<Image x:Name= "myImage" Source="http://www.silverlightinaction.com/image03.png" /> in Visual Basic .NET

Painting QR Code in Visual Basic .NET <Image x:Name= "myImage" Source="http://www.silverlightinaction.com/image03.png" />

This example shows how to access a loose resource via an absolute Uri. This Uri points at the location of the resource, and this location will be loaded as a loose resource. There s also a way to bundle resources along with your Silverlight application.

The third kind of resource used in Silverlight is referred to as a bundled resource. A bundled resource is an item included in the .xap file of a Silverlight application. The term bundled resource is a made-up expression used solely for the sake of communication. Bundled resources give you a way to include resources specific to a Silverlight application. Throughout this section, you ll learn about the two types of bundled resources that can be used in Silverlight. The first is known as a content file a file that s added to the .xap file and deployed alongside a Silverlight application. The other type of resource is known as an embedded file, which represents an item that gets embedded into a Silverlight assembly. This kind of resource can be useful for helping to hide your valuable resources.

A content file is one that s added to a .xap file and deployed alongside a Silverlight application within the .xap. If you define an image as a content file, that image will be included within the resulting .xap file when the Silverlight application is built. In fact,

Figure 23.2 Defining a file as a content file. When it s compiled, the content file is added to a .xap file.

any file with a build action of Content will be bundled into the resulting .xap file. Figure 23.2 shows a .png and .xml file being bundled into a .xap file as content files. Figure 23.2 shows two files that have been added and marked as content files. The first, xmlData.xml, is a basic XML file. Once the project is built, this file ends up in the root of the .xap file structure. The second, image.png, belongs to a nested directory called images. When the project is built, this relative directory structure is carried over to the final .xap file, which can be accessed using a relative path reference. All content files can be referenced by providing a path relative to the application assembly. This approach can be used at design time, as shown in this markup:

This example shows the syntax used to reference a content file at design time. The leading forward slash (/) informs Silverlight to begin looking at the same level as the application assembly. This approach is the recommended way to include content with a Silverlight application because it makes things more easily accessible. Sometimes, you may come across somebody who does things the old-school way the content files will be embedded within the Silverlight assembly. You ll now see how to access these embedded files.

An embedded file is a file embedded within a Silverlight assembly, which may be either an application or a library. Either way, an embedded file becomes a part of an assembly by changing the build action to Resource. This file can be retrieved at design time or runtime by providing a special URL structure. Embedded resources are accessible through a URL that has three parts. The first part names the assembly to which the resource belongs. The second piece is a special keyword called Component that declares a resource as being retrieved. The final part is a relative URL that maps to the location of the resource within the assembly. These three items come together to form a URL template that looks like the following:

[AssemblyName];component/[RelativePath]

This template can be used at design time or runtime. The design-time implementation relies on the element type to convert the resource. At runtime, you must manually convert the resource. First, you retrieve the embedded resource from the assembly through the Application class, as shown in this line of code:

StreamResourceInfo resource = Application.GetResourceStream( new Uri("SilverlightApp1;component/embedded.png", UriKind.Relative));

This example shows how to retrieve the resource from the assembly. This resource is represented as a StreamResourceInfo, which is part of the System.Windows. Resources namespace. This class instance must be converted to the type appropriate for your situation. As we mentioned earlier, you shouldn t come across this scenario very often. When it comes to content files, you ll probably come across a loose resource. In XAML, you ll most likely use declarative resources. This approach is especially true if you re giving your elements Style.