C#图片添加水印的实现代码

using System.Drawing;using System.Drawing.Imaging;using System.IO;namespace HoverTreeBatch.HovercFrame{public class HovercWarter{public static Image AddTextToImg(Image image, string text){Bitmap bitmap = new Bitmap(image, image.Width, image.Height);Graphics g = Graphics.FromImage(bitmap);float fontSize = 12.0f; //字体大小float textWidth = text.Length * fontSize; //文本的长度//下面定义一个矩形区域，以后在这个矩形里画上白底黑字float rectX = 0;float rectY = 0;float rectWidth = text.Length * (fontSize + 8);float rectHeight = fontSize + 8;//声明矩形域RectangleF textArea = new RectangleF(rectX, rectY, rectWidth, rectHeight);Font font = new Font("宋体", fontSize); //定义字体Brush whiteBrush = new SolidBrush(Color.White); //白笔刷，画文字用Brush blackBrush = new SolidBrush(Color.Black); //黑笔刷，画背景用g.FillRectangle(blackBrush, rectX, rectY, rectWidth, rectHeight);g.DrawString(text, font, whiteBrush, textArea);MemoryStream ms = new MemoryStream();//保存为Jpg类型bitmap.Save(ms, ImageFormat.Jpeg);Image h_hovercImg = Image.FromStream(ms);g.Dispose();bitmap.Dispose();return h_hovercImg;}/// <summary>/// 根据文件头判断上传的文件类型/// </summary>/// <param name="filePath">filePath是文件的完整路径 </param>/// <returns>返回true或false</returns>public static bool IsPicture(string filePath){try{FileStream fs = new FileStream(filePath, FileMode.Open, FileAccess.Read);BinaryReader reader = new BinaryReader(fs);string fileClass;byte buffer;buffer = reader.ReadByte();fileClass = buffer.ToString();buffer = reader.ReadByte();fileClass += buffer.ToString();reader.Close();fs.Close();if (fileClass == "255216" || fileClass == "7173" || fileClass == "13780" || fileClass == "6677")//何问起 hovertree.com//255216是jpg;7173是gif;6677是BMP,13780是PNG;7790是exe,8297是rar {return true;}else{return false;}}catch{return false;}}}}