最近一个项目中需要用到图片加平铺水印，于是从某个地方搜到了一些相关的方法，但都是定位添加没有平铺添加，于是稍做修改。

• 图片水印和文字水印代码

    public class WaterMark
    {
        #region 图片水印
        /// <summary>
        /// 图片水印
        /// </summary>
        /// <param name="imgPath">服务器图片相对路径</param>
        /// <param name="filename">保存文件名</param>
        /// <param name="watermarkFilename">水印文件相对路径</param>
        /// <param name="watermarkStatus">图片水印位置 -1=平铺 0=不使用 1=左上 2=中上 3=右上 4=左中  9=右下</param>
        /// <param name="quality">附加水印图片质量,0-100</param>
        /// <param name="watermarkTransparency">水印的透明度 1--10 10为不透明</param>
        public static void AddImageSignPic(string imgPath, string filename, string watermarkFilename, int watermarkStatus, int quality, int watermarkTransparency)
        {
            if (!File.Exists(Utils.GetMapPath(imgPath)))
                return;
            var imageBytes = File.ReadAllBytes(Utils.GetMapPath(imgPath));
            var img = Image.FromStream(new MemoryStream(imageBytes));
            filename = Utils.GetMapPath(filename);

            if (watermarkFilename.StartsWith("/") == false)
                watermarkFilename = "/" + watermarkFilename;
            watermarkFilename = Utils.GetMapPath(watermarkFilename);
            if (!File.Exists(watermarkFilename))
                return;
            var g = Graphics.FromImage(img);
            //设置高质量插值法
            g.InterpolationMode = InterpolationMode.High;
            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = SmoothingMode.HighQuality;
            Image watermark = new Bitmap(watermarkFilename);

            if (watermark.Height >= img.Height || watermark.Width >= img.Width)
                return;

            var imageAttributes = new ImageAttributes();
            var colorMap = new ColorMap
            {
                OldColor = Color.FromArgb(255, 0, 255, 0),
                NewColor = Color.FromArgb(0, 0, 0, 0)
            };

            ColorMap[] remapTable = { colorMap };

            imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);

            var transparency = 0.5F;
            if (watermarkTransparency >= 1 && watermarkTransparency <= 10)
                transparency = (watermarkTransparency / 10.0F);


            float[][] colorMatrixElements = {
												new float[] {1.0f,  0.0f,  0.0f,  0.0f, 0.0f},
												new float[] {0.0f,  1.0f,  0.0f,  0.0f, 0.0f},
												new float[] {0.0f,  0.0f,  1.0f,  0.0f, 0.0f},
												new float[] {0.0f,  0.0f,  0.0f,  transparency, 0.0f},
												new float[] {0.0f,  0.0f,  0.0f,  0.0f, 1.0f}
											};

            var colorMatrix = new ColorMatrix(colorMatrixElements);

            imageAttributes.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);

            var xpos = 0;
            var ypos = 0;

            switch (watermarkStatus)
            {
                case 1:
                    xpos = (int)(img.Width * (float).01);
                    ypos = (int)(img.Height * (float).01);
                    break;
                case 2:
                    xpos = (int)((img.Width * (float).50) - (watermark.Width / 2));
                    ypos = (int)(img.Height * (float).01);
                    break;
                case 3:
                    xpos = (int)((img.Width * (float).99) - (watermark.Width));
                    ypos = (int)(img.Height * (float).01);
                    break;
                case 4:
                    xpos = (int)(img.Width * (float).01);
                    ypos = (int)((img.Height * (float).50) - (watermark.Height / 2));
                    break;
                case 5:
                    xpos = (int)((img.Width * (float).50) - (watermark.Width / 2));
                    ypos = (int)((img.Height * (float).50) - (watermark.Height / 2));
                    break;
                case 6:
                    xpos = (int)((img.Width * (float).99) - (watermark.Width));
                    ypos = (int)((img.Height * (float).50) - (watermark.Height / 2));
                    break;
                case 7:
                    xpos = (int)(img.Width * (float).01);
                    ypos = (int)((img.Height * (float).99) - watermark.Height);
                    break;
                case 8:
                    xpos = (int)((img.Width * (float).50) - (watermark.Width / 2));
                    ypos = (int)((img.Height * (float).99) - watermark.Height);
                    break;
                case 9:
                    xpos = (int)((img.Width * (float).99) - (watermark.Width));
                    ypos = (int)((img.Height * (float).99) - watermark.Height);
                    break;
            }

            if (-1 == watermarkStatus)//设置平铺
            {
                imageAttributes.SetWrapMode(WrapMode.Tile);
                g.DrawImage(watermark, new Rectangle(xpos, ypos, img.Width, img.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel, imageAttributes);
            }
            else
            {
                g.DrawImage(watermark, new Rectangle(xpos, ypos, watermark.Width, watermark.Height), 0, 0, watermark.Width, watermark.Height, GraphicsUnit.Pixel, imageAttributes);
            }
            var codecs = ImageCodecInfo.GetImageEncoders();
            ImageCodecInfo ici = null;
            foreach (var codec in codecs)
            {
                if (codec.MimeType.IndexOf("jpeg") > -1)
                    ici = codec;
            }
            var encoderParams = new EncoderParameters();
            var qualityParam = new long[1];
            if (quality < 0 || quality > 100)
                quality = 80;

            qualityParam[0] = quality;

            var encoderParam = new EncoderParameter(Encoder.Quality, qualityParam);
            encoderParams.Param[0] = encoderParam;

            if (ici != null)
                img.Save(filename, ici, encoderParams);
            else
                img.Save(filename);

            g.Dispose();
            img.Dispose();
            watermark.Dispose();
            imageAttributes.Dispose();
        }

        #endregion

        #region 文字水印

        /// <summary>
        /// 文字水印
        /// </summary>
        /// <param name="imgPath">服务器图片相对路径</param>
        /// <param name="filename">保存文件名</param>
        /// <param name="watermarkText">水印文字</param>
        /// <param name="watermarkStatus">图片水印位置 0=不使用 1=左上 2=中上 3=右上 4=左中  9=右下</param>
        /// <param name="quality">附加水印图片质量,0-100</param>
        /// <param name="fontname">字体</param>
        /// <param name="fontsize">字体大小</param>
        public static void AddImageSignText(string imgPath, string filename, string watermarkText, int watermarkStatus,
            int quality, string fontname, int fontsize)
        {
            AddImageSignText(imgPath, filename, watermarkText, watermarkStatus, quality, fontname, fontsize, 255);
        }

        /// <summary>
        /// 文字水印
        /// </summary>
        /// <param name="imgPath">服务器图片相对路径</param>
        /// <param name="filename">保存文件名</param>
        /// <param name="watermarkText">水印文字</param>
        /// <param name="watermarkStatus">图片水印位置 0=不使用 1=左上 2=中上 3=右上 4=左中  9=右下</param>
        /// <param name="quality">附加水印图片质量,0-100</param>
        /// <param name="fontname">字体</param>
        /// <param name="fontsize">字体大小</param>
        /// <param name="watermarkTransparency">水印透明度 0-255 255为不透明</param>
        public static void AddImageSignText(string imgPath, string filename, string watermarkText, int watermarkStatus, int quality, string fontname, int fontsize, int watermarkTransparency)
        {
            var imageBytes = File.ReadAllBytes(Utils.GetMapPath(imgPath));
            var img = Image.FromStream(new MemoryStream(imageBytes));
            filename = Utils.GetMapPath(filename);

            var g = Graphics.FromImage(img);
            var drawFont = new Font(fontname, fontsize, FontStyle.Regular, GraphicsUnit.Pixel);
            SizeF crSize = g.MeasureString(watermarkText, drawFont);

            float xpos = 0;
            float ypos = 0;

            switch (watermarkStatus)
            {
                case 1:
                    xpos = (float)img.Width * (float).01;
                    ypos = (float)img.Height * (float).01;
                    break;
                case 2:
                    xpos = ((float)img.Width * (float).50) - (crSize.Width / 2);
                    ypos = (float)img.Height * (float).01;
                    break;
                case 3:
                    xpos = ((float)img.Width * (float).99) - crSize.Width;
                    ypos = (float)img.Height * (float).01;
                    break;
                case 4:
                    xpos = (float)img.Width * (float).01;
                    ypos = ((float)img.Height * (float).50) - (crSize.Height / 2);
                    break;
                case 5:
                    xpos = ((float)img.Width * (float).50) - (crSize.Width / 2);
                    ypos = ((float)img.Height * (float).50) - (crSize.Height / 2);
                    break;
                case 6:
                    xpos = ((float)img.Width * (float).99) - crSize.Width;
                    ypos = ((float)img.Height * (float).50) - (crSize.Height / 2);
                    break;
                case 7:
                    xpos = (float)img.Width * (float).01;
                    ypos = ((float)img.Height * (float).99) - crSize.Height;
                    break;
                case 8:
                    xpos = ((float)img.Width * (float).50) - (crSize.Width / 2);
                    ypos = ((float)img.Height * (float).99) - crSize.Height;
                    break;
                case 9:
                    xpos = ((float)img.Width * (float).99) - crSize.Width;
                    ypos = ((float)img.Height * (float).99) - crSize.Height;
                    break;
            }

            if (watermarkTransparency < 0 || watermarkTransparency > 255)//透明度
                watermarkTransparency = 255;
            g.DrawString(watermarkText, drawFont, new SolidBrush(Color.FromArgb(watermarkTransparency, Color.White)), xpos + 1, ypos + 1);
            g.DrawString(watermarkText, drawFont, new SolidBrush(Color.FromArgb(watermarkTransparency, Color.Black)), xpos, ypos);

            var codecs = ImageCodecInfo.GetImageEncoders();
            ImageCodecInfo ici = null;
            foreach (var codec in codecs)
            {
                if (codec.MimeType.IndexOf("jpeg") > -1)
                    ici = codec;
            }
            var encoderParams = new EncoderParameters();
            var qualityParam = new long[1];
            if (quality < 0 || quality > 100)
                quality = 80;

            qualityParam[0] = quality;

            var encoderParam = new EncoderParameter(Encoder.Quality, qualityParam);
            encoderParams.Param[0] = encoderParam;

            if (ici != null)
                img.Save(filename, ici, encoderParams);
            else
                img.Save(filename);

            g.Dispose();
            img.Dispose();
        }
        #endregion
    }

另附Utils.GetMapPath()代码

    public class Utils
    {
        #region 获得当前绝对路径
        /// <summary>
        /// 获得当前绝对路径
        /// </summary>
        /// <param name="strPath">指定的路径</param>
        /// <returns>绝对路径</returns>
        public static string GetMapPath(string strPath)
        {
            return "E:" + strPath;
        }
        #endregion
    }