分享一段，图片加水印的代码。本人修改过多次

分享一段，图片加水印的代码。本人修改过多次

        /// <summary>
        /// 图片加水印文字
        /// </summary>
        /// <param name="imgPath">原图片路径</param>
        /// <param name="newImgPath">新图片路径</param>
        /// <param name="text">水印文字</param>
        /// <param name="Alpha">透明度</param>
        /// <param name="fontsize">字体大小</param>
        public static bool PicAddWaterText(string imgPath,string newImgPath, string text, int Alpha = 1, int fontsize = 30)
        {
            try
            {
                //text = text + "仅限xx使用";
                //System.Drawing.Image imgPhoto = System.Drawing.Image.FromStream(oldstream);//文件流
                System.Drawing.Image imgPhoto = System.Drawing.Image.FromFile(imgPath);
                int imgPhotoWidth = imgPhoto.Width;
                int imgPhotoHeight = imgPhoto.Height;

                Bitmap bmPhoto = new Bitmap(imgPhotoWidth, imgPhotoHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

                bmPhoto.SetResolution(72, 72);
                Graphics gbmPhoto = Graphics.FromImage(bmPhoto);
                //gif背景色
                gbmPhoto.Clear(Color.FromName("White"));
                gbmPhoto.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
                gbmPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                gbmPhoto.DrawImage(imgPhoto, new Rectangle(0, 0, imgPhotoWidth, imgPhotoHeight), 0, 0, imgPhotoWidth, imgPhotoHeight, GraphicsUnit.Pixel);
                imgPhoto.Dispose();
                System.Drawing.Font font = null;
                System.Drawing.SizeF crSize = new SizeF();
                font = new Font("宋体", fontsize, FontStyle.Regular);
                //测量指定区域
                crSize = gbmPhoto.MeasureString(text, font);
                float y = (imgPhotoHeight - crSize.Height)/2;
                float x = (imgPhotoWidth - crSize.Width)/2;
                System.Drawing.StringFormat StrFormat = new System.Drawing.StringFormat();
                StrFormat.Alignment = System.Drawing.StringAlignment.Center;                
                //画两次制造透明效果
                var writeColor = Color.FromArgb(Alpha, System.Drawing.ColorTranslator.FromHtml("#999"));
                //var writeColor = Color.FromArgb(255, Color.Red);
                //System.Drawing.SolidBrush semiTransBrush2 = new System.Drawing.SolidBrush(Color.FromArgb(Alpha, Color.Red));
                System.Drawing.SolidBrush semiTransBrush2 = new System.Drawing.SolidBrush(writeColor);
               
                //float _x = -20, _y = y + 10;
                //if (imgPhotoHeight > imgPhotoWidth)
                //{
                //   // gbmPhoto.RotateTransform(-60);
                //    _y = 0; _x = 0;
                //}
                //else { gbmPhoto.RotateTransform(320); }
                gbmPhoto.TranslateTransform(x,y);
                var Var_trans = gbmPhoto.Transform;
                Var_trans.Shear(0.4F,0.00F);
                gbmPhoto.Transform = Var_trans;
                //gbmPhoto.DrawString(text, font, semiTransBrush2, _x, _y);
                // gbmPhoto.DrawString(text, font, semiTransBrush2, imgPhotoWidth, imgPhotoHeight / 2);
                gbmPhoto.DrawString(text, font, semiTransBrush2, 10, 10);
                //gbmPhoto.DrawString(text, font, semiTransBrush2, 0, y);


                //System.Drawing.SolidBrush semiTransBrush = new System.Drawing.SolidBrush(writeColor);
                // gbmPhoto.DrawString(text, font, semiTransBrush, _x, _y);
                //gbmPhoto.DrawString(text, font, semiTransBrush, imgPhotoWidth / 2, imgPhotoHeight / 2);
                //gbmPhoto.DrawString(text, font, semiTransBrush, 0, y);

                //gbmPhoto.DrawString(text, font, semiTransBrush2, 0, y);
                //Stream newStream = new MemoryStream();

                bmPhoto.Save(newImgPath, System.Drawing.Imaging.ImageFormat.Jpeg);

                gbmPhoto.Dispose();               
                bmPhoto.Dispose();
                //imgPhoto1.Dispose();
                return true;
            }
            catch (Exception e)
            {
                return false;
            }
        }

 新版，图片像支付宝证件一样，填满整张图片

        /// <summary>
        /// 图片加水印文字
        /// </summary>
        /// <param name="imgPath">原图片路径</param>
        /// <param name="newImgPath">新图片路径</param>
        /// <param name="text">水印文字</param>
        /// <param name="Alpha">透明度</param>
        /// <param name="fontsize">字体大小</param>
        public static bool PicAddWaterText(string imgPath,string newImgPath, string text, int Alpha = 1, int fontsize = 30)
        {
            try
            {
                //text = text + "仅限xx使用";
                //System.Drawing.Image imgPhoto = System.Drawing.Image.FromStream(oldstream);//文件流
                System.Drawing.Image imgPhoto = System.Drawing.Image.FromFile(imgPath);
                int imgPhotoWidth = imgPhoto.Width;
                int imgPhotoHeight = imgPhoto.Height;

                Bitmap bmPhoto = new Bitmap(imgPhotoWidth, imgPhotoHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

                bmPhoto.SetResolution(72, 72);
                Graphics gbmPhoto = Graphics.FromImage(bmPhoto);
                //gif背景色
                gbmPhoto.Clear(Color.FromName("White"));
                gbmPhoto.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
                gbmPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                gbmPhoto.DrawImage(imgPhoto, new Rectangle(0, 0, imgPhotoWidth, imgPhotoHeight), 0, 0, imgPhotoWidth, imgPhotoHeight, GraphicsUnit.Pixel);
                imgPhoto.Dispose();
                System.Drawing.Font font = null;
                System.Drawing.SizeF crSize = new SizeF();
                font = new Font("宋体", fontsize, FontStyle.Regular);
                //测量指定区域
                crSize = gbmPhoto.MeasureString(text, font);
                float y = (imgPhotoHeight - crSize.Height)/2;
                float x = (imgPhotoWidth - crSize.Width)/2;
                System.Drawing.StringFormat StrFormat = new System.Drawing.StringFormat();
                StrFormat.Alignment = System.Drawing.StringAlignment.Center;                
                //画两次制造透明效果
                var writeColor = Color.FromArgb(Alpha, System.Drawing.ColorTranslator.FromHtml("#999"));
                //var writeColor = Color.FromArgb(255, Color.Red);
                //System.Drawing.SolidBrush semiTransBrush2 = new System.Drawing.SolidBrush(Color.FromArgb(Alpha, Color.Red));
                System.Drawing.SolidBrush semiTransBrush2 = new System.Drawing.SolidBrush(writeColor);

                //float _x = -20, _y = y + 10;
                //if (imgPhotoHeight > imgPhotoWidth)
                //{
                //   // gbmPhoto.RotateTransform(-60);
                //    _y = 0; _x = 0;
                //}
                //else { gbmPhoto.RotateTransform(320); }
                //gbmPhoto.RotateTransform(90);
                var Var_trans = gbmPhoto.Transform;
                Var_trans.Shear(0.2F, 0.00F);
                gbmPhoto.Transform = Var_trans;
                gbmPhoto.TranslateTransform(-(imgPhotoWidth), 0);
                int hcount = 0;
                for (int i = -(imgPhotoWidth*2); i < imgPhotoWidth; i++)
                {
                    hcount = 0;
                    for (int j = 0; j < imgPhotoHeight*1.3f; j++)
                    {
                        //gbmPhoto.DrawString(text, font, semiTransBrush2, _x, _y);
                        // gbmPhoto.DrawString(text, font, semiTransBrush2, imgPhotoWidth, imgPhotoHeight / 2);
                        
                        gbmPhoto.DrawString(text, font, semiTransBrush2, 0, 0);
                        hcount += (int)crSize.Width;
                        gbmPhoto.TranslateTransform(0, crSize.Width);
                        j =j+ Convert.ToInt32(crSize.Width);
                    }
                    gbmPhoto.TranslateTransform(0, -(hcount));
                    gbmPhoto.TranslateTransform(crSize.Width, 0);
                    i =i+ Convert.ToInt32(crSize.Width);

                }
                
                //gbmPhoto.DrawString(text, font, semiTransBrush2, 0, y);


                //System.Drawing.SolidBrush semiTransBrush = new System.Drawing.SolidBrush(writeColor);
                // gbmPhoto.DrawString(text, font, semiTransBrush, _x, _y);
                //gbmPhoto.DrawString(text, font, semiTransBrush, imgPhotoWidth / 2, imgPhotoHeight / 2);
                //gbmPhoto.DrawString(text, font, semiTransBrush, 0, y);

                //gbmPhoto.DrawString(text, font, semiTransBrush2, 0, y);
                //Stream newStream = new MemoryStream();

                bmPhoto.Save(newImgPath, System.Drawing.Imaging.ImageFormat.Jpeg);

                gbmPhoto.Dispose();               
                bmPhoto.Dispose();
                //imgPhoto1.Dispose();
                return true;
            }
            catch (Exception e)
            {
                return false;
            }
        }

优化

        /// <summary>
        /// 图片加水印文字
        /// </summary>
        /// <param name="imgPath">原图片路径</param>
        /// <param name="newImgPath">新图片路径</param>
        /// <param name="text">水印文字</param>
        /// <param name="Alpha">透明度</param>
        /// <param name="fontsize">字体大小</param>
        public static bool PicAddWaterText(string imgPath, string newImgPath, string text, int Alpha = 1, int fontsize = 30)
        {
            try
            {
                //text = text + "仅限xx使用";
                //System.Drawing.Image imgPhoto = System.Drawing.Image.FromStream(oldstream);//文件流
                System.Drawing.Image imgPhoto = System.Drawing.Image.FromFile(imgPath);
                int imgPhotoWidth = imgPhoto.Width;
                int imgPhotoHeight = imgPhoto.Height;
                var tempWidth = imgPhotoWidth > imgPhotoHeight ? imgPhotoWidth : imgPhotoHeight;
                fontsize = tempWidth > 300 ? fontsize : 18;

                Bitmap bmPhoto = new Bitmap(imgPhotoWidth, imgPhotoHeight, System.Drawing.Imaging.PixelFormat.Format24bppRgb);

                bmPhoto.SetResolution(72, 72);
                Graphics gbmPhoto = Graphics.FromImage(bmPhoto);
                //gif背景色
                gbmPhoto.Clear(Color.FromName("White"));
                gbmPhoto.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
                gbmPhoto.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                gbmPhoto.DrawImage(imgPhoto, new Rectangle(0, 0, imgPhotoWidth, imgPhotoHeight), 0, 0, imgPhotoWidth, imgPhotoHeight, GraphicsUnit.Pixel);
                imgPhoto.Dispose();
                System.Drawing.Font font = null;
                System.Drawing.SizeF crSize = new SizeF();
                font = new Font("宋体", fontsize, FontStyle.Regular);
                //测量指定区域
                crSize = gbmPhoto.MeasureString(text, font);
                float y = (imgPhotoHeight - crSize.Height) / 2;
                float x = (imgPhotoWidth - crSize.Width) / 2;
                System.Drawing.StringFormat StrFormat = new System.Drawing.StringFormat();
                StrFormat.Alignment = System.Drawing.StringAlignment.Center;
                //画两次制造透明效果
                var writeColor = Color.FromArgb(Alpha, System.Drawing.ColorTranslator.FromHtml("#999"));
                //var writeColor = Color.FromArgb(255, Color.Red);
                //System.Drawing.SolidBrush semiTransBrush2 = new System.Drawing.SolidBrush(Color.FromArgb(Alpha, Color.Red));
                System.Drawing.SolidBrush semiTransBrush2 = new System.Drawing.SolidBrush(writeColor);

                //float _x = -20, _y = y + 10;
                //if (imgPhotoHeight > imgPhotoWidth)
                //{
                //   // gbmPhoto.RotateTransform(-60);
                //    _y = 0; _x = 0;
                //}
                //else { gbmPhoto.RotateTransform(320); }
                //gbmPhoto.RotateTransform(90);
           
                var Var_trans = gbmPhoto.Transform;
                Var_trans.Shear(-0.2F, 0.00F);
                gbmPhoto.Transform = Var_trans;
                gbmPhoto.TranslateTransform(-tempWidth, 0);
                int hcount = 0;
                int take = 0;
             
                for (int i = -(tempWidth * 2); i < tempWidth*2; i++)
                {
                    hcount = 0;
                    for (int j = 0; j < imgPhotoHeight * 1.2f; j++)
                    {
                        //gbmPhoto.DrawString(text, font, semiTransBrush2, _x, _y);
                        // gbmPhoto.DrawString(text, font, semiTransBrush2, imgPhotoWidth, imgPhotoHeight / 2);
                        if (++take % 2 == 0)
                        {
                            gbmPhoto.DrawString(text, font, semiTransBrush2, 0, 0);
                        }
                        hcount += (int)crSize.Width;
                        gbmPhoto.TranslateTransform(0, (int)crSize.Width);
                        j = j + Convert.ToInt32(crSize.Width);
                    }
                    gbmPhoto.TranslateTransform(crSize.Width, -(hcount));
                }

                //gbmPhoto.DrawString(text, font, semiTransBrush2, 0, y);


                //System.Drawing.SolidBrush semiTransBrush = new System.Drawing.SolidBrush(writeColor);
                // gbmPhoto.DrawString(text, font, semiTransBrush, _x, _y);
                //gbmPhoto.DrawString(text, font, semiTransBrush, imgPhotoWidth / 2, imgPhotoHeight / 2);
                //gbmPhoto.DrawString(text, font, semiTransBrush, 0, y);

                //gbmPhoto.DrawString(text, font, semiTransBrush2, 0, y);
                //Stream newStream = new MemoryStream();

                bmPhoto.Save(newImgPath, System.Drawing.Imaging.ImageFormat.Jpeg);

                gbmPhoto.Dispose();
                bmPhoto.Dispose();
                //imgPhoto1.Dispose();
                return true;
            }
            catch (Exception e)
            {
                return false;
            }
        }

　　

单元测试代码

   [TestMethod()]
        public void WXImgTest()
        {           

            ImgHelper.PicAddWaterText("D:/pic/1.jpg", "D:/pic1/3.jpg", "xxName", 150,40);
            //Log4.Write(result);
        }