上传图片生成缩略图

上传图片 生成不同大小的缩略图

/// <summary>
    /// 上传图片
    /// </summary>
    /// <param name="Path"></param>
    /// <param name="filePic"></param>
    /// <returns></returns>
    public static string[] UploadPic(string Path, FileUpload filePic)
    {
        //原图
        System.Drawing.Image original_image = null;
        System.Drawing.Bitmap final_image = null;
        System.Drawing.Graphics graphic = null;
        MemoryStream ms = null;
        //文件类型
        string preveiw = Path+"preview/";
        string display = Path + "display/";
        string print = Path + "print/";
        string[] uploadPath = new string[3];
        string filename;
        try
        {
            #region 判断目录是否存在            
            if (System.IO.Directory.Exists(HttpContext.Current.Request.PhysicalApplicationPath + preveiw) == false)
            {
                System.IO.Directory.CreateDirectory(HttpContext.Current.Request.PhysicalApplicationPath + preveiw);
            }
            if (System.IO.Directory.Exists(HttpContext.Current.Request.PhysicalApplicationPath + display) == false)
            {
                System.IO.Directory.CreateDirectory(HttpContext.Current.Request.PhysicalApplicationPath + display);
            }
            if (System.IO.Directory.Exists(HttpContext.Current.Request.PhysicalApplicationPath + print) == false)
            {
                System.IO.Directory.CreateDirectory(HttpContext.Current.Request.PhysicalApplicationPath + print);
            }
            #endregion

            HttpPostedFile image_upload = filePic.PostedFile;

            original_image = System.Drawing.Image.FromStream(image_upload.InputStream);

            #region 计算缩略各种图宽、高
            //preview
            int preview_width = original_image.Width / 4;
            int preview_height = original_image.Height / 4;
            //display
            int r=Convert.ToInt32(Math.Max(original_image.Width / 200, original_image.Height / 200));
            r = (r == 0 ? 1 : r);
            int display_width = original_image.Width / r;
            int display_height = original_image.Height / r;
            #endregion

            #region 上传图片
            //preview
            final_image = new System.Drawing.Bitmap(preview_width, preview_height);
            graphic = System.Drawing.Graphics.FromImage(final_image);
            graphic.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.Black), new System.Drawing.Rectangle(0, 0, preview_width, preview_height));
            graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            graphic.DrawImage(original_image, 0, 0, preview_width, preview_height);

            filename = FileName;
            final_image.Save(System.IO.Path.Combine(HttpContext.Current.Request.PhysicalApplicationPath, preveiw + filename), System.Drawing.Imaging.ImageFormat.Jpeg);
            final_image = null;
            graphic = null;
            uploadPath[0] = preveiw + filename;
            //display
            final_image = new System.Drawing.Bitmap(display_width, display_height);
            graphic = System.Drawing.Graphics.FromImage(final_image);
            graphic.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.Black), new System.Drawing.Rectangle(0, 0, display_width, display_height));
            graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            graphic.DrawImage(original_image, 0, 0, display_width, display_height);

            final_image.Save(System.IO.Path.Combine(HttpContext.Current.Request.PhysicalApplicationPath, display + filename), System.Drawing.Imaging.ImageFormat.Jpeg);
            final_image = null;
            graphic = null;
            uploadPath[1] = display + filename;

            //print
            final_image = new System.Drawing.Bitmap(original_image.Width, original_image.Height);
            graphic = System.Drawing.Graphics.FromImage(final_image);
            graphic.FillRectangle(new System.Drawing.SolidBrush(System.Drawing.Color.Black), new System.Drawing.Rectangle(0, 0, original_image.Width, original_image.Height));
            graphic.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
            graphic.DrawImage(original_image, 0, 0,original_image.Width,original_image.Height);

            final_image.Save(System.IO.Path.Combine(HttpContext.Current.Request.PhysicalApplicationPath, print+filename), System.Drawing.Imaging.ImageFormat.Jpeg);
            final_image = null;
            graphic = null;
            uploadPath[2] = print + filename;

            #endregion

            return uploadPath;
        }
        catch (Exception ex)
        {
            System.Console.Error.Write(ex.Message);
            return null;
        }
    }