EventArgs Class
EventArgs is the base class for classes containing event data.
Namespace: System
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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To run this example, see Building Examples That Use a Demo Method and a TextBlock Control. |
using System; using System.Windows.Controls; // FireEventArgs: a custom event inherited from EventArgs. public class FireEventArgs : EventArgs { public FireEventArgs(string room, int ferocity) { this.room = room; this.ferocity = ferocity; } // The fire event will have two pieces of information-- // 1) Where the fire is, and 2) how "ferocious" it is. public string room; public int ferocity; } // Class with a function that creates the eventargs and initiates the event public class FireAlarm { // Events are handled with delegates, so we must establish a FireEventHandler // as a delegate: public delegate void FireEventHandler(object sender, FireEventArgs fe); // Now, create a public event "FireEvent" whose type is our FireEventHandler delegate. public event FireEventHandler FireEvent; // This will be the starting point of our event-- it will create FireEventArgs, // and then raise the event, passing FireEventArgs. public void ActivateFireAlarm(string room, int ferocity) { FireEventArgs fireArgs = new FireEventArgs(room, ferocity); // Now, raise the event by invoking the delegate. Pass in // the object that initated the event (this) as well as FireEventArgs. // The call must match the signature of FireEventHandler. FireEvent(this, fireArgs); } } // Class which handles the event class FireHandlerClass { private static TextBlock _textblock; // Create a FireAlarm to handle and raise the fire events. public FireHandlerClass(FireAlarm fireAlarm, TextBlock outputBlock) { // Add a delegate containing the ExtinguishFire function to the class' // event so that when FireAlarm is raised, it will subsequently execute // ExtinguishFire. fireAlarm.FireEvent += new FireAlarm.FireEventHandler(ExtinguishFire); FireHandlerClass._textblock = outputBlock; } // This is the function to be executed when a fire event is raised. void ExtinguishFire(object sender, FireEventArgs fe) { _textblock.Text += String.Format("\nThe ExtinguishFire function was called by {0}.", sender.ToString()) + "\n"; // Now, act in response to the event. if (fe.ferocity < 2) _textblock.Text += String.Format("This fire in the {0} is no problem. I'm going to pour some water on it.", fe.room) + "\n"; else if (fe.ferocity < 5) _textblock.Text += String.Format("I'm using FireExtinguisher to put out the fire in the {0}.", fe.room) + "\n"; else _textblock.Text += String.Format("The fire in the {0} is out of control. I'm calling the fire department!", fe.room) + "\n"; } } public class Example { public static void Demo(System.Windows.Controls.TextBlock outputBlock) { // Create an instance of the class that will be firing an event. FireAlarm myFireAlarm = 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. FireHandlerClass myFireHandler = new FireHandlerClass(myFireAlarm, outputBlock); //use our class to raise a few events and watch them get handled myFireAlarm.ActivateFireAlarm("Kitchen", 3); myFireAlarm.ActivateFireAlarm("Study", 1); myFireAlarm.ActivateFireAlarm("Porch", 5); return; } }
For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.
System.EventArgs
System.Collections.Specialized.NotifyCollectionChangedEventArgs
System.ComponentModel.AsyncCompletedEventArgs
System.ComponentModel.CancelEventArgs
System.ComponentModel.Composition.Hosting.ComposablePartCatalogChangeEventArgs
System.ComponentModel.Composition.Hosting.ExportsChangeEventArgs
System.ComponentModel.CurrentChangingEventArgs
System.ComponentModel.DataErrorsChangedEventArgs
System.ComponentModel.DoWorkEventArgs
System.ComponentModel.ProgressChangedEventArgs
System.ComponentModel.PropertyChangedEventArgs
System.ComponentModel.PropertyChangingEventArgs
System.Data.Services.Client.ReadingWritingEntityEventArgs
System.Data.Services.Client.SendingRequestEventArgs
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.Browser.HtmlEventArgs
System.Windows.CheckAndDownloadUpdateCompletedEventArgs
System.Windows.Controls.DataGridCellEditEndedEventArgs
System.Windows.Controls.DataGridColumnEventArgs
System.Windows.Controls.DataGridPreparingCellForEditEventArgs
System.Windows.Controls.DataGridRowClipboardEventArgs
System.Windows.Controls.DataGridRowDetailsEventArgs
System.Windows.Controls.DataGridRowEditEndedEventArgs
System.Windows.Controls.DataGridRowEventArgs
System.Windows.Controls.DataGridRowGroupHeaderEventArgs
System.Windows.Controls.DatePickerDateValidationErrorEventArgs
System.Windows.Controls.DrawEventArgs
System.Windows.Controls.FocusingInvalidControlEventArgs
System.Windows.Controls.NotifyEventArgs
System.Windows.Controls.Pivot.CxmlCollectionStateChangedEventArgs
System.Windows.Controls.Pivot.PivotViewerCommandsRequestedEventArgs
System.Windows.Controls.Pivot.PivotViewerFilterEventArgs
System.Windows.Controls.Pivot.PivotViewerItemDoubleClickEventArgs
System.Windows.Controls.Pivot.PivotViewerLinkEventArgs
System.Windows.Controls.Pivot.PivotViewerViewUpdatingEventArgs
System.Windows.Controls.Primitives.ItemsChangedEventArgs
System.Windows.Data.FilterEventArgs
System.Windows.Graphics.RenderModeChangedEventArgs
System.Windows.Input.TouchFrameEventArgs
System.Windows.Interop.NavigationStateChangedEventArgs
System.Windows.Media.Imaging.DownloadProgressEventArgs
System.Windows.Media.RenderingEventArgs
System.Windows.Messaging.MessageReceivedEventArgs
System.Windows.Navigation.FragmentNavigationEventArgs
System.Windows.Navigation.NavigationEventArgs
System.Windows.Navigation.NavigationFailedEventArgs
System.Windows.Printing.BeginPrintEventArgs
System.Windows.Printing.EndPrintEventArgs
System.Windows.Printing.PrintPageEventArgs
System.Windows.RoutedEventArgs
System.Windows.StartupEventArgs
System.Windows.VisualStateChangedEventArgs
System.Xml.Linq.XObjectChangeEventArgs






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