IXRUIElement (Windows Embedded CE 6.0)

1/6/2010

This class is the base class for most objects in Silverlight for Windows Embedded that are graphical and can process basic user input.

Syntax

class IXRUIElement : public IXRDependencyObject

Methods

Remarks

This class provides a starting point for accessing and modifying element-layout characteristics. The derived class IXRFrameworkElement provides additional methods for managing element-layout characteristics.

This class defines much of the input behavior for UI elements, including the events for UI focus events and keyboard, mouse, and stylus input.

The events in Silverlight are routed events. A routed event is an event that is passed upward from a child object to each of its parent objects in the object tree. For routed events, the object that handles the event might not be the same object that initially raised it.

Routed events have a built-in event-handling notification system, so that unhandled input events that are routed from child objects in the visual tree are automatically passed to parent objects. This input behavior is useful for input-area grouping and control compositing.

To find out whether this element currently has UI focus, use the derived IXRControl class.

Z-order determines the visual layering of objects on the screen. You can set the z-order for this UI element to a value from 0 through 1,000,000. To do this, set its Canvas.ZIndex attached property by calling the inherited method IXRDependencyObject::SetAttachedProperty(const WCHAR*, int). To retrieve the Canvas.ZIndex attached property value, call IXRDependencyObject::GetAttachedProperty(const WCHAR*, int*).

To access an IXRUIElement object, first obtain a pointer to a visual host in the call to IXRApplication::ParseXaml, obtain the root element of the element tree by calling IXRVisualHost::GetRootElement, traverse through its visual-tree structure by calling IXRFrameworkElement::FindName, and then obtain a pointer to a named object in the visual tree.

You can also access an interface pointer to an IXRUIElement object from inside an event handler by calling IUnknown::QueryInterface on the object in pSender. Or, you can use a class derived from IXRUIElement to create a UI element yourself and insert it into a generated visual tree, instead of declaring it in the source XAML for your application.

For more information about how to create UI elements in the source XAML for your application, use the link to the Microsoft Silverlight 2 documentation in the class topic for each derived class.

Hit Testing

IXRUIElement contains various APIs that can affect hit testing. Hit testing is the process by which Silverlight takes the input stimulus (such as mouse clicks) from the application, and then determines which IXRUIElement object in the layout and visual tree to designate as the source of the input event.

IXRUIElement::GetVisibility and IXRUIElement::SetVisibility are methods that access Visibility state, which affects how all input is handled by this element. Elements that are not visible do not participate in hit testing and do not receive user-input events, even if the mouse is inside of where the element would appear if it were visible.

Finally, the GetBackground method, which is contained in various classes derived from IXRUIElement, can also influence hit-test behavior because a null background value makes the element invisible to hit testing.

Inheritance Hierarchy

IXRDependencyObject

    IXRUIElement

        IXRFrameworkElement

            IXRBorder

            IXRControl

            IXRGlyphs

            IXRImage

            IXRItemsPresenter

            IXRPanel

            IXRPopup

            IXRShape

            IXRTextBlock

.NET Framework Equivalent

System.Windows.UIElement

Requirements

See Also

Reference

Classes for UI Element Management