OFFICE 2049 custom shape enhancement

[Regina Henschel <regina.henschel@libreoffice.org>]

Hi all,

this comment is for https://issues.oasis-open.org/browse/OFFICE-2049 and 
result of my task to look, how LibreOffice handles lighten/darken.

Apache OpenOffice:
On import of a *.pptx file AOO keeps the information, which kind of 
preset shape it is. When converting to ODF format, it writes the kind of 
shape into the draw:type attribute, e.g. draw:type="quad-bevel". When 
the file is read later on, AOO depends rendering on the draw:type value. 
There exist no other information in the file. So if you change to 
draw:type="non-primitive" manually, the shape is rendered different, 
without lighten or darken.

LibreOffice:
When LO imports a *.pptx file and converts it to ODF format, then it too 
writes a specific attribute e.g. draw:type="ooxml-bevel". In addition it 
not only writes the attribute draw:enhanced-path, but an attribute 
drawooo:enhanced-path too.

In this own namespace the path has additional commands. LibreOffice uses 
H, I, J, K for the values darken, darkenLess, lighten, and lightenLess 
of the attribute "fill" of the "path" element in OOXML. The current 
implementation works already, but has some glitches.

SVG has nothing similar to lighten or darken, because in SVG the filling 
is not an attribute of the path, but it is only a style property. ODF 
refers to the commands in SVG path, but they are already different to 
ODF, e.g. ODF has not the distinction of upper and lower case and has 
the commands F and S, which you can use to exclude a subpath from fill 
or stroke. Therefore SVG is no obstacle for adding commands.

ODF should allow to keep and use those lighten/darken informations, 
which are possible in OOXML. That is needed for a better 
interoperability to OOXML.


The way LibreOffice does it, is one possible way to store those 
lighten/darken informations, which are possible in OOXML. With such 
additional path commands this feature is usable for all shapes with 
enhanced geometry.

Other ways I can think of:
(1) Specify a set of special draw:type values, which cover those shapes, 
which are contained in the file "presetShapeDefinitions.xml" of the 
OOXML standard. That way all consumers and producers of ODF whould use 
the same strings for those shapes. A disadvantage would be, that only 
this special preset shapes are treated. Other problems are mentioned in 
[OFFICE-2049], [OFFICE-1867] and the original mail 
http://lists.oasis-open.org/archives/opendocument-users/200601/msg00014.html
(2) Specify an additional attribute of the <draw:enhanced-geometry> 
element. Such attribute would carry a parallel list of fill information 
for the subpaths. Such attribute could take more information than 
lighten/darken, e.g. opacity would be possible or multiple colors.

There are three files attached, the original pptx file from PowerPoint 
2010 and the ODF files, which AOO and LO generate from the pptx. The 
shape type Bevel contains all four lighten/darken variants. The file has 
in the upper part three shapes and in the lower part an image of how it 
looks in PowerPoint.

Kind regards
Regina

Attachment: TypeBevel.pptx
Description: application/vnd.openxmlformats-officedocument.presentationml.presentation

Attachment: TypeBevel_resaved_by_AOO4.1.odp
Description: OpenOffice Impress presentation

Attachment: TypeBevel_resaved_by_LO54.odp
Description: OpenOffice Impress presentation