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Home » Newsletter » February 2012

By V. Subhash

In Version 4 of PDFOne .NET, we have introduced text redaction. You can redact text by specifying a region to be redacted. You can also provide a text string whose occurrences in the document can be redacted. The text string can be a literal search text or it can be a regular expression. In this article, we will see examples of both.

Simple Text Redaction

The following code snippet shows how to perform simple text redaction using literal search text.

PDFDocument PDFDocument1 = new PDFDocument("your-license-key");

// Load PDF document
PDFDocument1.Load("sample_doc1.pdf");

PDFDocument1.RedactText(
    // redact in page with number
    1,
    // redact text matching "gnostice"
    "gnostice",
    // search for literal matches
    PDFSearchMode.LITERAL,
    // match all cases and instances
    PDFSearchOptions.NONE,
    // stroke redacted regions in red color
    new Pen(Color.Red),
    // fill redacted region in lime color
    new SolidBrush(Color.Lime),
    // enable stroking of redacted regions
    true,
    // enable filling of redacted regions
    true);

PDFDocument1.Save("redacted_doc1.pdf");

// Close the document
PDFDocument1.Close();

Advanced Text Redaction

You can also use regular expressions with the redactText method. I have modified the above code snippet so that it will redact all phone numbers, like this:

PDFDocument1.RedactText(
  // redact in page with number 2
  17,
  // redact phone numbers
  @"\(\d{3}\)\s\d{3}-\d{4}",
  // search for regular expression matches
  PDFSearchMode.REGEX,
  // match all cases and instances
  PDFSearchOptions.NONE,
  // stroke redacted regions in red color
  new Pen(Color.Red),
  // fill redacted region in lime color
  new SolidBrush(Color.Lime),
  // enable stroking of redacted regions
  true,
  // enable filling of redacted regions
  true);