EventArgs Class
[ This article is for Windows Phone 8 developers. If you’re developing for Windows 10, see the latest documentation. ]
EventArgs is the base class for classes containing event data.
Assembly: mscorlib (in mscorlib.dll)
The EventArgs type exposes the following members.
| Name | Description | |
|---|---|---|
![]() | Equals(Object) | Determines whether the specified Object is equal to the current Object. (Inherited from Object.) |
![]() | Finalize | Allows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.) |
![]() | GetHashCode | Serves as a hash function for a particular type. (Inherited from Object.) |
![]() | GetType | Gets the Type of the current instance. (Inherited from Object.) |
![]() | MemberwiseClone | Creates a shallow copy of the current Object. (Inherited from Object.) |
![]() | ToString | Returns a string that represents the current object. (Inherited from Object.) |
This class contains no event data; it is used by events that do not pass state information to an event handler when an event is raised. If the event handler requires state information, the application must derive a class from this class to hold the data.
For more information about events, see the EventHandler topic.
The following code sample illustrates the use of EventArgs.
In this sample, FireEventArgs is a set of event arguments derived from EventArgs, and passed to the FireEventHandler when an event is raised by calling ActivateFireAlarm.
Note: |
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For information on how to compile and run this example code, see Building examples that have static TextBlock controls for Windows Phone 8. |
Imports System.Windows.Controls ' FireEventArgs: a custom event inherited from EventArgs. Public Class FireEventArgs Inherits EventArgs Public Sub New(ByVal room As String, ByVal ferocity As Integer) Me.room = room Me.ferocity = ferocity End Sub 'New ' The fire event will have two pieces of information-- ' 1) Where the fire is, and 2) how "ferocious" it is. Public room As String Public ferocity As Integer End Class Public Class FireAlarm ' Events are handled with delegates, so we must establish a FireEventHandler ' as a delegate: Delegate Sub FireEventHandler(ByVal sender As Object, ByVal fe As FireEventArgs) ' Now, create a public event "FireEvent" whose type is our FireEventHandler delegate. Public Event FireEvent As FireEventHandler ' This will be the starting point of our event-- it will create FireEventArgs, ' and then raise the event, passing FireEventArgs. Public Sub ActivateFireAlarm(ByVal room As String, ByVal ferocity As Integer) Dim fireArgs As New FireEventArgs(room, ferocity) ' Now, raise the event by invoking the delegate. Pass in ' the object that initated the event (Me) as well as FireEventArgs. ' The call must match the signature of FireEventHandler. RaiseEvent FireEvent(Me, fireArgs) End Sub End Class ' The following event will be the EventHandler. Class FireHandlerClass Private Shared _TextBlock As TextBlock ' Create a FireAlarm to handle and raise the fire events. Public Sub New(ByVal fireAlarm As FireAlarm, ByVal outputBlock As TextBlock) ' Add a delegate containing the ExtinguishFire function to the class' ' event so that when FireAlarm is raised, it will subsequently execute ' ExtinguishFire. AddHandler fireAlarm.FireEvent, AddressOf ExtinguishFire FireHandlerClass._TextBlock = outputBlock End Sub ' This is the function to be executed when a fire event is raised. Sub ExtinguishFire(ByVal sender As Object, ByVal fe As FireEventArgs) _TextBlock.Text &= vbCrLf _TextBlock.Text += String.Format("The ExtinguishFire function was called by {0}.", sender.ToString()) & vbCrLf ' Now, act in response to the event. If fe.ferocity < 2 Then _TextBlock.Text += String.Format("This fire in the {0} is no problem. I'm going to pour some water on it.", fe.room) & vbCrLf Else If fe.ferocity < 5 Then _TextBlock.Text += String.Format("Using Fire Extinguisher to put out the fire in the {0}.", fe.room) & vbCrLf Else _TextBlock.Text += String.Format("The fire in the {0} is out of control. I'm calling the fire department.", fe.room) & vbCrLf End If End If End Sub End Class Public Class Example Public Shared Sub Demo(ByVal outputBlock As System.Windows.Controls.TextBlock) ' Create an instance of the class that will be raising the event. Dim myFireAlarm As New FireAlarm() ' Create an instance of the class that will be handling the event. Note that ' it receives the class that will fire the event as a parameter. Dim myFireHandler As New FireHandlerClass(myFireAlarm, outputBlock) ' Now, use the FireAlarm class to raise a few events. myFireAlarm.ActivateFireAlarm("Kitchen", 3) myFireAlarm.ActivateFireAlarm("Study", 1) myFireAlarm.ActivateFireAlarm("Porch", 5) Return End Sub End Class
System.EventArgs
Microsoft.Devices.CameraOperationCompletedEventArgs
Microsoft.Devices.ContentReadyEventArgs
Microsoft.Devices.Sensors.AccelerometerReadingEventArgs
Microsoft.Devices.Sensors.CalibrationEventArgs
Microsoft.Devices.Sensors.SensorReadingEventArgs(Of T)
Microsoft.Phone.BackgroundAudio.PlayStateChangedEventArgs
Microsoft.Phone.BackgroundTransfer.BackgroundTransferEventArgs
Microsoft.Phone.Controls.ItemRealizationEventArgs
Microsoft.Phone.Controls.NotifyEventArgs
Microsoft.Phone.Controls.ObscuredEventArgs
Microsoft.Phone.Controls.OrientationChangedEventArgs
Microsoft.Phone.Controls.PivotItemEventArgs
Microsoft.Phone.Maps.Controls.MapEventArgs
Microsoft.Phone.Media.MediaStreamerEndedEventArgs
Microsoft.Phone.Media.MediaStreamerFailedEventArgs
Microsoft.Phone.Media.MediaStreamerOpenedEventArgs
Microsoft.Phone.Net.NetworkInformation.NetworkNotificationEventArgs
Microsoft.Phone.Notification.HttpNotificationEventArgs
Microsoft.Phone.Notification.NotificationChannelConnectionEventArgs
Microsoft.Phone.Notification.NotificationChannelErrorEventArgs
Microsoft.Phone.Notification.NotificationChannelUriEventArgs
Microsoft.Phone.Notification.NotificationEventArgs
Microsoft.Phone.SecureElement.RegisterSecureElementItemEventArgs
Microsoft.Phone.SecureElement.UserActionEventArgs
Microsoft.Phone.Shell.ActivatedEventArgs
Microsoft.Phone.Shell.ApplicationBarStateChangedEventArgs
Microsoft.Phone.Shell.ClosingEventArgs
Microsoft.Phone.Shell.DeactivatedEventArgs
Microsoft.Phone.Shell.HideEventArgs
Microsoft.Phone.Shell.LaunchingEventArgs
Microsoft.Phone.Shell.MinimizeEventArgs
Microsoft.Phone.Shell.RunningInBackgroundEventArgs
Microsoft.Phone.Shell.ShowEventArgs
Microsoft.Phone.Shell.VisibleRegionChangedEventArgs
Microsoft.Phone.Tasks.TaskEventArgs
Microsoft.Phone.UserData.AppointmentsSearchEventArgs
Microsoft.Phone.UserData.ContactsSearchEventArgs
System.Collections.Specialized.NotifyCollectionChangedEventArgs
System.ComponentModel.AsyncCompletedEventArgs
System.ComponentModel.CancelEventArgs
System.ComponentModel.CurrentChangingEventArgs
System.ComponentModel.DataErrorsChangedEventArgs
System.ComponentModel.DoWorkEventArgs
System.ComponentModel.ProgressChangedEventArgs
System.ComponentModel.PropertyChangedEventArgs
System.ComponentModel.PropertyChangingEventArgs
System.Device.Location.GeoPositionChangedEventArgs(Of T)
System.Device.Location.GeoPositionStatusChangedEventArgs
System.Diagnostics.Contracts.ContractFailedEventArgs
System.Net.Sockets.SocketAsyncEventArgs
System.Net.WriteStreamClosedEventArgs
System.ResolveEventArgs
System.Runtime.InteropServices.Automation.AutomationEventArgs
System.ServiceModel.UnknownMessageReceivedEventArgs
System.Threading.Tasks.UnobservedTaskExceptionEventArgs
System.UnhandledExceptionEventArgs
System.Windows.ApplicationUnhandledExceptionEventArgs
System.Windows.Controls.Primitives.ItemsChangedEventArgs
System.Windows.Controls.Primitives.ManipulationStateChangedEventArgs
System.Windows.Controls.Primitives.ViewportChangedEventArgs
System.Windows.Data.FilterEventArgs
System.Windows.Input.TouchFrameEventArgs
System.Windows.Interop.NavigationStateChangedEventArgs
System.Windows.Media.Imaging.DownloadProgressEventArgs
System.Windows.Media.RenderingEventArgs
System.Windows.Navigation.FragmentNavigationEventArgs
System.Windows.Navigation.JournalEntryRemovedEventArgs
System.Windows.Navigation.NavigationEventArgs
System.Windows.Navigation.NavigationFailedEventArgs
System.Windows.RoutedEventArgs
System.Windows.StartupEventArgs
System.Windows.VisualStateChangedEventArgs
System.Xml.Linq.XObjectChangeEventArgs




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