Develop Reference

How to binding other element in ToolTip

I want binding Text in Tooltip but i have one problem, it is binding value is other element controls, therefore i cannot basically get their value through binding.
<TextBlock x:Name="txb2" Text="Hello Stackoverflow"/>
<TextBox Grid.Row="1" TextChanged="TextBox_TextChanged">
<TextBox.ToolTip>
<TextBlock>
<Run Text="{Binding ElementName=txb2, Path=Text}" FontWeight="Bold"/>
</TextBlock>
</TextBox.ToolTip>
</TextBox>
basically I tried binding this code.

If you look at the output you will see an error:
System.Windows.Data Error: 4 : Cannot find source for binding with
reference 'ElementName=txb2'. BindingExpression:Path=Text;
DataItem=null; target element is 'Run' (HashCode=58577354); target
property is 'Text' (type 'String')
You can fix it by using x:Reference:
<TextBlock x:Name="txb2" Text="Hello Stackoverflow"/>
<TextBox Grid.Row="1">
<TextBox.ToolTip>
<TextBlock>
<Run Text="{Binding Source={x:Reference txb2}, Path=Text}" FontWeight="Bold"/>
</TextBlock>
</TextBox.ToolTip>
</TextBox>
As for the difference between ElementName and x:Reference take a look at the following thread. ElementName does not work since Tooltip is not a Ui property, but ElementName only works with Ui Element hierarchy (Visual Tree) when it searches txb2.

Tooltips exist outside the visual tree, so can't reference other controls by name. All that a tooltip knows about is its own PlacementTarget – the UIElement that it is displayed against.
One way to allow the tooltip to reference other controls is to hijack some otherwise unused property of this placement target control (Tag is most often suitable), which can then be referenced by the tooltip.
<TextBox x:Name="txb2" Text="Hello Stackoverflow" Width="200" />
<TextBox Grid.Row="1" Tag="{Binding ElementName=txb2}" Width="200">
<TextBox.ToolTip>
<ToolTip DataContext="{Binding PlacementTarget.Tag, RelativeSource={RelativeSource Self}}">
<TextBlock>
<Run Text="{Binding Text}" FontWeight="Bold" />
</TextBlock>
</ToolTip>
</TextBox.ToolTip>
</TextBox>
if you're using the MVVM design pattern, an alternative method (that doesn't require property hijacking) is to bind to the PlacementTarget's DataContext (usually the ViewModel). You can then bind the tooltip's content to whatever property of that you like.
<ToolTip DataContext="{Binding PlacementTarget.DataContext, RelativeSource={RelativeSource Self}}">
....

WPF Usercontrol, Hosting dynamic content for reuse of UserControl. MVVM

I'll try to be very clear of what I'm trying to accomplish and am open to suggestions on other ways to achieve my desired result.
The 1000 foot view.
I have a UserControl that I want to reuse in every screen in my application. This control is more of a template look and feel with an icon (bindable), dynamic (bindable) label.
UserControl.xaml (CardView.xaml)
<Border BorderBrush="{Binding Path=BorderColor, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}">
<StackPanel Orientation="Vertical" Style="{StaticResource CardStyle}">
<StackPanel>
<Border Style="{StaticResource MyBorderStyle}">
<Label Content="{Binding Path=CardTitle, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
</Border>
</StackPanel>
<Label Style="{StaticResource LabelIcon}">
<Path Fill="#FF000000" HorizontalAlignment="Center"
Stretch="UniformToFill" Data="{Binding Path=VectorString, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
</StackPanel>
<StackPanel Orientation="Horizontal">
// Dynamic Content Here.
// Any kind of XAML content for the consumer of the control.
// not in C# but I want to host the control and put controls in
// here that I can bind to in XMAL by parents view model.
</StackPanel>
</Border>
Consumer code (customer.xaml)
<local:CardView CardTitle="Test" VectorString="F1 M" BorderColor="#FF0088">
// Here's where I want to put dynamic XAML content.
// Want to host anything and bind to it using the consumers View Model.
// Example
<Button Content="{Binding SomeText}" />
<StackPanel>
<Button>..... variable content but bindable
</StackPanel>
</local:CardView>
So in summary I have a user control that I want to to use in multiple places and have variable content in the body. The variable content will be marked up in the consumer XAML.
Some suggestions I've dug up searching, but doesn't seem to fit the model
Use a content template. I was going to but how do you bind to controls in a content template?
Content presenter. How do I bind to consumers view model?

This is pretty easy doable by using a ContentControl. Just insert it into your CardView.xaml:
<Border BorderBrush="{Binding Path=BorderColor, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}">
<StackPanel Orientation="Vertical" Style="{StaticResource CardStyle}">
<StackPanel>
<Border Style="{StaticResource MyBorderStyle}">
<Label Content="{Binding Path=CardTitle, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
</Border>
</StackPanel>
<Label Style="{StaticResource LabelIcon}">
<Path Fill="#FF000000" HorizontalAlignment="Center"
Stretch="UniformToFill" Data="{Binding Path=VectorString, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}" />
</StackPanel>
<StackPanel Orientation="Horizontal">
// Dynamic Content Here.
<ContentControl Content={Binding CustomContent} />
</StackPanel>
And then in your ViewModel add a property 'CustomContent' of type object which contains an instance of your Customer.

set visibility of image dynamically in expanderview

I am trying to implement something where I need to display list of people and a green icon if they are online. these people are grouped by some categories. I am using an expanderview toolkit control to display the list. So how do I set the icon image to be visible dynamically ? I have tried something like this which didnt work.
<DataTemplate x:Key="groupsItemTemplate">
<StackPanel Orientation="Horizontal" Margin="30,5,0,0"">
<Image Height="30" Width="30" Source="/Assets/Online.png" Margin="10,5,0,0" Visibility="{Binding IsFriendOnline}"></Image>
<TextBlock TextWrapping="NoWrap" FontFamily="Segoe WP Light" FontSize="24" Margin="8,0,0,0" VerticalAlignment="Center" HorizontalAlignment="left" Height="auto" Width="300" Text="{Binding FriendName}"></TextBlock>
</StackPanel>
</DataTemplate>
IsFriendOnline is an integer property.

Firstly, you need to use a converter in order to convert the value of your IsFriendOnline property to the Visibility enum that you require.
WPF has a "BooleanToVisibilityConverter" built in so if you have the ability to change the IsFriendOnline to a boolean value (which sounds like it makes a little more sense anyway) I would go down this route... if its imperative that the property is an integer then you will need to roll your own converter which isnt difficult.
The syntax would look something like this when you have a converter (my code below assumes IsFriendOnline is a boolean)...
<BooleanToVisibilityConverter x:Key="BooleanToVisibilityConverter" />
<DataTemplate x:Key="groupsItemTemplate">
<StackPanel Orientation="Horizontal" Margin="30,5,0,0"">
<Image Height="30" Width="30" Source="/Assets/Online.png" Margin="10,5,0,0" Visibility="{Binding IsFriendOnline, Converter={StaticResource BooleanToVisibilityConverter}}"></Image>
<TextBlock TextWrapping="NoWrap" FontFamily="Segoe WP Light" FontSize="24" Margin="8,0,0,0" VerticalAlignment="Center" HorizontalAlignment="left" Height="auto" Width="300" Text="{Binding FriendName}"></TextBlock>
</StackPanel>
</DataTemplate>
Hope this helps...

Access XAML Control In DataTemplate From CodeBehind?

I have a control that I am unable to access in the codebehind, and I believe it is because it is defined in a DataTempalte.
The overall control is a slide show carousel. Each slide can be an Image or a MediaElement (video), the contents of which are defined in an ItemSource binding. The carousel is on a timer to switch from one slide to the next. Each time the slide changes I fire an event to that effect.
When I hit a slide with a video I'd like to stop the slide timer (done that) and start the video, which is where I've run into a problem. I can not access the MediaPlayer element Name from my codebehind. My assumption at this point is because it is a DataTemplate.
Is this assumption correct? If so, how can I get access to this control from the codebehind, or (more to the point) have it start playing when the slide comes up?
<ctrl:AutoScrollCarousel ...>
<ctrl:AutoScrollCarousel.ItemsPanel>
<ItemsPanelTemplate>
<StackPanel Orientation="Horizontal" />
</ItemsPanelTemplate>
</ctrl:AutoScrollCarousel.ItemsPanel>
<ctrl:AutoScrollCarousel.ItemTemplate>
<DataTemplate>
<Border x:Name="Border" VerticalAlignment="Center"
Width="{Binding ActualWidth, RelativeSource={RelativeSource AncestorType={x:Type UserControl},Mode=FindAncestor}}">
<Grid Background="White">
...
<Image Source="{Binding ContentImage}" Grid.Row="1" Grid.Column="1" Stretch="UniformToFill"
HorizontalAlignment="Center"
Visibility="{Binding ContentImage, Converter={StaticResource VisibilityConverter}}" />
<MediaElement Name="MediaPlayer" Source="{Binding ContentVideo}" Grid.Row="1" Grid.Column="1" Stretch="UniformToFill" LoadedBehavior="Play"
Visibility="{Binding ContentVideo, Converter={StaticResource VisibilityConverter}}" MediaEnded="MediaPlayer_MediaEnded" />
<TextBlock Grid.Row="0" Grid.Column="1" Text="{Binding Title}" Foreground="Black"
FontFamily="Segoe UI" FontWeight="Light" HorizontalAlignment="Left" FontSize="75" Margin="0" VerticalAlignment="Center" />
<TextBlock Grid.Row="2" Grid.Column="1" Text="{Binding ContentHeadline}" Foreground="Black"
FontFamily="Segoe UI" FontWeight="Light" HorizontalAlignment="Left" FontSize="50" VerticalAlignment="Center"
TextWrapping="Wrap">
</TextBlock>
</Grid>
</Border>
</DataTemplate>
</ctrl:AutoScrollCarousel.ItemTemplate>
</ctrl:AutoScrollCarousel>

WPF provides a simple and straightforward way to access named elements that are generated from DataTemplates. It is explained in the MSDN article How to: Find DataTemplate-Generated Elements.
Assumed that your AutoScrollCarousel is derived from ItemsControl, you would get the ContentPresenter that is the container of an item like this:
AutoScrollCarousel carousel = ...
object item = ...
var contentPresenter =
carousel.ItemContainerGenerator.ContainerFromItem(item) as ContentPresenter;
From the ContentPresenter you would get the named element in the DataTemplate by means of the FindName method:
var dataTemplate = contentPresenter.ContentTemplate;
var mediaPlayer = dataTemplate.FindName("MediaPlayer", contentPresenter) as MediaElement;

I would normally recommend not to touch UIElements from code... but the MediaElement is a special case... maybe you should wrap the whole template inside a usercontrol (maybe with some custom DepProps) and that will give you better control over the whole thing.
Edit: Another approach would be to create a Behavior with a couple of properties (such as IsPlaying) and manipulate the mediaelement from there. Then you could use this behavior in the XAML of the DataTemplate, with no need for code behind or usercontrols.

WPF Bindings : Editing a value in a TextBox inside a DataTemplate that displays that same value

I want to create a debug window that will allow us to edit properties from various objects in our app while it runs. This will allow us, for example, to tweak threshold values for certain heuristic rules in our app, without requiring a rebuild and/or app restart.
The goal is to tell the debug window to enable editing some property of an object. The window then obtains the property's value, keeps a weak reference to the object and displays an appropriate data template (based on the value's type) to enable us to edit the value and apply the new value to the object when needed.
Problem:
The data templates are applied correctly and the value is displayed for each debug item in a TextBox. However, the Value property of each DebugItem, to which the TextBox is bound, is NEVER updated. I have set a breakpoint on that property's setter; the breakpoint is never triggered.
Here is my current setup:
I have a DebugItems collection of DebugItem objects in my view model.
Each DebugItem has a Value property of type object.
For debugging purposes, the Value property always contains a string.
I have created a data template for the DebugItem type and the System:String type.
My window contains a ListBox that is bound to the DebugItems collection and displays DebugItems using the data template defined above, in a ContentPresenter. A TextBox inside that data template is also bound to the Value so that it enables us to edit the string value using the other, System:String data template defined above *.
* I am under the impression that this has to do with why the edit doesn't work. I could be mistaken, through.
Relevant part of the window:
<Grid Background="#CECECE">
<ScrollViewer VerticalScrollBarVisibility="Auto" HorizontalScrollBarVisibility="Disabled">
<ItemsControl ItemsSource="{Binding DebugItems}" Background="Transparent" BorderBrush="Transparent" />
</ScrollViewer>
</Grid>
My data template:
(Of particular interest are the inner ContentPresenter and its embedded System:String data template.)
<DataTemplate DataType="{x:Type Debug:DebugItem}">
<Grid Height="60" d:DesignWidth="403.06">
<Grid>
<Grid.ColumnDefinitions>
<ColumnDefinition Width="140" />
<ColumnDefinition Width="181*" />
<ColumnDefinition Width="110" />
</Grid.ColumnDefinitions>
<TextBlock Grid.Column="0" Text="{Binding Label}" HorizontalAlignment="Left" VerticalAlignment="Center" Margin="14,0,0,0" Foreground="Black" FontWeight="Bold" />
<ContentPresenter VerticalAlignment="Center" Grid.Column="1" Content="{Binding Value}" Height="Auto">
<ContentPresenter.Resources>
<!-- String -->
<DataTemplate DataType="{x:Type System:String}">
<TextBox Text="{Binding Path=., Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</DataTemplate>
</ContentPresenter.Resources>
</ContentPresenter>
<UniformGrid Grid.Column="2" Rows="1">
<Button Margin="8,8,0.5,8" Command="{Binding UpdateCommand}" Style="{DynamicResource ButtonStyle}" Content="Update" />
<Button Margin="4.5,8,8,8" Command="{Binding ApplyCommand}" Style="{DynamicResource ButtonStyle}" Content="Apply" />
</UniformGrid>
</Grid>
</Grid>
</DataTemplate>
Any ideas?