Resource:
As in HTML, we are able to define CSS styles that can be reused in different parts of the website or the page. XAML has introduced the concept of resources that can be applied to different controls in an application.
Basically every XAML control supports the Resources tag: thanks to the hierarchy structure, every other nested control will be able to use it. In the real world,
There are two common places to define a resource:
1. at page and
2. application level.
Page resources
This resource are defined in a single page and are available to all the controls that are part of that page. They are placed in a specific property called Resources of the PhoneApplicationPage class.
<phone:PhoneApplicationPage.Resources>
<!-- you can place resources here -->
</phone:PhoneApplicationPage.Resources>
Application resources, instead, are globally available and they can be used inside any page of the application. They are defined in the App.xaml file, and the standard template already includes the needed definition.
<Application.Resources>
<!-- here you can place global resources -->
</Application.Resources>
Every resource is univocally identified by a name that is assigned using the x:Key property. To apply a resource to a control, we need to introduce the concept of markup extensions. These are special extensions that allow us to apply different behaviors that would otherwise need some code to properly work. There are many markup extensions in the XAML world, and the one needed to apply a resource is called StaticResource. Here is an example of how to use it:
In this sample, the resource is applied to the Style property by including the StaticResource keyword inside braces, followed by the resource name which is the value of the x:Key property.
Resources can be also defined in an external file called ResourceDictionary if you want to better organize your project. To do this, right-click on your project in Visual Studio, click Add > New Item, and choose XML file. Give the file a name that ends with the .xaml extension and include the following definition:
Now you can add it to your project by declaring it in the App.xaml:
Notice the MergedDictionaries property: all the external resource files should be declared here. This way, they will be automatically merged and every resource declared in each external file will be available to every page, as if they were declared inline.
Let’s see now, in detail, which are the most important kind of resources available.
<TextBlock Text="MY APPLICATION" Style="{StaticResource PhoneTextNormalStyle}" />
In this sample, the resource is applied to the Style property by including the StaticResource keyword inside braces, followed by the resource name which is the value of the x:Key property.
Resources can be also defined in an external file called ResourceDictionary if you want to better organize your project. To do this, right-click on your project in Visual Studio, click Add > New Item, and choose XML file. Give the file a name that ends with the .xaml extension and include the following definition:
<ResourceDictionary
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<!-- put resources here -->
</ResourceDictionary>
Now you can add it to your project by declaring it in the App.xaml:
<Application.Resources>
<ResourceDictionary>
<ResourceDictionary.MergedDictionaries>
<ResourceDictionary Source="Assets/Resources/Styles.xaml" />
</ResourceDictionary.MergedDictionaries>
</ResourceDictionary>
</Application.Resources>
