【转】[C#] Aspose.pdf 添加文字水印

转自：https://www.cnblogs.com/Shi-zy/p/15494760.html

另一篇：https://www.cnblogs.com/z5337/p/7344636.html

用aspose.word把word 转pdf 的代码段：

            Document pdfDocument = new Document(@"D:\pdfdir\jhrs.com.pdf");
            for (int pageCount = 1; pageCount <= pdfDocument.Pages.Count; pageCount++)
            {
                using (FileStream imageStream = new FileStream($"jhrs.com_{i}.png", FileMode.Create))
                {
                    Resolution resolution = new Resolution(300);
                    PngDevice pngDevice = new PngDevice(resolution);
                    pngDevice.Process(pdfDocument.Pages[pageCount], imageStream);
                    imageStream.Close();
                }
            }

        /// <summary>
        /// pdf添加文字水印(自定义水印行数和列数)
        /// </summary>
        /// <param name="pdfStream">pdf文件流</param>
        /// <param name="watermarkText">水印文字</param>
        /// <param name="fontSize">文字大小</param>
        /// <param name="fontColor">文字颜色</param>
        /// <param name="typeface">字体：（中文水印请自行查找相应字体的英文名称，如：宋体（SimSun），黑体（SimHei），仿宋（FangSong），微软雅黑（Microsoft YaHei）等等...）</param>
        /// <param name="rotation">倾斜角度</param>
        /// <param name="opacity">不透明度（值为：0-1）</param>
        /// <param name="watermarkRowNum">水印行数</param>
        /// <param name="watermarkColumnNum">水印列数</param>
        /// <returns></returns>
        public Stream AddTextWatermarkCustom(Stream pdfStream, string watermarkText, float fontSize, Aspose.Pdf.Color fontColor, string typeface, double rotation = 0, double opacity = 0, int watermarkRowNum = 1, int watermarkColumnNum = 1)
        {
            try
            {
                /*计算倾斜高度-start*/
                var angle = Math.Abs(rotation);
                var width = watermarkText.Length * fontSize;
                var radian = 2 * Math.PI / 360 * angle;
                var top = Math.Sin(radian) * width;
                /*计算倾斜高度-end*/
                Document document = new Document(pdfStream);
                for (int i = 1; i <= document.Pages.Count; i++)
                {
                    var pageWidth = document.Pages[i].GetPageRect(false).Width;
                    var pageHeight = document.Pages[i].GetPageRect(false).Height;
                    WatermarkArtifact artifact = new WatermarkArtifact();
                    artifact.SetTextAndState(watermarkText, new TextState
                    {
                        FontSize = fontSize,
                        ForegroundColor = fontColor,
                        Font = FontRepository.FindFont(typeface),
                    });
                    artifact.Rotation = rotation;
                    artifact.Opacity = opacity;
                    artifact.IsBackground = false;
                    if (watermarkRowNum == 1 && watermarkColumnNum == 1)
                    {
                        artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Center;
                        artifact.ArtifactVerticalAlignment = VerticalAlignment.Center;
                        document.Pages[i].Artifacts.Add(artifact);
                    }
                    else
                    {
                        artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Left;
                        artifact.ArtifactVerticalAlignment = VerticalAlignment.Top;
                        for (int j = 1; j <= watermarkColumnNum; j++)
                        {
                            artifact.LeftMargin = (j - 1) * (pageWidth / watermarkColumnNum) + fontSize;
                            for (int z = 1; z <= watermarkRowNum; z++)
                            {
                                artifact.TopMargin = (z - 1) * (pageHeight / watermarkRowNum) + top;
                                document.Pages[i].Artifacts.Add(artifact);
                            }
                        }
                    }
                }
                Stream outStream = new MemoryStream();
                document.Save(outStream, SaveFormat.Pdf);
                outStream.Seek(0, SeekOrigin.Begin);
                return outStream;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

        /// <summary>
        /// pdf添加文字水印(平铺)
        /// </summary>
        /// <param name="pdfStream">pdf文件流</param>
        /// <param name="watermarkText">水印文字</param>
        /// <param name="fontSize">文字大小</param>
        /// <param name="fontColor">文字颜色</param>
        /// <param name="typeface">字体：（中文水印请自行查找相应字体的英文名称，如：宋体（SimSun），黑体（SimHei），仿宋（FangSong），微软雅黑（Microsoft YaHei）等等...）</param>
        /// <param name="rotation">倾斜角度</param>
        /// <param name="opacity">不透明度（值为：0-1）</param>
        /// <param name="density">水印密度（值为0-1）</param>
        /// <returns></returns>
        public Stream AddTextWatermarkTile(Stream pdfStream, string watermarkText, float fontSize, Aspose.Pdf.Color fontColor, string typeface, double rotation = 0, double opacity = 0, double density = 1)
        {
            try
            {
                Document document = new Document(pdfStream);
                /*计算水印详细-start*/
                var angle = Math.Abs(rotation);
                var width = watermarkText.Length * fontSize;
                var radian = 2 * Math.PI / 360 * angle;
                var top = Math.Sin(radian) * width;
                var row = Math.Cos(radian) * width;
                var pageWidth = document.Pages[1].GetPageRect(false).Width;
                var pageHeight = document.Pages[1].GetPageRect(false).Height;
                int watermarkRowNum = (int)(pageHeight / top * density);
                int watermarkColumnNum = (int)(pageHeight / row * density);
                if (rotation == 0)
                {
                    watermarkRowNum = (int)(pageHeight / fontSize * density);
                    watermarkColumnNum = (int)(pageHeight / width * density);
                }

                /*计算水印详细-end*/
                for (int i = 1; i <= document.Pages.Count; i++)
                {

                    WatermarkArtifact artifact = new WatermarkArtifact();
                    artifact.SetTextAndState(watermarkText, new TextState
                    {
                        FontSize = fontSize,
                        ForegroundColor = fontColor,
                        Font = FontRepository.FindFont(typeface),
                    });
                    artifact.Rotation = rotation;
                    artifact.Opacity = opacity;
                    artifact.IsBackground = false;
                    artifact.ArtifactHorizontalAlignment = HorizontalAlignment.Left;
                    artifact.ArtifactVerticalAlignment = VerticalAlignment.Top;
                    for (int j = 1; j <= watermarkColumnNum; j++)
                    {
                        artifact.LeftMargin = (j - 1) * (pageWidth / watermarkColumnNum) + fontSize;
                        for (int z = 1; z <= watermarkRowNum; z++)
                        {
                            artifact.TopMargin = (z - 1) * (pageHeight / watermarkRowNum) + top;
                            document.Pages[i].Artifacts.Add(artifact);
                        }
                    }
                }
                Stream outStream = new MemoryStream();
                document.Save(outStream, SaveFormat.Pdf);
                outStream.Seek(0, SeekOrigin.Begin);
                return outStream;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }

 调用代码：

Stream stream = File.OpenRead(@"C:\Users\HEDY\Desktop\Test\2.pdf");
var outStream = AddTextWatermarkCustom(stream, "测试水印文字", 32, Color.Blue, "SimSun", 45, 0.5, 6, 3);
var saveStream = new FileStream($@"C:\Users\HEDY\Desktop\Test\1_{Guid.NewGuid()}.pdf", FileMode.Create);
outStream.CopyTo(saveStream);
outStream.Close();
saveStream.Close();