FileUpload上传并压缩图片的几种方法（方法转）

    private bool UploadImg(FileUpload FileUpload, string FilePath, string imagess)
        {
            //string fileExtends = "";
            if (FileUpload.FileName.Trim().Length > 0)
            {
                string fileExt = System.IO.Path.GetExtension(FileUpload.FileName);
                if (fileExt == ".jpg" || fileExt == ".gif" || fileExt == ".png" || fileExt == "ico")
                {
                    try
                    {
                        if (FileUpload.PostedFile.ContentLength < 1048576)
                        {

                            //FileInfo fileinfo = new FileInfo(FileUpload.PostedFile.FileName);
                            //FileUpload.SaveAs(Server.MapPath(FilePath + imagess));
                            System.Drawing.Image image = System.Drawing.Image.FromStream(new System.IO.MemoryStream(FileUpload.FileBytes));
                            //if (GetPicThumbnail(image, FilePath + imagess, img1.Height, img1.Width, 100))
                            //{
                            //    return true;
                            //}
                            //else
                            //{
                            //    return false;
                            //}
                            if (MakeThumbnail(image, Server.MapPath(FilePath + imagess), img1.Width, img1.Height, "Cut", "JPG"))
                            {
                                return true;
                            }
                            else
                            {
                                return false;
                            }
                            //FileUpload.SaveAs(Server.MapPath("UiMain\\Employment\\images\\" + imagess));

                        }
                        else
                        {
                            Page.ClientScript.RegisterStartupScript(Page.GetType(), "", "<script type=\"text/javascript\">  new function(){alert('上传图片大小不能超过1MB');}</script>");
                            return false;
                        }
                    }
                    catch (Exception ex)
                    {
                        Page.ClientScript.RegisterStartupScript(Page.GetType(), "", "<script type=\"text/javascript\">  new function(){alert('发生错误'" + ex + "');}</script>");
                        return false;
                    }
                }
                else
                {
                    Page.ClientScript.RegisterStartupScript(Page.GetType(), "", "<script type=\"text/javascript\"> new function(){alert('只允许上传jpg、gif、png、ico.文件！')};</script>");
                    return false;
                }
            }
            else
            {
                return false;
            }
        }


        /// <summary>
        /// 压缩图片并存储
        /// </summary>
        /// <param name="originalImagePath">源图路径（物理路径）</param>
        /// <param name="thumbnailPath">压缩面存储路径（物理路径）</param>
        /// <param name="width">压缩图宽度</param>
        /// <param name="height">压缩图高度</param>
        /// <param name="mode">生成压缩图的方式</param> 
        /// <param name="type">保存压缩图类型</param> 
        public static bool MakeThumbnail(System.Drawing.Image originalImagePath, string thumbnailPath, int width, int height, string mode, string type)
        {
            //System.Drawing.Image originalImage = System.Drawing.Image.FromFile(originalImagePath);
            System.Drawing.Image originalImage = originalImagePath;//System.Drawing.Image.FromFile(originalImagePath);
            bool isture = true; ;
            int towidth = width;
            int toheight = height;
            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;
            switch (mode)
            {
                case "HW"://指定高宽缩放（可能变形） 
                    break;
                case "W"://指定宽，高按比例 
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H"://指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut"://指定高宽裁减（不变形） 
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                case "DB"://等比缩放（不变形，如果高大按高，宽大按宽缩放） 
                    if ((double)originalImage.Width / (double)towidth < (double)originalImage.Height / (double)toheight)
                    {
                        toheight = height;
                        towidth = originalImage.Width * height / originalImage.Height;
                    }
                    else
                    {
                        towidth = width;
                        toheight = originalImage.Height * width / originalImage.Width;
                    }
                    break;
                default:
                    break;
            }
            //新建一个bmp图片
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);
            //新建一个画板
            System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);
            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;
            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
            //清空画布并以透明背景色填充
            g.Clear(System.Drawing.Color.Transparent);
            //在指定位置并且按指定大小绘制原图片的指定部分
            g.DrawImage(originalImage, new System.Drawing.Rectangle(0, 0, towidth, toheight),
            new System.Drawing.Rectangle(x, y, ow, oh),
            System.Drawing.GraphicsUnit.Pixel);
            try
            {
                //保存缩略图
                if (type == "JPG")
                {
                    bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
                }
                if (type == "BMP")
                {
                    bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Bmp);
                }
                if (type == "GIF")
                {
                    bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Gif);
                }
                if (type == "PNG")
                {
                    bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Png);
                }
            }
            catch (System.Exception e)
            {
                isture = false;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
            return isture;
        }


        /// <summary>
        /// 无损压缩图片
        /// </summary>
        /// <param name="Image">原图片</param>
        /// <param name="dFile">压缩后保存位置</param>
        /// <param name="dHeight">高度</param>
        /// <param name="dWidth"></param>
        /// <param name="flag">压缩质量 1-100</param>
        /// <returns></returns>
        public bool GetPicThumbnail(System.Drawing.Image Image, string dFile, int dHeight, int dWidth, int flag)
        {
            System.Drawing.Image iSource = Image;
            ImageFormat tFormat = iSource.RawFormat;
            int sW = 0, sH = 0;
            //按比例缩放
            Size tem_size = new Size(iSource.Width, iSource.Height);
            if (tem_size.Width > dHeight || tem_size.Width > dWidth) //将**改成c#中的或者操作符号
            {
                if ((tem_size.Width * dHeight) > (tem_size.Height * dWidth))
                {
                    sW = dWidth;
                    sH = (dWidth * tem_size.Height) / tem_size.Width;
                }
                else
                {
                    sH = dHeight;
                    sW = (tem_size.Width * dHeight) / tem_size.Height;
                }
            }
            else
            {
                sW = tem_size.Width;
                sH = tem_size.Height;
            }
            Bitmap ob = new Bitmap(dWidth, dHeight);
            Graphics g = Graphics.FromImage(ob);
            g.Clear(Color.WhiteSmoke);
            g.CompositingQuality = CompositingQuality.HighQuality;
            g.SmoothingMode = SmoothingMode.HighQuality;
            g.InterpolationMode = InterpolationMode.HighQualityBicubic;
            g.DrawImage(iSource, new Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);
            g.Dispose();
            //以下代码为保存图片时，设置压缩质量
            EncoderParameters ep = new EncoderParameters();
            long[] qy = new long[1];
            qy[0] = flag;//设置压缩的比例1-100
            EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
            ep.Param[0] = eParam;
            try
            {
                ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
                ImageCodecInfo jpegICIinfo = null;
                for (int x = 0; x < arrayICI.Length; x++)
                {
                    if (arrayICI[x].FormatDescription.Equals("JPEG"))
                    {
                        jpegICIinfo = arrayICI[x];
                        break;
                    }
                }
                if (jpegICIinfo != null)
                {
                    ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径
                }
                else
                {
                    ob.Save(dFile, tFormat);
                }
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
            finally
            {
                iSource.Dispose();
                ob.Dispose();
            }
        }