Develop Reference

How to implement a delayed PointerEnter event into C# UWP project

I have been trying to implement a feature into my application where when a user hovers over a Grid item housed within a GridView for a couple seconds it will display a medium sized popup Grid with more details. I have tried a few methods I found online, but I have been running into errors that I am not understanding the root cause of, and I have the feeling there is a much simpler approach to add this feature than what I have found online so far.
First, I tried a solution I adapted by using a derivative class of Grid. I ran into some issues with that that (detailed a bit more in my last question) with the main issue being that my Timer no longer would trigger and items using my "HoverGrid" data template within the GridView template would no longer show Image as a child item of the HoverGrid. So, I abandoned that approach.
Then I tried to implement the Timer directly in my Page's code-behind, which seemed to work (partially) as it is properly triggering PointerEnter, PointerExit, and TimerElapsed events, however, when trying to manipulate anything UI related in the TimerElapsed event I would get:
System.Exception: 'The application called an interface that was marshalled for a different thread. (Exception from HRESULT: 0x8001010E (RPC_E_WRONG_THREAD))'
Here is the XAML:
<Page
x:Class="myproject.Pages.MyPage"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:controls="using:Microsoft.Toolkit.Uwp.UI.Controls"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
Height="950"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}"
mc:Ignorable="d">
<Grid x:Name="ContentGrid">
<ListView
x:Name="AreaPanels"
Margin="0,10,0,0"
HorizontalContentAlignment="Stretch"
SelectionMode="None">
<ListView.ItemsPanel>
<ItemsPanelTemplate>
<ItemsStackPanel AreStickyGroupHeadersEnabled="True" />
</ItemsPanelTemplate>
</ListView.ItemsPanel>
<controls:AdaptiveGridView
CanDragItems="True"
DesiredWidth="140"
ItemHeight="140">
<controls:AdaptiveGridView.ItemTemplate>
<DataTemplate x:Name="IconTextTemplate" x:DataType="Image">
<Grid
PointerEntered="ImageHoverStart"
PointerExited="ImageHoverEnd">
<Image
Opacity="1"
Source="/Assets/Placeholders/sample_image.jpg"
Stretch="UniformToFill" />
</Grid>
</DataTemplate>
</controls:AdaptiveGridView.ItemTemplate>
<Grid />
<Grid />
<Grid />
<Grid />
</controls:AdaptiveGridView>
</ListView>
</Grid>
</Page>
Code-behind (C#):
using System.Diagnostics;
using Windows.Foundation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Input;
namespace myproject.Pages
{
/// <summary>
/// An empty page that can be used on its own or navigated to within a Frame.
/// </summary>
public sealed partial class MyPage : Page
{
//Variables for Grid functions
public object hoveredGridItem = null;
public PointerRoutedEventArgs hoveredGridItemArgs = null;
public System.Timers.Timer hoverTimer = new System.Timers.Timer();
public event System.Timers.ElapsedEventHandler TimerElapsed
{ add { hoverTimer.Elapsed += value; } remove { hoverTimer.Elapsed -= value; } }
public MyPage()
{
this.InitializeComponent();
hoverTimer.Enabled = true;
hoverTimer.Interval = 2000;
TimerElapsed += OnTimerElapsed;
}
private void ImageHoverStart(object sender, PointerRoutedEventArgs e)
{
Debug.WriteLine("Fired: ImageHoverStart");
hoverTimer.Start();
hoveredGridItem = sender;
hoveredGridItemArgs = e;
}
private void ImageHoverEnd(object sender, PointerRoutedEventArgs e)
{
Debug.WriteLine("Fired: ImageHoverEnd");
hoverTimer.Stop();
hoveredGridItem = null;
hoveredGridItemArgs = null;
}
private void OnTimerElapsed(object source, System.Timers.ElapsedEventArgs e)
{
Debug.WriteLine("Timer elapsed!");
hoverTimer.Stop();
if (hoveredGridItem.GetType().ToString() == "Windows.UI.Xaml.Controls.Grid")
{
Debug.WriteLine(hoveredGridItem.ToString());
Debug.WriteLine(hoveredGridItemArgs.ToString());
//Get the hovered image and associated arguments that were stored
Grid itm = (Grid)hoveredGridItem;
PointerRoutedEventArgs f = hoveredGridItemArgs;
//Get image position and bounds
//GeneralTransform transform = itm.TransformToVisual(Window.Current.Content);
//Point coordinatePointToWindow = transform.TransformPoint(new Point(0, 0));
//Rect winBounds = Window.Current.Bounds;
//Testing other UI items
itm.Visibility = Visibility.Visible;
// other UI stuff ...
}
}
}
}
I tried to make references to some UI elements such as Window.Content.Current and other elements (as a workaround) but was still getting the same System.Exception. I understand this has something to do with TimerElapsed being on a different thread than the UI thread and looked around for how to fix this but was not able to fix it.
My two issues are that I was not able to fix the thread marshalling issue (some issues with running things async) but more importantly that the solution seemed a bit convoluted, maybe more difficult than it needs to be.

At first to fix the threading issue you have to use the Dispatcher of the UIElement:
await itm.Dispatcher.RunAsync(Windows.UI.Core.CoreDispatcherPriority.Normal, () =>
{
itm.Visibility = Visibility.Visible;
});
And second, have you thought about using a tooltip for this? It should be very easy to implement:
<Grid Background="Transparent">
<Image Opacity="1" Source="/Assets/StoreLogo.png" Stretch="UniformToFill" />
<!--Tooltip implementation:-->
<ToolTipService.ToolTip>
<Image Source="/Assets/StoreLogo.png"/>
</ToolTipService.ToolTip>
</Grid>

Binding TextBlock field to backend variable

First time really using WPF - thought I'd have a go at remaking something I did a while back in Java.
I'm trying to bind the Text value of a TextBlock on a popup to something that gets set in the backend, so I can use one handler method to display any message on said popup.
I've been trying multiple different routes, such as fully binding it in the cs instead of XAML like so:
<--XAML-->
<Popup Margin="89,75,0,0" Name="verif_popup" HorizontalAlignment="Left" VerticalAlignment="Top" IsOpen="False" PopupAnimation="Slide" Placement="Center" Width="100" Height="100" Grid.Column="1">
<Popup.Effect>
<BlurEffect/>
</Popup.Effect>
<Canvas Background="Azure">
<TextBlock Name="VerifTextBlock"/>
</Canvas>
</Popup>
<--CS-->
private void SmallPopupHandler(string text)
{
Binding binding = new("Text")
{
Source = text
};
VerifTextBlock.SetBinding(TextBlock.TextProperty, binding);
verif_popup.IsOpen = true;
}
But it doesn't like the fact that the string isn't a TextBlock property, I sort of knew this wouldn't work but it seems the most logical to me having come from swing. There also doesn't seem to be a way for me to cast it to it and im not in the mood for making my own dependency property rn...
The next thing I tried was to bind the value to a field in the class, but I just got a stackoverflow error (haha nice)
<--XAML-->
<Popup Margin="89,75,0,0" Name="verif_popup" HorizontalAlignment="Left" VerticalAlignment="Top" IsOpen="False" PopupAnimation="Slide" Placement="Center" Width="100" Height="100" Grid.Column="1">
<Popup.Effect>
<BlurEffect/>
</Popup.Effect>
<Canvas Background="Azure">
<Canvas.DataContext>
<local:MainWindow/>
</Canvas.DataContext>
<TextBlock Name="VerifTextBlock" Text="{Binding Popup_message}"/>
</Canvas>
</Popup>
<--CS-->
public partial class MainWindow : Window
{
public string? Popup_message { get; set; }
public MainWindow()
{
InitializeComponent();
this.DataContext = this;
}
I also tried making an interfacing class of sorts to see if that would work around the stackoverflow error (haha) but as im sure you could have guessed by now, that didn't work either...
Kinda pulling my hair out so any help would be greatly appreciated!
Thanks in advance!

You could just set the Text property of the VerifTextBlock directly as suggested by #Clemens:
private void SmallPopupHandler(string text)
{
VerifTextBlock.Text = text;
verif_popup.IsOpen = true;
}
If you really do want to use a binding for whatever reason, then remove the binding path. This should work:
private void SmallPopupHandler(string text)
{
Binding binding = new()
{
Source = text
};
VerifTextBlock.SetBinding(TextBlock.TextProperty, binding);
verif_popup.IsOpen = true;
}

How to deal with empty RichTextBox selection [duplicate]

I need to set the font family for the next text to be written in a RichTextBox.
I tried setting that with...
<RichTextBox x:Name="RichTextEditor" MaxWidth="1000" SpellCheck.IsEnabled="True"
FontFamily="{Binding ElementName=TextFontComboBox, Path=SelectedItem}"
FontSize="{Binding ElementName=TextSizeComboBox, Path=SelectedValue}"
Width="Auto" Height="Auto" HorizontalScrollBarVisibility="Auto"
VerticalScrollBarVisibility="Auto" />
...but it changed the whole text. I suppose that with the Selection property I can restrict the change to be applied just to the selected area. But how for the next -not yet typed- text?

In order to set the FontFamily based on the cursor position you need to define a custom control with a dependency property that helps insert a new Run section by overriding the OnTextInput method.
I included most of the code, you'll need to modify the namespaces to fit your development environment.
The code uses a ViewModel to manage the available fonts and manage if the font changed.
This code is only a prototype and does not deal with focusing issues between the two controls.
To use this code:
1- Type some text in the RichTectBox.
2- Change the font in the ComboBox.
3- Tab back to the RichTextBox.
4- Type some more text.
Here is the custom RichTextBox control:
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
namespace RichTextboxFont.Views
{
public class RichTextBoxCustom : RichTextBox
{
public static readonly DependencyProperty CurrentFontFamilyProperty =
DependencyProperty.Register("CurrentFontFamily",
typeof(FontFamily), typeof
(RichTextBoxCustom),
new FrameworkPropertyMetadata(new FontFamily("Tahoma"),
FrameworkPropertyMetadataOptions.BindsTwoWayByDefault,
new PropertyChangedCallback(OnCurrentFontChanged)));
public FontFamily CurrentFontFamily
{
get
{
return (FontFamily)GetValue(CurrentFontFamilyProperty);
}
set
{
SetValue(CurrentFontFamilyProperty, value);
}
}
private static void OnCurrentFontChanged(DependencyObject o, DependencyPropertyChangedEventArgs e)
{}
protected override void OnTextInput(TextCompositionEventArgs e)
{
ViewModels.MainViewModel mwvm = this.DataContext as ViewModels.MainViewModel;
if ((mwvm != null) && (mwvm.FontChanged))
{
TextPointer textPointer = this.CaretPosition.GetInsertionPosition(LogicalDirection.Forward);
Run run = new Run(e.Text, textPointer);
run.FontFamily = this.CurrentFontFamily;
this.CaretPosition = run.ElementEnd;
mwvm.FontChanged = false;
}
else
{
base.OnTextInput(e);
}
}
}
}
Here is the XAML:
<Window x:Class="RichTextboxFont.Views.MainView"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:local="clr-namespace:RichTextboxFont.Views"
xmlns:ViewModels="clr-namespace:RichTextboxFont.ViewModels"
Title="Main Window"
Height="400" Width="800">
<DockPanel>
<Grid>
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition/>
</Grid.RowDefinitions>
<ComboBox ItemsSource="{Binding Path=Fonts}"
SelectedItem="{Binding Path=SelectedFont, Mode=TwoWay}"/>
<local:RichTextBoxCustom Grid.Row="1"
CurrentFontFamily="{Binding Path=SelectedFont, Mode=TwoWay}"
FontSize="30"/>
</Grid>
</DockPanel>
</Window>
Here is the ViewModel:
If you do not use view models, let me know and I'll add the base class code too; otherwise, google/stackoverflow can help you too.
using System.Collections.ObjectModel;
using System.Windows.Media;
namespace RichTextboxFont.ViewModels
{
public class MainViewModel : ViewModelBase
{
#region Constructor
public MainViewModel()
{
FontFamily f1 = new FontFamily("Georgia");
_fonts.Add(f1);
FontFamily f2 = new FontFamily("Tahoma");
_fonts.Add(f2);
}
private ObservableCollection<FontFamily> _fonts = new ObservableCollection<FontFamily>();
public ObservableCollection<FontFamily> Fonts
{
get
{
return _fonts;
}
set
{
_fonts = value;
OnPropertyChanged("Fonts");
}
}
private FontFamily _selectedFont = new FontFamily("Tahoma");
public FontFamily SelectedFont
{
get
{
return _selectedFont;
}
set
{
_selectedFont = value;
FontChanged = true;
OnPropertyChanged("SelectedFont");
}
}
private bool _fontChanged = false;
public bool FontChanged
{
get
{
return _fontChanged;
}
set
{
_fontChanged = value;
OnPropertyChanged("FontChanged");
}
}
#endregion
}
}
Here is the Window code-behind where I initialise the ViewModel:
using System.Windows;
namespace RichTextboxFont.Views
{
public partial class MainView : Window
{
public MainView()
{
InitializeComponent();
this.DataContext = new ViewModels.MainViewModel();
}
}
}

There's a much easier way to do this: Implement a toolbar for your RichTextBox.
Unlike WinForms, the RichTextBox in WPF doesn't come with a toolbar by default, but it's really easy to create one yourself. The RichTextBox automatically handles many EditingCommands, so it's just a matter of creating a toolbar and some buttons. Microsoft has provided sample code for this at the bottom of the RichTextBox Overview on MSDN.
Unfortunately, those editing commands don't include setting the FontFace property of the selection, though you can create a ComboBox on the toolbar that can trigger the change with an event handler in the codebehind file.
That's the approach taken in this CodePlex article by Gregor Pross: WPF RichTextEditor
The project is commented in German, but the source itself is very clearly written. The codebehind used for his font selector ComboBox looks like this:
private void Fonttype_DropDownClosed(object sender, EventArgs e)
{
string fontName = (string)Fonttype.SelectedItem;
if (fontName != null)
{
RichTextControl.Selection.ApplyPropertyValue(System.Windows.Controls.RichTextBox.FontFamilyProperty, fontName);
RichTextControl.Focus();
}
}
The main reason that people struggle with the FontFace selection is that after the font selection has been made, you must return focus to the RichTextBox. If the user must manually press tab or click into the RichTextBox, a new text selection gets created and you lose the formatting options you've chosen.
One of the answers to this StackOverflow question discusses that problem.
WPF Richtextbox FontFace/FontSize

This isn't exactly a trivial answer.
To do inline text formatting in a Rich TextBox like you want you will have to modify the Document property of the RichTextBox. Very simply, something like this will work
<RichTextBox >
<RichTextBox.Document>
<FlowDocument>
<Paragraph>
<Run>Something</Run>
<Run FontWeight="Bold">Something Else</Run>
</Paragraph>
</FlowDocument>
</RichTextBox.Document>
</RichTextBox>
I think you could create a custom Control that creates a new block element and sets the font properties you need based on the user input.
For example, If the user types something then presses bold. You would want to wrap the previous text in a run and create a new run element setting the FontWeight to bold then the subsequent text will be wrapped in the bolded run.
Again, not a trivial solution but I can't think of any other way to accomplish what you are after.

Text Writing Animation like word2013 [duplicate]

This question already has answers here:
Is there any way I can integrate the MS Office Smooth Typing in a C# application?
(2 answers)
Closed 9 years ago.
I was wondering, if I can make a TextBox or any control that you can write some text on it, to be like Word 2013, the animation experience is very good.
I am now able to do type of animation on the control itself (TextBox,...), but to do this type of animation to the cursor or on the text itself this is new.

You could create a WPF UserControl or custom control which inherits from the default WPF textbox. I was able to create a textbox that animates the cursor position with the following method:
1-Create a user control and add a textbox to it.
2-Add a canvas with a rectangle inside it (the rectangle is your new cursor).
3-Set the Texboxes CaretBrush to transparent.
4-In the UserControl's code-behind create a method to animate the cursor when the cursor position changes.
5-Call the animation method from step 4 when certain events happen which would change the cursor position.
Example:
UserControl XAML
<UserControl
x:Class="YourNamespace.AnimatedCursorTextBox"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
mc:Ignorable="d"
d:DesignHeight="23"
d:DesignWidth="300"
xmlns:c="clr-namespace:System.Windows.Controls;assembly=PresentationFramework"
Name="Control">
<UserControl.Resources>
<c:BooleanToVisibilityConverter
x:Key="BoolToVisibility" />
</UserControl.Resources>
<Grid>
<TextBox
Name="MainTextBox"
CaretBrush="Transparent"
SelectionChanged="MainTextBox_SelectionChanged"
TextChanged="MainTextBox_TextChanged"
GotKeyboardFocus="MainTextBox_GotKeyboardFocus" />
<Canvas
Visibility="{Binding IsKeyboardFocusWithin,
ElementName=Control,
Converter={StaticResource BoolToVisibility}}"
Height="{Binding ActualHeight, ElementName=MainTextBox}"
Width="{Binding ActualWidth, ElementName=MainTextBox}">
<Rectangle
HorizontalAlignment="Left"
Name="Caret"
Width="1"
Fill="Black" />
</Canvas>
</Grid>
</UserControl>
Code-Behind:
public partial class AnimatedCursorTextBox : UserControl
{
private DoubleAnimation cursorAnimation = new DoubleAnimation();
public AnimatedCursorTextBox()
{
InitializeComponent();
}
private void UpdateCaretPosition()
{
var rectangle = MainTextBox.GetRectFromCharacterIndex(MainTextBox.CaretIndex);
Caret.Height = rectangle.Bottom - rectangle.Top;
Canvas.SetTop(Caret, rectangle.Top);
Canvas.SetBottom(Caret, rectangle.Bottom);
var left = Canvas.GetLeft(Caret);
if (!double.IsNaN(left))
{
cursorAnimation.From = left;
cursorAnimation.To = rectangle.Right;
cursorAnimation.Duration = new Duration(TimeSpan.FromSeconds(.05));
Caret.BeginAnimation(Canvas.LeftProperty, cursorAnimation);
}
else
{
Canvas.SetLeft(Caret, rectangle.Right);
}
}
private void MainTextBox_SelectionChanged(object sender, RoutedEventArgs e)
{
UpdateCaretPosition();
}
private void MainTextBox_TextChanged(object sender, TextChangedEventArgs e)
{
UpdateCaretPosition();
}
private void MainTextBox_GotKeyboardFocus(object sender, KeyboardFocusChangedEventArgs e)
{
UpdateCaretPosition();
}
}
Note: This isn't a comprehensive solution because it doesn't handle the animation of highlighting selected text and it doesn't hide the cursor when text is highlighted, but it is a start. I recommend creating this as a custom control inheriting from TextBox and then do the layout of the control in the textbox's default style's template rather than using a UserControl. That way you can preserve all the functionality of TextBox but still get the new animation features. For more information about Custom Controls in WPF see this article on codeproject.
To change the speed of the animation just change the duration of the cursorAnimation.

Scrolling to an element of a virtualising ItemsControl

I have a ItemsControl which displays its items in a ScrollViewer, and does virtualisation. I am trying to scroll that ScrollViewer to an (offscreen, hence virtualised) item it contains. However, since the item is virtualised, it doesn't really exist on the screen and has no position (IIUC).
I have tried BringIntoView on the child element, but it doesn't scroll into view. I have also tried manually doing it with TransformToAncestor, TransformBounds and ScrollToVerticalOffset, but TransformToAncestor never returns (I guess also because of the virtualisation, because it has no position, but I have no proof of that) and code after it never executes.
Is it possible to scroll to an item with a virtualising ItemsControl? If so, how?

I've been looking at getting a ItemsControl with a VirtualizingStackPanel to scroll to an item for a while now, and kept finding the "use a ListBox" answer. I didn't want to, so I found a way to do it. First you need to setup a control template for your ItemsControl that has a ScrollViewer in it (which you probably already have if you're using an items control). My basic template looks like the following (contained in a handy style for the ItemsControl)
<Style x:Key="TheItemsControlStyle" TargetType="{x:Type ItemsControl}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ItemsControl}">
<Border BorderThickness="{TemplateBinding Border.BorderThickness}" Padding="{TemplateBinding Control.Padding}" BorderBrush="{TemplateBinding Border.BorderBrush}" Background="{TemplateBinding Panel.Background}" SnapsToDevicePixels="True">
<ScrollViewer Padding="{TemplateBinding Control.Padding}" Focusable="False" HorizontalScrollBarVisibility="Auto">
<ItemsPresenter SnapsToDevicePixels="{TemplateBinding UIElement.SnapsToDevicePixels}" />
</ScrollViewer>
</Border>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
So I've basically got a border with a scroll viewer thats going to contain my content.
My ItemsControl is defined with:
<ItemsControl x:Name="myItemsControl" [..snip..] Style="{DynamicResource TheItemsControlStyle}" ScrollViewer.CanContentScroll="True" VirtualizingStackPanel.IsVirtualizing="True">
Ok now for the fun part. I've created a extension method to attach to any ItemsControl to get it to scroll to the given item:
public static void VirtualizedScrollIntoView(this ItemsControl control, object item) {
try {
// this is basically getting a reference to the ScrollViewer defined in the ItemsControl's style (identified above).
// you *could* enumerate over the ItemsControl's children until you hit a scroll viewer, but this is quick and
// dirty!
// First 0 in the GetChild returns the Border from the ControlTemplate, and the second 0 gets the ScrollViewer from
// the Border.
ScrollViewer sv = VisualTreeHelper.GetChild(VisualTreeHelper.GetChild((DependencyObject)control, 0), 0) as ScrollViewer;
// now get the index of the item your passing in
int index = control.Items.IndexOf(item);
if(index != -1) {
// since the scroll viewer is using content scrolling not pixel based scrolling we just tell it to scroll to the index of the item
// and viola! we scroll there!
sv.ScrollToVerticalOffset(index);
}
} catch(Exception ex) {
Debug.WriteLine("What the..." + ex.Message);
}
}
So with the extension method in place you would use it just like ListBox's companion method:
myItemsControl.VirtualizedScrollIntoView(someItemInTheList);
Works great!
Note that you can also call sv.ScrollToEnd() and the other usual scrolling methods to get around your items.

Poking around in the .NET source code leads me to recommend you the use of a ListBox and its ScrollIntoView method. The implementation of this method relies on a few internal methods like VirtualizingPanel.BringIndexIntoView which forces the creation of the item at that index and scrolls to it. The fact that many of those mechanism are internal means that if you try to do this on your own you're gonna have a bad time.
(To make the selection this brings with it invisible you can retemplate the ListBoxItems)

I know this is an old thread, but in case someone else (like me) comes across it, I figured it would be worth an updated answer that I just discovered.
As of .NET Framework 4.5, VirtualizingPanel has a public BringIndexIntoViewPublic method which works like a charm, including with pixel based scrolling. You'll have to either sub-class your ItemsControl, or use the VisualTreeHelper to find its child VirtualizingPanel, but either way it's now very easy to force your ItemsControl to scroll precisely to a particular item/index.

Using #AaronCook example, Created a behavior that works for my VirtualizingItemsControl. Here is the code for that:
public class ItemsControlScrollToSelectedBehavior : Behavior<ItemsControl>
{
public static readonly DependencyProperty SelectedItemProperty =
DependencyProperty.Register("SelectedItem", typeof(object), typeof(ItemsControlScrollToSelectedBehavior),
new FrameworkPropertyMetadata(null,
new PropertyChangedCallback(OnSelectedItemsChanged)));
public object SelectedItem
{
get => GetValue(SelectedItemProperty);
set => SetValue(SelectedItemProperty, value);
}
private static void OnSelectedItemsChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
ItemsControlScrollToSelectedBehavior target = (ItemsControlScrollToSelectedBehavior)d;
object oldSelectedItems = e.OldValue;
object newSelectedItems = target.SelectedItem;
target.OnSelectedItemsChanged(oldSelectedItems, newSelectedItems);
}
protected virtual void OnSelectedItemsChanged(object oldSelectedItems, object newSelectedItems)
{
try
{
var sv = VisualTreeHelper.GetChild(VisualTreeHelper.GetChild(AssociatedObject, 0), 0) as ScrollViewer;
// now get the index of the item your passing in
int index = AssociatedObject.Items.IndexOf(newSelectedItems);
if (index != -1)
{
sv?.ScrollToVerticalOffset(index);
}
}
catch
{
// Ignore
}
}
}
and usage is:
<ItemsControl Style="{StaticResource VirtualizingItemsControl}"
ItemsSource="{Binding BoundItems}">
<i:Interaction.Behaviors>
<behaviors:ItemsControlScrollToSelectedBehavior SelectedItem="{Binding SelectedItem}" />
</i:Interaction.Behaviors>
</ItemsControl>
Helpful for those who like Behaviors and clean XAML, no code-behind.

I know I'm pretty late to the party but hopefully this may help someone else coming along looking for the solution...
int index = myItemsControl.Items.IndexOf(*your item*).FirstOrDefault();
int rowHeight = *height of your rows*;
myScrollView.ScrollToVerticalOffset(index*rowHeight);
//this will bring the given item to the top of the scrollViewer window
... and my XAML is setup like this...
<ScrollViewer x:Name="myScrollView">
<ItemsControl x:Name="myItemsControl">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid>
<!-- data here -->
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
</ScrollViewer>

This is an old thread, but I would like to suggest one way:
/// <summary>
/// Scrolls to the desired item
/// </summary>
/// <param name="control">ItemsControl</param>
/// <param name="item">item</param>
public static void ScrollIntoView(this ItemsControl control, Object item)
{
FrameworkElement framework = control.ItemContainerGenerator.ContainerFromItem(item) as FrameworkElement;
if (framework == null) { return; }
framework.BringIntoView();
}