Add a comment to a slide in a presentation

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

Basic Presentation Document Structure

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="https://…/relationships" rel:id="rId1"/>
       </p:sldMasterIdLst>
       <p:notesMasterIdLst>
          <p:notesMasterId
             xmlns:rel="https://…/relationships" rel:id="rId4"/>
       </p:notesMasterIdLst>
       <p:handoutMasterIdLst>
          <p:handoutMasterId
             xmlns:rel="https://…/relationships" rel:id="rId5"/>
       </p:handoutMasterIdLst>
       <p:sldIdLst>
          <p:sldId id="267"
             xmlns:rel="https://…/relationships" rel:id="rId2"/>
          <p:sldId id="256"
             xmlns:rel="https://…/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, 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 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.

The Structure of the Comment Element

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>

Sample Code

The following code example shows how to add comments to a presentation document. To run the program, you can pass in the arguments:

dotnet run -- [filePath] [initials] [name] [test ...]

Note

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.

C#

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

AddCommentToPresentation(args[0], args[1], args[2], string.Join(' ', args[3..]));

static void AddCommentToPresentation(string file, string initials, string name, string text)
{
    using (PresentationDocument doc = PresentationDocument.Open(file, true))
    {

        // Declare a CommentAuthorsPart object.
        CommentAuthorsPart authorsPart;

        // If the presentation does not contain a comment authors part, add a new one.
        PresentationPart presentationPart = doc.PresentationPart ?? doc.AddPresentationPart();

        // Verify that there is an existing comment authors part and add a new one if not.
        authorsPart = presentationPart.CommentAuthorsPart ?? presentationPart.AddNewPart<CommentAuthorsPart>();

        // Verify that there is a comment author list in the comment authors part and add one if not.
        CommentAuthorList authorList = authorsPart.CommentAuthorList ?? new CommentAuthorList();
        authorsPart.CommentAuthorList = authorList;

        // Declare a new author ID as either the max existing ID + 1 or 1 if there are no existing IDs.
        uint authorId = authorList.Elements<CommentAuthor>().Select(a => a.Id?.Value).Max() ?? 0;
        authorId++;
        // If there is an existing author with matching name and initials, use that author otherwise create a new CommentAuthor.
        var foo = authorList.Elements<CommentAuthor>().Where(a => a.Name == name && a.Initials == initials).FirstOrDefault();
        CommentAuthor author = foo ??
            authorList.AppendChild
                (new CommentAuthor()
                {
                    Id = authorId,
                    Name = name,
                    Initials = initials,
                    ColorIndex = 0
                });
        // get the author id
        authorId = author.Id ?? authorId;

        // 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 is null)
        {
            // Add a new comments list.
            commentsPart.CommentList = new CommentList();
        }

        // Get the new comment ID.
        uint commentIdx = author.LastIndex is 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.
        authorList.Save();

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

// Get the slide part of the first slide in the presentation document.
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;
    if (relId is null)
    {
        throw new ArgumentNullException("The first slide does not contain a relationship ID.");
    }
    // Get the slide part by the relationship ID.
    SlidePart? slidePart = part?.GetPartById(relId) as SlidePart;

    if (slidePart is null)
    {
        throw new ArgumentNullException("The slide part is null.");
    }

    return slidePart;
}

Visual Basic

Imports DocumentFormat.OpenXml.Packaging
Imports DocumentFormat.OpenXml.Presentation

Module Program
    Sub Main(args As String())
        AddCommentToPresentation(args(0), args(1), args(2), String.Join(" ", args.Skip(3)))
    End Sub

    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

See also

• Open XML SDK class library reference