谁能给一个demo,上传图片时给图片加水印，最好还可以生成缩略图

//计算水印图片的比率

    //取背景的1/4宽度来比较

    if ((_width > watermark.Width * 4) && (_height > watermark.Height * 4))

    {

     bl = 1;

    }

    else if ((_width > watermark.Width * 4) && (_height<watermark.Height * 4))

    {

     bl = Convert.ToDouble(_height / 4) / Convert.ToDouble(watermark.Height);

            

    }

    else if ((_width < watermark.Width * 4) && (_height > watermark.Height * 4))

    {

     bl = Convert.ToDouble(_width / 4) / Convert.ToDouble(watermark.Width);

    }

    else

    {

     if ((_width * watermark.Height) > (_height * watermark.Width))

     {

      bl = Convert.ToDouble(_height / 4) / Convert.ToDouble(watermark.Height);

                    

     }

     else

     {

      bl = Convert.ToDouble(_width / 4) / Convert.ToDouble(watermark.Width);

                    

     }

            

    }



    WatermarkWidth = Convert.ToInt32(watermark.Width * bl);

    WatermarkHeight = Convert.ToInt32(watermark.Height * bl);



    switch (_watermarkPosition)

    {

     case "WM_TOP_LEFT":

      xpos = 10;

      ypos = 10;

      break;

     case "WM_TOP_RIGHT":

      xpos = _width - WatermarkWidth - 10;

      ypos = 10;

      break;

     case "WM_BOTTOM_RIGHT":

      xpos = _width - WatermarkWidth - 10;

      ypos = _height -WatermarkHeight - 10;

      break;

     case "WM_BOTTOM_LEFT":

      xpos = 10;

      ypos = _height - WatermarkHeight - 10;

      break;

    }



    picture.DrawImage(

     watermark, 

     new Rectangle(xpos, ypos, WatermarkWidth, WatermarkHeight), 

     0, 

     0, 

     watermark.Width, 

     watermark.Height, 

     GraphicsUnit.Pixel, 

     imageAttributes);



    watermark.Dispose();

    imageAttributes.Dispose();

   }



   /// <summary>

   ///   加水印图片

   /// </summary>

   /// <param name="picture">imge 对象</param>

   /// <param name="WaterMarkPicPath">水印图片的地址</param>

   /// <param name="_watermarkPosition">水印位置</param>

   /// <param name="_width">被加水印图片的宽</param>

   /// <param name="_height">被加水印图片的高</param>

   private void addWatermarkImage( Graphics picture,string WaterMarkPicPath, 

    string _watermarkPosition,int _width,int _height)

   {

    Image watermark = new Bitmap(WaterMarkPicPath);



    this.addWatermarkImage(picture, watermark, _watermarkPosition, _width, 

     _height);

   }

   #endregion



   #region 生成缩略图

   /// <summary>

   /// 保存图片

   /// </summary>

   /// <param name="image">Image 对象</param>

   /// <param name="savePath">保存路径</param>

   /// <param name="ici">指定格式的编解码参数</param>

   private void SaveImage(Image image, string savePath, ImageCodecInfo ici)

   {

    //设置 原图片 对象的 EncoderParameters 对象

    EncoderParameters parameters = new EncoderParameters(1);

    parameters.Param[0] = new EncoderParameter(

     System.Drawing.Imaging.Encoder.Quality, ((long) 90));

    image.Save(savePath, ici, parameters);

    parameters.Dispose();

   }



   /// <summary>

   /// 获取图像编码解码器的所有相关信息

   /// </summary>

   /// <param name="mimeType">包含编码解码器的多用途网际邮件扩充协议 (MIME) 类型的字符串</param>

   /// <returns>返回图像编码解码器的所有相关信息</returns>

   private ImageCodecInfo GetCodecInfo(string mimeType)

   {

    ImageCodecInfo[] CodecInfo = ImageCodecInfo.GetImageEncoders();

    foreach(ImageCodecInfo ici in CodecInfo)

    {

     if(ici.MimeType == mimeType)

      return ici;

    }

    return null;

   }



   /// <summary>

   /// 生成缩略图

   /// </summary>

   /// <param name="sourceImagePath">原图片路径(相对路径)</param>

   /// <param name="thumbnailImagePath">生成的缩略图路径,如果为空则保存为原图片路径(相对路径)</param>

   /// <param name="thumbnailImageWidth">缩略图的宽度（高度与按源图片比例自动生成）</param>

   public void ToThumbnailImages(

    string SourceImagePath,

    string ThumbnailImagePath,

    int ThumbnailImageWidth)

   {

    Hashtable htmimes = new Hashtable();

    htmimes[".jpeg"] = "image/jpeg";

    htmimes[".jpg"] = "image/jpeg";   

    htmimes[".png"] = "image/png";   

    htmimes[".tif"] = "image/tiff";

    htmimes[".tiff"] = "image/tiff";

    htmimes[".bmp"] = "image/bmp";

    htmimes[".gif"] = "image/gif";



    // 取得原图片的后缀

    string sExt = SourceImagePath.Substring(

     SourceImagePath.LastIndexOf(".")).ToLower();



    //从 原图片 创建 Image 对象

    Image image = Image.FromFile(SourceImagePath);  

    int num = ((ThumbnailImageWidth / 4) * 3);

    int width = image.Width;

    int height = image.Height;



    //计算图片的比例

    if ((((double) width) / ((double) height)) >= 1.3333333333333333f)

    {

     num = ((height * ThumbnailImageWidth) / width);

    }

    else

    {

     ThumbnailImageWidth = ((width * num) / height);

    }

    if ((ThumbnailImageWidth < 1) || (num < 1))

    {

     return;

    }



    //用指定的大小和格式初始化 Bitmap 类的新实例

    Bitmap bitmap = new Bitmap(ThumbnailImageWidth, num, 

     PixelFormat.Format32bppArgb);



    //从指定的 Image 对象创建新 Graphics 对象

    Graphics graphics = Graphics.FromImage(bitmap);



    //清除整个绘图面并以透明背景色填充

    graphics.Clear(Color.Transparent);



    graphics.SmoothingMode = SmoothingMode.HighQuality;

    graphics.InterpolationMode = InterpolationMode.High;



    //在指定位置并且按指定大小绘制 原图片 对象

    graphics.DrawImage(image, new Rectangle(0, 0, ThumbnailImageWidth, num));

    image.Dispose(); 

   

    try

    {   

     //将此 原图片 以指定格式并用指定的编解码参数保存到指定文件 

     SaveImage(bitmap, ThumbnailImagePath, 

      GetCodecInfo((string)htmimes[sExt]));

    }

    catch(System.Exception e)

    {

     throw e;

    }

   }

   #endregion

}

}

using System;

using System.IO;

using System.Collections;

using System.Drawing;

using System.Drawing.Drawing2D;

using System.Drawing.Imaging;



namespace Imag_writer

{

/// <summary>

/// 水印的类型

/// </summary>

public enum WaterMarkType

{

   /// <summary>

   /// 文字水印

   /// </summary>

   TextMark,

   /// <summary>

   /// 图片水印

   /// </summary>

   //ImageMark // 暂时只能添加文字水印

};



/// <summary>

/// 水印的位置

/// </summary>

public enum WaterMarkPosition

{

   /// <summary>

   /// 左上角

   /// </summary>

   WMP_Left_Top,

   /// <summary>

   /// 左下角

   /// </summary>

   WMP_Left_Bottom,

   /// <summary>

   /// 右上角

   /// </summary>

   WMP_Right_Top,

   /// <summary>

   /// 右下角

   /// </summary>

   WMP_Right_Bottom

};



/// <summary>

/// 处理图片的类（包括加水印，生成缩略图）

/// </summary>

public class ImageWaterMark

{

   public ImageWaterMark()

   {

    //

    // TODO: 在此处添加构造函数逻辑

    //

   }



   #region 给图片加水印

   /// <summary>

   /// 添加水印(分图片水印与文字水印两种)

   /// </summary>

   /// <param name="oldpath">原图片绝对地址</param>

   /// <param name="newpath">新图片放置的绝对地址</param>

   /// <param name="wmtType">要添加的水印的类型</param>

   /// <param name="sWaterMarkContent">水印内容，若添加文字水印，此即为要添加的文字；

   /// 若要添加图片水印，此为图片的路径</param>

   public void addWaterMark(string oldpath, string newpath, 

    WaterMarkType wmtType, string sWaterMarkContent)

   {

    try

    {

     Image image = Image.FromFile(oldpath);



     Bitmap b = new Bitmap(image.Width, image.Height, 

      PixelFormat.Format24bppRgb);



     Graphics g = Graphics.FromImage(b);

     g.Clear(Color.White);

     g.SmoothingMode = SmoothingMode.HighQuality;

     g.InterpolationMode = InterpolationMode.High;



     g.DrawImage(image, 0, 0, image.Width, image.Height);



     switch (wmtType)

     {

      /*case WaterMarkType.ImageMark:

       //图片水印

       this.addWatermarkImage(g, 

        Page.Server.MapPath(Watermarkimgpath), 

        WatermarkPosition,image.Width,image.Height);

       break;*/

      case WaterMarkType.TextMark:

       //文字水印

       this.addWatermarkText(g, sWaterMarkContent, "WM_BOTTOM_RIGHT", 

        image.Width, image.Height);

       break;

     }



     b.Save(newpath);

     b.Dispose();

     image.Dispose();

    }

    catch

    {

     if(File.Exists(oldpath))

     {

      File.Delete(oldpath);

     }

    }

    finally

    {

     if(File.Exists(oldpath))

     {

      File.Delete(oldpath);

     }

    }  

   }



   /// <summary>

   ///   加水印文字

   /// </summary>

   /// <param name="picture">imge 对象</param>

   /// <param name="_watermarkText">水印文字内容</param>

   /// <param name="_watermarkPosition">水印位置</param>

   /// <param name="_width">被加水印图片的宽</param>

   /// <param name="_height">被加水印图片的高</param>

   private void addWatermarkText(Graphics picture, string _watermarkText, 

    string _watermarkPosition, int _width, int _height)

   {

    // 确定水印文字的字体大小

    int[] sizes = new int[]{32, 30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4};

    Font crFont = null;

    SizeF crSize = new SizeF();

    for (int i = 0;i < sizes.Length; i++)

    {

     crFont = new Font("Arial Black", sizes[i], FontStyle.Bold);

     crSize = picture.MeasureString(_watermarkText, crFont);



     if((ushort)crSize.Width < (ushort)_width)

     {

      break;

     }

    }



    // 生成水印图片（将文字写到图片中）

    Bitmap floatBmp = new Bitmap((int)crSize.Width + 3, 

          (int)crSize.Height + 3, PixelFormat.Format32bppArgb);

    Graphics fg=Graphics.FromImage(floatBmp);

    PointF pt=new PointF(0,0);



    // 画阴影文字

    Brush TransparentBrush0 = new SolidBrush(Color.FromArgb(255, Color.Black));

    Brush TransparentBrush1 = new SolidBrush(Color.FromArgb(255, Color.Black));

    fg.DrawString(_watermarkText,crFont,TransparentBrush0, pt.X, pt.Y + 1); 

    fg.DrawString(_watermarkText,crFont,TransparentBrush0, pt.X + 1, pt.Y); 



    fg.DrawString(_watermarkText,crFont,TransparentBrush1, pt.X + 1, pt.Y + 1); 

    fg.DrawString(_watermarkText,crFont,TransparentBrush1, pt.X, pt.Y + 2); 

    fg.DrawString(_watermarkText,crFont,TransparentBrush1, pt.X + 2, pt.Y); 



    TransparentBrush0.Dispose(); 

    TransparentBrush1.Dispose();



    // 画文字

    fg.SmoothingMode=System.Drawing.Drawing2D.SmoothingMode.HighQuality; 

    fg.DrawString(_watermarkText, 

     crFont, new SolidBrush(Color.White), 

     pt.X, pt.Y, StringFormat.GenericDefault);



    // 保存刚才的操作

    fg.Save(); 

    fg.Dispose();

    // floatBmp.Save("d:\\WebSite\\DIGITALKM\\ttt.jpg");



    // 将水印图片加到原图中

    this.addWatermarkImage(

     picture, 

     new Bitmap(floatBmp), 

     "WM_BOTTOM_RIGHT", 

     _width, 

     _height);

   }



   /// <summary>

   ///   加水印图片

   /// </summary>

   /// <param name="picture">imge 对象</param>

   /// <param name="iTheImage">Image对象（以此图片为水印）</param>

   /// <param name="_watermarkPosition">水印位置</param>

   /// <param name="_width">被加水印图片的宽</param>

   /// <param name="_height">被加水印图片的高</param>

   private void addWatermarkImage( Graphics picture,Image iTheImage, 

    string _watermarkPosition,int _width,int _height)

   {

    Image watermark = new Bitmap(iTheImage);



    ImageAttributes imageAttributes = new ImageAttributes();

    ColorMap colorMap = new ColorMap();



    colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);

    colorMap.NewColor = Color.FromArgb(0, 0, 0, 0);

    ColorMap[] remapTable = {colorMap};



    imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);



    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, 0.3f, 0.0f},

             new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f}

            };



    ColorMatrix colorMatrix = new ColorMatrix(colorMatrixElements);



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



    int xpos = 0;

    int ypos = 0;

    int WatermarkWidth = 0;

    int WatermarkHeight = 0;

    double bl = 1d;



    

using System;

using System.Drawing;

using System.Drawing.Imaging;

using System.Drawing.Drawing2D;



namespace Tutorial

{

    class WaterMark

    {



        [STAThread]

        static void Main(string[] args)

        {

            //设置工作目录

            string WorkingDirectory = @"C:Documents and Settingsadministrator.JAZZMINEMy DocumentsProjectsTutorialsWaterMark";



            //定义版权声明的字符串信息或文本（看来原作者是老外）

            string Copyright = "Copyright @2002 - AP Photo/David Zalubowski";



            //创建一个需要添加水印的图像对象

            Image imgPhoto = Image.FromFile(WorkingDirectory + "\watermark_photo.jpg");

            int phWidth = imgPhoto.Width;

            int phHeight = imgPhoto.Height;



            //创建一个原始图像大小的Bitmap

            Bitmap bmPhoto = new Bitmap(phWidth, phHeight, PixelFormat.Format24bppRgb);



            bmPhoto.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);



            //把Bitmap装载进Graphics对象 

            Graphics grPhoto = Graphics.FromImage(bmPhoto);



            //创建一个包含水印的image对象

            Image imgWatermark = new Bitmap(WorkingDirectory + "\watermark.bmp");

            int wmWidth = imgWatermark.Width;

            int wmHeight = imgWatermark.Height;



            //------------------------------------------------------------

            //第一步 -插入版权信息

            //------------------------------------------------------------



            //设置这个要转换Graphics对象的图像质量

            grPhoto.SmoothingMode = SmoothingMode.AntiAlias;



            //绘制图像对象到graphics对象（保留原始的宽高）

            grPhoto.DrawImage(

                imgPhoto,                               // Photo Image object

                new Rectangle(0, 0, phWidth, phHeight), // 构造矩形

                0,                                      // 要绘制的源图像的x坐标 

                0,                                      // 要绘制的源图像的y坐标

                phWidth,                                // 要绘制的源图像的宽度

                phHeight,                               // 要绘制的源图像的高度

                GraphicsUnit.Pixel);                    // 图像所使用的单位



            //-------------------------------------------------------

            //为了最大化版权信息的字体，我们通过测试多个字体大小，定一个了一个数组来包含不同的字体大小

            //-------------------------------------------------------

            int[] sizes = new int[]{16,14,12,10,8,6,4};



            Font crFont = null;

            SizeF crSize = new SizeF();



            //通过循环这个数组，来选用不同的字体大小

            //如果它的大小小于图像的宽度，就选用这个大小的字体

            for (int i=0 ;i<7; i++)

            {

                //设置字体，这里是用arial，黑体

                crFont = new Font("arial", sizes[i], FontStyle.Bold);

                //Measure the Copyright string in this Font

                crSize = grPhoto.MeasureString(Copyright, crFont);



                if((ushort)crSize.Width < (ushort)phWidth)

                    break;

            }



            //因为图片的高度可能不尽相同, 所以定义了

            //从图片底部算起预留了5%的空间

            int yPixlesFromBottom = (int)(phHeight *.05);



            //现在使用版权信息字符串的高度来确定要绘制的图像的字符串的y坐标

 

            float yPosFromBottom = ((phHeight - yPixlesFromBottom)-(crSize.Height/2));



            //计算x坐标

            float xCenterOfImg = (phWidth/2);



            //把文本布局设置为居中

            StringFormat StrFormat = new StringFormat();

            StrFormat.Alignment = StringAlignment.Center;



            //通过Brush来设置黑色半透明

            SolidBrush semiTransBrush2 = new SolidBrush(Color.FromArgb(153, 0, 0, 0));



            //绘制版权字符串

            grPhoto.DrawString(Copyright,                 //版权字符串文本

                crFont,                                   //字体

                semiTransBrush2,                           //Brush

                new PointF(xCenterOfImg+1,yPosFromBottom+1),  //位置

                StrFormat);



            //设置成白色半透明

            SolidBrush semiTransBrush = new SolidBrush(Color.FromArgb(153, 255, 255, 255));



            //第二次绘制版权字符串来创建阴影效果

            //记住移动文本的位置1像素

            grPhoto.DrawString(Copyright,                 //版权文本

                crFont,                                   //字体

                semiTransBrush,                           //Brush

                new PointF(xCenterOfImg,yPosFromBottom),  //位置

                StrFormat);                               //文本对齐



            



            //------------------------------------------------------------

            //第二步：插入水印图像

            //------------------------------------------------------------



            //通过之前创建的Bitmap创建一个 Bitmap

            Bitmap bmWatermark = new Bitmap(bmPhoto);

            bmWatermark.SetResolution(imgPhoto.HorizontalResolution, imgPhoto.VerticalResolution);

            

            Graphics grWatermark = Graphics.FromImage(bmWatermark);



            //To achieve a transulcent watermark we will apply (2) color 

            //manipulations by defineing a ImageAttributes object and 

            //seting (2) of its properties.

            ImageAttributes imageAttributes = new ImageAttributes();



            //第一步是用水印来替代背景颜色 

            //(Alpha=0, R=0, G=0, B=0)

            //要使用 Colormap 来定义一个RemapTable

            ColorMap colorMap = new ColorMap();



            //这个水印的背景定义成100%绿色，并用来替代透明           

            colorMap.OldColor = Color.FromArgb(255, 0, 255, 0);

            colorMap.NewColor = Color.FromArgb(0, 0, 0, 0); 



            ColorMap[] remapTable = {colorMap};



            imageAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap);



            //第二个颜色是用来控制水印图片的不透明度的 

            //是使用一个5*5的RGBA矩阵来实现的 

            // 设置第4行、第4列的值为0.3来不透明度的级别

            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,  0.3f, 0.0f},        

                                                new float[] {0.0f,  0.0f,  0.0f,  0.0f, 1.0f}}; 

            ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements);



            imageAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default,

                ColorAdjustType.Bitmap);



            //本例的水印放置在右上方

            // 偏移量是10

            



            int xPosOfWm = ((phWidth - wmWidth)-10);

            int yPosOfWm = 10;



            grWatermark.DrawImage(imgWatermark, 

                new Rectangle(xPosOfWm,yPosOfWm,wmWidth,wmHeight),  //Set the detination Position

                0,                  // x坐标

                0,                  // y坐标

                wmWidth,            // 水印宽度

                wmHeight,            // 水印高度

                GraphicsUnit.Pixel, // 单位

                imageAttributes);   //ImageAttributes对象



            //使用新生成的加了水印图片替代原始图片

            imgPhoto = bmWatermark;

            grPhoto.Dispose();

            grWatermark.Dispose();



            //保存的路径

            imgPhoto.Save(WorkingDirectory + @"\watermark_final.jpg", ImageFormat.Jpeg);

            imgPhoto.Dispose();

            imgWatermark.Dispose();



        }

    }

}

 private void Btn_Upload_Click(object sender, System.EventArgs e)

        {

            if(UploadFile.PostedFile.FileName.Trim()!="")

            {

                //上传文件

                string extension = Path.GetExtension(UploadFile.PostedFile.FileName).ToUpper();

                string fileName = DateTime.Now.Year.ToString() + DateTime.Now.Month.ToString() + DateTime.Now.Day.ToString() + DateTime.Now.Hour.ToString() + DateTime.Now.Minute.ToString() + DateTime.Now.Second.ToString();

                string path = Server.MapPath(".") + "/UploadFile/" + fileName + extension;

                UploadFile.PostedFile.SaveAs(path);



                //加文字水印，注意，这里的代码和以下加图片水印的代码不能共存

                System.Drawing.Image image = System.Drawing.Image.FromFile(path);

                Graphics g = Graphics.FromImage(image);

                g.DrawImage(image, 0, 0, image.Width, image.Height);

                Font f = new Font("Verdana", 32);

                Brush b = new SolidBrush(Color.White);

                string addText = AddText.Value.Trim();

                g.DrawString(addText, f, b, 10, 10);

                g.Dispose();



                //加图片水印

                System.Drawing.Image image = System.Drawing.Image.FromFile(path);

                System.Drawing.Image copyImage = System.Drawing.Image.FromFile( Server.MapPath(".") + "/Alex.gif");

                Graphics g = Graphics.FromImage(image);

                g.DrawImage(copyImage, new Rectangle(image.Width-copyImage.Width, image.Height-copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);

                g.Dispose();



                //保存加水印过后的图片,删除原始图片

                string newPath = Server.MapPath(".") + "/UploadFile/" + fileName + "_new" + extension;

                image.Save(newPath);

                image.Dispose();

                if(File.Exists(path))

                {

                    File.Delete(path);

                }



                Response.Redirect(newPath);

            }

        }