Building an online PDF editor from scratch

My talk at PyWaw #20.
http://www.pywaw.org/21-01-2013

Transcript

1. Building an online
   PDF editor from scratch
   PyWaw #20, 21.01.2013
   Zbigniew Siciarz @zsiciarz http://siciarz.net
   

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2. Why?
   

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3. Disclaimer
   • still not a full-blown editor
   • proof of concept
   • simple way to add rich media content to
   digital magazines
   

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4. Current status
   

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5. Links
   

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6. Multimedia
   

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7. Go to page
   

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8. Everything is a link
   • website URLs (d’oh!)
   • multimedia content (audio/video/galleries)
   • internal links („go to page”)
   • custom HTML5 widgets
   

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9. Workflow
   1. upload a PDF file
   2. preprocessing on the server
   3. add widgets, links etc.
   in web editor
   4. save and create package
   5. publish to mobile devices
   6. download package
   and display content
   Publisher
   

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10. Preprocessing
    • run asynchronously as a queued task
    • extract metadata from uploaded file
    • create page thumbnails (with ImageMagick)
    • find any existing links
    • mark as unpublished
    

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11. Keep existing links!
    • extract links with PyPDF2
    • store in database as PdfLink objects
    • display in web editor
    

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12. Dimensions and boxes
    • cartesian coordinate
    system
    • box is a list of 4 floats:
    [x1, y1, x2, y2]
    • PDF units = 1/72”= pt
    x
    y
    (0, 0)
    (x1, y1)
    (x2, y2)
    

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13. Dimensions and boxes
    • artBox
    

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14. Dimensions and boxes
    • artBox
    • bleedBox
    

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15. Dimensions and boxes
    • artBox
    • bleedBox
    • cropBox
    

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16. Dimensions and boxes
    • artBox
    • bleedBox
    • cropBox
    • mediaBox
    

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17. Dimensions and boxes
    • artBox
    • bleedBox
    • cropBox
    • mediaBox
    • trimBox
    

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18. Dimensions and boxes
    • artBox
    • bleedBox
    • cropBox
    • mediaBox
    • trimBox
    

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19. PDF Encryption
    

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20. Links
    • PDF annotations are messy
    • 4 (or more?) different
    representations
    • indirect objects
    all the way down
    • reversed coordinates
    • peculiar edge cases
    still not covered
    

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21. Watermarking
    • create blank PDF (watch
    out for page dimensions!)
    • draw links with ReportLab
    • cross your fingers
    • merge with original file
    

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22. Watermarking
    

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23. Merging
    + =
    

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24. Merging
    • PyPDF2 can’t properly merge PDFs with
    links :(
    • ReportLab can’t extract links from PDFs*
    • several hours wasted on hacking PyPDF2
    • pdftk…?
    • pdftk!
    *Open Source version
    

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25. Merging
    • apply watermark page by page to original
    PDF
    • does not work :(
    • works!
    

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26. Final package
    • encrypted PDF + media assets
    • digitally signed archive
    • publication = push notification to devices
    • mobile application downloads the package
    and displays content
    

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27. Conclusion
    • sadly, 3 different toolkits are necessary to
    get the job done
    PyPDF2 ReportLab pdftk
    Extract links Yes No* No
    Draw links No Yes No
    Merge and
    preserve links
    No No Yes
    *Open Source version
    

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28. ReportLab PLUS?
    • „ Reuse your existing pdfs in new and
    exciting ways”
    • might just work
    • pricey :(
    

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29. Appendix
    

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30. Appendix
    

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31. Credits
    • Businessperson designed by Devochkina
    Oxana from The Noun Project
    • Servers designed by Daniel Campos from
    The Noun Project
    • Maru - http://sisinmaru.blog17.fc2.com/
    

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32. Questions?
    

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33. Thank you!
    

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