Timeline.BeginTime Property
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Gets or sets the time at which this Timeline should begin.
Namespace: System.Windows.Media.Animation
Assembly: System.Windows (in System.Windows.dll)
Syntax
'Declaration
Public Property BeginTime As Nullable(Of TimeSpan)
public Nullable<TimeSpan> BeginTime { get; set; }
<timeline BeginTime="keyTimeString"/>
XAML Values
- keyTimeString
A string in the form [days.]hours:minutes:seconds[.fractionalSeconds]. For more information, see KeyTime.
Property Value
Type: System.Nullable<TimeSpan>
The start time of the time line. The default value is zero.
Remarks
Dependency property identifier field: BeginTimeProperty
The BeginTime property is useful for creating timelines that play in a sequence: by increasing the BeginTime of successive timelines that share the same parent Storyboard, you can stagger their play times.
Creating a TimeSpan in XAML is possible through a type conversion syntax when setting a property that takes a TimeSpan as an attribute string.
You can set the value of BeginTime on a running animation, and the value will apply the next time that animation is started. You can get the BeginTime value programmatically by using value=object.BeginTime syntax. However, if the BeginTime for an animation is not explicitly set (either programmatically or in XAML), the value of object.BeginTime will be null. A null value for BeginTime has the same implied effect on an animation as a TimeSpan that is explicitly set to 0.
Negative Values
A negative BeginTime value causes a Timeline to behave as though it started at some time in the past. For example, a Timeline with a BeginTime of negative 2.5 seconds and a Duration of 5 seconds will appear to be half-way finished when it starts.
BeginTime and SpeedRatio
The time described by the BeginTime property is measured in the timeline's parent's time. For example, a timeline with a BeginTime of 5 whose parent has a SpeedRatio of 2 actually starts after 2.5 seconds.
A timeline's own SpeedRatio setting does not affect its BeginTime. For example, a timeline with a BeginTime of 5 seconds, a SpeedRatio of 2, and a parent timeline with a SpeedRatio of 1 starts after 5 seconds, not 2.5.
Examples
As the name suggests, the BeginTime property allows you to specify a time at which point the animation object begins activity. For example, you could specify a time of two seconds on the BeginTime of a Storyboard. When you begin the Storyboard using the Begin method, the Storyboard will wait two seconds and then begin. In addition you can specify BeginTime on the animation objects inside of the Storyboard. For example, if you have a Storyboard with a two second BeginTime and this Storyboard contains two DoubleAnimation objects -- one with no BeginTime specified and the other with a BeginTime of three, the first DoubleAnimation will start two seconds after the Begin method is called on the Storyboard and the second DoubleAnimation will begin five seconds afterward (two seconds delay for the Storyboard plus three second delay for the DoubleAnimation). The following example shows this.
<StackPanel>
<StackPanel.Resources>
<!-- Storyboard starts 2 seconds after its Begin
method is called. -->
<Storyboard BeginTime="0:0:2" x:Name="myStoryboard">
<!-- Animates the rectangle's width. No
BeginTime specified so by default begins
as soon as it's parent (the Storyboard)
begins. -->
<DoubleAnimation
Storyboard.TargetName="MyAnimatedRectangle"
Storyboard.TargetProperty="Width"
To="300" Duration="0:0:1" />
<!-- Animates the rectangle's opacity. A BeginTime
of 3 seconds specified so begins three seconds
after the Storyboard begins (total of 5 seconds)-->
<DoubleAnimation BeginTime="0:0:3"
Storyboard.TargetName="MyAnimatedRectangle"
Storyboard.TargetProperty="Opacity"
To="0" Duration="0:0:1" />
</Storyboard>
</StackPanel.Resources>
<Rectangle x:Name="MyAnimatedRectangle"
Loaded="Start_Animation"
Width="100" Height="100" Fill="Blue" />
</StackPanel>
</StackPanel>
' Start the animation when the object loads.
Private Sub Start_Animation(ByVal sender As Object, ByVal e As EventArgs)
myStoryboard.Begin()
End Sub
// Start the animation when the object loads.
private void Start_Animation(object sender, EventArgs e)
{
myStoryboard.Begin();
}
You can think of a Storyboard as a container for other animation objects (e.g. DoubleAnimation) as well as other Storyboard objects, that is, you can nest Storyboard objects within each other and specify BeginTime values for each Storyboard separately. Using nested Storyboards can help you orchestrate elaborate animation sequences. Each child Storyboard will wait until its parent Storyboard begins and then start the countdown before it in turn begins.
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.
See Also