import com.spire.doc.Document;
import com.spire.doc.FileFormat;
import com.spire.doc.PictureWatermark;
import com.spire.doc.TextWatermark;
import com.spire.doc.documents.WatermarkLayout;

import java.awt.*;
import java.io.ByteArrayInputStream;
import java.util.UUID;


public class AddWatermark {

    public void addWaterMark(String docFile, String WaterMarkType, String watermarkText, String imageFile, String resultFilePath) {
        Document document = new Document();
        document.loadFromFile(docFile);
        switch (WaterMarkType) {
            case "Text":
                addTextWatermark(document, watermarkText);
                break;
            case "Image":
                addImageWatermark(document, imageFile);
                break;
        }
        document.saveToFile(resultFilePath, FileFormat.Docx);
    }


    private void addImageWatermark(Document doc, String imageFile){
        PictureWatermark pictureWatermark=new PictureWatermark();
        pictureWatermark.setPicture(imageFile);
        pictureWatermark.setScaling(250);
        pictureWatermark.isWashout(false);
        doc.setWatermark(pictureWatermark);
    }

    private void addTextWatermark(Document doc, String watermarkText){
        TextWatermark textWatermark=new TextWatermark();
        textWatermark.setText(watermarkText);
        textWatermark.setFontSize(14);
        textWatermark.setColor(Color.RED);
        textWatermark.setLayout(WatermarkLayout.Diagonal);
        doc.setWatermark(textWatermark);
    }


}

using Spire.Doc;
using Spire.Doc.Documents;
using System;
using System.Drawing;

namespace DemoOnlineCode
{
    class Watermark
    {
        public void demoAddWaterMark(
            String docFile,
            String watermarkType,
            String watermarkText,String imageFile=null)
        {
            Document document = new Document();
            document.LoadFromFile(docFile,FileFormat.Auto);
            switch (watermarkType)
            {
                case "Text":
                    addTextWatermark(document, watermarkText);
                    break;
                case "Image":
                    addImageWatermark(document, imageFile);
                    break;
            }
        }
        private void addImageWatermark(Document doc, String imageFile)
        {
            PictureWatermark pictureWatermark = new PictureWatermark();
            pictureWatermark.SetPicture(imageFile);
            pictureWatermark.Scaling=250;
            pictureWatermark.IsWashout=false;
            doc.Watermark=pictureWatermark;
        }
        private void addTextWatermark(Document doc, String watermarkText)
        {
            TextWatermark textWatermark = new TextWatermark();
            textWatermark.Text=watermarkText;
            textWatermark.FontSize=14;
            textWatermark.Color=Color.Red;
            textWatermark.Layout=WatermarkLayout.Diagonal;
            doc.Watermark=textWatermark;
        }
    }
}