PDF: Working with PDF annotations of PDF document

In This Topic

VintaSoft PDF .NET Plug-in provides the functionality for non-visual low-level work with annotations of PDF document.
A combination of VintaSoft PDF .NET Plug-in and VintaSoft Annotation .NET Plug-in provides the functionality for full-featured visual and non-visual annotating of PDF document in WinForms, WPF and ASP.NET. Detailed information about functionality of VintaSoft Annotation .NET Plug-in please see here.

PdfAnnotation class defines annotation of PDF document and allows to:

define the location of annotation on PDF page using PdfAnnotation.Rectangle property
define annotation data using PdfAnnotation.Contents, PdfAnnotation.Title, PdfAnnotation.Subject, PdfAnnotation.Modified properties
define the visual appearance of annotation using PdfAnnotation.Appearances, PdfAnnotation.BorderStyle, PdfAnnotation.Color properties
define an action, which will be performed when annotation become active, using PdfAnnotation.ActivateAction property
define some additional actions of annotation using PdfAnnotation.AdditionalActions property
get PdfGraphics object, which defines the visual appearance of annotation in the Normal state, using PdfAnnotation.CreateNormalAppearanceGraphics method
get PdfGraphics object, which defines the visual appearance of annotation in the Rollover state, using PdfAnnotation.CreateRolloverAppearanceGraphics method
get PdfGraphics object, which defines the visual appearance of annotation in the Down state, using PdfAnnotation.CreateDownAppearanceGraphics method

Here is the hierarchy of classes, that defines standard annotations of PDF document:

PdfAnnotation - provides the base class that contains information about PDF annotation.
- PdfMarkupAnnotation - provides the base class that represents a PDF markup annotation.
  - PdfLineAnnotation - represents a PDF annotation that displays a line.
  - PdfRectangularAnnotation - provides the base class that represents PDF rectangular (square, circle) annotation.
    - PdfCircleAnnotation - represents a PDF annotation that displays a circle.
    - PdfSquareAnnotation - represents a PDF annotation that displays a square.
  - PdfPolygonalAnnotation - provides the base class that represents a point-based (polyline, polygon) PDF annotation.
    - PdfPolygonAnnotation - represents a PDF annotation that displays a polygon.
    - PdfPolylineAnnotation - represents a PDF annotation that displays a polyline.
  - PdfFreeTextAnnotation - represents a PDF annotation that displays an editable text area and a leader polyline used to point to the area of PDF page.
  - PdfRubberStampAnnotation - represents a PDF annotation that displays a rubber stamp.
  - PdfTextMarkupAnnotation - represents a PDF annotation that can appears as as highlight, underline, strikeout, or jagged ("squiggly") underline in the text of a document.
  - PdfCaretAnnotation - represents a PDF annotation that displays a visual symbol that indicates the presence of text edits.
- PdfLinkAnnotation - represents a PDF annotation that displays a link.
- PdfTextAnnotation - represents a PDF annotation that displays a "sticky note" attached to a point in the PDF document.
- PdfWidgetAnnotation - represents a Widget annotation that displays interactive element.

Here is C#/VB.NET code that demonstrates how to obtain information about all annotations of PDF page:

/// <summary>
/// Gets and prints information about all annotations of PDF page.
/// </summary>
/// <param name="pdfFileName">The filename of PDF document.</param>
public static void PrintAnnotationsInfo(string pdfFileName)
{
    // open PDF document
    using (Vintasoft.Imaging.Pdf.PdfDocument document =
        new Vintasoft.Imaging.Pdf.PdfDocument(pdfFileName))
    {
        // for each PDF page
        for (int pageIndex = 0; pageIndex < document.Pages.Count; pageIndex++)
        {
            // get PDF page
            Vintasoft.Imaging.Pdf.Tree.PdfPage page = document.Pages[pageIndex];
            // get a collection of annotations of PDF page
            Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList annotations = page.Annotations;
            if (annotations == null)
            {
                System.Console.WriteLine("Page {0}: no annotations.", pageIndex + 1);
            }
            else
            {
                // print the page index and count of annotations
                System.Console.WriteLine("Page {0} Annotation count: {1}", pageIndex + 1, annotations.Count);
                // for each annotation
                foreach (Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotation annotation in annotations)
                {
                    // print information about annotation
                    System.Console.WriteLine("Annotation:");
                    System.Console.WriteLine("           Name: \"{0}\"", annotation.Name);
                    System.Console.WriteLine(" Title (Author): \"{0}\"", annotation.Title);
                    System.Console.WriteLine("        Subject: \"{0}\"", annotation.Subject);
                    System.Console.WriteLine("       Contents: \"{0}\"", annotation.Contents);
                    System.Console.WriteLine("AppearanceState: \"{0}\"", annotation.AppearanceState);
                    System.Console.WriteLine("       Modified: {0}", annotation.Modified);
                    System.Console.WriteLine("          Flags: {0}", annotation.Flags);
                    System.Console.WriteLine();
                }
            }
        }
    }
}

VB.NET

''' <summary>
''' Gets and prints information about all annotations of PDF page.
''' </summary>
''' <param name="pdfFileName">The filename of PDF document.</param>
Public Shared Sub PrintAnnotationsInfo(pdfFileName As String)
    ' open PDF document
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(pdfFileName)
        ' for each PDF page
        For pageIndex As Integer = 0 To document.Pages.Count - 1
            ' get PDF page
            Dim page As Vintasoft.Imaging.Pdf.Tree.PdfPage = document.Pages(pageIndex)
            ' get a collection of annotations of PDF page
            Dim annotations As Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList = page.Annotations
            If annotations Is Nothing Then
                System.Console.WriteLine("Page {0}: no annotations.", pageIndex + 1)
            Else
                ' print the page index and count of annotations
                System.Console.WriteLine("Page {0} Annotation count: {1}", pageIndex + 1, annotations.Count)
                ' for each annotation
                For Each annotation As Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotation In annotations
                    ' print information about annotation
                    System.Console.WriteLine("Annotation:")
                    System.Console.WriteLine("           Name: ""{0}""", annotation.Name)
                    System.Console.WriteLine(" Title (Author): ""{0}""", annotation.Title)
                    System.Console.WriteLine("        Subject: ""{0}""", annotation.Subject)
                    System.Console.WriteLine("       Contents: ""{0}""", annotation.Contents)
                    System.Console.WriteLine("AppearanceState: ""{0}""", annotation.AppearanceState)
                    System.Console.WriteLine("       Modified: {0}", annotation.Modified)
                    System.Console.WriteLine("          Flags: {0}", annotation.Flags)
                    System.Console.WriteLine()
                Next
            End If
        Next
    End Using
End Sub

Create new PDF annotation

To create a new annotation it is necessary to do the following:

Create an instance of class derived from PdfAnnotation
If necessary, define the visual appearance of annotation by drawing it on PdfGraphics object, which represents the visual appearance of annotation

Here is C#/VB.NET code that demonstrates how to create an annotation, which consists from red rectangle:

/// <summary>
/// Creates an annotation, which consists from red rectangle.
/// </summary>
/// <param name="page">The page.</param>
/// <returns>The created annotation.</returns>
public static Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotation CreatePdfAnnotation(
    Vintasoft.Imaging.Pdf.Tree.PdfPage page)
{
    // create a rectangular annotation
    Vintasoft.Imaging.Pdf.Tree.Annotations.PdfSquareAnnotation annotation = 
        new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfSquareAnnotation(page);
    // set interior color
    annotation.InteriorColor = System.Drawing.Color.Red;
    // set rectangle
    annotation.Rectangle = new System.Drawing.RectangleF(40, 40, 160, 80);
    // create graphics for normal appearance
    using (Vintasoft.Imaging.Pdf.Drawing.PdfGraphics pdfGraphics = annotation.CreateNormalAppearanceGraphics())
    {
        // draw an appearance of the annotation
        pdfGraphics.FillRectangle(
            new Vintasoft.Imaging.Pdf.Drawing.PdfBrush(System.Drawing.Color.Red), 
            0, 0, 
            annotation.Rectangle.Width, annotation.Rectangle.Height);
    }

    // return created annotation
    return annotation;
}

VB.NET

''' <summary>
''' Creates an annotation, which consists from red rectangle.
''' </summary>
''' <param name="page">The page.</param>
''' <returns>The created annotation.</returns>
Public Shared Function CreatePdfAnnotation(page As Vintasoft.Imaging.Pdf.Tree.PdfPage) As Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotation
    ' create a rectangular annotation
    Dim annotation As New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfSquareAnnotation(page)
    ' set interior color
    annotation.InteriorColor = System.Drawing.Color.Red
    ' set rectangle
    annotation.Rectangle = New System.Drawing.RectangleF(40, 40, 160, 80)
    ' create graphics for normal appearance
    Using pdfGraphics As Vintasoft.Imaging.Pdf.Drawing.PdfGraphics = annotation.CreateNormalAppearanceGraphics()
        ' draw an appearance of the annotation
        pdfGraphics.FillRectangle(New Vintasoft.Imaging.Pdf.Drawing.PdfBrush(System.Drawing.Color.Red), 0, 0, annotation.Rectangle.Width, annotation.Rectangle.Height)
    End Using

    ' return created annotation
    Return annotation
End Function

Add annotation onto PDF page

To add a new annotation onto PDF page it is necessary to do the following:

Create annotation
Define annotation location on PDF page
Add annotation to the list of PDF page annotations

Here is C#/VB.NET code that demonstrates how to create a line annotation and add it onto PDF page:

/// <summary>
/// Creates a Line annotation and adds it onto PDF page.
/// </summary>
/// <param name="pdfFilename">The filename of PDF document.</param>
public static void AddLineAnnotationOntoPage(string pdfFilename)
{
    // open PDF document
    using (Vintasoft.Imaging.Pdf.PdfDocument pdfDocument = new Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename))
    {
        // get first page of the document
        Vintasoft.Imaging.Pdf.Tree.PdfPage page = pdfDocument.Pages[0];
        // create line annotation
        Vintasoft.Imaging.Pdf.Tree.Annotations.PdfLineAnnotation lineAnnotation = 
            new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfLineAnnotation(page);
        // set color of the annotation
        lineAnnotation.Color = System.Drawing.Color.Green;
        // set rectangle of the annotation
        lineAnnotation.Rectangle = page.CropBox;
        // set start point of the annotation
        lineAnnotation.StartPoint = new System.Drawing.PointF(0, 0);
        // set end point of the annotation
        lineAnnotation.EndPoint = new System.Drawing.PointF(page.CropBox.Width, page.CropBox.Height);
        // create graphics for normal appearance
        using (Vintasoft.Imaging.Pdf.Drawing.PdfGraphics pdfGraphics = lineAnnotation.CreateNormalAppearanceGraphics())
        {
            // draw appearance of the annotation
            pdfGraphics.DrawLine(new Vintasoft.Imaging.Pdf.Drawing.PdfPen(System.Drawing.Color.Green, 3f),
                0, 0, lineAnnotation.Rectangle.Width, lineAnnotation.Rectangle.Height);
        }
        // if there is no annotations
        if (page.Annotations == null)
            // create collection of annotations of the page
            page.Annotations = new Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList(pdfDocument);
        // add the annotation to the collection
        page.Annotations.Add(lineAnnotation);
        // save changes to the source
        pdfDocument.SaveChanges();
    }
}

VB.NET

''' <summary>
''' Creates a Line annotation and adds it onto PDF page.
''' </summary>
''' <param name="pdfFilename">The filename of PDF document.</param>
Public Shared Sub AddLineAnnotationOntoPage(pdfFilename As String)
    ' open PDF document
    Using pdfDocument As New Vintasoft.Imaging.Pdf.PdfDocument(pdfFilename)
        ' get first page of the document
        Dim page As Vintasoft.Imaging.Pdf.Tree.PdfPage = pdfDocument.Pages(0)
        ' create line annotation
        Dim lineAnnotation As New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfLineAnnotation(page)
        ' set color of the annotation
        lineAnnotation.Color = System.Drawing.Color.Green
        ' set rectangle of the annotation
        lineAnnotation.Rectangle = page.CropBox
        ' set start point of the annotation
        lineAnnotation.StartPoint = New System.Drawing.PointF(0, 0)
        ' set end point of the annotation
        lineAnnotation.EndPoint = New System.Drawing.PointF(page.CropBox.Width, page.CropBox.Height)
        ' create graphics for normal appearance
        Using pdfGraphics As Vintasoft.Imaging.Pdf.Drawing.PdfGraphics = lineAnnotation.CreateNormalAppearanceGraphics()
            ' draw appearance of the annotation
            pdfGraphics.DrawLine(New Vintasoft.Imaging.Pdf.Drawing.PdfPen(System.Drawing.Color.Green, 3F), 0, 0, lineAnnotation.Rectangle.Width, lineAnnotation.Rectangle.Height)
        End Using
        ' if there is no annotations
        If page.Annotations Is Nothing Then
            ' create collection of annotations of the page
            page.Annotations = New Vintasoft.Imaging.Pdf.Tree.Annotations.PdfAnnotationList(pdfDocument)
        End If
        ' add the annotation to the collection
        page.Annotations.Add(lineAnnotation)
        ' save changes to the source
        pdfDocument.SaveChanges()
    End Using
End Sub

Delete annotation from PDF page

To delete an annotation from PDF page it is necessary to do the following:

Find annotation subjected for deleting
Remove annotation from the list of PDF page annotations

Here is C#/VB.NET code that demonstrates how to delete annotation from PDF page:

/// <summary>
/// Removes the first annotation from PDF page
/// if it is a link annotation.
/// </summary>
/// <param name="page">The page of PDF document.</param>
public static bool RemoveAnnotationFromPdfPage(Vintasoft.Imaging.Pdf.Tree.PdfPage page)
{
    // if annotations exist
    if (page.Annotations != null && page.Annotations.Count > 0)
    {
        // if contents of the first annotation if it is a link
        if (page.Annotations[0] is Vintasoft.Imaging.Pdf.Tree.Annotations.PdfLinkAnnotation)
        {
            // remove the annotation
            page.Annotations.RemoveAt(0);
            return true;
        }
    }

    return false;
}

VB.NET

''' <summary>
''' Removes the first annotation from PDF page
''' if it is a link annotation.
''' </summary>
''' <param name="page">The page of PDF document.</param>
Public Shared Function RemoveAnnotationFromPdfPage(page As Vintasoft.Imaging.Pdf.Tree.PdfPage) As Boolean
    ' if annotations exist
    If page.Annotations IsNot Nothing AndAlso page.Annotations.Count > 0 Then
        ' if contents of the first annotation if it is a link
        If TypeOf page.Annotations(0) Is Vintasoft.Imaging.Pdf.Tree.Annotations.PdfLinkAnnotation Then
            ' remove the annotation
            page.Annotations.RemoveAt(0)
            Return True
        End If
    End If

    Return False
End Function

Change appearance of PDF annotation

The PdfAnnotation.AppearanceGenerator property allows to get or set the appearance generator of PDF annotation. Custom appearance generator must be created if annotation appearance must be changed. PDF Editor Demo has an example of custom appearance generator for PDF signature field - the SignatureAppearanceGenerator class, which can be found in file "<install_path>\Examples\WinForms\CSharp\PdfEditorDemo\DemosCommonCode.Pdf\AnnotationTool\FormFields\AppearanceGenerators\Signature\SignatureAppearanceGenerator.cs".

Add comments to PDF annotation

For working with comments of PDF page is necessary to do the following steps:

Create image collection - an instance of ImageCollection class
Add PDF document to the image collection - call ImageCollection.Add method
Create PDF annotation comment controller - an instance of ImageCollectionPdfAnnotationCommentController class
Specify that PDF annotation comment controller is associated with image collection - set value of ImageCollectionCommentController.Images property
Get comment collection, which is associated with image/PDF page - call the ImageCollectionCommentController.GetComments method and get instance of CommentCollection class
Add, edit or remove comments - call methods of CommentCollection class

Here is C#/VB.NET code that demonstrates how to print comments comments of specified PDF document:

/// <summary>
/// Demonstrates how to prints comments of specified PDF document.
/// </summary>
public class PdfAnnotationCommentExample
{
    /// <summary>
    /// Prints comments of specified PDF document.
    /// </summary>
    /// <param name="pdfFilename">The PDF filename.</param>
    public static void PrintComments(string pdfFilename)
    {
        // create an image collection
        using (Vintasoft.Imaging.ImageCollection images = new Vintasoft.Imaging.ImageCollection())
        {
            // add PDF document to the image collection
            images.Add(pdfFilename);

            // create PDF annotation comment controller
            using (Vintasoft.Imaging.Annotation.Comments.Pdf.ImageCollectionPdfAnnotationCommentController pdfAnnotationCommentController =
                new Vintasoft.Imaging.Annotation.Comments.Pdf.ImageCollectionPdfAnnotationCommentController())
            {
                // specify that PDF annotation comment controller is associated with image collection
                pdfAnnotationCommentController.Images = images;

                // print comments from PDF annotation comment controller
                PrintComments(pdfAnnotationCommentController);
            }

            // clear and dispose images
            images.ClearAndDisposeItems();
        }
    }

    /// <summary>
    /// Prints comments from specified comment controller.
    /// </summary>
    /// <param name="commentController">The comment controller.</param>
    public static void PrintComments(Vintasoft.Imaging.Annotation.Comments.ImageCollectionCommentController commentController)
    {
        // for each image
        for (int i = 0; i < commentController.Images.Count; i++)
        {
            Vintasoft.Imaging.VintasoftImage image = commentController.Images[i];

            // get comment collection, which is associated with image/PDF page
            Vintasoft.Imaging.Annotation.Comments.CommentCollection comments = commentController.GetComments(image);
            // if comments are found
            if (comments != null && comments.Count > 0)
            {
                System.Console.WriteLine(string.Format("Page {0}:", i + 1));

                // for each comment
                foreach (Vintasoft.Imaging.Annotation.Comments.Comment comment in comments)
                {
                    // print comment
                    PrintComment(comment, 0);
                }
            }
        }
    }

    /// <summary>
    /// Prints the comment.
    /// </summary>
    /// <param name="comment">The comment.</param>
    /// <param name="replyLevel">The reply level.</param>
    private static void PrintComment(Vintasoft.Imaging.Annotation.Comments.Comment comment, int replyLevel)
    {
        // print comment
        System.Console.Write(string.Empty.PadLeft(replyLevel * 4));
        System.Console.WriteLine(string.Format("[{0}] {1}: {2} ({3})",comment.Type, comment.UserName, comment.Text, comment.ModifyDate));

        // if comment has replies
        if (comment.Replies != null)
        {
            // print replies
            foreach (Vintasoft.Imaging.Annotation.Comments.Comment reply in comment.Replies)
                PrintComment(reply, replyLevel + 1);
        }
    }

}

VB.NET

''' <summary>
''' Demonstrates how to prints comments of specified PDF document.
''' </summary>
Public Class PdfAnnotationCommentExample
    ''' <summary>
    ''' Prints comments of specified PDF document.
    ''' </summary>
    ''' <param name="pdfFilename">The PDF filename.</param>
    Public Shared Sub PrintComments(pdfFilename As String)
        ' create an image collection
        Using images As New Vintasoft.Imaging.ImageCollection()
            ' add PDF document to the image collection
            images.Add(pdfFilename)

            ' create PDF annotation comment controller
            Using pdfAnnotationCommentController As New Vintasoft.Imaging.Annotation.Comments.Pdf.ImageCollectionPdfAnnotationCommentController()
                ' specify that PDF annotation comment controller is associated with image collection
                pdfAnnotationCommentController.Images = images

                ' print comments from PDF annotation comment controller
                PrintComments(pdfAnnotationCommentController)
            End Using

            ' clear and dispose images
            images.ClearAndDisposeItems()
        End Using
    End Sub

    ''' <summary>
    ''' Prints comments from specified comment controller.
    ''' </summary>
    ''' <param name="commentController">The comment controller.</param>
    Public Shared Sub PrintComments(commentController As Vintasoft.Imaging.Annotation.Comments.ImageCollectionCommentController)
        ' for each image
        For i As Integer = 0 To commentController.Images.Count - 1
            Dim image As Vintasoft.Imaging.VintasoftImage = commentController.Images(i)

            ' get comment collection, which is associated with image/PDF page
            Dim comments As Vintasoft.Imaging.Annotation.Comments.CommentCollection = commentController.GetComments(image)
            ' if comments are found
            If comments IsNot Nothing AndAlso comments.Count > 0 Then
                System.Console.WriteLine(String.Format("Page {0}:", i + 1))

                ' for each comment
                For Each comment As Vintasoft.Imaging.Annotation.Comments.Comment In comments
                    ' print comment
                    PrintComment(comment, 0)
                Next
            End If
        Next
    End Sub

    ''' <summary>
    ''' Prints the comment.
    ''' </summary>
    ''' <param name="comment">The comment.</param>
    ''' <param name="replyLevel">The reply level.</param>
    Private Shared Sub PrintComment(comment As Vintasoft.Imaging.Annotation.Comments.Comment, replyLevel As Integer)
        ' print comment
        System.Console.Write(String.Empty.PadLeft(replyLevel * 4))
        System.Console.WriteLine(String.Format("[{0}] {1}: {2} ({3})", comment.Type, comment.UserName, comment.Text, comment.ModifyDate))

        ' if comment has replies
        If comment.Replies IsNot Nothing Then
            ' print replies
            For Each reply As Vintasoft.Imaging.Annotation.Comments.Comment In comment.Replies
                PrintComment(reply, replyLevel + 1)
            Next
        End If
    End Sub

End Class

Send Feedback