Some might be wondering why the Visio import filter project is so quiet. But the answer is easy: we were busy as bees adding new features.
You might remember my blog about the bounding box of an elliptical arc. It is because Eilidh added the support of elliptical arcs into libvisio. And then we discovered that LibreOffice did not support elliptical arcs in the path at all, just ignored them. Fortunately, there was this patch of a hacker extraordinaire, Thorsten that was used to teach LibreOffice some sane behaviour.
Eilidh implemented further the conversion of gradient fill and with this and the support of elliptical arcs, this Visio document:
looks in Draw pretty well:
You will realize that we do not support text in Visio documents yet, but be assured that it is now our top priority feature. It is also worthy to note that the above-mentionned document is actually a document in Visio file-format 6 (used by Visio 2000 and Visio XP). We refactored libvisio the way that our support of both version 6 and 11 is equivalent. Moreover, we implemented two-pass parsing of Visio documents which allows us to draw shapes in a correct order and position them accurately.
In the same line, Eilidh implemented reading of NURBS, which is pretty tedious since the conversion must be done by approximation, since neither ODF, nor SVG support this kind of non-uniform rational basis splines. For the while, we are approximating them with 50 lineto segments for one spline, but it is our intention to use a serie of smooth cubic splines to achieve as much visual similarity as possible.
The libvisio library now is able to position correctly any point even if it is in a rotated shape that is part of a group rotated differently, which also might be part of another group with a diferent transformation. This allows us to load this Visio document:
in Draw this way:
You can see some graphic problems. The missing shapes are polylines that we will very soon correctly support. Nevertheless, this could be another one of my "we all love ODF, but ..." blogs, because some of the visual glitches are given by the fact that OpenDocument Graphics (ODG) file-format is suboptimal for representing more complex drawings. One is not even able to specify fill-rules or rules of polygon clipping. Clerly, this SVG inside XHTML version, converted using the vsd2xhtml tool, that is part of the libvisio library, is much closer to the original:
So, a bottom line is that the project is well alive and kicking. We even tagged the second alpha release and the tarball is now what LibreOffice master build is using. So, if you build your LibreOffice yourself, you will be able to enjoy the fruits of the work or Eilidh's hands and — why not — even start to contribute to this cool and interesting project.
Stay tuned for more news soon ...
