Custom HighlightTextBlock

The RadHighlightTextBlock control allows you to customize the highlighted text, as well as add/remove the matches. To do so, inherit from the RadHighlightTextBlock class and override the HighlightTextRange and GetHighlightInfos methods.

Styling the Matches

To style the matches, override the HighlightTextRange method. It provides a parameter of the type HighlightTextInfo. It stores information about the portion of the RadHighlightTextBlock text that needs to be highlighted. To style it, call the ApplyPropertyValue method on the TextRange property of the HighlightTextRange's parameter. This method accepts a DependencyProperty as a first parameter and as a second-value that will be applied to it.

Inheriting from the RadHighlightTextBlock class and styling the matches

public class CustomHighlightTextBlock : RadHighlightTextBlock 
{ 
    protected override void HighlightTextRange(HighlightTextInfo info) 
    { 
        base.HighlightTextRange(info); 
 
        info.TextRange.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.SemiBold); 
        info.TextRange.ApplyPropertyValue(TextElement.BackgroundProperty, (SolidColorBrush)new BrushConverter().ConvertFrom("#F4FFFF")); 
        info.TextRange.ApplyPropertyValue(TextElement.ForegroundProperty, (SolidColorBrush)new BrushConverter().ConvertFrom("#E60000")); 
    } 
} 

Public Class CustomHighlightTextBlock 
    Inherits RadHighlightTextBlock 
 
    Protected Overrides Sub HighlightTextRange(ByVal info As HighlightTextInfo) 
        MyBase.HighlightTextRange(info) 
        info.TextRange.ApplyPropertyValue(TextElement.FontWeightProperty, FontWeights.SemiBold) 
        info.TextRange.ApplyPropertyValue(TextElement.BackgroundProperty, CType(New BrushConverter().ConvertFrom("#F4FFFF"), SolidColorBrush)) 
        info.TextRange.ApplyPropertyValue(TextElement.ForegroundProperty, CType(New BrushConverter().ConvertFrom("#E60000"), SolidColorBrush)) 
    End Sub 
End Class 

Using the custom RadHighlightTextBlock custom styled matches

<local:CustomHighlightTextBlock Text="Thank you for choosing Telerik UI for WPF." HighlightText="Telerik UI for WPF"/> 

Custom RadHighlightTextBlock with custom styled matches

Adding/Removing the Matches

To add or remove a match, override the GetHighlightInfos method. It will return a collection of HighlightTextInfo instances that the RadHighlightTextBlock control will use to highlight each match. You can modify the entries before returning the collection.

Inheriting from the RadHighlightTextBlock class and removing a match

public class CustomHighlightTextBlock : RadHighlightTextBlock 
{ 
    protected override IEnumerable<HighlightTextInfo> GetHighlightInfos() 
    { 
        List<HighlightTextInfo> matches = base.GetHighlightInfos().ToList<HighlightTextInfo>(); 
        matches.RemoveAt(matches.Count - 1); 
        return matches; 
    } 
} 

Public Class CustomHighlightTextBlock 
    Inherits RadHighlightTextBlock 
 
    Protected Overrides Function GetHighlightInfos() As IEnumerable(Of HighlightTextInfo) 
        Dim matches As List(Of HighlightTextInfo) = MyBase.GetHighlightInfos().ToList(Of HighlightTextInfo)() 
        matches.RemoveAt(matches.Count - 1) 
        Return matches 
    End Function 
End Class 

Using the custom RadHighlightTextBlock where the last item is removed

<local:CustomHighlightTextBlock HighlightMode="AllMatches" 
                                Text="Thank you for choosing Telerik UI for WPF. To learn mode please visit the Telerik UI for WPF product overview page."  
                                HighlightText="Telerik UI for WPF"/> 

RadHighlightTextBlock where the last match is omitted