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How to detect scrolling direction in Xamarin Forms ListView (SfListView)?
2 mins read
You can find the scrolling direction in Xamarin.Forms SfListView by using the Scrolled event of the ScollView.
XAML
In the SfListView.HeaderTemplate, bind the ViewModel property to show the scroll direction.
<ContentPage xmlns:syncfusion="clr-namespace:Syncfusion.ListView.XForms;assembly=Syncfusion.SfListView.XForms">
<syncfusion:SfListView x:Name="listView"
ItemsSource="{Binding ContactsInfo}"
IsStickyHeader="True"
ItemSize="70">
<syncfusion:SfListView.Behaviors>
<local:Behavior/>
</syncfusion:SfListView.Behaviors>
<syncfusion:SfListView.HeaderTemplate>
<DataTemplate>
<Label Text="{Binding ScrollDirection}" />
</DataTemplate>
</syncfusion:SfListView.HeaderTemplate>
<syncfusion:SfListView.ItemTemplate>
<DataTemplate>
<Grid>
<Image Source="{Binding ContactImage}"
Aspect="AspectFill"/>
<Label LineBreakMode="NoWrap"
Text="{Binding ContactName}"/>
<Label LineBreakMode="NoWrap"
Text="{Binding ContactNumber}"/>
<Label LineBreakMode="NoWrap"
Text="{Binding ContactType}"/>
</Grid>
</DataTemplate>
</syncfusion:SfListView.ItemTemplate>
</syncfusion:SfListView>
</ContentPage>
C#
You can get the ExtendedScrollView using the ListView.GetScrollView helper method and update the ScrollDirection value based on the previous offset.
public class Behavior : Behavior <SfListView>
{
ExtendedScrollView scrollview;
double previousOffset;
public SfListView listview { get; private set; }
protected override void OnAttachedTo(SfListView bindable)
{
base.OnAttachedTo(bindable);
listview = bindable as SfListView;
scrollview = listview.GetScrollView();
scrollview.Scrolled += Scrollview_Scrolled;
}
private void Scrollview_Scrolled(object sender, ScrolledEventArgs e)
{
if (e.ScrollY == 0)
return;
if (previousOffset >= e.ScrollY)
{
// Up direction
viewModel.ScrollDirection = "Up Direction";
}
else
{
//Down direction
viewModel.ScrollDirection = "Down Direction";
}
previousOffset = e.ScrollY;
}
}
