C# - Adding XAML elements to UWP app via x:Bind

Question

Context: I'm writing a UWP Twitter client.

One of the useful bits of data Twitter returns via its API are objects for content that can be linked directly in a tweet - #hashtags, @usernames, $symbols, and URLs. This makes it easy to extract these objects from the string containing a tweet's full text, in order to turn them into links.

I understand how the XAML needs to look for this, with <run> and <hyperlink> tags, and I've figured out how to create that XAML dynamically for each tweet object.

What I can't figure out is how to inject my generated XAML into my app's DataTemplate. Because tweet content needs to be displayed on multiple pages in the app, I'm using a ResourceDictionary to hold all my XAML styling, including my DataTemplate. So, I'm entirely unsure how to connect my generated XAML to my app's UI.

For example, if a tweet looks like this:

"Hey @twitter, you're a time waster! #FridayFeeling"

My generated XAML objects look like this:

<Run>Hey </Run>
<Hyperlink link="http://twitter.com/twitter/">@twitter</Hyperlink>
<Run>, you're a time waster! </Run>
<Hyperlink link="http://twitter.com/search?hashtag=FridayFeeling">#FridayFeeling</Hyperlink>

If there's nothing to link in a tweet's text, then I can just use Tweet.Text as-is, so I'm trying to bind this to a TextBox. How can I handle inserting this XAML dynamically?

Am I stuck abandoning data binding entirely and looping through my collection to programmatically add all my XAML?

Here's my DataTemplate:

<DataTemplate x:Key="TweetTemplate" x:DataType="tweeter:Tweet2">
    <Grid Style="{StaticResource ListItemStyle}">
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="30"/>
            <RowDefinition Height="*"/>
            <RowDefinition Height="40"/>
        </Grid.RowDefinitions>
        <Grid Grid.Row="0" x:Name="RetweetedBy" x:Load="{x:Bind IsRetweet}" Height="28">
            <StackPanel Orientation="Horizontal" Padding="4 8 4 0">
                <StackPanel.Resources>
                    <Style TargetType="TextBlock">
                        <Setter Property="FontSize" Value="12"/>
                        <Setter Property="Foreground" Value="{ThemeResource SystemControlPageTextBaseMediumBrush}" />
                    </Style>
                </StackPanel.Resources>
                <Border Height="28">
                    <TextBlock Height="24" FontFamily="{StaticResource FontAwesome}" xml:space="preserve"><Run Text="&#xf079;&#160;"/></TextBlock>
                </Border>
                <TextBlock Text="{x:Bind Path=User.Name}" />
                <TextBlock Text=" retweeted"/>
            </StackPanel>
        </Grid>
        <Grid Grid.Row="1">
            <StackPanel Orientation="Horizontal" Padding="5">
                <TextBlock Text="{x:Bind Path=Tweet.User.Name}" Margin="0 0 8 0"  FontWeight="Bold" />
                <TextBlock Text="{x:Bind Path=Tweet.User.ScreenName, Converter={StaticResource GetHandle}}" Foreground="{ThemeResource SystemControlPageTextBaseMediumBrush}" />
                <TextBlock Text="&#x2981;" Margin="8 0" />
                <TextBlock Text="{x:Bind Path=Tweet.CreationDate, Converter={StaticResource FormatDate}}" />
            </StackPanel>
        </Grid>
        <Grid Grid.Row="2">
            <TextBlock Text="***this is where I'm having problems***" Padding="5" TextWrapping="WrapWholeWords"/>
        </Grid>
        <Grid Grid.Row="3">
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="2.5*" MaxWidth="100"/>
                <ColumnDefinition Width="2.5*"/>
                <ColumnDefinition Width="2.5*"/>
                <ColumnDefinition Width="2.5*"/>
            </Grid.ColumnDefinitions>
            <Grid Grid.Column="0">
                <Button x:Name="cmdComment" Content="&#xf075;" Style="{StaticResource MetaButtons}" />
            </Grid>
            <Grid Grid.Column="1">
                <Button x:Name="cmdRetweet" Content="&#xf079;" Style="{StaticResource MetaButtons}" />
            </Grid>
            <Grid Grid.Column="2">
                <Button x:Name="cmdLike" Content="&#xf004;" Style="{StaticResource MetaButtons}" />
            </Grid>
            <Grid Grid.Column="3">
                <Button x:Name="cmdMessage" Content="&#xf0e0;" Style="{StaticResource MetaButtons}" />
            </Grid>
        </Grid>
    </Grid>
</DataTemplate>

Answer 1

If you want to use attached property, here is an example to start with :

public static class Twitter
{
    public static readonly DependencyProperty InlinesProperty = DependencyProperty.RegisterAttached(
        "Inlines", typeof(ICollection<Inline>), typeof(Twitter), new PropertyMetadata(default(ICollection<Inline>), PropertyChangedCallback));

    private static void PropertyChangedCallback(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        if (!(d is TextBlock tb)) return;

        tb.Inlines.Clear();

        if (!(e.NewValue is ICollection<Inline> inlines)) return;

        foreach (var inline in inlines)
        {
            tb.Inlines.Add(inline);
        }
    }

    public static void SetInlines(DependencyObject element, ICollection<Inline> value)
    {
        element.SetValue(InlinesProperty, value);
    }

    public static ICollection<Inline> GetInlines(DependencyObject element)
    {
        return (ICollection<Inline>) element.GetValue(InlinesProperty);
    }
}

And in xaml :

        <TextBlock local:Twitter.Inlines ="{x:Bind TwitterData}"></TextBlock>

Where TwitterData is a List<Inline>