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Read width & Height of jpeg file

Scheduled Pinned Locked Moved C#
data-structuresbeta-testingquestion
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  • L Luc Pattyn

    I have now tried with Visual Studio 7.1 and it behaves identically: return without break is fine, return+break gives warning. :)

    Luc Pattyn [My Articles] [Forum Guidelines]

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    Alaric_
    wrote on last edited by
    #21

    ...same in Visual C# 2005 Express

    Welcome my son...Welcome..to the Machine

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    • A Alaric_

      ...same in Visual C# 2005 Express

      Welcome my son...Welcome..to the Machine

      L Offline
      L Offline
      Luc Pattyn
      wrote on last edited by
      #22

      Well, that's a small mystery, one we will not solve easily, but I guess you can live with it ? Anyway, I trust you got the code up and running... :)

      Luc Pattyn [My Articles] [Forum Guidelines]

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      • L Luc Pattyn

        Well, that's a small mystery, one we will not solve easily, but I guess you can live with it ? Anyway, I trust you got the code up and running... :)

        Luc Pattyn [My Articles] [Forum Guidelines]

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        Alaric_
        wrote on last edited by
        #23

        yeah, I can live with it...I'm having a new problem though:

        if (code != 0xFF) throw new ApplicationException(
        "Unexpected value in file " + filename);

        throws ....code equaled 216. What exactly is that check for? Do you know what the value of 216 means in this context? The first pass through, "code" was 255, then the next value was ...[Fixed it before I finished the post] ...Since the only thing I'm wanting to do is determine the width & height of the file, I just place a check for them inside the code check so it's now looking for

        if(code != 0xFF && width == 0 && height == 0)
        {
        throw;
        }

        so now it will only throw if the width & height haven't been set yet..if they've been set, then I simply break when the code is not 0xFF. ...Is 0xFF like a key value for the header or something like that?

        Welcome my son...Welcome..to the Machine

        L 1 Reply Last reply
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        • A Alaric_

          yeah, I can live with it...I'm having a new problem though:

          if (code != 0xFF) throw new ApplicationException(
          "Unexpected value in file " + filename);

          throws ....code equaled 216. What exactly is that check for? Do you know what the value of 216 means in this context? The first pass through, "code" was 255, then the next value was ...[Fixed it before I finished the post] ...Since the only thing I'm wanting to do is determine the width & height of the file, I just place a check for them inside the code check so it's now looking for

          if(code != 0xFF && width == 0 && height == 0)
          {
          throw;
          }

          so now it will only throw if the width & height haven't been set yet..if they've been set, then I simply break when the code is not 0xFF. ...Is 0xFF like a key value for the header or something like that?

          Welcome my son...Welcome..to the Machine

          L Offline
          L Offline
          Luc Pattyn
          wrote on last edited by
          #24

          Hi, the FF-check is for protection (I want the code to fail on something that isnt a JPEG at all!); so far all valid packets have a two-byte code that looks like 0xFFXX, and my code did return as soon as size was seen; you should not continue scanning the file after that ! (typically the size info is in the first few % of the file, and the scanner as is probably is unable to handle everything that might follow it). If there is any more trouble, please publish the entire method again. If you think there are some valid JPEG files that my code does not handle well, then mail me one or two of them. :)

          Luc Pattyn [My Articles] [Forum Guidelines]

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          • L Luc Pattyn

            Hi, the FF-check is for protection (I want the code to fail on something that isnt a JPEG at all!); so far all valid packets have a two-byte code that looks like 0xFFXX, and my code did return as soon as size was seen; you should not continue scanning the file after that ! (typically the size info is in the first few % of the file, and the scanner as is probably is unable to handle everything that might follow it). If there is any more trouble, please publish the entire method again. If you think there are some valid JPEG files that my code does not handle well, then mail me one or two of them. :)

            Luc Pattyn [My Articles] [Forum Guidelines]

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            Alaric_
            wrote on last edited by
            #25

            yeah...I didn't remove the return from your case code, but it was definitely not hitting it, which is extremely odd. ...It was definitely continuing past the point that it determined the width & height, which is why doing the assignment checks for width & height automagically switched the block. I'll look into what I did when I get home from work...and I'll post a screenshot of what I got completed.

            Welcome my son...Welcome..to the Machine

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