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Home » Newsletter » January 2008

Girish Patil & Suraj C. B.

In this article, we will see part of the code that was used in the CodeRage II Gnostice session titled Top 5 PDF User Needs Solved using Gnostice PDF Tools. One of the top PDF-related needs that we addressed in the demo was about splitting PDF documents based on a given criteria.

In the session, we demonstrated how to split a PDF documents by its bookmarks. Imagine that you have a PDF document where the content is divided into several chapters. If each of these chapters have a corresponding bookmark, then we could split the document in such a manner that each chapter would be available in a separate PDF document.

The main procedure in the code was SplitByBookmark. It uses a function GetFirstBookmarkWithSiblings recursively to parse the bookmark tree of the PDF document and return bookmark nodes that have child bookmarks.

// Object used to load
// the input PDF document
PDFDoc: TgtPDFDocument;

edOutputFile: TEdit;

...

procedure TSplitByBkmark.SplitByBookmark;
  function GetFirstBookmarkWithSiblings: TgtPDFOutline;
  begin
    // Get hold of root bookmark object and then the
    // first node, which is always the first 
    // child of the root
    with PDFDoc do
    begin
      Result := GetBookmarkRoot;
      if Result = nil then
        Exit;
      Result := Result.GetFirstChild;
      // Traverse down the bookmark tree until multiple
      // siblings are found at the same level
      while (Result.GetNextNode = nil) and (Result <> nil) do
        Result := Result.GetFirstChild;
    end;
  end;

var
  LBookmark1: TgtPDFOutline;
begin
  with PDFDoc do
  begin
    LBookmark1 := GetFirstBookmarkWithSiblings;
    if LBookmark1 = nil then
    begin
      ShowMessage(
        'The specified document does not contain ' +
	'bookmarks.'#13#10 +
        'Aborting splitting operation.');
      LSplitDone := False;
      Exit;
    end;

    // Loop through all bookmarks in the same level
    while LBookmark1.GetNextNode <> nil do
    begin
      // Use bookmark title text for the name of
      // the output document and copy pages until
      // page linked by the next bookmark is reached
      ExtractPagesTo(
        MakeOutputFilename(edOutputFile.Text, LBookmark1.Title),
        Format('%d-%d',
	       [LBookmark1.Destination.PageNo,
               LBookmark1.GetNextNode.Destination.PageNo - 1]));
      LBookmark1 := LBookmark1.GetNextNode;
    end;

    // Copy last chapter into new document
    ExtractPagesTo(
      MakeOutputFilename(edOutputFile.Text, LBookmark1.Title),
      Format('%d-%d',
             [LBookmark1.Destination.PageNo, PageCount]));
    LSplitDone := True;
  end;

end;

The procedure also uses a function MakeOutputFilename that creates valid output filenames by appending the text used to display the bookmark to the original filename. Invalid filename characters are automatically stripped out of the resulting filename.

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Downloads:

• Full project source code - Split_PDF_by_Bookmark.zip