How to add underline in TextElement using pdftron 9.1.0?

Question

I am creating tab at top right corner of pdf page. I was trying to add underline in text element using com.pdftron.pdf.annots.Underline

        Element textElement1 = builder.createTextBegin(Font.create(pdfDoc, Font.e_times_bold_italic), 12);
        //writer.writeElement(textElement1);
        Element textRun1 = builder.createTextRun("Tab 1");
        textElement1.getGState().setTransform(0, -1, 1, 0, 612 - 18, 792-18-72);
        textElement1.getGState().setTextRenderMode(GState.e_fill_text);
        textElement1.getGState().setFillColorSpace(ColorSpace.createDeviceRGB());
        textElement1.getGState().setFillColor(new ColorPt(0, 0, 0)); // Set text color to black
        
        Underline underline =  Underline.create(pdfDoc, new Rect(612 - 18, 792-18-72, 612 - 18, 792-18-12));
        underline.setColor(new ColorPt(1, 0, 0)); // Red color
        
        page.annotPushBack(underline);
        
        writer.writeElement(textElement1);
        writer.writeElement(textRun1);
        writer.writePlacedElement(element1);

Code output: enter image description here

Answer 1

There is no concept of underline in PDF (as there is with Word) so there is no straight forward way of adding the underline to the text.

One way to do it is by adding an underline annotation at the correct location (as you are doing in your code), but you then want to flatten the annotation directly on the page. You can do this by calling PDFDoc.FlattenAnnotations() https://docs.apryse.com/api/PDFTronSDK/dotnet/pdftron.PDF.PDFDoc.html#pdftron_PDF_PDFDoc_FlattenAnnotations