ASP.NET图片加水印的实现代码(C#)

using System; 
using System.Collections.Generic; 
using System.Text; 
 
using System.IO; 
using System.Drawing; 
using System.Drawing.Imaging; 
using System.Drawing.Drawing2D; 
 
namespace DocMIS.AppConfig 
{ 
    /**//// < summary> 
    /// 水印位置 
    /// < /summary> 
    public enum ImagePosition 
    { 
        /**//// < summary> 
        /// 左上 
        /// < /summary> 
        LeftTop, 
        /**//// < summary> 
        /// 左下 
        /// < /summary> 
        LeftBottom, 
        /**//// < summary> 
        /// 右上 
        /// < /summary> 
        RightTop, 
        /**//// < summary> 
        /// 右下 
        /// < /summary> 
        RigthBottom, 
        /**//// < summary> 
        /// 顶部居中 
        /// < /summary> 
        TopMiddle, 
        /**//// < summary> 
        /// 底部居中 
        /// < /summary> 
        BottomMiddle, 
        /**//// < summary> 
        /// 中心 
        /// < /summary> 
        Center  
    } 
 
    /**//// < summary> 
    /// 图像操作类(主要用于给图片加上透明文字水印) 
    /// < /summary> 
    class ImageWater_Word 
    { 
        private string _ErrMsg; 
        #region 出错信息 
        /**//// < summary> 
        /// 出错信息 
        /// < /summary> 
        public string ErrMsg 
        { 
            get { return _ErrMsg; } 
            set { _ErrMsg = value; } 
        } 
        #endregion 
 
 
        #region 将文件转换成流 
        //public byte[] SetImageToByteArray(string fileName, ref string fileSize) 
        /**//// < summary> 
        /// 将文件转换成流 
        /// < /summary> 
        /// < param name="fileName">文件全路径< /param> 
        /// < returns>< /returns> 
        private byte[] SetImageToByteArray(string fileName) 
        { 
            byte[] image = null; 
            try
            { 
                FileStream fs = new FileStream(fileName, FileMode.Open); 
                FileInfo fileInfo = new FileInfo(fileName); 
                //fileSize = Convert.ToDecimal(fileInfo.Length / 1024).ToString("f2") + " K"; 
                int streamLength = (int)fs.Length; 
                image = new byte[streamLength]; 
                fs.Read(image, 0, streamLength); 
                fs.Close(); 
                return image; 
            } 
            catch
            { 
                return image; 
            } 
        } 
        #endregion 
 
        #region 将byte转换成MemoryStream类型 
        /**//// < summary> 
        /// ASP.NET图片加水印：将byte转换成MemoryStream类型 
        /// < /summary> 
        /// < param name="mybyte">byte[]变量< /param> 
        /// < returns>< /returns> 
        private MemoryStream ByteToStream(byte[] mybyte) 
        { 
            MemoryStream mymemorystream = new MemoryStream(mybyte, 0, mybyte.Length); 
            return mymemorystream; 
        } 
        #endregion 
 
        #region 将byte转换成Image文件 
        /**//// < summary> 
        /// ASP.NET图片加水印：将byte转换成Image文件 
        /// < /summary> 
        /// < param name="mybyte">byte[]变量< /param> 
        /// < returns>< /returns> 
        private System.Drawing.Image SetByteToImage(byte[] mybyte) 
        { 
            System.Drawing.Image image; 
            MemoryStream mymemorystream = new MemoryStream(mybyte, 0, mybyte.Length); 
            image = System.Drawing.Image.FromStream(mymemorystream); 
            return image; 
        } 
        #endregion 
 
 
        #region 批量在图片上添加透明水印文字 
        /**//// < summary> 
        /// ASP.NET图片加水印：批量在图片上添加透明水印文字 
        /// < /summary> 
        /// < param name="arrsourcePicture">原来图片地址(路径+文件名)< /param> 
        /// < param name="waterWords">需要添加到图片上的文字< /param> 
        /// < param name="alpha">透明度(0.1'1.0之间)< /param> 
        /// < param name="position">文字显示的位置< /param> 
        /// < param name="fRewrite">是否覆盖原图片(如果不覆盖，那么将在同目录下生成一个文件名带0607的文件)< /param> 
        /// < returns>< /returns> 
        public bool DrawWords(string[] arrsourcePicture, string waterWords, float alpha, ImagePosition position, bool fRewrite) 
        { 
            foreach (string imgPath in arrsourcePicture) 
            { 
                if (!DrawWords(imgPath, waterWords, alpha, position, fRewrite)) 
                { 
                    _ErrMsg += "——处理文件：" + imgPath + " 时出错  。"; 
                    return false; 
                } 
            } 
            return true; 
        } 
        #endregion 
 
        #region 在图片上添加透明水印文字 
        /**//// < summary> 
        /// ASP.NET图片加水印：在图片上添加透明水印文字 
        /// < /summary> 
        /// < param name="sourcePicture">原来图片地址(路径+文件名)< /param> 
        /// < param name="waterWords">需要添加到图片上的文字< /param> 
        /// < param name="alpha">透明度(0.1'1.0之间)< /param> 
        /// < param name="position">文字显示的位置< /param> 
        /// < param name="fRewrite">是否覆盖原图片(如果不覆盖，那么将在同目录下生成一个文件名带0607的文件)< /param> 
        /// < returns>< /returns> 
        public bool DrawWords(string sourcePicture, string waterWords, float alpha, ImagePosition position, bool fRewrite) 
        { 
            if (!System.IO.File.Exists(sourcePicture)) 
            { 
                _ErrMsg = "文件不存在！"; 
                return false; 
            } 
            string fileExtension = System.IO.Path.GetExtension(sourcePicture).ToLower(); 
            if (fileExtension != ".gif" && fileExtension != ".jpg" && fileExtension != ".png" && fileExtension != ".bmp") 
            { 
                _ErrMsg = "不是图片文件！"; 
                return false; 
            } 
 
            Image imgPhoto = null; 
            Bitmap bmPhoto = null; 
            Graphics grPhoto = null; 
            try
            { 
                //创建一个图片对象用来装载要被添加水印的图片 
                imgPhoto = Image.FromStream(ByteToStream(SetImageToByteArray(sourcePicture))); 
 
                //获取图片的宽和高 
                int phWidth = imgPhoto.Width; 
                int phHeight = imgPhoto.Height; 
 
                //建立一个bitmap，和我们需要加水印的图片一样大小 
                bmPhoto = new Bitmap(phWidth, phHeight, PixelFormat.Format24bppRgb); 
 
                //SetResolution：设置此 Bitmap 的分辨率 
                //这里直接将我们需要添加水印的图片的分辨率赋给了bitmap 
                bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution); 
 
                //Graphics：封装一个 GDI+ 绘图图面  。 
                grPhoto = Graphics.FromImage(bmPhoto); 
 
                //设置图形的品质 
                grPhoto.SmoothingMode = SmoothingMode.AntiAlias; 
 
                //将我们要添加水印的图片按照原始大小描绘（复制）到图形中 
                grPhoto.DrawImage( 
                 imgPhoto,                                           //   要添加水印的图片 
                 new Rectangle(0, 0, phWidth, phHeight), //  根据要添加的水印图片的宽和高 
                 0,                                                     //  X方向从0点开始描绘 
                 0,                                                     // Y方向  
                 phWidth,                                            //  X方向描绘长度 
                 phHeight,                                           //  Y方向描绘长度 
                 GraphicsUnit.Pixel);                              // 描绘的单位，这里用的是像素 
 
                //根据图片的大小我们来确定添加上去的文字的大小 
                //在这里我们定义一个数组来确定 
                int[] sizes = new int[] { 48, 36, 28, 24, 16, 14, 12, 10 }; 
 
                //字体 
                Font crFont = null; 
                //矩形的宽度和高度，SizeF有三个属性，分别为Height高，width宽，IsEmpty是否为空 
                SizeF crSize = new SizeF(); 
 
                //利用一个循环语句来选择我们要添加文字的型号 
                //直到它的长度比图片的宽度小 
                for (int i = 0; i <  sizes.Length; i++) 
                { 
                    crFont = new Font("arial", sizes[i], FontStyle.Bold); 
 
                    //测量用指定的 Font 对象绘制并用指定的 StringFormat 对象格式化的指定字符串  。 
                    crSize = grPhoto.MeasureString(waterWords, crFont); 
 
                    // ushort 关键字表示一种整数数据类型 
                    if ((ushort)crSize.Width <  (ushort)phWidth) 
                        break; 
                } 
 
                //截边5%的距离，定义文字显示(由于不同的图片显示的高和宽不同，所以按百分比截取) 
                int yPixlesFromBottom = (int)(phHeight * .05); 
 
                //定义在图片上文字的位置 
                float wmHeight = crSize.Height; 
                float wmWidth = crSize.Width; 
 
                float xPosOfWm; 
                float yPosOfWm; 
 
                //设置水印的位置 
                switch (position) 
                { 
                    case ImagePosition.BottomMiddle: 
                        xPosOfWm = phWidth / 2; 
                        yPosOfWm = phHeight - wmHeight - 10; 
                        break; 
                    case ImagePosition.Center: 
                        xPosOfWm = phWidth / 2; 
                        yPosOfWm = phHeight / 2; 
                        break; 
                    case ImagePosition.LeftBottom: 
                        xPosOfWm = wmWidth; 
                        yPosOfWm = phHeight - wmHeight - 10; 
                        break; 
                    case ImagePosition.LeftTop: 
                        xPosOfWm = wmWidth / 2; 
                        yPosOfWm = wmHeight / 2; 
                        break; 
                    case ImagePosition.RightTop: 
                        xPosOfWm = phWidth - wmWidth - 10; 
                        yPosOfWm = wmHeight; 
                        break; 
                    case ImagePosition.RigthBottom: 
                        xPosOfWm = phWidth - wmWidth - 10; 
                        yPosOfWm = phHeight - wmHeight - 10; 
                        break; 
                    case ImagePosition.TopMiddle: 
                        xPosOfWm = phWidth / 2; 
                        yPosOfWm = wmWidth; 
                        break; 
                    default: 
                        xPosOfWm = wmWidth; 
                        yPosOfWm = phHeight - wmHeight - 10; 
                        break; 
                } 
                //封装文本布局信息（如对齐、文字方向和 Tab 停靠位），显示操作（如省略号插入和国家标准 (National) 数字替换）和 OpenType 功能  。 
                StringFormat StrFormat = new StringFormat(); 
 
                //定义需要印的文字居中对齐 
                StrFormat.Alignment = StringAlignment.Center; 
 
                //SolidBrush:定义单色画笔  。画笔用于填充图形形状，如矩形、椭圆、扇形、多边形和封闭路径  。 
                //这个画笔为描绘阴影的画笔，呈灰色 
                int m_alpha = Convert.ToInt32(256 * alpha); 
                SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(m_alpha, 0, 0, 0)); 
 
                //描绘文字信息，这个图层向右和向下偏移一个像素，表示阴影效果 
                //DrawString 在指定矩形并且用指定的 Brush 和 Font 对象绘制指定的文本字符串  。 
                grPhoto.DrawString(waterWords,                                    //string of text 
                                           crFont,                                         //font 
                                           semiTransBrush2,                            //Brush 
                                           new PointF(xPosOfWm + 1, yPosOfWm + 1),  //Position 
                                           StrFormat); 
 
                //从四个 ARGB 分量（alpha、红色、绿色和蓝色）值创建 Color 结构，这里设置透明度为153 
                //这个画笔为描绘正式文字的笔刷，呈白色 
                SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255)); 
 
                //第二次绘制这个图形，建立在第一次描绘的基础上 
                grPhoto.DrawString(waterWords,                 //string of text 
                                           crFont,                                   //font 
                                           semiTransBrush,                           //Brush 
                                           new PointF(xPosOfWm, yPosOfWm),  //Position 
                                           StrFormat); 
 
                //imgPhoto是我们建立的用来装载最终图形的Image对象 
                //bmPhoto是我们用来制作图形的容器，为Bitmap对象 
                imgPhoto = bmPhoto; 
                //释放资源，将定义的Graphics实例grPhoto释放，grPhoto功德圆满 
                //grPhoto.Dispose(); 
 
                //将grPhoto保存 
                if (fRewrite) 
                { 
                    imgPhoto.Save(sourcePicture); 
                } 
                else
                { 
                    // 目标图片名称及全路径 
                    string targetImage = sourcePicture.Replace(System.IO.Path.GetExtension(sourcePicture), "") + "_0607" + fileExtension; 
                    imgPhoto.Save(targetImage); 
                } 
                //imgPhoto.Dispose(); 
                return true; 
            } 
            catch (Exception ex) 
            { 
                _ErrMsg = ex.Message; 
                return false; 
            } 
            finally
            { 
                if (imgPhoto != null) 
                    imgPhoto.Dispose(); 
                if (bmPhoto != null) 
                    bmPhoto.Dispose(); 
                if (grPhoto != null) 
                    grPhoto.Dispose(); 
            } 
 
 
        } 
        #endregion 
 
    } 
}