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ViewportBehavior

This behavior allows you to listen an element enter or exit the ScrollViewer viewport.

Syntax

<Page 
    xmlns:interactivity="using:Microsoft.Xaml.Interactivity"
    xmlns:behaviors="using:Microsoft.Toolkit.Uwp.UI.Behaviors" />

<ScrollViewer>
    <StackPanel Orientation="Vertical"
                Height="3000">
        <Border Width="100"
                Height="100">
            <interactivity:Interaction.Behaviors>
                <behaviors:ViewportBehavior x:Name="ViewportBehavior"
                                            EnteringViewport="Border_EnteringViewport"
                                            EnteredViewport="Border_EnteredViewport"
                                            ExitingViewport="Border_ExitingViewport"
                                            ExitedViewport="Border_ExitedViewport" />
            </interactivity:Interaction.Behaviors>
        </Border>
    </StackPanel>
</ScrollViewer>

Properties

Property Type Description
IsInViewport bool Gets a value indicating whether associated element is in the ScrollViewer viewport
IsFullyInViewport bool Gets a value indicating whether associated element is fully in the ScrollViewer viewport
IsAlwaysOn bool Gets or sets a value indicating whether this behavior will remain attached after the associated element enters the viewport. By default, when false, the behavior will remove itself after the attached element enters.

Events

Event Description
EnteringViewport Associated element enter the ScrollViewer viewport event
EnteredViewport Associated element fully enter the ScrollViewer viewport event
ExitingViewport Associated element exit the ScrollViewer viewport event
ExitedViewport Associated element fully exit the ScrollViewer viewport event

Sample Code

ViewportBehavior Sample Page Source. You can see this in action in Windows Community Toolkit Sample App.

Requirements

Device family Universal, 10.0.16299.0 or higher
Namespace Microsoft.Toolkit.Uwp.UI.Behaviors
NuGet package Microsoft.Toolkit.Uwp.UI

API