Scroll to row when programmatically setting selected item

[Maria]

Hello,

I'm trying to implement a "find" feature where the user can enter a value in a textbox (outside of the grid) then click a button to find the row that matches the search criteria.  I'm able to programmatically set the selectitem on the grid successfully, but if the item is not in the current scroll region the user has to scroll down to to the item.  Is there a way to ensure that the selected item is always in view?  Also, I should mention that we are using MVVM, so there is no code behind.

Thanks.

[Vlad]

Hi,

 You can use our ScrollIntoView() method to achieve your goal. Since your using MVVM you can create your custom attached behavior to do this - you can check for the project in this blog post for more info about attached behaviors. 

Kind regards,
Vlad
the Telerik team

[Thomas]

The blog did not help me. Can you please give a example for this problem?

[Erik]

This is what I came up with

In your ViewModel:

private Requirement _scrollIntoViewObject;
public Requirement ScrollIntoViewObject
{
    get { return _scrollIntoViewObject; }
    private set
    {
        _scrollIntoViewObject = value;
       OnPropertyChanged("ScrollIntoViewObject");
    }
}

In your RadGridView:

<telerik:RadGridView ItemsSource="{Binding MyItems}">
      <i:Interaction.Behaviors>
            <Utils:RadGridScrollIntoViewBehavior/>
      </i:Interaction.Behaviors>
</telerik:RadGridView>

And lastly:

public class RadGridScrollIntoViewBehavior : Behavior<RadGridView>
{
    private RadGridView Grid
    {
        get
        {
            return AssociatedObject;
        }
    }

    protected override void OnAttached()
    {
        base.OnAttached();

        Grid.DataContextChanged += GridDataContextChanged;
    }

    private void GridDataContextChanged(object sender, DependencyPropertyChangedEventArgs e)
    {
        if (e.OldValue != null)
        {
            ((INotifyPropertyChanged) e.OldValue).PropertyChanged -= DataContextOnPropertyChanged;
        }
        if (e.NewValue != null)
        {
            ((INotifyPropertyChanged) e.NewValue).PropertyChanged += DataContextOnPropertyChanged;
        }
    }

    private void DataContextOnPropertyChanged(object sender, PropertyChangedEventArgs e)
    {
        if (!e.PropertyName.Equals("ScrollIntoViewObject")) return;

        var propertyInfo = sender.GetType().GetProperty(e.PropertyName);
        var scrollIntoViewObject = propertyInfo.GetValue(sender, null);

        if(scrollIntoViewObject != null)
        {
            Grid.ScrollIntoView(scrollIntoViewObject);
        }
    }
}

There must be a better solution without the propertyname and the reflection, but this works in my scenario

[Lawrence]

Here's an Extension method that I wrote that will scroll into view and select the row with a data pager.

public void ScrollIntoView<T>(T dataItem, RadDataPager radDataPager)
{
    var items = (Collection<T>)this.ItemsSource;
    int index = items.IndexOf(dataItem);
    int page = (int)Math.Floor((double)index / radDataPager.PageSize);

    radDataPager.MoveToPage(page);

    this.SelectedItem = items[index];
    this.ScrollIntoView(this.SelectedItem);
}

[MG]

Based on Erik's post, here is another attempt..

public class RadGridViewScrollIntoViewBehavior: Behavior<RadGridView>
    {
        private RadGridView Grid
        {
            get { return AssociatedObject; }
        }

        protected override void OnAttached()
        {
            base.OnAttached();
            Grid.Items.CollectionChanged += Items_CollectionChanged;
        }

        private void Items_CollectionChanged(object sender, NotifyCollectionChangedEventArgs e)
        {
            if (e.Action == NotifyCollectionChangedAction.Add)
            {
                var myRow = e.NewItems[0] as MyClassType;
                if (labelSet != null)
                {
                    Grid.ScrollIntoView(myRow );
                }
            }
        }
    }

In the RadGridView,

<telerik:RadGridView ItemsSource="{Binding MyItems}">
      <i:Interaction.Behaviors>
            <Utils:RadGridScrollIntoViewBehavior/>
      </i:Interaction.Behaviors>
</telerik:RadGridView>

 

Thanks

[Dimitrina]

Hi,

You can check the documentation on Scroll to a particular row or column on the different options RadGridView suggests and how the scroll methods are expected to work.

Regards,
Dimitrina
Telerik

[Dan]

public class RadGridViewScrollSelectedItemIntoViewBehavior : Behavior<RadGridView>
    {
        #region Overrides
        protected override void OnAttached()
        {
            base.OnAttached();
            AssociatedObject.Unloaded += OnUnloaded;
            AssociatedObject.SelectionChanged += OnSelectionChanged;
        }


        #endregion

        #region Implementation
        private void OnUnloaded(object sender, System.Windows.RoutedEventArgs e)
        {
            AssociatedObject.Unloaded -= OnUnloaded;
            AssociatedObject.SelectionChanged -= OnSelectionChanged;
        }
        private void OnSelectionChanged(object sender, SelectionChangeEventArgs e)
        {
            object si = AssociatedObject.SelectedItem;
            if (si != null)
            {
                AssociatedObject.ScrollIntoView(si);
            }
        }


        #endregion
    }

[Stefan Nenchev]

Hello Dan,

Thank you for providing the additional approach and contributing to the Telerik community.

Regards,
Stefan Nenchev
Telerik

[Dinesh]

I just need some help on how to scroll HORIZONTALLY by using (SHIFT + MOUSE SCROLL) IN WPF application. Give some idea or Code & Project Solution....

[Dinesh]

I just need some help on how to scroll HORIZONTALLY by using (SHIFT + MOUSE SCROLL) IN WPF application. Give some idea or Code & Project Solution...

[Dinesh]

I just need some help on how to scroll HORIZONTALLY by using (SHIFT + MOUSE SCROLL) IN WPF application. Give some idea or Code & Project Solution...

[Shanthosh]

using telerik not working on shift + mousewheel 

try this code without telerik

 private void ScrollViewer_PreviewMouseWheel(object sender, MouseWheelEventArgs e)
        {  
             ScrollViewer scrollviewer = sender as ScrollViewer;

            if (Keyboard.Modifiers == ModifierKeys.Shift)
            {
                if (e.Delta > 0)
                    scrollviewer.PageLeft();
                else
                    scrollviewer.PageRight();
                e.Handled = true;
            }
        }

xaml code:

<ScrollViewer HorizontalScrollBarVisibility="Visible" VerticalScrollBarVisibility="Visible" PreviewMouseWheel="ScrollViewer_PreviewMouseWheel" />

 

[Vladimir Stoyanov]

Hello Dinesh,

I replied to your question in the other forum thread: https://www.telerik.com/forums/ctrl-mousescroll-for-zoom-mousescroll-for-scrolling#_sxWZEbW80ySdQ1Swtiruw.

Regards,
Vladimir Stoyanov
Progress Telerik