How to: Add a Comment to a Slide in a Presentation

Last modified: October 14, 2010

Applies to: Excel 2010 | Office 2010 | PowerPoint 2010 | Word 2010

In this article
Getting a PresentationDocument Object
Basic Presentation Document Structure
The Structure of the Comment Element
How the Sample Code Works
Sample Code

This topic shows how to use the classes in the Open XML SDK 2.0 for Microsoft Office to add a comment to the first slide in a presentation programmatically.

The following assembly directives are required to compile the code in this topic.

using System;
using System.Linq;
using DocumentFormat.OpenXml.Presentation;
using DocumentFormat.OpenXml.Packaging;

In the Open XML SDK, the PresentationDocument class represents a presentation document package. To work with a presentation document, first create an instance of the PresentationDocument class, and then work with that instance. To create the class instance from the document call the Open(String, Boolean) method that uses a file path, and a Boolean value as the second parameter to specify whether a document is editable. To open a document for read/write, specify the value true for this parameter as shown in the following using statement. In this code, the file parameter is a string that represents the path for the file from which you want to open the document.

using (PresentationDocument doc = PresentationDocument.Open(file, true))
{
    // Insert other code here.
}

The using statement provides a recommended alternative to the typical .Open, .Save, .Close sequence. It ensures that the Dispose method (internal method used by the Open XML SDK to clean up resources) is automatically called when the closing brace is reached. The block that follows the using statement establishes a scope for the object that is created or named in the using statement, in this case doc.

The basic document structure of a PresentationML document consists of a number of parts, among which is the main part that contains the presentation definition. The following text from the ISO/IEC 29500 specification introduces the overall form of a PresentationML package.

The main part of a PresentationML package starts with a presentation root element. That element contains a presentation, which, in turn, refers to a slide list, a slide master list, a notes master list, and a handout master list. The slide list refers to all of the slides in the presentation; the slide master list refers to the entire slide masters used in the presentation; the notes master contains information about the formatting of notes pages; and the handout master describes how a handout looks.A handout is a printed set of slides that can be provided to an audience.As well as text and graphics, each slide can contain comments and notes, can have a layout, and can be part of one or more custom presentations. A comment is an annotation intended for the person maintaining the presentation slide deck. A note is a reminder or piece of text intended for the presenter or the audience.Other features that a PresentationML document can include the following: animation, audio, video, and transitions between slides.A PresentationML document is not stored as one large body in a single part. Instead, the elements that implement certain groupings of functionality are stored in separate parts. For example, all comments in a document are stored in one comment part while each slide has its own part.© ISO/IEC29500: 2008.

The following XML code example represents a presentation that contains two slides denoted by the IDs 267 and 256.

<p:presentation xmlns:p="…" … > 
   <p:sldMasterIdLst>
      <p:sldMasterId
         xmlns:rel="http://…/relationships" rel:id="rId1"/>
   </p:sldMasterIdLst>
   <p:notesMasterIdLst>
      <p:notesMasterId
         xmlns:rel="http://…/relationships" rel:id="rId4"/>
   </p:notesMasterIdLst>
   <p:handoutMasterIdLst>
      <p:handoutMasterId
         xmlns:rel="http://…/relationships" rel:id="rId5"/>
   </p:handoutMasterIdLst>
   <p:sldIdLst>
      <p:sldId id="267"
         xmlns:rel="http://…/relationships" rel:id="rId2"/>
      <p:sldId id="256"
         xmlns:rel="http://…/relationships" rel:id="rId3"/>
   </p:sldIdLst>
       <p:sldSz cx="9144000" cy="6858000"/>
   <p:notesSz cx="6858000" cy="9144000"/>
</p:presentation>

Using the Open XML SDK 2.0, you can create document structure and content using strongly-typed classes that correspond to PresentationML elements. You can find these classes in the DocumentFormat.OpenXml.Presentation namespace. The following table lists the class names of the classes that correspond to the sld, sldLayout, sldMaster, and notesMaster elements.

PresentationML Element

Open XML SDK 2.0 Class

Description

sld

Slide

Presentation Slide. It is the root element of SlidePart.

sldLayout

SlideLayout

Slide Layout. It is the root element of SlideLayoutPart.

sldMaster

SlideMaster

Slide Master. It is the root element of SlideMasterPart.

notesMaster

NotesMaster

Notes Master (or handoutMaster). It is the root element of NotesMasterPart.

A comment is a text note attached to a slide, with the primary purpose of enabling readers of a presentation to provide feedback to the presentation author. Each comment contains an unformatted text string and information about its author, and is attached to a particular location on a slide. Comments can be visible while editing the presentation, but do not appear when a slide show is given. The displaying application decides when to display comments and determines their visual appearance.

The following XML element specifies a single comment attached to a slide. It contains the text of the comment (text), its position on the slide (pos), and attributes referring to its author (authorId), date and time (dt), and comment index (idx).

<p:cm authorId="0" dt="2006-08-28T17:26:44.129" idx="1">
    <p:pos x="10" y="10"/>
    <p:text>Add diagram to clarify.</p:text>
</p:cm>

The following table contains the definitions of the members and attributes of the cm (comment) element.

Member/Attribute

Definition

authorId

Refers to the ID of an author in the comment author list for the document.

dt

The date and time this comment was last modified.

idx

An identifier for this comment that is unique within a list of all comments by this author in this document. An author's first comment in a document has index 1.

pos

The positioning information for the placement of a comment on a slide surface.

text

Comment text.

extLst

Specifies the extension list with modification ability within which all future extensions of element type ext are defined. The extension list along with corresponding future extensions is used to extend the storage capabilities of the PresentationML framework. This allows for various new kinds of data to be stored natively within the framework.

The following XML schema code example defines the members of the cm element in addition to the required and optional attributes.

<complexType name="CT_Comment">
   <sequence>
       <element name="pos" type="a:CT_Point2D" minOccurs="1" maxOccurs="1"/>
       <element name="text" type="xsd:string" minOccurs="1" maxOccurs="1"/>
       <element name="extLst" type="CT_ExtensionListModify" minOccurs="0" maxOccurs="1"/>
   </sequence>
   <attribute name="authorId" type="xsd:unsignedInt" use="required"/>
   <attribute name="dt" type="xsd:dateTime" use="optional"/>
   <attribute name="idx" type="ST_Index" use="required"/>
</complexType>

The sample code opens the presentation document in the using statement. Then it instantiates the CommentAuthorsPart, and verifies that there is an existing comment authors part. If there is not, it adds one.

// Declare a CommentAuthorsPart object.
CommentAuthorsPart authorsPart;

// Verify that there is an existing comment authors part. 
if (doc.PresentationPart.CommentAuthorsPart == null)
{
    // If not, add a new one.
    authorsPart = doc.PresentationPart.AddNewPart<CommentAuthorsPart>();
}
else
{
    authorsPart = doc.PresentationPart.CommentAuthorsPart;
}

The code determines whether there is an existing comment author list in the comment-authors part; if not, it adds one. It also verifies that the author that is passed in is on the list of existing comment authors; if so, it assigns the existing author ID. If not, it adds a new author to the list of comment authors and assigns an author ID and the parameter values.

// Verify that there is a comment author list in the comment authors part.
if (authorsPart.CommentAuthorList == null)
{
    // If not, add a new one.
    authorsPart.CommentAuthorList = new CommentAuthorList();
}

// Declare a new author ID.
uint authorId = 0;
CommentAuthor author = null;

// If there are existing child elements in the comment authors list...
if (authorsPart.CommentAuthorList.HasChildren)
{
    // Verify that the author passed in is on the list.
    var authors = authorsPart.CommentAuthorList.Elements<CommentAuthor>().Where(a => a.Name == name && a.Initials == initials);

    // If so...
    if (authors.Any())
    {
        // Assign the new comment author the existing author ID.
        author = authors.First();
        authorId = author.Id;
    }

    // If not...
    if (author == null)
    {
        // Assign the author passed in a new ID                        
        authorId = authorsPart.CommentAuthorList.Elements<CommentAuthor>().Select(a => a.Id.Value).Max();
    }
}

// If there are no existing child elements in the comment authors list.
if (author == null)
{
    authorId++;

    // Add a new child element(comment author) to the comment author list.
    author = authorsPart.CommentAuthorList.AppendChild<CommentAuthor>
        (new CommentAuthor()
        {
            Id = authorId,
            Name = name,
            Initials = initials,
            ColorIndex = 0
        });
}

In the following code segment, the code gets the first slide in the presentation by calling the GetFirstSlide method. Then it verifies that there is a comments part in the slide; if not, it adds one. It also verifies that a comments list exists in the comments part; if not, it creates one.

// Get the first slide, using the GetFirstSlide method.
SlidePart slidePart1 = GetFirstSlide(doc);

// Declare a comments part.
SlideCommentsPart commentsPart;

// Verify that there is a comments part in the first slide part.
if (slidePart1.GetPartsOfType<SlideCommentsPart>().Count() == 0)
{
    // If not, add a new comments part.
    commentsPart = slidePart1.AddNewPart<SlideCommentsPart>();
}
else
{
    // Else, use the first comments part in the slide part.
    commentsPart = slidePart1.SlideCommentsPart;
}

// If the comment list does not exist.
if (commentsPart.CommentList == null)
{
    // Add a new comments list.
    commentsPart.CommentList = new CommentList();
}

The code then gets the ID of the new comment, and adds the specified comment, containing the specified text, at the specified position. Then it saves the comment authors part and the comments part.

// Get the new comment ID.
uint commentIdx = author.LastIndex == null ? 1 : author.LastIndex + 1;
author.LastIndex = commentIdx;

// Add a new comment.
Comment comment = commentsPart.CommentList.AppendChild<Comment>(
new Comment()
{
    AuthorId = authorId,
    Index = commentIdx,
    DateTime = DateTime.Now
});

// Add the position child node to the comment element.
comment.Append(
new Position() { X = 100, Y = 200 },
new Text() { Text = text }); 

// Save the comment authors part.
authorsPart.CommentAuthorList.Save();

// Save the comments part.
commentsPart.CommentList.Save();

The AddCommentToPresentation method can be used to add a comment to a slide. The method takes as parameters the source presentation file name and path, the initials and name of the comment author, and the text of the comment to be added. It adds an author to the list of comment authors and then adds the specified comment text at the specified coordinates in the first slide in the presentation.

The second method, GetFirstSlide, is used to get the first slide in the presentation. It takes the PresentationDocument object passed in, gets its presentation part, and then gets the ID of the first slide in its slide list. It then gets the relationship ID of the slide, gets the slide part from the relationship ID, and returns the slide part to the calling method.

The following code example shows a call to the AddCommentToPresentation which adds the specified comment string to the first slide in the presentation file Myppt1.pptx.

AddCommentToPresentation(@"C:\Users\Public\Documents\Myppt1.pptx", 
"Katie Jordan", "KJ", 
"This is my programmatically added comment.");

NoteNote

To get the exact author name and initials, open the presentation file and click the File menu item, and then click Options. The PowerPointOptions window opens and the content of the General tab is displayed. The author name and initials must match the User name and Initials in this tab.

// Adds a comment to the first slide of the presentation document.
// The presentation document must contain at least one slide.
public static void AddCommentToPresentation(string file, string initials, string name, string text)
{
    using (PresentationDocument doc = PresentationDocument.Open(file, true))
    {

        // Declare a CommentAuthorsPart object.
        CommentAuthorsPart authorsPart;

        // Verify that there is an existing comment authors part. 
        if (doc.PresentationPart.CommentAuthorsPart == null)
        {
            // If not, add a new one.
            authorsPart = doc.PresentationPart.AddNewPart<CommentAuthorsPart>();
        }
        else
        {
            authorsPart = doc.PresentationPart.CommentAuthorsPart;
        }

        // Verify that there is a comment author list in the comment authors part.
        if (authorsPart.CommentAuthorList == null)
        {
            // If not, add a new one.
            authorsPart.CommentAuthorList = new CommentAuthorList();
        }

        // Declare a new author ID.
        uint authorId = 0;
        CommentAuthor author = null;

        // If there are existing child elements in the comment authors list...
        if (authorsPart.CommentAuthorList.HasChildren)
        {
            // Verify that the author passed in is on the list.
            var authors = authorsPart.CommentAuthorList.Elements<CommentAuthor>().Where(a => a.Name == name && a.Initials == initials);

            // If so...
            if (authors.Any())
            {
                // Assign the new comment author the existing author ID.
                author = authors.First();
                authorId = author.Id;
            }

            // If not...
            if (author == null)
            {
                // Assign the author passed in a new ID                        
                authorId = authorsPart.CommentAuthorList.Elements<CommentAuthor>().Select(a => a.Id.Value).Max();
            }
        }

        // If there are no existing child elements in the comment authors list.
        if (author == null)
        {

            authorId++;

            // Add a new child element(comment author) to the comment author list.
            author = authorsPart.CommentAuthorList.AppendChild<CommentAuthor>
                (new CommentAuthor()
                {
                    Id = authorId,
                    Name = name,
                    Initials = initials,
                    ColorIndex = 0
                });
        }

        // Get the first slide, using the GetFirstSlide method.
        SlidePart slidePart1 = GetFirstSlide(doc);

        // Declare a comments part.
        SlideCommentsPart commentsPart;

        // Verify that there is a comments part in the first slide part.
        if (slidePart1.GetPartsOfType<SlideCommentsPart>().Count() == 0)
        {
            // If not, add a new comments part.
            commentsPart = slidePart1.AddNewPart<SlideCommentsPart>();
        }
        else
        {
            // Else, use the first comments part in the slide part.
            commentsPart = slidePart1.GetPartsOfType<SlideCommentsPart>().First();
        }

        // If the comment list does not exist.
        if (commentsPart.CommentList == null)
        {
            // Add a new comments list.
            commentsPart.CommentList = new CommentList();
        }

        // Get the new comment ID.
        uint commentIdx = author.LastIndex == null ? 1 : author.LastIndex + 1;
        author.LastIndex = commentIdx;

        // Add a new comment.
        Comment comment = commentsPart.CommentList.AppendChild<Comment>(
            new Comment()
            {
                AuthorId = authorId,
                Index = commentIdx,
                DateTime = DateTime.Now
            });

        // Add the position child node to the comment element.
        comment.Append(
            new Position() { X = 100, Y = 200 },
            new Text() { Text = text });

        // Save the comment authors part.
        authorsPart.CommentAuthorList.Save();

        // Save the comments part.
        commentsPart.CommentList.Save();
    }
 }
// Get the slide part of the first slide in the presentation document.
public static SlidePart GetFirstSlide(PresentationDocument presentationDocument)
{
    // Get relationship ID of the first slide
    PresentationPart part = presentationDocument.PresentationPart;
    SlideId slideId = part.Presentation.SlideIdList.GetFirstChild<SlideId>();
    string relId = slideId.RelationshipId;

    // Get the slide part by the relationship ID.
    SlidePart slidePart = (SlidePart)part.GetPartById(relId);

    return slidePart;
}

' Adds a comment to the first slide of the presentation document.
' The presentation document must contain at least one slide.
Public Sub AddCommentToPresentation(ByVal file As String, _
            ByVal initials As String, _
            ByVal name As String, _
            ByVal text As String)

   Dim doc As PresentationDocument = _
      PresentationDocument.Open(file, True)

   Using (doc)

      ' Declare a CommentAuthorsPart object.
      Dim authorsPart As CommentAuthorsPart

      ' Verify that there is an existing comment authors part.
      If (doc.PresentationPart.CommentAuthorsPart Is Nothing) Then

         ' If not, add a new one.
         authorsPart = doc.PresentationPart.AddNewPart(Of CommentAuthorsPart)()
      Else
         authorsPart = doc.PresentationPart.CommentAuthorsPart
      End If

      ' Verify that there is a comment author list in the comment authors part.
      If (authorsPart.CommentAuthorList Is Nothing) Then

         ' If not, add a new one.
         authorsPart.CommentAuthorList = New CommentAuthorList()
      End If

      ' Declare a new author ID.
      Dim authorId As UInteger = 0
      Dim author As CommentAuthor = Nothing

      ' If there are existing child elements in the comment authors list.
      If authorsPart.CommentAuthorList.HasChildren = True Then

         ' Verify that the author passed in is on the list.
         Dim authors = authorsPart.CommentAuthorList.Elements(Of CommentAuthor)().Where _
          (Function(a) a.Name = name AndAlso a.Initials = initials)

         ' If so...
         If (authors.Any()) Then

            ' Assign the new comment author the existing ID.
            author = authors.First()
            authorId = author.Id
         End If

         ' If not...
         If (author Is Nothing) Then

            ' Assign the author passed in a new ID.
            authorId = _
            authorsPart.CommentAuthorList.Elements(Of CommentAuthor)().Select(Function(a) a.Id.Value).Max()
         End If

      End If

      ' If there are no existing child elements in the comment authors list.
      If (author Is Nothing) Then

         authorId = authorId + 1

         ' Add a new child element (comment author) to the comment author list.
         author = (authorsPart.CommentAuthorList.AppendChild(Of CommentAuthor) _
          (New CommentAuthor() With {.Id = authorId, _
           .Name = name, _
           .Initials = initials, _
           .ColorIndex = 0}))
      End If

      ' Get the first slide, using the GetFirstSlide() method.
      Dim slidePart1 As SlidePart
      slidePart1 = GetFirstSlide(doc)

      ' Declare a comments part.
      Dim commentsPart As SlideCommentsPart

      ' Verify that there is a comments part in the first slide part.
      If slidePart1.GetPartsOfType(Of SlideCommentsPart)().Count() = 0 Then

         ' If not, add a new comments part.
         commentsPart = slidePart1.AddNewPart(Of SlideCommentsPart)()
      Else

         ' Else, use the first comments part in the slide part.
         commentsPart = _
          slidePart1.GetPartsOfType(Of SlideCommentsPart)().First()
      End If

      ' If the comment list does not exist.
      If (commentsPart.CommentList Is Nothing) Then

         ' Add a new comments list.
         commentsPart.CommentList = New CommentList()
      End If

      ' Get the new comment ID.
      Dim commentIdx As UInteger
      If author.LastIndex Is Nothing Then
         commentIdx = 1
      Else
         commentIdx = CType(author.LastIndex, UInteger) + 1
      End If

      author.LastIndex = commentIdx

      ' Add a new comment.
      Dim comment As Comment = _
       (commentsPart.CommentList.AppendChild(Of Comment)(New Comment() _
         With {.AuthorId = authorId, .Index = commentIdx, .DateTime = DateTime.Now}))

      ' Add the position child node to the comment element.
      comment.Append(New Position() With _
           {.X = 100, .Y = 200}, New Text() With {.Text = text})


      ' Save comment authors part.
      authorsPart.CommentAuthorList.Save()

      ' Save comments part.
      commentsPart.CommentList.Save()

   End Using

End Sub

' Get the slide part of the first slide in the presentation document.
Public Function GetFirstSlide(ByVal presentationDocument As PresentationDocument) As SlidePart
   ' Get relationship ID of the first slide
   Dim part As PresentationPart = presentationDocument.PresentationPart
   Dim slideId As SlideId = part.Presentation.SlideIdList.GetFirstChild(Of SlideId)()
   Dim relId As String = slideId.RelationshipId

   ' Get the slide part by the relationship ID.
   Dim slidePart As SlidePart = DirectCast(part.GetPartById(relId), SlidePart)

   Return slidePart
End Function
End Module
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