[Libreoffice-bugs] [Bug 99497] an 'arc' saved in .docx becomes a filled closed shape

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=99497

--- Comment #9 from Regina Henschel <rb.henschel at t-online.de> ---
The "arc" and the "circleCut" are not custom-shapes, but legacy shapes from the
toolbar "ovals" or single commands. In ODF they are not draw:custom-shape
elements but draw:circle or draw:ellipse elements. The OOXML format has
nothing, which corresponds to this kind of shapes. Therefore export of them to
OOXML will always only be a workaround.

We have several options:

(A) Export "arc" as prstGeom with preset type "arc". The import of such shape
works.
That approach has some downsides.
* Saving such OOXML shape in ODF uses the command G, which is not yet in the
standard and requires a private namespace. The ODF 1.2 conform path does not
result in an "arc" geometry.
* The current formulas in ODF use 'logwidth' and 'logheight', which MS does not
interpret.
* The legacy "arc" is stored as draw:circle or draw:ellipse in ODF, not as
draw:custom-shape. But OOXML preset shapes are always imported as
custom-shapes.
* The export of OOXML reset shape type "arc" to doc does not work in current
LibreOffice.
* Another difference is, that the legacy "arc" does not allow filling, but the
OOXML preset shape "arc" allows filling, resulting in a sector.

(B) Export "arc" as custGeom in OOXML format including adjustment handles. The
geometry needs to be defined. The geometry can be defined so, that it is never
filled. Problem are roundtrips, because there exists no generic export from ODF
formula syntax to OOXML formulas, because ODF formulas a more complex. It would
be needed to find a way, to write application information so, that they are not
removed by MS Office, to be able to detect, that this shape comes from an
"arc".

(C) Export "arc" as custGeom in OOXML format without adjustment handles, with
command "arcTo". MS Office uses this, if it opens an ODF file with draw:circle
or draw:ellipse shape. That results in command G, if the file is resaved to ODF
by LO. Same roundtrip problems as in (B).

(D) Export "arc" as custGeom in OOXML format without adjustment handles with
Bézier-curves. Those exist in OOXML and ODF. Same roundtrip problems as in (B).

Export in VML format is no option. VML is outdated. Current MS Office supports
it only partly and only in compatibility mode. And roundtrip will not work,
because export of VML inside OOXML is buggy in LibreOffice.

I think, that it was no good idea, to have legacy shapes inside the
custom-shape floaters at all. They behave too different.

We might consider to add a shape, that is equal to that shape we use on import
of preset shape type "arc" from OOXML. Only that I would use an ODF 1.2 conform
enhanced-path in addition to the path with command G. The command G will be in
ODF 1.4 (I estimate in five years), not in ODF 1.3. An additional problem is
the export to doc, which currently does not work for an imported OOXML preset
shape of type "arc". For our own shape, we might use a similar export to doc
format as for the legacy shapes. All together a large task.

-- 
You are receiving this mail because:
You are the assignee for the bug.
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://lists.freedesktop.org/archives/libreoffice-bugs/attachments/20190718/128e5684/attachment.html>