Incorrect Text Redaction Formatting after Modifying TextFragment.Text

Aspose.PDF Product Family
1

We are using TextFragmentAbsorber to find and redact text in a PDF. The redactions are marked with square brackets like [Reason], and the logic does the following:

  • Finds all fragments matching regex: \[(?s)(.*?)\]
  • Updates the Text property to remove [ ] and newline characters \r\n
  • Applies TextState.ForegroundColor and TextState.BackgroundColor (e.g., white text on black background)

However, after updating textFragment.Text, the rendered output in the final PDF shows inconsistent coloring — e.g., only partial background color applied, or text overlaps (see attached screenshots).

Observed Behavior

  • Background color is only partially applied (e.g., half black, half white areas in same fragment)
  • Some fragments lose proper layout/alignment after .Text is reassigned
  • Issue is worse when the original [Reason] includes a line break (\r\n)

We noticed that adding the following line improves formatting in some cases:

csharp

CopyEdit

textFragment.TextState.FontSize = textFragment.TextState.FontSize;

It seems to trigger a layout recalculation, but it doesn’t resolve the issue for all fragments — especially longer or multi-line ones.

Attachments

  1. Original PDF before redaction (optional)
  2. Output PDF showing issue
  3. Screenshot: incorrect formatting (attached)
  4. Sample code block (see below)

Code Snippet

csharp

CopyEdit

var searchTerm = "\\[(?s)(.*?)\\]";
TextFragmentAbsorber absorber = new TextFragmentAbsorber(searchTerm);
absorber.TextSearchOptions = new TextSearchOptions(true);
doc.Pages.Accept(absorber);

var fragments = absorber.TextFragments;

foreach (var fragment in fragments)
{
    string text = fragment.Text;
    StringBuilder sb = new StringBuilder(text.Length);
    foreach (char c in text)
    {
        if (c != '\r' && c != '\n' && c != '[' && c != ']')
            sb.Append(c);
    }

    fragment.Text = sb.ToString();
    fragment.TextState.FontSize = fragment.TextState.FontSize; // partial fix
    fragment.TextState.ForegroundColor = Color.White;
    fragment.TextState.BackgroundColor = Color.Black;
}

Request for Support

  • Is there a recommended way to force proper re-rendering after modifying TextFragment.Text?
  • Is there any known issue when replacing text containing line breaks and applying formatting?
  • Can this be fixed in a future release, or is there an internal method to force layout recalculation?

attachments for Pdf.zip (9.4 MB)

2

@nraj

We have opened the following new ticket(s) in our internal issue tracking system and will deliver their fixes according to the terms mentioned in Free Support Policies.

Issue ID(s): PDFNET-60366

You can obtain Paid Support Services if you need support on a priority basis, along with the direct access to our Paid Support management team.