WPF TextBlock with custom StringFormat and variable number of Run/Inline

Question

I have a list of phrases which needs to be displayed. These phrases have a static text and a variable number of bits that need to be highlighted on the screen (bold, colored differently).

Here's a sample of how this would look like if I am to build everything from xaml.

    <TextBlock Grid.Row="2">
        <Run Text="Your"/>
        <Run Text="{Binding Text1}"/>
        <Run Text="has a limit of $"/>
        <Run Text="{Binding Limit}" FontWeight="Bold" Foreground="Red"/>
        <Run Text="for period "/>
        <Run Text="{Binding StartDate}" FontWeight="Bold" Foreground="Blue"/>
        <Run Text=" : "/>
        <Run Text="{Binding EndDate}" FontWeight="Bold" Foreground="Blue"/>
        <Run Text=". Your up to date expenses are $"/>
        <Run Text="{Binding Expenses}" FontWeight="Bold" Foreground="Red"/>
    </TextBlock>

    <TextBlock Grid.Row="3">
        <Run Text="Your"/>
        <Run Text="{Binding Text2}"/>
        <Run Text="has a limit of $"/>
        <Run Text="{Binding Limit2}" FontWeight="Bold" Foreground="Red"/>
        <Run Text="for period "/>
    </TextBlock>

What I would like to achieve is to somehow bind the text with {0} in it and an bind an ItemsSource that will set the Inlines for a TextBlock, and further, bind an ItemsSource maybe for styles (font weight and text color) each inline should have:

Text: Your {0} has a limit of ${1} for period.

Values to populate inlines: abc,1000

Styles to apply {none,none}, {bold,red}

Is this possible in the first place? And if so, can you please point me in the right direction or give me a few hints?

Thanks.

you can try with ItemsControl bound to list of parts where ItemsPanel is horizontal StackPanel (for example) and ItemTemplate is TextBlock — dkozl
– dkozl, Commented Feb 27, 2015 at 12:44

Steven Rands · Accepted Answer · 2015-02-27 16:56:52Z

I would create a custom TextBlock descendant for this, and create the inlines programmatically.

First, create a model to control the display of your text:

public class TextModel
{
    public string Text { get; set; }
    public Color Color { get; set; }
    public FontWeight Weight { get; set; }
}

You might want to implement INotifyPropertyChanged on this, although that will complicate things later.

Next, you need a collection of these:

public class TextModelCollection : ObservableCollection<TextModel>
{
}

Finally, create a custom class derived from TextBlock:

public class MyCustomTextBlock : TextBlock
{
    public static readonly DependencyProperty ItemsProperty =
        DependencyProperty.Register("Items", typeof(TextModelCollection),
        typeof(MyCustomTextBlock), new PropertyMetadata(OnItemsChanged));

    public TextModelCollection Items
    {
        get
        {
            return (TextModelCollection) GetValue(ItemsProperty);
        }
        set
        {
            SetValue(ItemsProperty, value);
        }
    }

    public MyCustomTextBlock()
    {
        RefreshInlines();
    }

    static void OnItemsChanged(DependencyObject d,
        DependencyPropertyChangedEventArgs e)
    {
        ((MyCustomTextBlock) d).RefreshInlines();
    }
}

Then you just need a method (called RefreshInlines here) that will refresh the text block's inlines collection when the custom property changes.

void RefreshInlines()
{
    Inlines.Clear();
    foreach (TextModel text in Items)
    {
        var run = new Run(text.Text);
        run.Foreground = new SolidColorBrush(text.Color);
        run.FontWeight = text.Weight;
        Inlines.Add(run);
    }
}

As TextModelCollection is an observable collection, you will need to register for list changes so that you can refresh the inlines when items are added or removed. I haven't shown that code here, but it would basically tie-in to the OnItemsChanged method.

This sounds like it might just work exactly how I need. I`ll give it a try. Thanks.

Bizhan · Accepted Answer · 2015-02-27 13:26:28Z

0

It's actually two questions:

First

You are looking for MultiBinding and StringFormat:

This one is for when the Text starts with a static text:

<TextBlock>
   <TextBlock.Text>
       <MultiBinding StringFormat="Write Static Text Here {1} Something else {1}">
          <Binding Path="Text2" />
          <Binding Path="Text2" />
       </MultiBinding>
   </TextBlock.Text>
</TextBlock>

And this one is for when the Text starts with a variable text:

<TextBlock>
   <TextBlock.Text>
       <MultiBinding StringFormat="{}{0} Write Static Text Here {1} Something else">
          <Binding Path="Text2" />
          <Binding Path="Text2" />
       </MultiBinding>
   </TextBlock.Text>
</TextBlock>

Second

You need to use anything like ItemsControl (ListBox DataGrid etc)

<ItemsControl ItemsSource="{Binding MyList}">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
             put anything here to display as an element of MyList
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

You also need to create a collection for MyList in the DataContext of window. for example:

public MainWindow()
{
    InitializeComponent();
    var vm = new MainVm();
    DataContext = vm;
}

this MainVm should derive from DependencyObject and contains something like:

public ObservableCollection<string> MyList { get { return _myList; } }
private ObservableCollection<string> _myList = new ObservableCollection<string>();

for more information, google MVVM.

edited Feb 27, 2015 at 13:26

answered Feb 27, 2015 at 13:11

Bizhan

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2 Comments

Horia Over a year ago

Yes, but on top of this, i need to make the list of bindings containing Text1,Text2 bind-able somehow, and also add font weight and color to elements from that list ... that is my challenge.

Bizhan Over a year ago

Oh I missed that part. Please take a look at the updated answer

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