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DispatcherTimer Class

A timer that is integrated into the Dispatcher queue, which is processed at a specified interval of time and at a specified priority.

System.Object
  System.Windows.Threading.DispatcherTimer

Namespace:  System.Windows.Threading
Assembly:  System.Windows (in System.Windows.dll)
'Declaration
Public Class DispatcherTimer

The DispatcherTimer type exposes the following members.

  NameDescription
Public methodSupported by Silverlight for Windows PhoneDispatcherTimerInitializes a new instance of the DispatcherTimer class.
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  NameDescription
Public propertySupported by Silverlight for Windows PhoneIntervalGets or sets the amount of time between timer ticks.
Public propertySupported by Silverlight for Windows PhoneIsEnabledGets a value that indicates whether the timer is running.
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  NameDescription
Public methodSupported by Silverlight for Windows PhoneEquals(Object)Determines whether the specified Object is equal to the current Object. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows PhoneFinalizeAllows an object to try to free resources and perform other cleanup operations before the Object is reclaimed by garbage collection. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneGetHashCodeServes as a hash function for a particular type. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneGetTypeGets the Type of the current instance. (Inherited from Object.)
Protected methodSupported by Silverlight for Windows PhoneMemberwiseCloneCreates a shallow copy of the current Object. (Inherited from Object.)
Public methodSupported by Silverlight for Windows PhoneStartStarts the DispatcherTimer.
Public methodSupported by Silverlight for Windows PhoneStopStops the DispatcherTimer.
Public methodSupported by Silverlight for Windows PhoneToStringReturns a string that represents the current object. (Inherited from Object.)
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  NameDescription
Public eventSupported by Silverlight for Windows PhoneTickOccurs when the timer interval has elapsed.
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The DispatcherTimer is reevaluated at the top of every DispatcherTimer loop.

Timers are not guaranteed to execute exactly when the time interval occurs, but they are guaranteed to not execute before the time interval occurs. This is because DispatcherTimer operations are placed on the DispatcherTimer queue like other operations. When the DispatcherTimer operation executes is dependent on the other jobs in the queue and their priorities.

If a System.Threading.Timer is used, it is worth noting that the Timer runs on a different thread then the user interface (UI) thread. In order to access objects on the UI thread, it is necessary to post the operation onto the UI thread using Dispatcher.BeginInvoke. This is unnecessary when using a DispatcherTimer.

A DispatcherTimer will keep an object alive whenever the object's methods are bound to the timer.

The following code example demonstrates how to use this class.


Private WithEvents counterPanel As Panel
Private WithEvents timer As DispatcherTimer = New DispatcherTimer()
Private counter As Integer = 0

Private Sub PanelClick(ByVal sender As System.Object, _
    ByVal e As System.Windows.Input.MouseButtonEventArgs) _
    Handles counterPanel.MouseLeftButtonDown

    If timer.IsEnabled Then timer.Stop() Else timer.Start()

End Sub

Private Sub TimerClick(ByVal sender As System.Object, _
    ByVal e As EventArgs) Handles timer.Tick

    counter += 1
    counterPanel.Children.Clear()
    Dim t As New TextBlock
    t.Text = counter.ToString
    counterPanel.Children.Add(t)

End Sub

Private Sub TestDispatcherTimer(ByVal p As Panel)

    Me.counterPanel = p
    timer.Interval = New TimeSpan(0, 0, 1)
    timer.Start()

End Sub


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Any public static (Shared in Visual Basic) members of this type are thread safe. Any instance members are not guaranteed to be thread safe.
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