Статья
11/18/2011

TimelineMarker Class

Microsoft Silverlight will reach end of support after October 2021. Learn more.

Represents metadata associated with a specific point in a media file.

Inheritance Hierarchy

System.Object
System.Windows.DependencyObject
System.Windows.Media.TimelineMarker

Namespace: System.Windows.Media
Assembly: System.Windows (in System.Windows.dll)

Syntax

'Declaration
Public NotInheritable Class TimelineMarker _
    Inherits DependencyObject

public sealed class TimelineMarker : DependencyObject

The TimelineMarker type exposes the following members.

Constructors

	Name	Description
	TimelineMarker	Initializes a new instance of the TimelineMarker class.

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Properties

	Name	Description
	Dispatcher	Gets the Dispatcher this object is associated with. (Inherited from DependencyObject.)
	Text	Gets or sets the text value of a TimelineMarker.
	Time	Gets or sets the time at which a TimelineMarker is reached.
	Type	Gets or sets the marker type of a TimelineMarker.

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Methods

	Name	Description
	CheckAccess	Determines whether the calling thread has access to this object. (Inherited from DependencyObject.)
	ClearValue	Clears the local value of a dependency property. (Inherited from DependencyObject.)
	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.)
	GetAnimationBaseValue	Returns any base value established for a Silverlight dependency property, which would apply in cases where an animation is not active. (Inherited from DependencyObject.)
	GetHashCode	Serves as a hash function for a particular type. (Inherited from Object.)
	GetType	Gets the Type of the current instance. (Inherited from Object.)
	GetValue	Returns the current effective value of a dependency property from a DependencyObject. (Inherited from DependencyObject.)
	MemberwiseClone	Creates a shallow copy of the current Object. (Inherited from Object.)
	ReadLocalValue	Returns the local value of a dependency property, if a local value is set. (Inherited from DependencyObject.)
	SetValue	Sets the local value of a dependency property on a DependencyObject. (Inherited from DependencyObject.)
	ToString	Returns a string that represents the current object. (Inherited from Object.)

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Fields

	Name	Description
	TextProperty	Identifies the Text dependency property.
	TimeProperty	Identifies the Time dependency property.
	TypeProperty	Identifies the Type dependency property.

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Remarks

A timeline marker is metadata associated with a particular point in a media file. These markers are usually created ahead of time and stored in the media file itself. They are typically used to name different scenes in a video or provide scripting cues. By handling the MediaElement object's MarkerReached event or by accessing the MediaElement object's Markers property, you can use timeline markers to trigger actions or enable users to seek to selected positions in the media file.

TimelineMarker objects are used to represent all types of Windows Media technology timeline markers: markers and script commands (both metadata and separate stream). The following table lists how the Text and Type properties map to their source marker or script command.

TimelineMarker property	Windows Media marker	Windows Media script command
Text	"Name" field	"Param" field
Type	Always set to Name	"Type" field

The following example creates a MediaElement object and responds to its MarkerReached event. Each time a timeline marker is reached, the example displays the timeline marker's Time, Type, and Text values.

Run this sample

<StackPanel Margin="40">
  <StackPanel Orientation="Horizontal">
    <TextBlock FontSize="12" Foreground="DarkGray">Time:</TextBlock>
      <TextBlock x:Name="timeTextBlock" FontSize="12" />   
  </StackPanel>
  <StackPanel Orientation="Horizontal">
    <TextBlock FontSize="12" Foreground="DarkGray">Type:</TextBlock>
    <TextBlock x:Name="typeTextBlock" FontSize="12" />
  </StackPanel>
  <StackPanel Orientation="Horizontal">
    <TextBlock FontSize="12" Foreground="DarkGray">Value:</TextBlock>
    <TextBlock x:Name="valueTextBlock" FontSize="12" />
  </StackPanel>

  <!-- The MediaElement has the MarkerReached event attached. -->
  <MediaElement MarkerReached="OnMarkerReached" HorizontalAlignment="Left"
   Source="thebutterflyandthebear.wmv" Width="300" Height="200" />

</StackPanel>

Private Sub OnMarkerReached(ByVal sender As Object, ByVal e As TimelineMarkerRoutedEventArgs)
    timeTextBlock.Text = e.Marker.Time.Seconds.ToString
    typeTextBlock.Text = e.Marker.Type.ToString
    valueTextBlock.Text = e.Marker.Text.ToString
End Sub

private void OnMarkerReached(object sender, TimelineMarkerRoutedEventArgs e)
{
    timeTextBlock.Text = e.Marker.Time.Seconds.ToString();
    typeTextBlock.Text = e.Marker.Type.ToString();
    valueTextBlock.Text = e.Marker.Text.ToString();
}

Version Information

Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

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

Platforms

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

Thread Safety

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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