java - Why font is not being embedded to the PDF using content stream before in Itext7?

Question

I am trying to add a watermark text with font Helvitica to a simple PDF using one of the examples provided in the IText examples site (https://developers.itextpdf.com/examples/stamping-content-existing-pdfs/clone-watermark-examples), but for some reason the PDF is not showing the font properly in the PDF.

I looked at the pdf property fonts and it seems the font is not embedded to the PDF.

I am using itext 7.0.8 version.

Am I doing some thing wrong here.

My Code:

import java.io.FileNotFoundException;
import java.io.IOException;
import com.itextpdf.io.font.FontConstants;
import com.itextpdf.io.font.FontProgramFactory;
import com.itextpdf.kernel.font.PdfFont;
import com.itextpdf.kernel.font.PdfFontFactory;
import com.itextpdf.kernel.pdf.PdfDocument;
import com.itextpdf.kernel.pdf.PdfReader;
import com.itextpdf.kernel.pdf.PdfResources;
import com.itextpdf.kernel.pdf.PdfWriter;
import com.itextpdf.kernel.pdf.canvas.PdfCanvas;
import com.itextpdf.layout.Canvas;
import com.itextpdf.layout.element.Paragraph;
import com.itextpdf.layout.property.TextAlignment;
import com.itextpdf.layout.property.VerticalAlignment;

public class AddTextToPDF {
    public static void main(String[] args) throws FileNotFoundException, IOException {
        PdfDocument pdfDoc = new PdfDocument(new PdfReader("c:\Development\test.pdf"),
                new PdfWriter("c:\Development\test_result.pdf"));
        PdfCanvas under = new PdfCanvas(pdfDoc.getFirstPage().newContentStreamBefore(), new PdfResources(), pdfDoc);
        PdfFont font = PdfFontFactory.createFont(FontProgramFactory.createFont(FontConstants.HELVETICA));
        Paragraph p = new Paragraph("This watermark is added UNDER the existing content")
                .setFont(font).setFontSize(15);
        new Canvas(under, pdfDoc, pdfDoc.getDefaultPageSize())
                .showTextAligned(p, 297, 550, 1, TextAlignment.CENTER, VerticalAlignment.TOP, 0);
        pdfDoc.close();
    }
}

If I change the line:

PdfCanvas under = new PdfCanvas(pdfDoc.getFirstPage().newContentStreamBefore(), new PdfResources(), pdfDoc);

To

PdfCanvas over = new PdfCanvas(pdfDoc.getFirstPage());

the font is being embedded to the PDF..

Answer 1

As you found out yourself, the issue is related to this line:

PdfCanvas under = new PdfCanvas(pdfDoc.getFirstPage().newContentStreamBefore(), new PdfResources(), pdfDoc);

The problem is that you use a new PdfResources() object here which is not used for anything later on.

The resources object you provide in this PdfCanvas constructor is where new resources are put that are required for what you draw on the canvas, e.g. new font resources.

Thus, in your case the new font is added to a new resources object which then is added nowhere and so does not end up in the final pdf at all. So the font is lost.

To fix this use the resources of the page instead.