iTextSharp - Adding an image and resize pages in PDF

Question

I have a PDF file which I need to insert an image on the 1st page and then resize the original size from A4 to some other size.

I manage to add an image into the PDF but not resizing it with the following code:

        string pdfFile = @"C:\Temp\a.pdf";

        PdfReader reader = new PdfReader(pdfFile);

        PdfStamper stamper = new PdfStamper(reader, new FileStream(@"C:\Temp\out.pdf", FileMode.Create), PdfWriter.VERSION_1_5);

        PdfContentByte writer = stamper.GetOverContent(1);

        stamper.FormFlattening = true;
        stamper.SetFullCompression();

        Image topImage = Image.GetInstance(@"C:\Temp\c.jpg");
        topImage.ScalePercent(19f);
        topImage.SetAbsolutePosition(142, 700);
        writer.AddImage(topImage);

        Document myPDF = writer.PdfDocument;
        myPDF.SetPageSize(PageSize.A3);

        stamper.Close();
        stamper = null;

Is there anything wrong or missing in my code?

Answer 1

Despite being an older thread the original question & thread was very helpful recently.

Here's another version that processes the Pdf input as a byte array instead of file path (more helpful for web app environment), and handles all IDisposable references...

    public static byte[] ResizePdfPageSize(byte[] pdfBytes, Rectangle pageSize)
    {
        Document.Compress = true;

        using (var outputMemoryStream = new MemoryStream())
        using (var targetDoc = new Document(pageSize))
        using (var pdfReader = new PdfReader(pdfBytes))
        using (var pdfWriter = PdfWriter.GetInstance(targetDoc, outputMemoryStream))
        {
            targetDoc.Open();

            PdfContentByte pdfContentByte = pdfWriter.DirectContent;

            var pageCount = pdfReader.NumberOfPages;
            for (int pageNumber = 1; pageNumber <= pageCount; pageNumber++)
            {
                PdfImportedPage page = pdfWriter.GetImportedPage(pdfReader, pageNumber);

                var currentPageSize = pdfReader.GetPageSize(pageNumber);
                var scaledPageWidth = pageSize.Width / currentPageSize.Width;
                var scaledPageHeight = pageSize.Height / currentPageSize.Height;

                pdfContentByte.AddTemplate(
                        page,
                        scaledPageWidth,
                        0, 0,
                        scaledPageHeight,
                        0, 0
                    );

                //Move document cursor to next Page!
                targetDoc.NewPage();
            }

            targetDoc.Close();

            byte[] finalFileBytes = outputMemoryStream.ToArray();
            return finalFileBytes;
        }
    }

Usage with pre-set PageSizes from iTextSharp is very handy:

 var originalPdfBytes = File.ReadAllBytes(fileInfo.FullName);
 var resizedBytes = PdfHelper.ResizePdfPageSize(originalPdfBytes, PageSize.A4);
 File.WriteAllBytes(fileName, resizedBytes);

EDIT: The above method answers the core question and got me where I needed to get for my issues. However, after working on this and ironing out numerous issues and shortcomings of the above simplified method, I've now put the whole helpful code base on github to share for anyone else interested. The github PdfHelpers project now handle aspect ratio better, page margins, rotation of content for better scaling as landscape, content that's already rotated (in my limited test cases), etc. while also providing other helpful code for simple Pdf tasks.

https://github.com/cajuncoding/PdfHelpers

Answer 2

Below is how a PDF can be resized:

    private string PdfResize(string tmpPdfFilename, string resultRootName)
    {
        try
        {
            string newPdfFilename = resultRootName + ".pdf";
            PdfReader resizeReader = new PdfReader(tmpPdfFilename);

            Rectangle newRect = new Rectangle(0, 0, Convert.ToSingle(_pdfNewSizeW), Convert.ToSingle(_pdfNewSizeH));
            Document doc = new Document(newRect);
            Document.Compress = true;

            PdfWriter resizeWriter = PdfWriter.GetInstance(doc, new FileStream(newPdfFilename, FileMode.Create));
            doc.Open();

            PdfContentByte cb = resizeWriter.DirectContent;

            for (int pageNumber = 1; pageNumber <= resizeReader.NumberOfPages; pageNumber++)
            {
                PdfImportedPage page = resizeWriter.GetImportedPage(resizeReader, pageNumber);
                cb.AddTemplate(page, newRect.Width / resizeReader.GetPageSize(pageNumber).Width, 0, 0,
                               newRect.Height / resizeReader.GetPageSize(pageNumber).Height, 0, 0);
                doc.NewPage();
            }

            doc.Close();
            doc = null;

            return newPdfFilename;
        }
        catch (Exception exp)
        {
            return String.Empty;
        }
    }