WpfSearchAndHighlightText

Search and highlight text in wpf (Rich Text Box)

This is a simple Wpf app, where it has a text box to enter the text we want to search. The app contain a rich text box, where you can post your text. Enter the text to search and click 'Search' button. This will find all the matches and highlights them in yellow.

Also, in status bar at bottom, it will show how many matched found or no matches found.

Method used to search and highlight: (Upon Search button click)

private void bnt_Search_Click(object sender, RoutedEventArgs e)
{
    TextRange textRange = new TextRange(rich.Document.ContentStart, rich.Document.ContentEnd);

    //clear up highlighted text before starting a new search
    textRange.ClearAllProperties();
    lbl_Status.Content = "";

   //get the richtextbox text
   string textBoxText = textRange.Text;

    //get search text
    string searchText = searchTextBox.Text;

    if (string.IsNullOrWhiteSpace(textBoxText) || string.IsNullOrWhiteSpace(searchText))
    {
        lbl_Status.Content = "Please provide search text or source text to search from";
    }

    else
    {

        //using regex to get the search count
        //this will include search word even it is part of another word
        //say we are searching "hi" in "hi, how are you Mahi?" --> match count will be 2 (hi in 'Mahi' also)

        Regex regex = new Regex(searchText);
        int count_MatchFound = Regex.Matches(textBoxText, regex.ToString()).Count;

        for (TextPointer startPointer = rich.Document.ContentStart;
                    startPointer.CompareTo(rich.Document.ContentEnd) <= 0;
                        startPointer = startPointer.GetNextContextPosition(LogicalDirection.Forward))
        {
            //check if end of text
            if (startPointer.CompareTo(rich.Document.ContentEnd) == 0)
            {
                break;
            }

            //get the adjacent string
            string parsedString = startPointer.GetTextInRun(LogicalDirection.Forward);

            //check if the search string present here
            int indexOfParseString = parsedString.IndexOf(searchText);

            if (indexOfParseString >= 0) //present
            {
                //setting up the pointer here at this matched index
                startPointer = startPointer.GetPositionAtOffset(indexOfParseString);

                if (startPointer != null)
                {
                    //next pointer will be the length of the search string
                    TextPointer nextPointer = startPointer.GetPositionAtOffset(searchText.Length);

                    //create the text range
                    TextRange searchedTextRange = new TextRange(startPointer, nextPointer);

                    //color up 
                    searchedTextRange.ApplyPropertyValue(TextElement.BackgroundProperty, new  SolidColorBrush(Colors.Yellow));

                    //add other setting property

                }
            }
        }

        //update the label text with count
        if (count_MatchFound > 0)
        {
            lbl_Status.Content = "Total Match Found : " + count_MatchFound;
        }
        else
        {
            lbl_Status.Content = "No Match Found !";
        }
    }
}