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Get all the external hyperlinks in a presentation

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This topic shows how to use the classes in the Open XML SDK for Office to get all the external hyperlinks in a presentation programmatically.

Getting a PresentationDocument Object

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 method that uses a file path, and a Boolean value as the second parameter to specify whether a document is editable. Set this second parameter to false to open the file for read-only access, or true if you want to open the file for read/write access. In this topic, it is best to open the file for read-only access to protect the file against accidental writing. The following using statement opens the file for read-only access. In this code segment, the fileName parameter is a string that represents the path for the file from which you want to open the document.

// Open the presentation file as read-only.
using (PresentationDocument document = PresentationDocument.Open(fileName, false))

With v3.0.0+ the Close() method has been removed in favor of relying on the using statement. This ensures that the Dispose() method 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 document.

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 authors in a document are stored in one authors part while each slide has its own part.

ISO/IEC 29500: 2016

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 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.

In this how-to code example, you are going to work with external hyperlinks. Therefore, it is best to familiarize yourself with the hyperlink element. The following text from the ISO/IEC 29500 specification introduces the id (Hyperlink Target).

Specifies the ID of the relationship whose target shall be used as the target for thishyperlink.

If this attribute is omitted, then there shall be no external hyperlink target for the current hyperlink - a location in the current document can still be target via the anchor attribute. If this attribute exists, it shall supersede the value in the anchor attribute.

[Example: Consider the following PresentationML fragment for a hyperlink:

    <w:hyperlink r:id="rId9">
      <w:r>
        <w:t>https://www.example.com</w:t>
      </w:r>
    </w:hyperlink>

The id attribute value of rId9 specifies that relationship in the associated relationship part item with a corresponding Id attribute value must be navigated to when this hyperlink is invoked. For example, if the following XML is present in the associated relationship part item:

    <Relationships xmlns="…">
      <Relationship Id="rId9" Mode="External" Target="https://www.example.com" />
    </Relationships>

The target of this hyperlink would therefore be the target of relationship rId9 - in this case, https://www.example.com. end example]

The possible values for this attribute are defined by the ST_RelationshipId simple type(§22.8.2.1).

© ISO/IEC 29500: 2016

How the Sample Code Works

The sample code in this topic consists of one method that takes as a parameter the full path of the presentation file. It iterates through all the slides in the presentation and returns a list of strings that represent the Universal Resource Identifiers (URIs) of all the external hyperlinks in the presentation.

// Iterate through all the slide parts in the presentation part.
foreach (SlidePart slidePart in document.PresentationPart.SlideParts)
{
    IEnumerable<Drawing.HyperlinkType> links = slidePart.Slide.Descendants<Drawing.HyperlinkType>();

    // Iterate through all the links in the slide part.
    foreach (Drawing.HyperlinkType link in links)
    {
        // Iterate through all the external relationships in the slide part. 
        foreach (HyperlinkRelationship relation in slidePart.HyperlinkRelationships)
        {
            // If the relationship ID matches the link ID…
            if (relation.Id.Equals(link.Id))
            {
                // Add the URI of the external relationship to the list of strings.
                ret.Add(relation.Uri.AbsoluteUri);
            }
        }
    }
}

Sample Code

Following is the complete code sample that you can use to return the list of all external links in a presentation. You can use the following loop in your program to call the GetAllExternalHyperlinksInPresentation method to get the list of URIs in your presentation.

if (args is [{ } fileName])
{
    foreach (string link in GetAllExternalHyperlinksInPresentation(fileName))
    {
        Console.WriteLine(link);
    }
}

Following is the complete sample code in both C# and Visual Basic.

// Returns all the external hyperlinks in the slides of a presentation.
static IEnumerable<String> GetAllExternalHyperlinksInPresentation(string fileName)
{
    // Declare a list of strings.
    List<string> ret = new List<string>();

    // Open the presentation file as read-only.
    using (PresentationDocument document = PresentationDocument.Open(fileName, false))
    {
        // If there is no PresentationPart then there are no hyperlinks
        if (document.PresentationPart is null)
        {
            return ret;
        }

        // Iterate through all the slide parts in the presentation part.
        foreach (SlidePart slidePart in document.PresentationPart.SlideParts)
        {
            IEnumerable<Drawing.HyperlinkType> links = slidePart.Slide.Descendants<Drawing.HyperlinkType>();

            // Iterate through all the links in the slide part.
            foreach (Drawing.HyperlinkType link in links)
            {
                // Iterate through all the external relationships in the slide part. 
                foreach (HyperlinkRelationship relation in slidePart.HyperlinkRelationships)
                {
                    // If the relationship ID matches the link ID…
                    if (relation.Id.Equals(link.Id))
                    {
                        // Add the URI of the external relationship to the list of strings.
                        ret.Add(relation.Uri.AbsoluteUri);
                    }
                }
            }
        }
    }

    // Return the list of strings.
    return ret;
}

See also