asp.Net生成サムネイルの例方法の共有

ステーションを作るとき、サムネイルを生成する機能によく遭遇します.異なる場合、異なるサイズのサムネイルに使用する必要がある可能性があります.
本文で生成した画像はすべて正方形で、正方形の略図だけが画像が十分にはっきりしていることを保証します.
私がここで言った正方形は、まず比例して圧縮され、固定された白い底を加えて中央に表示されます.
コード:
新規作成ashx

 
  
//       
  
private static Size NewSize(int maxWidth, int maxHeight, int Width, int Height) 
  
        { 
  
            double w = 0.0; 
  
            double h = 0.0; 
  
            double sw = Convert.ToDouble(Width); 
  
            double sh = Convert.ToDouble(Height); 
  
            double mw = Convert.ToDouble(maxWidth); 
  
            double mh = Convert.ToDouble(maxHeight); 
   
  
            if (sw < mw && sh < mh)//  maxWidth maxHeight     ，          
            {
                w = sw;
                h = sh;
            }
            else if ((sw / sh) > (mw / mh))
            {
                w = maxWidth;
                h = (w * sh) / sw;
            }
            else
            {
                h = maxHeight;
                w = (h * sw) / sh;
            }
            return new Size(Convert.ToInt32(w), Convert.ToInt32(h));
        }
 
 

 
  
//      
  
public static void SendSmallImage(string filename, string newfile, int maxHeight, int maxWidth, string mode) 
  
        { 
  
            System.Drawing.Image img = System.Drawing.Image.FromFile(filename);//       
  
            System.Drawing.Imaging.ImageFormat thisformat = img.RawFormat; //       
  
            Size newSize = NewSize(maxWidth, maxHeight, img.Width, img.Height); //        Width Height 
  
            Bitmap outBmp = new Bitmap(maxWidth, maxHeight); 
  
            Graphics g = Graphics.FromImage(outBmp); 
  
            //          
  
            g.CompositingQuality = CompositingQuality.HighQuality; 
  
            g.SmoothingMode = SmoothingMode.HighQuality; 
  
            g.InterpolationMode = InterpolationMode.HighQualityBicubic; 
  
            g.Clear(Color.White); 
  
            g.DrawImage(img, new Rectangle(((maxWidth - newSize.Width) / 2), ((maxHeight - newSize.Height) / 2), newSize.Width, newSize.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel); 
  
            g.Dispose(); 
  
            //          ，       
  
            EncoderParameters encoderParams = new EncoderParameters(); 
  
            long[] quality = new long[1]; 
  
            quality[0] = 100; 
  
            EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality); 
  
            encoderParams.Param[0] = encoderParam; 
  
            //                   ImageCodecInfo  。 
  
            ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders(); 
  
            ImageCodecInfo jpegICI = null; 
  
            for (int x = 0; x < arrayICI.Length; x++) 
  
            { 
  
                if (arrayICI[x].FormatDescription.Equals("JPEG")) 
  
                { 
  
                    jpegICI = arrayICI[x];//  jpeg   
  
                    break; 
  
                } 
  
            } 
  
            if (jpegICI != null) 
  
            { 
  
                outBmp.Save(newfile, jpegICI, encoderParams); 
  
            } 
  
            else 
  
            { 
  
                outBmp.Save(newfile, thisformat); 
  
            } 
  
            img.Dispose(); 
  
            outBmp.Dispose(); 
  
        } 
  
 
 

画像を出力:

 
  
//     
  
        public static void OutPutImg(string imgFilePath) 
  
        { 
  
            FileStream fs = new FileStream(HttpContext.Current.Server.MapPath(imgFilePath), FileMode.Open, FileAccess.Read); 
  
            DateTime contentModified = System.IO.File.GetLastWriteTime(HttpContext.Current.Server.MapPath(imgFilePath)); 
  
            if (IsClientCached(contentModified)) 
  
            { 
  
                HttpContext.Current.Response.StatusCode = 304; 
  
                HttpContext.Current.Response.SuppressContent = true; 
  
            } 
  
            else 
  
            { 
  
                byte[] mydata = new byte[fs.Length]; 
  
                int Length = Convert.ToInt32(fs.Length); 
  
                fs.Read(mydata, 0, Length); 
  
                fs.Close(); 
  
                HttpContext.Current.Response.OutputStream.Write(mydata, 0, Length); 
  
                HttpContext.Current.Response.ContentType = "image/jpeg"; 
  
                HttpContext.Current.Response.End(); 
  
                HttpContext.Current.Response.Cache.SetETagFromFileDependencies(); 
  
                HttpContext.Current.Response.Cache.SetAllowResponseInBrowserHistory(true); 
  
                HttpContext.Current.Response.Cache.SetLastModified(contentModified); 
  
            } 
  
        } 
  
 
 

 
  
//outpuimg.ashx?src=/images/weimeidesc/8af30049-797e-4eb4-8a54-cc4de47c1694.jpg!100x100.jpg 
  
        public void ProcessRequest(HttpContext context) 
  
        { 
  
            //     
  
            string imgUrl = context.Request.QueryString["src"]; 
  
            string trueFilePath = imgUrl.Split('!')[0]; 
  
            //       
  
            int width = Convert.ToInt32(imgUrl.Split('!')[1].Replace(".jpg", "").Split('x')[0]); 
  
            int height = Convert.ToInt32(imgUrl.Split('!')[1].Replace(".jpg", "").Split('x')[1]); 
  
 
  
            //           
  
            if (File.Exists(context.Server.MapPath("~/" + imgUrl))) 
  
            { 
  
                OutPutImg("~/"+imgUrl); 
  
            } 
  
            else 
  
            { 
  
                if (!string.IsNullOrEmpty(imgUrl) && File.Exists(context.Server.MapPath("~/" + trueFilePath))) 
  
                { 
  
                    Image originalImage = System.Drawing.Image.FromFile(context.Server.MapPath("~/" + trueFilePath)); 
  
                    var newBitmap = new Bitmap(originalImage); 
  
                    //           
  
                    SendSmallImage(context.Server.MapPath("~/" + trueFilePath),context.Server.MapPath("~/" + imgUrl), width, height, "meiyouyisi"); 
  
                    //   
  
                    OutPutImg("~/" + imgUrl); 
  
                } 
  
                else//               
  
                { 
  
                    //OutPutImg(imgUrl); 
  
                } 
  
            } 
  
        }