#!c#

using System;
using System.IO;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using DocumentFormat.OpenXml.Packaging;
using DocumentFormat.OpenXml.Wordprocessing;
using DocumentFormat.OpenXml;
using V = DocumentFormat.OpenXml.Vml;
using System.Diagnostics;

namespace WindowsFormsApplication3
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            using (WordprocessingDocument package = WordprocessingDocument.Open(@"C:\Users\*****\****.docx", true))
            {
                InsertCustomWatermark(package, @"C:\Users\*******\****.jpg");
            }
        }

        private void InsertCustomWatermark(WordprocessingDocument package, string p)
        {
            SetWaterMarkPicture(p);
            MainDocumentPart mainDocumentPart1 = package.MainDocumentPart;
            if (mainDocumentPart1 != null)
            {
                mainDocumentPart1.DeleteParts(mainDocumentPart1.HeaderParts);
                HeaderPart headPart1 = mainDocumentPart1.AddNewPart<HeaderPart>();
                GenerateHeaderPart1Content(headPart1);
                string rId = mainDocumentPart1.GetIdOfPart(headPart1);
                ImagePart image = headPart1.AddNewPart<ImagePart>("image/jpeg", "rId999");
                GenerateImagePart1Content(image);
                IEnumerable<SectionProperties> sectPrs = mainDocumentPart1.Document.Body.Elements<SectionProperties>();
                foreach (var sectPr in sectPrs)
                {
                    sectPr.RemoveAllChildren<HeaderReference>();
                    sectPr.PrependChild<HeaderReference>(new HeaderReference() { Id = rId });
                }
            }
            else
            {
                MessageBox.Show("alert");
            }
        }
        private void GenerateHeaderPart1Content(HeaderPart headerPart1)
        {
            Header header1 = new Header();
            Paragraph paragraph2 = new Paragraph();
            Run run1 = new Run();
            Picture picture1 = new Picture();
            V.Shape shape1 = new V.Shape() { Id = "WordPictureWatermark75517470", Style = "position:absolute;left:0;text-align:left;margin-left:0;margin-top:0;width:415.2pt;height:456.15pt;z-index:-251656192;mso-position-horizontal:center;mso-position-horizontal-relative:margin;mso-position-vertical:center;mso-position-vertical-relative:margin", OptionalString = "_x0000_s2051", AllowInCell = false, Type = "#_x0000_t75" };
            V.ImageData imageData1 = new V.ImageData() { Gain = "19661f", BlackLevel = "22938f", Title = "水印", RelationshipId = "rId999" };
            shape1.Append(imageData1);
            picture1.Append(shape1);
            run1.Append(picture1);
            paragraph2.Append(run1);
            header1.Append(paragraph2);
            headerPart1.Header = header1;
        }
        private void GenerateImagePart1Content(ImagePart imagePart1)
        {
            System.IO.Stream data = GetBinaryDataStream(imagePart1Data);
            imagePart1.FeedData(data);
            data.Close();
        }
        private string imagePart1Data = "";
        private System.IO.Stream GetBinaryDataStream(string base64String)
        {
            return new System.IO.MemoryStream(System.Convert.FromBase64String(base64String));
        }
        public void SetWaterMarkPicture(string file)
        {
            FileStream inFile;
            byte[] byteArray;
            try
            {
                inFile = new FileStream(file, FileMode.Open, FileAccess.Read);
                byteArray = new byte[inFile.Length];
                long byteRead = inFile.Read(byteArray, 0, (int)inFile.Length);
                inFile.Close();
                imagePart1Data = Convert.ToBase64String(byteArray, 0, byteArray.Length);
            }
            catch (Exception ex)
            {
                Debug.Print(ex.Message);
            }
        }
    }
}

#!c#

using System;
using System.IO;
using System.Reflection;

using Aspose.Words;
using Aspose.Words.Drawing;
using Aspose.Words.Fields;
using System.Drawing;

namespace Watermark
{
    public class Program
    {
        public static void Main(string[] args)
        {
            // Sample infrastructure.
            string projectFiles = Path.GetFullPath("../../Files/");

            Document doc = new Document(projectFiles + "TestDoc.doc");
            InsertWatermarkText(doc, "CONFIDENTIAL");
            doc.Save(projectFiles + "TestDoc Out.doc");

            System.Console.WriteLine("Press any key to continue");
            System.Console.ReadKey();
        }

        /// <summary>
        /// Inserts a watermark into a document.
        /// </summary>
        /// <param name="doc">The input document.</param>
        /// <param name="watermarkText">Text of the watermark.</param>
        private static void InsertWatermarkText(Document doc, string watermarkText)
        {
            // Create a watermark shape. This will be a WordArt shape. 
            // You are free to try other shape types as watermarks.
            Shape watermark = new Shape(doc, ShapeType.TextPlainText);            

            // Set up the text of the watermark.
            watermark.TextPath.Text = watermarkText;
            watermark.TextPath.FontFamily = "Arial";
            watermark.Width = 500;
            watermark.Height = 100;
            // Text will be directed from the bottom-left to the top-right corner.
            watermark.Rotation = -40;
            // Remove the following two lines if you need a solid black text.
            //watermark.Fill.Color = Color.Gray; // Try LightGray to get more Word-style watermark
            //watermark.StrokeColor = Color.Gray; // Try LightGray to get more Word-style watermark

            // Place the watermark in the page center.
            watermark.RelativeHorizontalPosition = RelativeHorizontalPosition.Page;
            watermark.RelativeVerticalPosition = RelativeVerticalPosition.Page;
            watermark.WrapType = WrapType.None;
            watermark.VerticalAlignment = VerticalAlignment.Center;
            watermark.HorizontalAlignment = HorizontalAlignment.Center;

            // Create a new paragraph and append the watermark to this paragraph.
            Paragraph watermarkPara = new Paragraph(doc);
            watermarkPara.AppendChild(watermark);

            // Insert the watermark into all headers of each document section.
            foreach (Section sect in doc.Sections)
            {
                // There could be up to three different headers in each section, since we want
                // the watermark to appear on all pages, insert into all headers.
                InsertWatermarkIntoHeader(watermarkPara, sect, HeaderFooterType.HeaderPrimary);
                InsertWatermarkIntoHeader(watermarkPara, sect, HeaderFooterType.HeaderFirst);
                InsertWatermarkIntoHeader(watermarkPara, sect, HeaderFooterType.HeaderEven);
            }
        }

        private static void InsertWatermarkIntoHeader(Paragraph watermarkPara, Section sect, HeaderFooterType headerType)
        {
            HeaderFooter header = sect.HeadersFooters[headerType];

            if (header == null)
            {
                // There is no header of the specified type in the current section, create it.
                header = new HeaderFooter(sect.Document, headerType);
                sect.HeadersFooters.Add(header);
            }

            // Insert a clone of the watermark into the header.
            header.AppendChild(watermarkPara.Clone(true));
        }
    }
}