Changing page sizes of existing PDFs

JAVA

/*
    This file is part of the iText (R) project.
    Copyright (c) 1998-2023 Apryse Group NV
    Authors: Apryse Software.

    For more information, please contact iText Software at this address:
    sales@itextpdf.com
 */
package com.itextpdf.samples.sandbox.stamper;

import com.itextpdf.kernel.colors.DeviceGray;
import com.itextpdf.kernel.pdf.PdfArray;
import com.itextpdf.kernel.pdf.PdfDictionary;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfName;
import com.itextpdf.kernel.pdf.PdfNumber;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;

import java.io.File;

public class AddExtraMargin {
    public static final String DEST = "./target/sandbox/stamper/add_extra_margin.pdf";
    public static final String SRC = "./src/main/resources/pdfs/primes.pdf";

    public static void main(String[] args) throws Exception {
        File file = new File(DEST);
        file.getParentFile().mkdirs();

        new AddExtraMargin().manipulatePdf(DEST);
    }

    protected void manipulatePdf(String dest) throws Exception {
        PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));

        // Loop over every page
        for (int i = 1; i <= pdfDoc.getNumberOfPages(); i++) {
            PdfDictionary pageDict = pdfDoc.getPage(i).getPdfObject();
            PdfArray mediaBox = pageDict.getAsArray(PdfName.MediaBox);
            float llx = mediaBox.getAsNumber(0).floatValue();
            float lly = mediaBox.getAsNumber(1).floatValue();
            float ury = mediaBox.getAsNumber(3).floatValue();
            mediaBox.set(0, new PdfNumber(llx - 36));
            PdfCanvas over = new PdfCanvas(pdfDoc.getPage(i));
            over.saveState();
            over.setFillColor(new DeviceGray(0.5f));
            over.rectangle(llx - 36, lly, 36, ury - llx);
            over.fill();
            over.restoreState();
        }

        pdfDoc.close();
    }
}

C#

using System;
using System.IO;
using iText.Kernel.Colors;
using iText.Kernel.Pdf;
using iText.Kernel.Pdf.Canvas;

namespace iText.Samples.Sandbox.Stamper 
{
    public class AddExtraMargin 
    {
        public static readonly String DEST = "results/sandbox/stamper/add_extra_margin.pdf";
        public static readonly String SRC = "../../../resources/pdfs/primes.pdf";

        public static void Main(String[] args) 
        {
            FileInfo file = new FileInfo(DEST);
            file.Directory.Create();
            
            new AddExtraMargin().ManipulatePdf(DEST);
        }

        protected void ManipulatePdf(String dest) 
        {
            PdfDocument pdfDoc = new PdfDocument(new PdfReader(SRC), new PdfWriter(dest));
            
            // Loop over every page
            for (int i = 1; i <= pdfDoc.GetNumberOfPages(); i++) {
                PdfDictionary pageDict = pdfDoc.GetPage(i).GetPdfObject();
                PdfArray mediaBox = pageDict.GetAsArray(PdfName.MediaBox);
                float llx = mediaBox.GetAsNumber(0).FloatValue();
                float lly = mediaBox.GetAsNumber(1).FloatValue();
                float ury = mediaBox.GetAsNumber(3).FloatValue();
                mediaBox.Set(0, new PdfNumber(llx - 36));
                PdfCanvas over = new PdfCanvas(pdfDoc.GetPage(i));
                over.SaveState();
                over.SetFillColor(new DeviceGray(0.5f));
                over.Rectangle(llx - 36, lly, 36, ury - llx);
                over.Fill();
                over.RestoreState();
            }
            
            pdfDoc.Close();
        }
    }
}