Imposition

Sample C# code for using Apryse SDK to impose (combine) multiple PDF pages. Page imposition can be used to arrange/order pages prior to printing or for document assembly (assemble a 'master' page from several 'source' pages). It is also possible to write applications that can re-order the pages such that they will display in the correct order when the hard copy pages are compiled and folded correctly. Learn more about our UWP SDK and PDF Editing & Manipulation Library.

C#

//
// Copyright (c) 2001-2020 by PDFTron Systems Inc. All Rights Reserved.
//

using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using Windows.Foundation;

using pdftron.PDF;
using pdftron.SDF;

using PDFNetUniversalSamples.ViewModels;

namespace PDFNetSamples
{
    public sealed class ImpositionTest : Sample
    {
        public ImpositionTest() :
            base("Imposition", "The sample illustrates how multiple pages can be combined/imposed using PDFNet. Page imposition can be used to arrange/order pages prior to printing or to assemble a 'master' page from several 'source' pages. Using PDFNet API it is possible to write applications that can re-order the pages such that they will display in the correct order when the hard copy pages are compiled and folded correctly.")
        {
        }

        public override IAsyncAction RunAsync()
        {
            return Task.Run(new System.Action(async () => {
                WriteLine("--------------------------------");
                WriteLine("Starting Imposition Test...");
                WriteLine("--------------------------------\n");
			    try	
			    {
                    string input_file_path = Path.Combine(InputPath, "newsletter.pdf");
                    WriteLine("Opening input file " + input_file_path);
                    PDFDoc in_doc = new PDFDoc(input_file_path);
				    in_doc.InitSecurityHandler();

				    // Create a list of pages to import from one PDF document to another.
                    IList<pdftron.PDF.Page> import_list = new List<pdftron.PDF.Page>();
				    for (PageIterator itr = in_doc.GetPageIterator(); itr.HasNext(); itr.Next()) 
					    import_list.Add(itr.Current());

				    PDFDoc new_doc = new PDFDoc(); //  Create a new document
                    IList<pdftron.PDF.Page> imported_pages = new_doc.ImportPages(import_list);

				    // Paper dimension for A3 format in points. Because one inch has 
				    // 72 points, 11.69 inch 72 = 841.69 points
                    pdftron.PDF.Rect media_box = new pdftron.PDF.Rect(0, 0, 1190.88, 841.69); 
				    double mid_point = media_box.Width()/2;

				    ElementBuilder builder = new ElementBuilder();
				    ElementWriter  writer  = new ElementWriter();

				    for (int i=0; i<imported_pages.Count; ++i)
				    {
					    // Create a blank new A3 page and place on it two pages from the input document.
                        pdftron.PDF.Page new_page = new_doc.PageCreate(media_box);
					    writer.Begin(new_page);

					    // Place the first page
                        pdftron.PDF.Page src_page = (pdftron.PDF.Page)imported_pages[i];
					    Element element = builder.CreateForm(src_page);

					    double sc_x = mid_point / src_page.GetPageWidth();
					    double sc_y = media_box.Height() / src_page.GetPageHeight();
					    double scale = Math.Min(sc_x, sc_y);
					    element.GetGState().SetTransform(scale, 0, 0, scale, 0, 0);
					    writer.WritePlacedElement(element);

					    // Place the second page
					    ++i; 
					    if (i<imported_pages.Count)	
					    {
                            src_page = (pdftron.PDF.Page)imported_pages[i];
						    element = builder.CreateForm(src_page);
						    sc_x = mid_point / src_page.GetPageWidth();
						    sc_y = media_box.Height() / src_page.GetPageHeight();
						    scale = Math.Min(sc_x, sc_y);
						    element.GetGState().SetTransform(scale, 0, 0, scale, mid_point, 0);
						    writer.WritePlacedElement(element);
					    }

                        writer.End();
					    new_doc.PagePushBack(new_page);
				    }

                    string output_file_path = Path.Combine(OutputPath, "newsletter_booklet.pdf");
                    await new_doc.SaveAsync(output_file_path, SDFDocSaveOptions.e_linearized);
                    new_doc.Destroy();
                    in_doc.Destroy();
                    WriteLine("Done. Results saved in " + output_file_path);
                    await AddFileToOutputList(output_file_path).ConfigureAwait(false);
			    }
			    catch (Exception e)
			    {
                    WriteLine(GetExceptionMessage(e));
                }

                WriteLine("\n--------------------------------");
                WriteLine("Done Annotation Test.");
                WriteLine("--------------------------------\n");
            })).AsAsyncAction();
		}
	}
}