[ 
https://issues.apache.org/jira/browse/PDFBOX-1000?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13182451#comment-13182451
 ] 

Maruan Sahyoun commented on PDFBOX-1000:
----------------------------------------

a) for the two parsing modes: relaxed lessens the requirements (e.g. an xref 
entry doesn't have to be 20 bytes long, but still there need to be three 
distinct parts of information number, number, usage flag) for parsing. For 
workarounds these will be part of the relaxed mode but the user will be 
informed where the default behaviors of relaxed mode will not be reported back. 
So I think we have the same understanding.
b) fine. I think that's something we can revisit later. After doing the parser 
I think I will have a much better understanding how PDFBOX works :-)

                
> Conforming parser
> -----------------
>
>                 Key: PDFBOX-1000
>                 URL: https://issues.apache.org/jira/browse/PDFBOX-1000
>             Project: PDFBox
>          Issue Type: New Feature
>          Components: Parsing
>            Reporter: Adam Nichols
>            Assignee: Adam Nichols
>         Attachments: COSUnread.java, ConformingPDDocument.java, 
> ConformingPDFParser.java, ConformingPDFParserTest.java, XrefEntry.java, 
> conforming-parser.patch, gdb-refcard.pdf
>
>
> A conforming parser will start at the end of the file and read backward until 
> it has read the EOF marker, the xref location, and trailer[1].  Once this is 
> read, it will read in the xref table so it can locate other objects and 
> revisions.  This also allows skipping objects which have been rendered 
> obsolete (per the xref table)[2].  It also allows the minimum amount of 
> information to be read when the file is loaded, and then subsequent 
> information will be loaded if and when it is requested.  This is all laid out 
> in the official PDF specification, ISO 32000-1:2008.
> Existing code will be re-used where possible, but this will require new 
> classes in order to accommodate the lazy reading which is a very different 
> paradigm from the existing parser.  Using separate classes will also 
> eliminate the possibility of regression bugs from making their way into the 
> PDDocument or BaseParser classes.  Changes to existing classes will be kept 
> to a minimum in order to prevent regression bugs.
> [1] Section 7.5.5 "Conforming readers should read a PDF file from its end"
> [2] Section 7.5.4 "the entire file need not be read to locate any particular 
> object"

--
This message is automatically generated by JIRA.
If you think it was sent incorrectly, please contact your JIRA administrators: 
https://issues.apache.org/jira/secure/ContactAdministrators!default.jspa
For more information on JIRA, see: http://www.atlassian.com/software/jira

        

Reply via email to