[JAVA] Set watermark to be output only when printing with iText

Is there output only when printing?

Well, there is such a thing as PDF. I understand, let's make it. Speaking of PDF, iText. There's nothing you can't do with iText. e? Is it possible to create a linearized PDF? If you know that kind of thing, don't read this article.

Honestly, it looks like this on the Acrobat settings screen. I see.

Okay, I'll write it right away

Now, if you use Japanese, don't forget ** iTextAsian.jar ** and ** iTextAsianCmaps.jar **.

Watermark.java

import java.awt.Color;
import java.io.FileOutputStream;
import java.util.stream.IntStream;

import com.lowagie.text.pdf.BaseFont;
import com.lowagie.text.pdf.PdfContentByte;
import com.lowagie.text.pdf.PdfGState;
import com.lowagie.text.pdf.PdfLayer;
import com.lowagie.text.pdf.PdfReader;
import com.lowagie.text.pdf.PdfStamper;

import lombok.val;

public class Watermark {

	public static void draw(String src, String dest) {
		try {
			val reader = new PdfReader(src);

			val stamp = new PdfStamper(reader, new FileOutputStream(dest));

			val layer = new PdfLayer("watermark", stamp.getWriter());

			layer.setOnPanel(true);

			layer.setOn(false);
			layer.setPrint("Watermark", true);
			layer.setView(false);

			val transparent = new PdfGState();
			
			//Transparency
			transparent.setStrokeOpacity(0.3f);
			transparent.setFillOpacity(0.3f);

			val bf_courier = BaseFont.createFont("HeiseiKakuGo-W5", "UniJIS-UCS2-H", BaseFont.NOT_EMBEDDED);

			IntStream.rangeClosed(1, stamp.getReader().getNumberOfPages()).forEach(page-> {

				val cb = stamp.getOverContent(page);

				cb.setColorFill(Color.RED);

				cb.beginLayer(layer);
				cb.setGState(transparent);

				val watermarkText = "Do not take out";

				val cropBox = reader.getCropBox(page);
				
				cb.beginText();
				cb.setFontAndSize(bf_courier, 20);
				
				//Try to write diagonally at appropriate intervals
				for(int x = 0; x < cropBox.getWidth(); x += 100) {
					for(int y = 0; y < cropBox.getHeight(); y += 100) {
						cb.showTextAligned(PdfContentByte.ALIGN_CENTER, watermarkText, x, y, 45);
					}
				}
				
				cb.endText();

				cb.endLayer();
			});

			stamp.close();
		} 
		catch (Exception e) {
			e.printStackTrace();
		}
	}

	public static void main(String[] args) {

		if (args.length < 2) {
			System.out.println("Usage: Watermark src.pdf dest.pdf");
			return;
		}

		Watermark.draw(args[0], args[1]);
	}
}

It looks like this

It's a little small and hard to see, but the watermark was drawn only in the print preview. Well, it looks like this.