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Home » Newsletter » February 2008

Mohammed Najeemudheen and Suraj C. B.

In this article, we will see how to rearrange pages in an existing PDF document. For an example, we will use a document with say 10 pages. We will try to move page 2 to the position of page 5.

First, we use the ExtractPagesTo() method of TgtPDFDocument class to extract Page 2. Next, we delete Page 2 from the document using DeletePages() method. Finally, we copy the extracted page from the temporary document to location of Page 5 in the original document using the method InsertPagesFrom().

var
 LFrom: String;
 LToPage: Integer;
 LTempDoc, PDFDoc: TgtPDFDocument;
 Lstream:TMemoryStream;
begin
 try
  PDFDoc := TgtPDFDocument.Create(Nil);

  // Load input PDF document
  PDFDoc.LoadFromFile('Input.pdf');

  // Disable interactivity
  PDFDoc.ShowSetupDialog := False;
  PDFDoc.OpenAfterSave := False;

  // Create a memory stream
  Lstream :=TMemoryStream.Create;

  // Create a temporary PDF document object
  LTempDoc := TgtPDFDocument.Create(self);

  LTempDoc.ShowSetupDialog := False;
  LTempDoc.OpenAfterSave := False;

  // Page position from a page
  // needs to be moved
  LFrom := '2';

  // Page position to which a page
  // needs to moved
  LToPage := 5;

  if LToPage <= PDFDoc.PageCount then
   begin
    
    // Extract page 1
    // to a temporary document
    PDFDoc.ExtractPagesTo(LTempDoc,LFrom);

    // Save extracted page to a memory stream
    LTempDoc.SaveToStream(Lstream);

    // Delete extracted page from input
    // PDF document
    PDFDoc.DeletePages(LFrom);

    // Load the temporary PDF document
    LTempDoc.LoadFromStream(Lstream);

    // Insert the extracted page (currently
    // page 1 in the temporary document) at 
    // position page 5
    PDFDoc.InsertPagesFrom(LTempDoc,'1',LToPage-1);

    // Save modified document
    PDFDoc.SaveToFile('Output.pdf');
   end
  else
   ShowMessage('Page out of range ! Max Page =
               '+IntToStr(PDFDoc.PageCount));
 finally
  LTempDoc.free;
  Lstream.Free;
  PDFDoc.Free;
end;

You may have wondered why we are saving the temporary document object to a memory stream. When we call ExtractPagesTo(), it does retrieve Page 2 to the LTempDoc object, holding just a reference to that page but not yet representing the structure of a wholesome PDF document.

For this reason, we save it to a memory stream and load it again from that memory stream. When we do this, LTempDoc represents a wholesome independent PDF document with a very retrievable Page 1 (originally Page 2), which we can then insert at position of Page 5.