WpfHighlighter

A simple project enabling highlighting in WPF.

Project SearchHighlight.Wpf contains converter implementation: SearchMatchValueConverter. The implementation converts text into collection of inlines (WPF). Areas matching the search are decorated different style. Text should be bound to a control via attached property BindableInlines which adds inlines provided by the converter to the control. The control must be a subclass of TextBlock.

See project WpfHighlighter.Demo for details.

Example

Below you can see a xaml fragment of the demo project:

<Window x:Class="WpfHighlighter.Demo.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:conv="clr-namespace:WpfHighlighter.Demo.Converters;assembly=SearchHighlight.Wpf"
        mc:Ignorable="d">

    <Window.Resources>
        <conv:SearchMatchValueConverter x:Key="SearchMatchValueConverter" />
    </Window.Resources>

    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="*" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>

        <TextBox Grid.Row="0" HorizontalAlignment="Left" Width="200" 
                 Text="{Binding SearchText, UpdateSourceTrigger=PropertyChanged, Delay=250}" />

        <DataGrid Grid.Row="1" ItemsSource="{Binding Lines}" 
                  AutoGenerateColumns="False" 
                  CanUserAddRows="False"
                  IsReadOnly="True">
            <DataGrid.Columns>
                <DataGridTemplateColumn Header="First Name">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <TextBlock>
                                <conv:BindableInlinesExtensions.BindableInlines>
                                    <MultiBinding Converter="{StaticResource SearchMatchValueConverter}" ConverterParameter="FirstName">
                                        <Binding Path="FirstName" />
                                        <Binding Path="Matches" />
                                    </MultiBinding>
                                </conv:BindableInlinesExtensions.BindableInlines>
                            </TextBlock>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
                <DataGridTemplateColumn Header="Last Name">
                    <DataGridTemplateColumn.CellTemplate>
                        <DataTemplate>
                            <TextBlock>
                                <conv:BindableInlinesExtensions.BindableInlines>
                                    <MultiBinding Converter="{StaticResource SearchMatchValueConverter}" ConverterParameter="LastName">
                                        <Binding Path="LastName" />
                                        <Binding Path="Matches" />
                                    </MultiBinding>
                                </conv:BindableInlinesExtensions.BindableInlines>
                            </TextBlock>
                        </DataTemplate>
                    </DataGridTemplateColumn.CellTemplate>
                </DataGridTemplateColumn>
                <DataGridTextColumn Header="Birth Date" Binding="{Binding BirthDate}" />
            </DataGrid.Columns>
        </DataGrid>
    </Grid>
</Window>

Presenter SamplePresenter used to drive the view has method OnPropertyChanged bound to view model's PropertyChanged event. So it is raised every time the property in the view model changes. Thus, when SearchText in that view model changes, the following code runs to handle new search text and to recompute matches passed to the converter:

private void OnPropertyChanged(object sender, PropertyChangedEventArgs e)
{
    if (e.PropertyName == nameof(SampleViewModel.SearchText))
    {
        var matcher = new Matcher();
        var st = viewModel.SearchText;
        foreach (var l in viewModel.Lines)
        {
            var matches = new List<LineMatch>();
            if (!string.IsNullOrWhiteSpace(st))
            {
                matches.AddRange(matcher.GetMatches(nameof(l.FirstName), l.FirstName, st));
                matches.AddRange(matcher.GetMatches(nameof(l.LastName), l.LastName, st));
            }
            l.Matches = matches;
        }
    }
}