c# asp.net 给一个图片打上水印,并且上传

using System;
using System.Data;
using System.Configuration;
using System.Web;
using System.Web.Security;
using System.Web.UI;

using System.Web.UI.WebControls.WebParts;
using System.Web.UI.HtmlControls;

using System.Drawing;
using System.Drawing.Drawing2D;
using System.Drawing.Imaging;
using System.IO;
using System.Reflection;

/// <summary>
/// FileUpload 的摘要说明
/// </summary>
public class FileUpload
{
    private string BasePath;

    public FileUpload()
    {
        //
        // TODO: 在此处添加构造函数逻辑
        //
    }

    /// <summary>
    /// 给图片上水印
    /// </summary>
    /// <param name="filePath">原图片地址</param>
    /// <param name="waterFile">水印图片地址</param>
    public void MarkWater(string filePath, string waterFile)
    {
        //GIF不水印
        int i = filePath.LastIndexOf(".");
        string ex = filePath.Substring(i, filePath.Length - i);
        if (string.Compare(ex, ".gif", true) == 0)
        {
            return;
        }

        string ModifyImagePath = BasePath + filePath;//修改的图像路径
        int lucencyPercent = 25;
        Image modifyImage = null;
        Image drawedImage = null;
        Graphics g = null;
        try
        {
            //建立图形对象
            modifyImage = Image.FromFile(ModifyImagePath, true);
            drawedImage = Image.FromFile(BasePath + waterFile, true);
            g = Graphics.FromImage(modifyImage);
            //获取要绘制图形坐标
            int x = modifyImage.Width - drawedImage.Width;
            int y = modifyImage.Height - drawedImage.Height;
            //设置颜色矩阵
            float[][] matrixItems ={
new float[] {1, 0, 0, 0, 0},
new float[] {0, 1, 0, 0, 0},
new float[] {0, 0, 1, 0, 0},
new float[] {0, 0, 0, (float)lucencyPercent/100f, 0},
new float[] {0, 0, 0, 0, 1}};

            ColorMatrix colorMatrix = new ColorMatrix(matrixItems);
            ImageAttributes imgAttr = new ImageAttributes();
            imgAttr.SetColorMatrix(colorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap);
            //绘制阴影图像
            g.DrawImage(drawedImage, new Rectangle(x, y, drawedImage.Width, drawedImage.Height), 10, 10, drawedImage.Width, drawedImage.Height, GraphicsUnit.Pixel, imgAttr);
            //保存文件
            string[] allowImageType ={ ".jpg", ".gif", ".png", ".bmp", ".tiff", ".wmf", ".ico" };
            FileInfo fi = new FileInfo(ModifyImagePath);
            ImageFormat imageType = ImageFormat.Gif;
            switch (fi.Extension.ToLower())
            {
                case ".jpg":
                    imageType = ImageFormat.Jpeg;
                    break;
                case ".gif":
                    imageType = ImageFormat.Gif;
                    break;
                case ".png":
                    imageType = ImageFormat.Png;
                    break;
                case ".bmp":
                    imageType = ImageFormat.Bmp;
                    break;
                case ".tif":
                    imageType = ImageFormat.Tiff;
                    break;
                case ".wmf":
                    imageType = ImageFormat.Wmf;
                    break;
                case ".ico":
                    imageType = ImageFormat.Icon;
                    break;
                default:
                    break;
            }
            MemoryStream ms = new MemoryStream();
            modifyImage.Save(ms, imageType);
            byte[] imgData = ms.ToArray();
            modifyImage.Dispose();
            drawedImage.Dispose();
            g.Dispose();
            FileStream fs = null;
            File.Delete(ModifyImagePath);
            fs = new FileStream(ModifyImagePath, FileMode.Create, FileAccess.Write);
            if (fs != null)
            {
                fs.Write(imgData, 0, imgData.Length);
                fs.Close();
            }
        }
        finally
        {
            try
            {
                drawedImage.Dispose();
                modifyImage.Dispose();
                g.Dispose();
            }
            catch { ;}
        }
    }
}