page looks like Figure 10-15. All well and good save for one little problem unique to this page: The PreInit event fires before the postback which doesn t allow for the theme to be applied to the current page the first time you choose an option from the list box. To get around that, you can add a Preview button to the page beneath the ListBox, and provide some sort of instruction telling the user to click a theme name, then click Preview. Figure 10-15: Here s the C# codebehind page for Choose Theme. aspx. Chapter 10: Using Themes 215
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The C# code needed to copy the selected value to the user s profile is simply this: Profile.PreferredTheme = ListBox1.SelectedValue; Another detail to think about here is the fact that when the user first opens the page, she will already have a theme name selected in her profile. Then the ChooseTheme page first opens; the ListBox control should show that current theme as the selected theme. So in the Page_Load event, you need some code to set the SelectedValue of the ListBox control to whatever is currently in the user s PreferredTheme property. Hence, the Page_Load event needs this statement: ListBox1.SelectedValue = Profile.PreferredTheme; But, as is often the case with page loads, we have to take postbacks into consideration. Every time the user clicks the ListBox control, that s going to cause a postback, as we really only want to load the preferred theme when the user first opens the page. So once again, we need some if not postback logic in the Page_Load event handler, as shown here (in C#): if (!Page.IsPostBack) { ListBox1.SelectedValue = Profile.PreferredTheme; } Applying a theme Given our whole approach to themes in this chapter, it stands to reason that whenever a page loads, its theme must be set to the user s preferred theme. To get that done in your code, simply set Page.Theme to the user s preferred theme. In C#, the code looks like this: Page.Theme = Profile.PreferredTheme; But, you can t set a theme in the Page_Load event because the theme has to be applied before content and controls are rendered on the page. The Page_Load event fires after all that stuff is done, which is too late to apply a theme. So use the Page_PreInitI() event handler instead. You won t necessarily find a predefined pre-init handler in the page. But you can just copy and paste one of the existing handlers into the code and change its name to Page_PreInit. Then type in the code to apply the preferred theme, as given here: protected void Page_PreInit(object sender, EventArgs e) { Page.Theme = Profile.PreferredTheme; } 214 Part III: Personalization and Databases
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Next you populate the ListBox with some options. Click Edit Items and use the ListItem Collection Editor (Figure 10-14) to list options to appear in the control. For each option, enter two things: Text: The text that appears in the box. This can be any text you want. Value: The value that the selection returns. This must exactly match the name of a Theme folder in the App_Themes folder. Each time you click the Add button, you re prompted to enter another item. In Figure 10-14, I ve added an option for each theme. I left the highlighter on the No Squint option to illustrate that it s okay to show No Squint as two words in the list. However, the value of that option must be NoSquint to match the name of the Theme folder. When you click OK in the ListItem Collection Editor, you ll be returned to the page and the options are visible. You can then set the height of the control by dragging its bottom edge (or by setting the Height property in the control s Properties dialog box). Storing the preferred theme When the user makes a selection from the ListBox, that control s SelectedValue property will equal the Value of the selected item. For starters, we need some code to copy the value to the user s PreferredTheme property. To get to the code-behind file, first double-click the ListBox control. The event handler for the ListBox is named ListBox1_SelectedIndexChanged. Figure 10-14: The ListItem Collection Editor. Chapter 10: Using Themes 213
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Okay, at this point there s nothing special about the page. It s just a table with some text, a Textbox control, and a couple of buttons that do nothing. (The Sample2 button has its SkinID property set to Bold to test the Bold skin in my Button.skin themes.) The two top table cells have their Class properties set to ColHead to test the TD.ColHead style in my themes. Creating a control for choosing a theme Next comes the tricky part where I need a control that allows users to choose a theme. The trickiness comes from the fact that as soon as the user chooses a theme, we need to do a postback to the server to update the user s profile and also to apply the theme to the page. But let s start with the control itself. I ll use a ListBox control for this example. Drag a ListBox control from the Standard controls in the Toolbox onto the page. Then choose Enable AutoPostBack from its common tasks menu (as in Figure 10-13), so a postback occurs as soon as the user chooses a theme. Figure 10-13: A ListBox control added to the page. Figure 10-12: A page that uses elements styled by themes. 212 Part III: Personalization and Databases
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That takes care of having a place to store each user s preferred theme. In code, you can use Profile.PreferredTheme whenever you want to get, or set, the current user s preferred theme. Next, you need some means of allowing users to explore themes and choose one, which means some sort of interactive form. Creating a page for viewing themes Next, you d need a page where a user can go and take a look at various themes, and then choose a preferred theme. On my site, this page would go in my MemberPages folder because I d only allow authenticated users to choose themes. So it s just a matter of right-clicking the MemberPages folder and choosing Add New Item. I d choose Web Form as the template, enter ChooseTheme.aspx as my page, choose Visual C# as the language, and check both the check boxes for choosing a Master Page and using a code-behind page. Nothing new or different there. To allow users to choose a theme, you ll need a control that allows users to choose any one of several mutually exclusive options such as a drop-down list, a list box, or perhaps a set of option buttons (although you could just as easily use buttons or links). The page also needs some content that uses styles defined in the themes. That way, when the user chooses a theme, you can simply apply the theme to show the user how the theme looks. How you design the page is entirely up to you, of course. As an example, I started off with the page shown in Figure 10-12. Chapter 10: Using Themes 211
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The control to which you apply a skin won t actually take on the skin s appearance immediately. (That s why the Submit button doesn t look any different from the Reset button in Figure 10-11.) Keep in mind that so far we ve only taken the first step to adding themes to the site. There s still plenty more to do here. There are many ways to implement themes. But it seems to me the most likely scenario would be that you want each member to be able to choose their own theme, which means to be able to store each user s theme preference as a profile property. So let s start with that. Letting Members Choose a Theme If the goal is to allow members to choose a theme, the first thing you ll want to do is create a profile property say, named PreferredTheme in which you store each user s preferred theme. To ensure that each new user has some theme selected, you can give the profile property the name of your default theme. You can add the profile property to the Web.config file as described in Chapter 9. In my example where I already created profile properties, I would just add a new property named PreferredTheme, give it a default value of DefaultTheme, and a data type of System.String as shown in the following code: Figure 10-11: Using skins in pages. 210 Part III: Personalization and Databases
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I ve intentionally kept these skin examples small and simple, so as not to obscure the basic facts with lots of details. But you can style your controls however you see fit. As with background pictures and style sheets, you ll need to create skin files for all your themes. (As you can imagine, one could end up putting a lot of time into this sort of thing.) The result would be as in Figure 10-10, which shows some of my sample theme folders. Though you can t tell from looking at the figure, the Stylesheet.css, Textbox.skin, and Button.skin files in each folder provide a style that s unique to that theme. Using Themes in Pages To take advantage of themes while creating and editing pages, you really don t have to do anything special; as always, style-sheet themes are applied automatically. Default skins are also applied automatically to ASP controls. For example, every Textbox control automatically takes on the appearance of the currently selected theme s Textbox.skin file. If you want a control on a page to use a non-default skin file, just set the control s SkinID property to the name of the skin you want to use. For example, suppose you re creating a new page and you want to add some buttons to it. One of the buttons should use the Bold skin. After you add the button to your page, set its SkinID property to Bold (as in Figure 10-11). Figure 10-10: Each theme can contain its own skin files. Chapter 10: Using Themes 209
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Changing from Design view to Source view reveals the ASP tags for the two buttons, as shown in Figure 10-8. In the figure, I ve already selected the tags for the two buttons, so I can copy them to a skin file. Next, just copy both tags to a new skin file. Because these are for ASP Button controls, you d right-click a theme folder and choose Add New Item. Choose Skin File in the Add New Item dialog box, name the file Button.skin and click Add. Then paste the tags into the skin file. Recall that you always need to remove from the skin file any attribute that will vary from one control to the next. That means you always have to take out the ID= attribute. In the case of a Button control, you also want to remove the Text= attribute because that defines the text that appears on the button. That will vary from one button to the next. (OK buttons, Cancel buttons, Submit buttons, and so forth, all have unique text.) Finally, add a SkinID= yourName attribute to all but the default skin. The yourName part can be anything you like. In the case of my bold button, I d probably use something like SkinID= Bold . In my own Button.skin file I replaced the comment text with the tags. I removed the ID= name and Text= Button attributes from both tags. Then I added a SkinID= Bold to the second button style to differentiate it from the default button style, just above in the same skin file. The result is shown in Figure 10-9 where the Button.skin file in DefaultTheme contains a default skin for buttons, and a Bold skin for buttons. Figure 10-9: New Button.skin file in Default- Theme theme. Figure 10-8: Tags for buttons selected. 208 Part III: Personalization and Databases
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