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PostPosted: Fri Jul 06, 2012 8:12 pm 
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Joined: Fri Jul 06, 2012 7:59 pm
Posts: 1
It appears there is a bug in PdfImage.FaxEncode.cs. The "CountZeroBits" and "CountOneBits" does not properly detect the right edge in certain circumstances where the width is not divisible by 8. Basically it confuses the encoder so it thinks the current line is different length from the previous line.

I fixed it by replacing "return found + hits;" with the following code:

Code:
          found += hits;
          if (found >= bitsLeft)
              return bitsLeft;
          return found;



Code:
    private static uint CountOneBits(BitReader reader, uint bitsLeft)
    {
      uint found = 0;
      for (; ; )
      {
        uint bits;
        int @byte = reader.PeekByte(out bits);
        uint hits = OneRuns[@byte];
        if (hits < bits)
        {
          if (hits > 0)
            reader.SkipBits(hits);
          found += hits;
          if (found >= bitsLeft)
              return bitsLeft;
          return found;
        }
        found += bits;
        if (found >= bitsLeft)
          return bitsLeft;
        reader.NextByte();
      }
    }


Code:
    private static uint CountZeroBits(BitReader reader, uint bitsLeft)
    {
      uint found = 0;
      for (; ; )
      {
        uint bits;
        int @byte = reader.PeekByte(out bits);
        uint hits = ZeroRuns[@byte];
        if (hits < bits)
        {
          if (hits > 0)
            reader.SkipBits(hits);
          found += hits;
          if (found >= bitsLeft)
              return bitsLeft;
          return found;
        }
        found += bits;
        if (found >= bitsLeft)
          return bitsLeft;
        reader.NextByte();
      }
    }


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PostPosted: Mon Jul 09, 2012 8:46 am 
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Joined: Mon Oct 16, 2006 8:16 am
Posts: 2953
Location: Cologne, Germany
Thank you for your feedback, bug will be fixed with the next release.

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Thomas Hoevel
PDFsharp Team


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PostPosted: Thu Jun 05, 2014 8:38 am 
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Joined: Mon Jun 02, 2014 8:46 am
Posts: 1
I see the above code fix has not been integrated into the source. And there hasn't been a release since this was posted, coming up on 2 years ago.

Is the above fix problematic? We've encountered the same issue and the fix appears to resolve, but if it has not been committed to the source I am wary of why.


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PostPosted: Thu Jun 05, 2014 3:52 pm 
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Posts: 2953
Location: Cologne, Germany
Two years ago we thought we would publish a new release very dang soon.

We still want to publish a new release with improvements and bug fixes ASAP (I cannot give any EDA).

Nothing wrong with this correction in particular.

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Thomas Hoevel
PDFsharp Team


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PostPosted: Fri Mar 20, 2015 1:07 pm 
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Joined: Fri Mar 20, 2015 1:00 pm
Posts: 13
Is this fixed in 1.50 Beta?


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PostPosted: Sat Mar 21, 2015 9:10 pm 
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Joined: Wed Dec 09, 2009 8:59 am
Posts: 316
That bug should be fixed with 1.50 beta.

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Ă–hmesh Volta ("() => true")
PDFsharp Team Holiday Substitute


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