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
2. Why?
3. Disclaimer • still not a full-blown editor • proof of concept • simple way to add rich media content to digital magazines
4. Current status
5. Links
6. Multimedia
7. Go to page
8. Everything is a link • website URLs (d’oh!) • multimedia content (audio/video/galleries) • internal links („go to page”) • custom HTML5 widgets
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
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• extract metadata from uploaded file • create page thumbnails (with ImageMagick) • find any existing links • mark as unpublished
11. Keep existing links! • extract links with PyPDF2 • store in database as PdfLink objects • display in web editor
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)
13. Dimensions and boxes • artBox
14. Dimensions and boxes • artBox • bleedBox
15. Dimensions and boxes • artBox • bleedBox • cropBox
16. Dimensions and boxes • artBox • bleedBox • cropBox • mediaBox
17. Dimensions and boxes • artBox • bleedBox • cropBox • mediaBox • trimBox
18. Dimensions and boxes • artBox • bleedBox • cropBox • mediaBox • trimBox
19. PDF Encryption
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
21. Watermarking • create blank PDF (watch out for page dimensions!) • draw links with ReportLab • cross your fingers • merge with original file
22. Watermarking
23. Merging + =
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
25. Merging • apply watermark page by page to original PDF • does not work :( • works!
26. Final package • encrypted PDF + media assets • digitally signed archive • publication = push notification to devices • mobile application downloads the package and displays content
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
28. ReportLab PLUS? • „ Reuse your existing pdfs in new and exciting ways” • might just work • pricey :(
29. Appendix
30. Appendix
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/
32. Questions?
33. Thank you!