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Iterating Annotations from existing pdf
https://forum.pdfsharp.net/viewtopic.php?f=2&t=1111		 Page 1 of 1
Author:  BillE [ Tue Mar 23, 2010 6:28 pm ]
Post subject:  Iterating Annotations from existing pdf
Hi all,

I am trying to walk the annotations list per page in an existing pdf. I have tried various permutations of the following foreach loops in C#

Code:
                foreach (PdfPage page in pdf.Pages)
                {
                    PdfAnnotations annots = page.Annotations;
                    PdfArray annArray = annots;
                    foreach (var ann in annArray)
                    {
                    }
               }



Every variation recives an invalid cast error

Unable to cast object of type 'AnnotationsIterator' to type 'System.Collections.Generic.IEnumerator`1[PdfSharp.Pdf.PdfItem]'

I can get around this by walking the document internal looking for dictionaries that are /Annot /Link. but that looses page affinity.

any thoughts on how to get around this.

Bille
Author:  RichardD [ Thu May 27, 2010 11:53 am ]
Post subject:  Re: Iterating Annotations from existing pdf
This is a bug introduced in v1.31:
  • In v1.2, the PdfAnnotations class implemented IEnumerable, and the nested AnnotationsIterator class implemented IEnumerator;
  • In v1.31, PdfAnnotations implements IEnumerable<PdfItem>, and the AnnotationsIterator implements IEnumerator<PdfAnnotation>;
  • The v1.31 GetEnumerator method tries to cast the AnnontationsIterator instance to an IEnumerator<PdfItem>, which would only work in .NET 4.0;

Unfortunately, short of switching to v1.2, the only solution is to iterate by hand:
Code:
for (int index = 0; index < page.Annotations.Count; index++)
{
    var ann = page.Annotations[index];
    ...
}
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