CODEWITHSUNDEEP
c#openxmlopenxml-sdk
Trevor Daniel
Trevor Daniel

Reputation: 3954

OpenXML - Get Image Alt Text Title

I am attempting to iterate through the images in a PowerPoint presentation using OpenXML.

I have worked out how to do that.

I am now attempting to get the Images Alt-Text Title....

Here is my code:

List<ImagePart> imageParts = new List<ImagePart>();

part.GetPartsOfType<ImagePart>(imageParts);

foreach (ImagePart imagePart in imageParts)
{
    if (imagePart != null)
    {

    // Get the Relationship Id
    string oldRelID = part.GetIdOfPart(imagePart);

    // Get the Alt-Text Tile relating to this image

    }
}

Any OpenXML experts out there that could give me some pointers?

Thanks

UPDATE:

I have tried iterating through the XML but when there are multiple images on the slide I am getting the incorrect value for title for the relating image.

I think I need to be able to use the ImagePart Id to then find the corresponding title

The code below gets the titles out of order...

foreach (ImagePart imagePart in imageParts)
{
    string mapReference = "";

    XmlNode thisNode = pictureNodeList[imageCounter];

    foreach (XmlNode xmlnode in thisNode)
    {
        foreach (XmlNode xmlchildnode in xmlnode)
        {
            foreach (XmlAttribute att in xmlchildnode.Attributes)
            {
                if (att.Name == "title")
                {
                    mapReference = att.Value;
                    imageCounter += 1;
                 }
            }
         }
    }
}

Upvotes: 6

Views: 2831

Answers (1)

petelids
petelids

Reputation: 12815

You're 90% of the way there.

You need to find the Blip element whose Embed property matches the Id of the ImagePart you have. The Blip is contained within a BlipFill which in turn is contained within a Picture element. The Picture (pic in the XML) element has a NonVisualPictureDrawingProperties element (nvPicPr) which in turn has a NonVisualDrawingProperties element (cNvPr) and it's in there where you'll find the title. For example your XML could look like this:

<p:pic>
    <p:nvPicPr>
       <p:cNvPr id="4" name="Picture 3" descr="My Description" title="My Title" />
       <p:cNvPicPr>
          <a:picLocks noChangeAspect="1" />
       </p:cNvPicPr>
       <p:nvPr />
    </p:nvPicPr>
    <p:blipFill>
       <a:blip r:embed="rId2" cstate="print">
          <a:extLst>
             <a:ext uri="{28A0092B-C50C-407E-A947-70E740481C1C}">
                <a14:useLocalDpi xmlns:a14="http://schemas.microsoft.com/office/drawing/2010/main" val="0" />
             </a:ext>
          </a:extLst>
       </a:blip>
       <a:stretch>
          <a:fillRect />
       </a:stretch>
    </p:blipFill>
    <p:spPr>
       <a:xfrm>
          <a:off x="7260298" y="5445224" />
          <a:ext cx="1883701" cy="1412776" />
       </a:xfrm>
       <a:prstGeom prst="rect">
          <a:avLst />
       </a:prstGeom>
    </p:spPr>
 </p:pic>

The following code will output the Title property of each image. Note that as you have a strongly typed Picture object you can get to the other properties easily too (such as Description for example).

using (PresentationDocument doc =
            PresentationDocument.Open(filename, false))
{
    //get the first slide
    SlidePart part = doc.PresentationPart.SlideParts.First();

    //get all ImageParts in the first slide
    List<ImagePart> imageParts = new List<ImagePart>();
    part.GetPartsOfType<ImagePart>(imageParts);

    foreach (ImagePart imagePart in imageParts)
    {
        //find the picture related to the image
        Picture pic = part.Slide.Descendants<Picture>().Where(p => 
                        p.BlipFill.Blip.Embed == part.GetIdOfPart(imagePart)).FirstOrDefault();

        //Output the Title property
        Console.WriteLine(pic.NonVisualPictureProperties.NonVisualDrawingProperties.Title);
    }
}

Upvotes: 6

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