XAML Elements | Introducing WinFX(TM) The Application Programming Interface for the Next Generation of Microsoft Windows Code Name Longhorn (Pro Developer)

Each XAML page contains one or more elements that control the layout and behavior of the page. You arrange these elements hierarchically in a tree. Every element has only one parent. Elements can generally have any number of child elements. However, some element types ”for example, Scrollbar ” have no children; and other element types ”for example, Border ” can have a single child element.

Each element name corresponds to the name of a managed class. Adding an element to a XAML document causes the runtime to create an instance of the corresponding class. For example, the following markup represents a root DockPanel element that has a single child Table element. The Table element contains three child Row elements. Each Row element contains three children, and a few of them have child text nodes.

 <Border xmlns="http://schemas.microsoft.com/2003/xaml" 
 Background="BlanchedAlmond"> 
 <DockPanel> 
 <Table> 
 <Body> 
 <Row> 
 <Cell><Button/></Cell> 
 <Cell><Text>Item</Text></Cell> 
 <Cell><Text>Price</Text></Cell> 
 </Row> 
 <Row> 
 <Cell><CheckBox Checked="true"/></Cell> 
 <Cell><TextBox Height="50">Nissan 350Z</TextBox></Cell> 
 <Cell><TextBox Height="50">29.95</TextBox></Cell> 
 </Row> 
 <Row> 
 <Cell><CheckBox/></Cell> 
 <Cell><TextBox Height="50">Porsche Boxster</TextBox></Cell> 
 <Cell><TextBox Height="50">9.95</TextBox></Cell> 
 </Row> 
 </Body> 
 </Table> 
 </DockPanel> 
 </Border>

This XAML document creates an object hierarchy as shown in Figure 3-1 and the display shown in Figure 3-2.

Figure 3-1: An example XAML page object model

Figure 3-2: The display from the previous XAML

You can access much of the functionality of such objects using only markup. Using only markup, you can do any of the following:

Describe a hierarchical set of objects that the runtime will instantiate
Set object properties to values known statically
Set object properties to values retrieved from a data source
Cause changed property values to be stored back into the data source
Repeatedly change a property s value over time
Bind an event handler to an object s event

However, although you can create some amazing user interfaces using only markup, you can also access an element s functionality programmatically using the XAML object model. The object model allows you to manipulate every aspect of the elements on a page. It actually provides additional capabilities that are not accessible through XAML.

Every XAML element derives from System.Windows.UIElement or System.Windows.ContentElement , and therefore all elements possess a number of common features. Elements can be grouped in the following four basic categories:

Controls derive from System.Windows.Control and handle user interaction.
Panels are specialized controls that derive from System.Windows.Panel and handle page layout and act as containers for elements.
Text formatting elements derive from System.Windows.TextElement and handle text formatting and document structure.
Shapes handle vector graphic shapes.