AutomationPeer class

Provides a base class that exposes the automation peer for an associated owner class to Microsoft UI Automation.

Inheritance

Object

  DependencyObject

    AutomationPeer

Syntax

public class AutomationPeer : DependencyObject

Attributes

MarshalingBehaviorAttribute(Agile)

StaticAttribute(Windows.UI.Xaml.Automation.Peers.IAutomationPeerStatics, NTDDI_WIN8)

ThreadingAttribute(Both)

VersionAttribute(NTDDI_WIN8)

WebHostHiddenAttribute()

Members

The AutomationPeer class has these types of members:

• Constructors
• Methods
• Properties

Constructors

The AutomationPeer class has these constructors.

Methods

The AutomationPeer class has these methods. It also inherits methods from the Object class.

Properties

The AutomationPeer class has these properties.

Remarks

AutomationPeer is the class that provides almost all of the API that eventually forwards the UI Automation information for a Windows Store app built for Windows using C++, C#, or Visual Basic to a UI Automation client. Typical UI Automation clients aren't calling AutomationPeer methods directly. These clients are often assistive technologies that are using other programming models and operating as services, and are not likely to be calling Windows Runtime methods. But the general UI Automation support in the Windows Runtime forwards all this information as a provider such that any clients to UI Automation can interact with the representative automation trees of a Windows Store app using C++, C#, or Visual Basic.

Firing automation events

The AutomationPeer class is relevant to Windows Runtime control authors because you will have a peer instance available at run-time, after the runtime invokes the OnCreateAutomationPeer method. Using this peer, you can raise automation events by calling RaiseAutomationEvent and RaisePropertyChangedEvent. You would do this whenever a related property in the peer's owner (your class) changes, or when firing an event is needed for correct automation support.

The automation support design doesn't retain a handle to your own peer as part of how you implement OnCreateAutomationPeer, because there aren't any guarantees of when the peer is actually created. Instead, you can check for run-time automation event listeners inside your control class definitions just-in-time, using code like this:

if (AutomationPeer.ListenerExists(AutomationEvents.PropertyChanged))
{
    MyAutomationPeer peer = 
        FrameworkElementAutomationPeer.FromElement(myCtrl) as MyAutomationPeer;

    if (peer != null)
    {
        peer.RaisePropertyChangedEvent(
            RangeValuePatternIdentifiers.ValueProperty,
            (double)oldValue,
            (double)newValue);
    }
}

Requirements

See also

DependencyObject

Custom automation peers

XAML accessibility sample

Build date: 12/4/2012