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Snap text to an attached object

My question is similar to this one: WPF Generate TextBlock Inlines , but I don't have enough reputation for comments. Here is a nested property class:

public class Attached
{
    public static readonly DependencyProperty FormattedTextProperty = DependencyProperty.RegisterAttached(
        "FormattedText",
        typeof(string),
        typeof(TextBlock),
        new FrameworkPropertyMetadata(string.Empty, FrameworkPropertyMetadataOptions.AffectsMeasure));

    public static void SetFormattedText(DependencyObject textBlock, string value)
    {
        textBlock.SetValue(FormattedTextProperty, value);
    }

    public static string GetFormattedText(DependencyObject textBlock)
    {
        return (string)textBlock.GetValue(FormattedTextProperty);
    }

    private static void FormattedTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var textBlock = d as TextBlock;
        if (textBlock == null)
        {
            return;
        }

        var formattedText = (string)e.NewValue ?? string.Empty;
        formattedText = string.Format("<Span xml:space=\"preserve\" xmlns=\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\">{0}</Span>", formattedText);

        textBlock.Inlines.Clear();
        using (var xmlReader = XmlReader.Create(new StringReader(formattedText)))
        {
            var result = (Span)XamlReader.Load(xmlReader);
            textBlock.Inlines.Add(result);
        }
    }
}

I use this class of nested properties and try to apply it to a text block so that the text recognizes inline values ​​such as bold, underline, etc. from a row in a view model class. I have the following XAML in my text block:

<TextBlock Grid.Row="1" Grid.Column="1" TextWrapping="Wrap" my:Attached.FormattedText="test" />

However, when I run the program, I get nothing in the text block. I would also like to bind the text to a property in my view model in the end, but I want something to appear first ...

, , , , , . , . , :

{ "A Binding" "SetFormattedText" "TextBlock". "" DependencyProperty DependencyObject. "}

+3
1

-, , TextBlock:

public static readonly DependencyProperty FormattedTextProperty = DependencyProperty.RegisterAttached(
    "FormattedText",
    typeof(string),
    typeof(TextBlock), <----- Here

-, , :

new FrameworkPropertyMetadata(string.Empty, 
                              FrameworkPropertyMetadataOptions.AffectsMeasure,
                              YOUR_PropertyChanged_HANDLER)

-, , :

<Bold>My little text</Bold>

:

XAML

<Window x:Class="InlineTextBlockHelp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:this="clr-namespace:InlineTextBlockHelp"
        Title="MainWindow" Height="350" Width="525">

    <Grid>
        <TextBlock Name="TestText"
                   this:AttachedPropertyTest.FormattedText="TestString"
                   Width="200"
                   Height="100" 
                   TextWrapping="Wrap" />

        <Button Name="TestButton"
                Width="100"
                Height="30"
                VerticalAlignment="Top"
                Content="TestClick" 
                Click="Button_Click" />
    </Grid>
</Window>

Code-behind

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        string inlineExpression = "<Bold>Once I saw a little bird, go hop, hop, hop.</Bold>";
        AttachedPropertyTest.SetFormattedText(TestText, inlineExpression);
    }
}

public class AttachedPropertyTest
{
    public static readonly DependencyProperty FormattedTextProperty = DependencyProperty.RegisterAttached(
        "FormattedText",
        typeof(string),
        typeof(AttachedPropertyTest),
        new FrameworkPropertyMetadata(string.Empty, FrameworkPropertyMetadataOptions.AffectsMeasure, FormattedTextPropertyChanged));

    public static void SetFormattedText(DependencyObject textBlock, string value)
    {
        textBlock.SetValue(FormattedTextProperty, value);
    }

    public static string GetFormattedText(DependencyObject textBlock)
    {
        return (string)textBlock.GetValue(FormattedTextProperty);
    }

    private static void FormattedTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var textBlock = d as TextBlock;

        if (textBlock == null)
        {
            return;
        }

        var formattedText = (string)e.NewValue ?? string.Empty;
        formattedText = string.Format("<Span xml:space=\"preserve\" xmlns=\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\">{0}</Span>", formattedText);

        textBlock.Inlines.Clear();
        using (var xmlReader = XmlReader.Create(new StringReader(formattedText)))
        {
            var result = (Span)XamlReader.Load(xmlReader);
            textBlock.Inlines.Add(result);
        }
    }
}

, Button .

Example for MVVM version

MVVM, Model/ViewModel :

<TextBlock Name="TestText"
           PropertiesExtension:TextBlockExt.FormattedText="{Binding Path=InlineText, 
                                                                    Mode=TwoWay,
                                                                    UpdateSourceTrigger=PropertyChanged}"
           Width="200"
           Height="100" 
           TextWrapping="Wrap" />

Model/ViewModel NotifyPropertyChanged.

:

AttachedProperty

public class TextBlockExt
{
    public static readonly DependencyProperty FormattedTextProperty = DependencyProperty.RegisterAttached(
        "FormattedText",
        typeof(string),
        typeof(TextBlockExt),
        new FrameworkPropertyMetadata(string.Empty, FrameworkPropertyMetadataOptions.AffectsMeasure, FormattedTextPropertyChanged));

    public static void SetFormattedText(DependencyObject textBlock, string value)
    {
        textBlock.SetValue(FormattedTextProperty, value);
    }

    public static string GetFormattedText(DependencyObject textBlock)
    {
        return (string)textBlock.GetValue(FormattedTextProperty);
    }

    private static void FormattedTextPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
    {
        var textBlock = d as TextBlock;

        if (textBlock == null)
        {
            return;
        }

        var formattedText = (string)e.NewValue ?? string.Empty;
        formattedText = string.Format("<Span xml:space=\"preserve\" xmlns=\"http://schemas.microsoft.com/winfx/2006/xaml/presentation\">{0}</Span>", formattedText);

        textBlock.Inlines.Clear();
        using (var xmlReader = XmlReader.Create(new StringReader(formattedText)))
        {
            var result = (Span)XamlReader.Load(xmlReader);
            textBlock.Inlines.Add(result);
        }
    }
}

MainViewModel

public class MainViewModel : NotificationObject
{
    private string _inlineText = "";

    public string InlineText
    {
        get
        {
            return _inlineText;
        }

        set
        {
            _inlineText = value;
            NotifyPropertyChanged("InlineText");
        }
    }
}

MainWindow.xaml

<Window x:Class="InlineTextBlockHelp.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:ViewModels="clr-namespace:InlineTextBlockHelp.ViewModels"
        xmlns:PropertiesExtension="clr-namespace:InlineTextBlockHelp.PropertiesExtension"
        Title="MainWindow" Height="350" Width="525"
        ContentRendered="Window_ContentRendered">

    <Window.DataContext>
        <ViewModels:MainViewModel />
    </Window.DataContext>

    <Grid>
        <TextBlock Name="TestText"
                   PropertiesExtension:TextBlockExt.FormattedText="{Binding Path=InlineText, 
                                                                            Mode=TwoWay,
                                                                            UpdateSourceTrigger=PropertyChanged}"
                   Width="200"
                   Height="100" 
                   TextWrapping="Wrap" />
    </Grid>
</Window>

Code-behind (just for test)

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
    }

    private void Window_ContentRendered(object sender, EventArgs e)
    {
        MainViewModel mainViewModel = this.DataContext as MainViewModel;

        mainViewModel.InlineText = "<Bold>Once I saw a little bird, go hop, hop, hop.</Bold>";
    }
}

link.

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