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Create page labels and get page page by name.
https://forum.pdfsharp.net/viewtopic.php?f=2&t=3693		 Page 1 of 1
Author:  Goertz [ Fri Nov 17, 2017 10:34 pm ]
Post subject:  Create page labels and get page page by name.
Hi all,

How would one go about creating a page label for pages of a PDF.

Also, i cant seem to find anything on how to retrieve a specific page by a name from a book mark, or page label.

i was able to create bookmarks using the outline property and add method.

when i later open this PDF again for more editing, how would i find a specific page using a name from the bookmark?


Thanks.
Author:  (void) [ Tue Nov 21, 2017 2:18 pm ]
Post subject:  Re: Create page labels and get page page by name.
That should be easy, just follow the references ! ;-)
If you open a Pdf with a text-editor, you should be able to see, what i mean.
The outlines are defined in the document catalog: (object numbers will probably differ)
Code:
2 0 obj
<<
/Type/Catalog
/Pages 3 0 R
/Outlines 13 0 R

The "/Outlines" Entry is a reference to the Outlines-Dictionary:
Code:
13 0 obj
<<
/First 14 0 R
/Last 83 0 R

The "/First" entry references the first outline:
Code:
14 0 obj
<<
/Title(Page1)
/Parent 13 0 R
/Dest[4 0 R /XYZ null null 0]
/Next 28 0 R
>>

The "/Title" entry contains the name of the bookmark.
The "/Next" entry contains a reference to the next bookmark.
The "Dest" entry contains an array; the first element is a reference to the page.
Note, that the "/Next" entry will be missing if you reached the last bookmark.

Now, what i would do to find a page by a bookmark's name: (in pseudocode)
Code:
var outlinesDict = Catalog.GetDictionary("/Outlines");
if (outlinesDict != null)
{
   var outline = outlinesDict.GetDictionary("/First");
   while (outline != null)
   {
      var title = outline.GetString("/Title");
      if (title == "title_i_search_for")      // bookmark we're looking for ?
      {
         var destArray = outline.GetArray("/Dest");
         var pageRef = destArray.GetReference(0);   // stored at index zero
         for (var i = 0; i < document.NumPages; i++)
            if (document.Pages[i].ObjectNumber == pageRef.ObjectNumber)
               // Page found ! return page or whatever
      }
      // not the right bookmark, check next one
      outline = outline.GetDictionary("/Next");
   }
}

You should probably add more error-checking (i.e. check, whether destArray and pageRef are valid).
Author:  Goertz [ Tue Nov 21, 2017 3:01 pm ]
Post subject:  Re: Create page labels and get page page by name.
Thanks for the help!

First time working with PDF's.
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