Extra Annotations using C#

How to add Caret Annotation into existing PDF file

Caret Annotation is a symbol that indicates text editing. Caret Annotation is also markup annotation, so the Caret class derives from the Markup class and also provides functions to get or set properties of the Caret Annotation and reset the flow of the Caret Annotation appearance.

The following code snippet also work with Aspose.PDF.Drawing library.

Steps with which we create Caret annotation:

  1. Load the PDF file - new Document.
  2. Create new Caret Annotation and set Caret parameters (new Rectangle, title, Subject, Flags, color, width, StartingStyle and EndingStyle). This annotation is used to indicate the insertion of text.
  3. Create new Caret Annotation and set Caret parameters (new Rectangle, title, Subject, Flags, color, width, StartingStyle and EndingStyle). This annotation is used to indicate the replacement of text.
  4. Create new StrikeOutAnnotation and set parameters (new Rectangle, title, color, new QuadPoints and new points, Subject, InReplyTo,ReplyType).
  5. After we can Add annotations to the page.

The following code snippet shows how to add Caret Annotation to a PDF file:

using Aspose.Pdf.Annotations;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Aspose.Pdf.Examples.Advanced
{
    class ExampleCaretAnnotation
    {
        // The path to the documents directory.
        private const string _dataDir = "..\\..\\..\\..\\Samples";
        public static void AddCaretAnnotation()
        {
            // Load the PDF file
            Document document = new Document(System.IO.Path.Combine(_dataDir, "sample.pdf"));
            // This annotation is used to indicate the insertion of text
            var caretAnnotation1 = new CaretAnnotation(document.Pages[1], new Rectangle(299.988, 713.664, 308.708, 720.769))
            {
                Title = "Aspose User",
                Subject = "Inserted text 1",
                Flags = AnnotationFlags.Print,
                Color = Color.Blue
            };
            // This annotation is used to indicate the replacement of text
            var caretAnnotation2 = new CaretAnnotation(document.Pages[1], new Rectangle(361.246, 727.908, 370.081, 735.107))
            {
                Flags = AnnotationFlags.Print,
                Subject = "Inserted text 2",
                Title = "Aspose User",
                Color = Color.Blue
            };

            var strikeOutAnnotation = new StrikeOutAnnotation(document.Pages[1],
                new Rectangle(318.407, 727.826, 368.916, 740.098))
            {
                Color = Color.Blue,
                QuadPoints = new[] {
                new Point(321.66, 739.416),
                new Point(365.664, 739.416),
                new Point(321.66, 728.508),
                new Point(365.664, 728.508)
            },
                Subject = "Cross-out",
                InReplyTo = caretAnnotation2,
                ReplyType = ReplyType.Group
            };

            document.Pages[1].Annotations.Add(caretAnnotation1);
            document.Pages[1].Annotations.Add(caretAnnotation2);
            document.Pages[1].Annotations.Add(strikeOutAnnotation);

            document.Save(System.IO.Path.Combine(_dataDir, "sample_caret.pdf"));
        }
    }
}

Get Caret Annotation

Please try using the following code snippet to Get Caret Annotation in PDF document:

public static void GetCaretAnnotation()
{
    // Load the PDF file
    Document document = new Document(System.IO.Path.Combine(_dataDir, "sample_caret.pdf"));
    var caretAnnotations = document.Pages[1].Annotations
        .Where(a => a.AnnotationType == AnnotationType.Caret)
        .Cast<CaretAnnotation>();
    foreach (var ca in caretAnnotations)
    {
        Console.WriteLine($"{ca.Rect}");
    }
}

Delete Caret Annotation

The following code snippet shows how Delete Caret Annotation from a PDF file.

public static void DeleteCaretAnnotation()
{
    // Load the PDF file
    Document document = new Document(System.IO.Path.Combine(_dataDir, "sample_caret.pdf"));
    var caretAnnotations = document.Pages[1].Annotations
        .Where(a => a.AnnotationType == AnnotationType.Caret)
        .Cast<CaretAnnotation>();

    foreach (var ca in caretAnnotations)
    {
        document.Pages[1].Annotations.Delete(ca);
    }
    document.Save(System.IO.Path.Combine(_dataDir, "sample_caret_del.pdf"));
}

Redact certain page region with Redaction Annotation using Aspose.PDF for .NET

Aspose.PDF for .NET supports the feature to add as well as manipulate Annotations in an existing PDF file. Recently some of our customers posted a required to redact (remove text, image, etc elements from) a certain page region of PDF document. In order to fulfill this requirement, a class named RedactionAnnotation is provided, which can be used to redact certain page regions or it can be used to manipulate existing RedactionAnnotations and redact them (i.e. flatten annotation and remove the text under it).

// For complete examples and data files, please go to https://github.com/aspose-pdf/Aspose.PDF-for-.NET
// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Annotations();

// Open document
Document doc = new Document(dataDir + "input.pdf");

// Create RedactionAnnotation instance for specific page region
RedactionAnnotation annot = new RedactionAnnotation(doc.Pages[1], new Aspose.Pdf.Rectangle(200, 500, 300, 600));
annot.FillColor = Aspose.Pdf.Color.Green;
annot.BorderColor = Aspose.Pdf.Color.Yellow;
annot.Color = Aspose.Pdf.Color.Blue;
// Text to be printed on redact annotation
annot.OverlayText = "REDACTED";
annot.TextAlignment = Aspose.Pdf.HorizontalAlignment.Center;
// Repat Overlay text over redact Annotation
annot.Repeat = true;
// Add annotation to annotations collection of first page
doc.Pages[1].Annotations.Add(annot);
// Flattens annotation and redacts page contents (i.e. removes text and image
// Under redacted annotation)
annot.Redact();
dataDir = dataDir + "RedactPage_out.pdf";
doc.Save(dataDir);

Facades approach

Aspose.PDF.Facades namespace also has a class named PdfAnnotationEditor which provides the feature to manipulate existing Annotations inside PDF file. This class contains a method named RedactArea(..) which provides the capability to remove certain page regions.

// For complete examples and data files, please go to https://github.com/aspose-pdf/Aspose.PDF-for-.NET
// The path to the documents directory.
string dataDir = RunExamples.GetDataDir_AsposePdf_Annotations();

Aspose.Pdf.Facades.PdfAnnotationEditor editor = new Aspose.Pdf.Facades.PdfAnnotationEditor();
// Redact certain page region
editor.RedactArea(1, new Aspose.Pdf.Rectangle(100, 100, 20, 70), System.Drawing.Color.White);
editor.BindPdf(dataDir + "input.pdf");
editor.Save(dataDir + "FacadesApproach_out.pdf");
PDF sticky Annotations using C# Using Link Annotations in PDF