Watermarking with PDFBox

Question

I am trying to add a watermark to a PDF specifically with PDFBox. I\'ve been able to get the image to appear on each page, but it loses the background transparency because i

Answer 1

This is how I was able to add a text watermark with the date using PdfBox 2.0.x in C#. It centres the watermark at the top of the page.

public static void AddWatermark(string fileName)
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("watermark_text  ");
            sb.Append(DateTime.Now.ToString());

            string waterMarkText = sb.ToString();

            PDDocument origDoc = PDDocument.load(new java.io.File(fileName));
            PDPageTree allPages = origDoc.getPages();
            PDFont font = PDType1Font.HELVETICA_BOLD;
            for (int i = 0, len = allPages.getCount(); i < len; ++i)
            {
                PDPage pg = (PDPage)allPages.get(i);

                AddWatermarkText(origDoc, pg, font, waterMarkText);
            }

            origDoc.save(fileName);
            origDoc.close();
        }

static void AddWatermarkText(PDDocument doc, PDPage page, PDFont font, string text)
        {
            using (PDPageContentStream cs = new PDPageContentStream(doc, page, PDPageContentStream.AppendMode.APPEND, true, true))
            {
                float fontHeight = 30;
                float width = page.getMediaBox().getWidth();
                float height = page.getMediaBox().getHeight();
                float stringWidth = font.getStringWidth(text) / 1000 * fontHeight;

                float x = (width / 2) - (stringWidth / 2);
                float y = height - 25;

                cs.setFont(font, fontHeight);

                PDExtendedGraphicsState gs = new PDExtendedGraphicsState();
                gs.setNonStrokingAlphaConstant(new java.lang.Float(0.2f));
                gs.setStrokingAlphaConstant(new java.lang.Float(0.2f));
                gs.setBlendMode(BlendMode.MULTIPLY);
                gs.setLineWidth(new java.lang.Float(3f));
                cs.setGraphicsStateParameters(gs);

                cs.setNonStrokingColor(Color.red);
                cs.setStrokingColor(Color.red);

                cs.beginText();
                cs.newLineAtOffset(x, y);
                cs.showText(text);
                cs.endText();
            }
        }

pdfbox c# watermark pdf