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How do I get the width of an element generated by Binding?

I generate a list of elements with an ObservableList and an ItemsControl.
But I need to know the ActualWidth of the single controls with reference to the bound item in the list.
I need the Width to cut down my Polyline so that it is no longer than the Canvas
I tried a OneWayToSource and a TwoWay Binding back to the Item in the List with the Width Property. Always got NaN or 0.
<ItemsControl x:Name="GraphLB" ItemsSource="{Binding}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Border Padding="5, 0, 5, 0">
<StackPanel>
<TextBlock Text="{Binding Text}" Foreground="{Binding Foreground}"/>
<Border BorderBrush="{Binding Foreground}" BorderThickness="0.5">
<Canvas MinHeight="40" MinWidth="100"
Height="{Binding Height, Mode = TwoWay }"
Width="{Binding Width, Mode = TwoWay }">
<Polyline Points="{Binding Line}" Stroke="{Binding Foreground}" StrokeThickness="1"/>
</Canvas>
</Border>
</StackPanel>
</Border>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
And the Class for the Bound Objects
class GraphListObject : LabelListObject
{
public double Height { get; set; }
public double Width { get; set; }
private getProperty<PointCollection> getLine;
public PointCollection Line { get { return GetLine(); } }
internal getProperty<PointCollection> GetLine { get => getLine; set { getLine = value; } }
}
I expected that the Width="{Binding Width, Mode = TwoWay }" would set the Value in the Element of the List to the Width of the Canvas Element, but the actual output is 0.
Sadly the Polyline is drawn outside the borders:

Is there any control for auto resize items inside

is there any control that can auto resize items inside. I need to contain textblocks inside ItemsControl only in one row, so if total items width larger then container.Width, it will change each item's width. UWP
<ItemsControl Grid.Column="1"
ItemsSource="{Binding Path=NavigationHistory, ElementName=Main, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
x:Name="BroadComb"
MaxHeight="24"
Margin="10,0,0,0" VerticalAlignment="Center" >
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal"/>
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemTemplate>
<DataTemplate>
<HyperlinkButton Command="{Binding Path=NavigateCommand, ElementName=Main}" CommandParameter="{Binding}" Margin="10,0,0,0" Foreground="{ThemeResource AppAccentForegroundLowBrush}" >
<HyperlinkButton.ContentTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<TextBlock VerticalAlignment="Center"
TextTrimming="None"
Text="{Binding Path=DisplayName}"
FontSize="10"
FontWeight="Bold"
Foreground="{ThemeResource AppAccentForegroundLowBrush}">
<i:Interaction.Behaviors>
<core:DataTriggerBehavior Binding="{Binding Path=CanBeTrim}" Value="True">
<core:ChangePropertyAction PropertyName="TextTrimming" Value="WordEllipsis"/>
</core:DataTriggerBehavior>
<core:DataTriggerBehavior Binding="{Binding Path=CanBeTrim}" Value="False">
<core:ChangePropertyAction PropertyName="TextTrimming" Value="None"/>
</core:DataTriggerBehavior>
</i:Interaction.Behaviors>
</TextBlock>
<FontIcon Margin="10,0,0,0" HorizontalAlignment="Center"
VerticalAlignment="Center"
FontFamily="ms-appx:/Assets/Fonts/MyBook-Regular.ttf#MyBook"
FontSize="10"
Glyph="2" Foreground="{ThemeResource AppAccentForegroundLowBrush}" />
</StackPanel>
</DataTemplate>
</HyperlinkButton.ContentTemplate>
</HyperlinkButton>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>

One possibility is to use a Grid with your desired controls in it's columns set to HorizontalAlignment="Stretch":
<Grid HorizontalAlignment="Stretch">
<Grid.ColumnDefinitions>
<ColumnDefinition Width="*"/>
<ColumnDefinition Width="*"/>
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0" Text="abc" HorizontalAlignment="Stretch" />
<TextBlock Grid.Column="1" Text="xyz" HorizontalAlignment="Stretch" />
</Grid>
This will stretch both controls over the maximum available width according to the Grid's container and make them smaller or bigger if the available space changes.
Most of the time, you will only want to set one column to fill the available space (Width="*") and set the other columns to a fixed or relative width. You can experiment with those settings.
Else we would need a more exact specification of what you want to achieve.

is there any control that can auto resize items inside. I need to contain textblocks inside ItemsControl only in one row, so if total items width larger then container.Width, it will change each item's width. UWP
What you need is to change the default ItemsPanel of GridView. You can create your own Custom Panel to let the texts be arranged in only one row:
Create your own custom Panel OneRowPanel.cs:
public class OneRowPanel:Panel
{
double itemHeight=0;
protected override Size MeasureOverride(Size availableSize)
{
int count = Children.Count;
foreach (FrameworkElement child in Children)
{
child.Measure(new Size(availableSize.Width/count,availableSize.Height));
if (child.DesiredSize.Height > itemHeight)
{
itemHeight = child.DesiredSize.Height;
};
}
// return the size available to the whole panel
return new Size(availableSize.Width, itemHeight);
}
protected override Size ArrangeOverride(Size finalSize)
{
// Get the collection of children
UIElementCollection mychildren = Children;
// Get total number of children
int count = mychildren.Count;
// Arrange children
int i;
for (i = 0; i < count; i++)
{
//get the item Origin Point
Point cellOrigin = new Point(finalSize.Width / count * i,0);
// Arrange child
// Get desired height and width. This will not be larger than 100x100 as set in MeasureOverride.
double dw = mychildren[i].DesiredSize.Width;
double dh = mychildren[i].DesiredSize.Height;
mychildren[i].Arrange(new Rect(cellOrigin.X, cellOrigin.Y, dw, dh));
}
// Return final size of the panel
return new Size(finalSize.Width, itemHeight);
}
}
Use it in your Xaml and set the TextBlock.TextTrimming to CharacterEllipsis:
<Page
x:Class="AutoResizeItemsSample.MainPage"
...
mc:Ignorable="d">
<Page.Resources>
<DataTemplate x:Key="TextTemplate">
<TextBlock Text="{Binding Text}" TextTrimming="CharacterEllipsis">
</TextBlock>
</DataTemplate>
</Page.Resources>
<Grid Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<StackPanel Name="rootPanel">
<GridView Name="gridView" ItemTemplate="{StaticResource TextTemplate}" >
<GridView.ItemsPanel>
<ItemsPanelTemplate>
<local:OneRowPanel ></local:OneRowPanel>
</ItemsPanelTemplate>
</GridView.ItemsPanel>
</GridView>
</StackPanel>
</Grid>
</Page>
Here is the Result:
Here is the complete demo:AutoResizeItemsSample.

Solve this easily with ListView. The ItemsPanel is already a StackPanel and the individual item will resize as needed. If you need the horizontal width of each item to be different, that's supported out of the box, too. I think the solution is to simply choose the ListView control.

Get control inside DataTemplate

So I have a FlipView defined in xaml by the following code:
<FlipView x:Name="carrousel" Height="175" Background="Transparent" Margin="0,20,0,0">
<FlipView.ItemTemplate>
<DataTemplate>
<Grid>
<Rectangle x:Name="profile" Stroke="White" StrokeThickness="0" HorizontalAlignment="Center" VerticalAlignment="Center" Width="175" Height="175" Canvas.ZIndex="1" RadiusX="88" RadiusY="88" Tapped="profile_Tapped"/>
</Grid>
</DataTemplate>
</FlipView.ItemTemplate>
</FlipView>
When a user clicks on the rectangle, it's animated to become bigger, but I also want all the other rectangles of every other FlipViewItem to change size too. How can I achieve this? I tried:
foreach(FlipViewItem fvi in carrousel.Items)
{
Rectangle g = (fvi.Content as Grid).FindName("profile") as Rectangle;
g.Width = double;
g.Height = double;
}
But seeing as my flipview doesn't contain FlipViewItems but custom classes I've binded to it (which obviously have no .Content), it doesn't work. How can I get this to work?

foreach(var fvi in carrousel.Items)
{
FlipViewItem item=carrousel.ContainerFromItem(fvi);
var rectangle =FindElementInVisualTree<Rectangle>(item);
//Or without VisualTreeHelper you can do like what were you trying before
Rectangle g = (item.Content as Grid).FindName("profile") as Rectangle;
g.Width = double;
g.Height = double;
}
private T FindElementInVisualTree<T>(DependencyObject parentElement) where T : DependencyObject
{
var count = VisualTreeHelper.GetChildrenCount(parentElement);
if (count == 0) return null;
for (int i = 0; i < count; i++)
{
var child = VisualTreeHelper.GetChild(parentElement, i);
if (child != null && child is T)
return (T)child;
else
{
var result = FindElementInVisualTree<T>(child);
if (result != null)
return result;
}
}
return null;
}

This solution is a turn around solution (because I could not manage the relative binding).
<Grid Background="{ThemeResource SystemControlBackgroundListMediumBrush}">
<StackPanel Margin="100,10,10,10">
<FlipView x:Name="carrousel" Height="350" Width="350" Background="Red" Margin="0,20,0,0">
<FlipView.ItemTemplate>
<DataTemplate>
<Grid>
<Rectangle x:Name="profile" Stroke="White" StrokeThickness="1" Fill="Aqua"
HorizontalAlignment="Center" VerticalAlignment="Center"
Width="{Binding ElementName=RefValueRect, Path=Width, Mode=OneWay}"
Height="{Binding ElementName=RefValueRect, Path=Height, Mode=OneWay}" Canvas.ZIndex="1" RadiusX="88"
RadiusY="88" Tapped="profile_Tapped"/>
</Grid>
</DataTemplate>
</FlipView.ItemTemplate>
</FlipView>
</StackPanel>
<Rectangle x:Name="RefValueRect" Width="175" Height="175" Visibility="Collapsed" />
</Grid>
code behind
private void profile_Tapped(object sender, TappedRoutedEventArgs e)
{
RefValueRect.Width *= 2;
RefValueRect.Height *= 2;
}

Windows Phone 8.1 Listview unique first and last item template

Last year I made an app for Windows Phone 8, containing a LongListSelector with a unique first and last item template, as described here:
LongListSelector different item template for first and last item
I recently updated the app to Windows Phone 8.1 Store and this functionality broke. Here's my class (the only difference from the post being, that I'm using a ListView instead of a LongListSelector for Windows Phone 8.1 Store, since LongListSelector is not a part of the Windows Phone 8.1 Store framework):
public abstract class TemplateSelector : ContentControl
{
public abstract DataTemplate SelectTemplate(object item, int index, int totalCount, DependencyObject container);
protected override void OnContentChanged(object oldContent, object newContent)
{
base.OnContentChanged(oldContent, newContent);
var parent = GetParentByType<ListView>(this);
var index = (parent.ItemsSource as IList).IndexOf(newContent);
var totalCount = (parent.ItemsSource as IList).Count;
ContentTemplate = SelectTemplate(newContent, index, totalCount, this);
}
private static T GetParentByType<T>(DependencyObject element) where T : FrameworkElement
{
T result = null;
DependencyObject parent = VisualTreeHelper.GetParent(element);
while (parent != null)
{
result = parent as T;
if (result != null)
{
return result;
}
parent = VisualTreeHelper.GetParent(parent);
}
return null;
}
}
The problem is that this:
DependencyObject parent = VisualTreeHelper.GetParent(element);
of the GetParentByType function returns null for some reason. Anyone knows why or have an alternative solution?
Below is my XAML code(with a few xmlns's removed). The DataTrigger is there because sometimes a unique first item template is enough (controlled by the LoadMore property of the ViewModel, which is a bool).
<controls:WP81Page
xmlns:core="using:Microsoft.Xaml.Interactions.Core"
xmlns:interactivity="using:Microsoft.Xaml.Interactivity"
Background="{ThemeResource ApplicationPageBackgroundThemeBrush}">
<controls:WP81Page.Resources>
<DataTemplate x:Key="first">
<Grid HorizontalAlignment="Left" Width="Auto" Height="200">
<Border BorderThickness="1" BorderBrush="Black" Visibility="{Binding NoLargeImage, Converter={StaticResource BoolToVisibilityConverter}}" >
<Image Source="/Images/default-image.png" Stretch="UniformToFill" />
</Border>
<Border BorderThickness="1" BorderBrush="Black" Visibility="{Binding NoLargeImage, Converter={StaticResource BoolToVisibilityConverterReverse}}" >
<Image Source="{Binding LargeImageUrl}" Stretch="UniformToFill" />
</Border>
<StackPanel VerticalAlignment="Bottom" Background="#7F000000" >
<TextBlock Text="{Binding Header}" VerticalAlignment="Center" TextWrapping="Wrap" Foreground="White" FontWeight="Bold" Margin="15,0,15,15"/>
</StackPanel>
</Grid>
</DataTemplate>
<DataTemplate x:Key="default">
<StackPanel Orientation="Horizontal" Margin="0,10,0,0" Height="105" Width="Auto">
<Border BorderThickness="1" BorderBrush="Black" Margin="0,2" Visibility="{Binding NoSmallImage, Converter={StaticResource BoolToVisibilityConverter}}" >
<Image Source="/Images/default-image.png" Width="130" Height="100" Stretch="UniformToFill" />
</Border>
<Border BorderThickness="1" BorderBrush="Black" Margin="0,2" Visibility="{Binding NoSmallImage, Converter={StaticResource BoolToVisibilityConverterReverse}}">
<Image Source="{Binding SmallImageUrl}" Width="130" Height="100" Stretch="UniformToFill"/>
</Border>
<StackPanel Orientation="Vertical" Width="300" Margin="8,0,0,0">
<TextBlock Text="{Binding Header}" TextWrapping="Wrap" FontWeight="Bold" />
<TextBlock Margin="0,3,0,0" Text="{Binding DisplayDate}" TextWrapping="Wrap" Foreground="#FFB9B9B9" FontSize="16" />
</StackPanel>
</StackPanel>
</DataTemplate>
<DataTemplate x:Key="last">
<TextBlock Text="hent flere nyheder" FontSize="25" Margin="0,20" TextWrapping="Wrap" VerticalAlignment="Center" HorizontalAlignment="Center" Height="75" />
</DataTemplate>
<DataTemplate x:Key="UniqueFirstTemplateSelector">
<common:UniqueFirstTemplateSelector Content="{Binding}" First="{StaticResource first}" Default="{StaticResource default}" HorizontalAlignment="Stretch"/>
</DataTemplate>
<DataTemplate x:Key="UniqueFirstAndLastTemplateSelector">
<common:UniqueFirstAndLastTemplateSelector Content="{Binding}" First="{StaticResource first}" Default="{StaticResource default}" Last="{StaticResource last}" HorizontalAlignment="Stretch"/>
</DataTemplate>
</controls:WP81Page.Resources>
<controls:WP81Page.DataContext>
<viewModels:NewsViewModel/>
</controls:WP81Page.DataContext>
<Grid x:Name="LayoutRoot" Style="{Binding Source={StaticResource Background}}">
<Grid.RowDefinitions>
<RowDefinition Height="Auto"/>
<RowDefinition Height="*"/>
</Grid.RowDefinitions>
<ProgressBar Grid.Row="0" VerticalAlignment="Top" IsIndeterminate="True" Background="Transparent" Foreground="White" Visibility="{Binding IsLoading, Converter={StaticResource BoolToVisibilityConverter}}" />
<StackPanel Grid.Row="0" Margin="12,17,0,28">
<TextBlock Text="NYHEDER" FontSize="35" FontWeight="Bold" Style="{StaticResource PhoneTextNormalStyle}"/>
</StackPanel>
<Grid x:Name="ContentPanel" Grid.Row="1">
<controls:WP81ListView x:Name="listSelector" Margin="22,0" Grid.Row="2" ItemsSource="{Binding News}" Command="{Binding NewsEntrySelectedCommand}" >
<interactivity:Interaction.Behaviors>
<core:DataTriggerBehavior Binding="{Binding LoadMore}" Value="True">
<core:ChangePropertyAction TargetObject="{Binding ElementName=listSelector}"
Value="{StaticResource UniqueFirstAndLastTemplateSelector}"
PropertyName="ItemTemplate" />
</core:DataTriggerBehavior>
<core:DataTriggerBehavior Binding="{Binding LoadMore}" Value="False">
<core:ChangePropertyAction TargetObject="{Binding ElementName=listSelector}"
Value="{StaticResource UniqueFirstTemplateSelector}"
PropertyName="ItemTemplate" />
</core:DataTriggerBehavior>
</interactivity:Interaction.Behaviors>
</controls:WP81ListView>
</Grid>
</Grid>
</controls:WP81Page>
Thank you in advance.
EDIT
Alright, so what I want is not for the first and last item to be unique all the time. I'm making a news feed where the last item is only unique when there are more news entries to load (when the last item are clicked, more news entries are added to the ListView). If however, the end of the news entries are reached, the last item must not be unique (hence the combination with interactivity).

ListView has a property called ItemTemplateSelector which accepts objects based on DataTemplateSelector. So you need to change a couple of things to get it to work.
First of all, the definition of your template selector. It needs to be based on DataTemplateSelector and override method called SelectTemplateCore. It takes an object which is a ListViewItem. At that point you can go up the VisualTree to get the ListView and choose the DataTemplate based on index.
public class MyTemplateSelector : DataTemplateSelector
{
public DataTemplate First { get; set; }
public DataTemplate Default { get; set; }
public DataTemplate Last { get; set; }
protected override DataTemplate SelectTemplateCore(object item, DependencyObject container)
{
var listViewItem = container as ListViewItem;
var listView = GetParentByType<ListView>(listViewItem);
var index = (listView.ItemsSource as IList).IndexOf(item);
var totalCount = (listView.ItemsSource as IList).Count;
if (index == 0)
return First;
else if (index == totalCount - 1)
return Last;
else
return Default;
}
private T GetParentByType<T>(DependencyObject element) where T : FrameworkElement
{
T result = null;
DependencyObject parent = VisualTreeHelper.GetParent(element);
while (parent != null)
{
result = parent as T;
if (result != null)
{
return result;
}
parent = VisualTreeHelper.GetParent(parent);
}
return null;
}
}
Then, you need to create an instance of it in static resources
<local:MyTemplateSelector x:Key="SelectingTemplate"
First="{StaticResource first}"
Default="{StaticResource default}"
Last="{StaticResource last}" />
with the First, Default and Last DataTemplates, just like you did before.
The last step is to apply it to the ListView you're using.
<ListView ItemsSource="{Binding SomeItemsSource}"
ItemTemplateSelector="{StaticResource SelectingTemplate}" />
And that's it!

Trying to bind the height/width of a grid to a ViewModel

So I have a grid inside a viewbox. Now the grid scales with the viewbox fine. However, I need to know the height and width of the grid in my ViewModel. However it doesn't seem to ever set the Height to anything?
<Viewbox VerticalAlignment="Top" Margin="5,20,5,0">
<Border BorderThickness="6" BorderBrush="Black" CornerRadius="2">
<Grid MinHeight="300" MinWidth="400" Height="{Binding Height, Mode=TwoWay}" Width="{Binding Width, Mode=TwoWay}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" Grid.Column="0" >
<ItemsControl ItemsSource="{Binding Viewers}">
<ItemsControl.ItemsPanel>
<ItemsPanelTemplate>
<Canvas />
</ItemsPanelTemplate>
</ItemsControl.ItemsPanel>
<ItemsControl.ItemContainerStyle>
<Style>
<Setter Property="Canvas.Left" Value="{Binding X}" />
<Setter Property="Canvas.Top" Value="{Binding Y}"/>
</Style>
</ItemsControl.ItemContainerStyle>
</ItemsControl>
</Grid>
</Border>
</Viewbox>
And in my ViewModel:
private int _height;
public int Height
{
get
{
return _height;
}
set
{
_height = value;
OnPropertyChanged("Height");
}
}
private int _width;
public int Width
{
get
{
return _width;
}
set
{
_width = value;
OnPropertyChanged("Width");
}
}
Any ideas?

You would need a OneWayToSource binding on ActualWidth/Height as those properties are readonly, so far i have seen any good solutions to that as WPF reject bindings outright if set on a readonly dependency property.