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This chapter is from the book

Controls, Binding, and Styling in Blend

Previous versions of Blend focused on the XAML developer. The Windows 8 version of Blend adds support for HTML to enable the design of Windows Store apps specifically with the following features:

  • Integration with Visual Studio: You can load the same projects in both Visual Studio 2012 and Blend at the same time. In fact, you can load the project you’re currently working on in VS by right-clicking on a project in the Solution Explorer and choosing Open in Blend.
  • Project Templates: Visual Studio 2012 and Blend have the same set of project templates.
  • WYSIWYG Design for HTML: Each page of your app is laid out as you’d see it when the app is running because Blend is actually running your app to display it accurately as you edit.
  • Interactive Mode: You can throw a switch in Blend to run your app interactively as you navigate from page to page; then, when you get to a page you’d like to edit, you can flip the switch again and design the elements currently in view.9
  • HTML Tool Palettes: The full set of controls and options are available from a tool palette and property editor.
  • Layout Simulator: In the same way that VS provides a device simulator, Blend allows your app to be run and edited in one of several sizes and rotations.

Figure 1.9 shows Blend in action on our RSS Reader sample so far.

Figure 1.9

Figure 1.9. Microsoft Blend for Visual Studio 2012

You’ll notice in Figure 1.9 that even though we’re inside Blend, our JavaScript code is executing, which is producing the list of feed titles we have. Blend executes your HTML, JavaScript, and CSS as it detects changes to make sure that you’re editing the live version of your app. Sometimes it gets a little confused, however, so you can kick it in the pants manually with the Refresh button in the upper right of the design surface.

To take advantage of that power, let’s do a little work in Blend. Right now the JavaScript code is generating a bunch of div elements instead of using one of the many controls that comes out of the box for Windows Store development. In particular, we’d like to use a ListView control to display those feed titles. Before we do that, however, we want to open the home.js file either in Blend (via the Projects tab in the upper left) or in Visual Studio 2012 (making sure to save it and let Blend reload it when it asks) to remove the code in the ready function:

 // home.js
(function () {
   "use strict";

   // define the feeds
  window.feeds = new WinJS.Binding.List([
    { title:  "Brandon Satrom", url:  ... },
    ...
  ]);

  WinJS.UI.Pages.define( "/pages/home/home.html", {
    ready: function (element, options) {
       // let the ListView show the feeds
    }
  });
})();

In addition to removing the code in the ready function that creates the div elements for our feed titles, we’ve wrapped our feed data in an instance of the WinJS.Binding.List object, which will let the ListView consume it via data binding.

Once we’ve updated home.js, Blend will show that there are no elements showing the feed data (and if it doesn’t, the Refresh button in the upper right above the design surface will put it right). Instead, it will show the paragraph element that says, “Content goes here.” You can delete that by clicking on it twice—first to select the contenthost element on default.html, and then again to select the paragraph in the hosted home.html—and then pressing the Delete key.

To see the set of WinJS controls so that you can add a ListView control, click on the Assets tab in the top left and choose JavaScript Controls. Figure 1.10 shows the Assets tab and the ListView control.

Figure 1.10

Figure 1.10. Using Blend to add a ListView control to a Windows Store app

Before adding a ListView, make sure you’ve got the section where we’ve been putting our content selected so that it makes a big target. The easiest way to do that is to drill into the Live DOM on the lower left until you find it, as Figure 1.10 also shows. Now, you can drag the ListView from the Assets tab either onto the section tag in the Live DOM or onto the design surface—it’s up to you.

Once you have the ListView in the DOM, you can edit the HTML and CSS properties on the right, as Figure 1.11 shows.

Figure 1.11

Figure 1.11. Using Blend to bind a ListView to a list of data

The Windows App Controls section of the HTML Attributes tab (as seen in Figure 1.11) is where you get to set all of the options specific to a particular control. For the ListView, we want to set the itemDataSource property to bind to the feeds data we created earlier in home.js. Specifically, we want to set itemDataSource to feeds.dataSource, which is a property of the WinJS.Binding.List object we created earlier, specifically for binding with list controls. Once we’ve done that, you’ll see the ListView update itself immediately to show the data, as Figure 1.11 shows, in a jumbled mess.

The problem is that we’re no longer separating the data from the feeds list into the specific parts we want to show (the title) and the parts we don’t want to show (the url). To do that, we’ll need to provide the ListView with a template.

A template is a reusable chunk of HTML that is provided for the purpose of binding items, like what we want to do here. The easiest way to do this is to click on the itemTemplate property right underneath the itemDataSource property and choose the <Create new template> option, which will give you the Create New Template dialog shown in Figure 1.12.

Figure 1.12

Figure 1.12. Using Blend to create a data template

Once you identify your new template, you’ll see that the display has updated a little, as Figure 1.13 shows.

Figure 1.13

Figure 1.13. Using Blend to examine the contents of a data template

By selecting an item from the ListView, you’ll see that the textContent for that item is binding to the entirety of each object, which you can see by clicking on the little square next to the textContent field and choosing Edit Data Binding. The “Binding value” dialog shows the binding to the this value, but we only want to bind to the title property of each object instead of the whole object. To fix this, set the value of the binding to text instead of this, click the Refresh button, and you’ll get exactly what you’re after, as Figure 1.14 shows.

Figure 1.14

Figure 1.14. Using Blend to modify the contents of a data template

Some important stuff is going on under the covers in the HTML with respect to binding and controls that you’ll want to read all about in Chapter 2, “Binding and Controls.”

In addition to editing HTML—especially HTML5, which works well with WinJS—Blend is also excellent at managing CSS styles. To see the set of styles in our project, click on the Style Rules tab on the upper left (Figure 1.15).

Figure 1.15

Figure 1.15. Using Blend to manage the styles in your project

If we want to increase the size of the feed titles to make them more visible, we’ll first want to create a new style, which you can do by right-clicking on home.css, choosing Add Style Rule, and then entering the selector of your new style; for example, .feedTitle (including the leading dot). To associate the new CSS class with your feed titles, select one of the feed titles on the design surface and set the class property in the HTML tab to the new class; for example, feedTitle (no leading dot). Figure 1.16 shows what this looks like.

Figure 1.16

Figure 1.16. Using Blend to associate a class with one item from a template associates it with all items from that template.

Associating the feedTitle class with one of the feed titles in the list actually sets it for all of them because the feed titles come from a repeating template, and Blend knows that. You can see this by selecting .feedTitle from the Applied Rules list of the CSS Properties tab, as Figure 1.17 shows.

Figure 1.17

Figure 1.17. Selecting a CSS rule in Blend shows all elements to which that rule is applied.

The boxes around the feed titles in Figure 1.18 make it clear what elements will be affected when you make CSS property changes. Now, it’s very easy to set the width and font size for all feed titles at once, as Figure 1.18 shows.

Figure 1.18

Figure 1.18. Using Blend to change CSS properties interactively

Blend allows you to edit an app interactively while it’s running, which gives you a very fast turnaround time when you’re designing the look and feel of your app. For a much more thorough examination of what you can do with CSS in Windows Store apps, including Blend’s support for styling and view modes (e.g., landscape, portrait, etc.), you’ll want to read Chapter 3.

So, at this point our feed titles are attractive. However, they’re not yet interactive. As the user invokes one of the items—using the keyboard, mouse, or finger—we want to take the user to a page showing the items from that feed. And for that, we’ll need navigation.

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