I have single page document made with iTextSharp (A4 size in portrait orientation). Now I copy first page, paste it as second - there are two same pages. In Acrobat Reader there is option to print multiple sheets per page - so I can print those 2 pages on 1 in landscape orientation.
How to achieve the same effect, using only iTextSharp?
Please read the tutorial on how to use iText 7, more specifically Chapter 6: Reusing existing PDF documents
In that chapter, you'll find an example called TheGoldenGateBridge_N_up:
PdfDocument pdf = new PdfDocument(new PdfWriter(dest));
PdfDocument sourcePdf = new PdfDocument(new PdfReader(SRC));
//Original page
PdfPage origPage = sourcePdf.getPage(1);
Rectangle orig = origPage.getPageSize();
PdfFormXObject pageCopy = origPage.copyAsFormXObject(pdf);
//N-up page
PageSize nUpPageSize = PageSize.A4.rotate();
PdfPage page = pdf.addNewPage(nUpPageSize);
PdfCanvas canvas = new PdfCanvas(page);
//Scale page
AffineTransform transformationMatrix = AffineTransform.getScaleInstance(
nUpPageSize.getWidth() / orig.getWidth() / 2f,
nUpPageSize.getHeight() / orig.getHeight() / 2f);
canvas.concatMatrix(transformationMatrix);
//Add pages to N-up page
canvas.addXObject(pageCopy, 0, orig.getHeight());
canvas.addXObject(pageCopy, orig.getWidth(), orig.getHeight());
canvas.addXObject(pageCopy, 0, 0);
canvas.addXObject(pageCopy, orig.getWidth(), 0);
// close the documents
pdf.close();
sourcePdf.close();
In this example, we add 4 pages of an existing PDF to one page. The principle is called N-upping in which you replace N by a power of 2. In the example, we do 4-upping; you want 2-upping. Changing the 4-up example into a 2-up example is only a matter of applying some simple Math.
You will also benefit from reading this FAQ entry: How to convert an A4 size PDF to a PDF booklet? If you are still using an old version of iText, you can read the iText 5 version of the FAQ entry.