Thumbnail refresh RSS

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  kvh

  Member

  131 Points

  108 Posts

  Thumbnail refresh

  Feb 13, 2012 08:09 PM|LINK

  Thumnail image is returned via handler. First time all is OK. but when I do refresh, then istead of image is displayd some machine code in Firefox.

  I traced to root cause with Fiddler, it is because first time Content-Type comes correctly image/png

  but with refresh it is coming as text/html. what should be added, that after refresh browser still could get image/png? below is my code

  Bitmap target = new Bitmap(width, height);
                      context.Response.ContentType = "image/png";
                      
  
                      using (Graphics graphics = Graphics.FromImage(target))
                      {
                          graphics.CompositingQuality = CompositingQuality.HighSpeed;
                          graphics.InterpolationMode = InterpolationMode.HighQualityBicubic;
                          graphics.CompositingMode = CompositingMode.SourceCopy;
                          graphics.DrawImage(photo, 0, 0, width, height);
  
  
                          HttpCachePolicy cachePolicy = context.Response.Cache;
                          cachePolicy.SetCacheability(HttpCacheability.Public);
                          cachePolicy.VaryByParams["car_image_id"] = true;
                          cachePolicy.SetOmitVaryStar(true);
                          cachePolicy.SetExpires(DateTime.Now + TimeSpan.FromDays(365));
                          cachePolicy.SetValidUntilExpires(true);
  
                          using (MemoryStream memoryStream = new MemoryStream())
                          {
                              target.Save(memoryStream, ImageFormat.Png);
                              //cashing
  
                              using (FileStream diskCacheStream = new FileStream(cachePath, FileMode.CreateNew))
                              {
                                  memoryStream.WriteTo(diskCacheStream);
                              }
                              memoryStream.WriteTo(context.Response.OutputStream);
                          }
                          context.Response.End();
                          target.Dispose();

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  bbcompent1

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  Re: Thumbnail refresh

  Feb 13, 2012 08:22 PM|LINK

  I'm thinking you might need to have some of this inside a (!PageIsPostBack) because the second time the pages loads I doubt it is a full postback.

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  kvh

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  108 Posts

  Re: Thumbnail refresh

  Feb 13, 2012 10:54 PM|LINK

  this is HttpHandler and only thing here is "ProcessRequest". I tried adding Postback check, but got error "IsPostback does not exist in the current context".

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  bbcompent1

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  Re: Thumbnail refresh

  Feb 14, 2012 11:42 AM|LINK

  To get access to it, you have to do something like HTTPContext.Current or something like that.

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  • Marked as answer by Song-Tian - MSFT on Feb 17, 2012 08:32 AM