Give me my drawing back! - The Document Foundation Wiki

Give me my drawing back!
Dragging your Visio, Publisher and CorelDraw files
to free-sofware world
Fridrich Štrba
Software Engineer, SUSE
1

Agenda
LibreOffice's contribution to wider
FOSS eco-system
Visio, CorelDraw, Publisher,...
Interesting parts of the reverseengineering
Incremental reverse-engineering
Evolution of file-formats observed
2

LibreOffice's contribution to wider
FOSS eco-system

Designed to be re-used
LibreOffice uses technologies available in the FOSS ecosystem
We love to give back and share the fruit of our sweat
Libwpg, libvisio, libcdr and libmspub
Standalone libraries
Using the same interface
Internal class generating SVG for lazy hackers :)
More users, more bug reports and (eventually) fixes
Reverse-engineering is by principle trial & error exercise
4

Visio Import filter - libvisio
Google Summer of Code 2011
Eilidh McAdam
Previous reverse-engineering work by re-lab's Valentin
Filippov
Started with Visio 2000 – Visio 2010 file-formats
LibreOffice 3.5 release
Visio 2000 and Visio 2002 – version 6 file-format
Visio 2003 to Visio 2010 – version 11 file-format
Extended in 2012 to ALL Visio file-format versions that ever
existed
Upcoming LibreOffice 4.0 release
Visio 2013 – OOXML-ish version (*.vsdx)
Visio 1 – 5
Visio XML Drawings (*.vdx)
5

The team
Valentin Filippov Fridrich Štrba Eilidh McAdam
6

CorelDraw import filter - libcdr
Work started in late 2011
Released in LibreOffice 3.6.x
Still improving
Valek's reverse-engineering work
cdr_explorer
Some of it reused in sk1 project, which is currently dormant
An interesting challenge after the success of libvisio
Continuation of a fruitful collaboration
Support for ALL CorelDraw file-formats
Starting from version 1 (code Waldo)
Ending by CorelDraw x6 released in March 2012
7

Microsoft Publisher Import filter - libmspub
Google Summer of Code 2012
Brennan T. Vincent
Flagship feature of LibreOffice 4.0
Reverse-engineering started by Valek Filippov
Completed in tandem.
Version support
MS Publisher 97
MS Publisher 98/2000
MS Publisher 2002-2013
8

Interesting elements:
Incremental reverse-engineering

Progressive development of file-formats
Nobody reinvents a wheel from scratch
It is useful to know the release dates of different versions when doing
reverse-engineering
Two subsequent versions of the same file-format will have many things in
common
Design parser to be able to parse lower and higher versions
Opened version conditions
Guard assumptions by exceptions and be verbose in debug mode
Try to parse lower or higher version using the existing parser
Fix issues as they appear
Importance of a small number of reference documents covering many
features
10

Extending the CorelDraw version coverage (1)
Departing point
Support for versions 7 to x3
Basically the knowledge from cdr_explorer
Extending the coverage upwards
x4 and x5
Support for RIFF documents inside structured ZIP storage
x6
More complicated structure inside the ZIP storage
Extending the coverage downwards
Version 6 (first 32-bit version)
Only some RIFF names different
Versions 4 and 5 (16-bit versions)
Different way to express coordinates
11

Extending the CorelDraw version coverage (2)
Extending the coverage downwards (cont'ed)
Version 3
First RIFF based CDR file-format
but we did not know it by then
Fill and outline information embedded inside the shape
Shape transform does not accumulate group transforms
Versions 2 and 1
Not RIFF based at all
Version 2 more structured
With some exception handling both can be parsed alike
A header with pointers to different sequences of chunks
Implementation of linked list (“type 1”) and shape information (“type 2”)
Embedded raster (“type 3” and “6”), group transforms (“type 7”),
arrow information (“type 8”),
12

Extending the Visio version coverage (1)
Departing point
Versions 6 and 11
Difference in some offsets and in text encoding
Common structure
A trailer pointing to “streams”
Some “streams” consist in a hierarchical sequence of “chunks”
Shapes and text content in “chunks”
Bug driven rewrite
A document (most likely generated by SDK)
Challenged completely our assumptions and led to more generalized
parser
13

Extending the Visio version coverage (2)
Microsoft Visio 2013 Preview
We wanted to support it before the official release
xml-based (ooxml-ish) file-format (*.vsdx)
Another rewrite of the parsers
Need to separate more clearly the parsing and information processing
Side-effect: support of Visio XML Drawing (*.vdx)
Versions 1 to 5
Some “chunks” of type list different
An override for readers of some chunks
“streams” format very similar
Little abstractions and generalizations needed
Improved understanding of the file-format
Cleaner and simpler parser
14

Getting involved ...
how you can make a difference

Future file-formats to import?
Google Summer of Code
The possibility for a student to work with outstanding
mentors
Valentin Filippov
Your faithful
(Altsys, Aldus, Macromedia & Adobe) Freehand
File-format partially reverse-engineered
The big lines of the structure
Ripe to be a successful project
A talented student can make difference in LibreOffice
16

Impact within LibreOffice and the known universe
Happy users will reward you
You will be the hero of the people who can now read their
documents...
… and they will get on your nerves listing features that are
not converted.
Users outside LibreOffice
Inkscape reuses libvisio and libcdr in 0.49
Calligra reuses libvisio and (possibly) libcdr since 2.5
17

QA and Stoning session
All text and image content in this document is licensed under the Creative Commons Attribution-Share Alike 3.0 License
(unless otherwise specified). "LibreOffice" and "The Document Foundation" are registered trademarks. Their respective logos
and icons are subject to international copyright laws. The use of these therefore is subject to the trademark policy.
18