Problems with import of shape type 'arc' from binary MS Office

Hi all,

I'm currently working on bug tdf#122899. It is about import of the shape 
'arc' (= mso-spt19 = mso_sptArc). I have already found one error and 
made https://gerrit.libreoffice.org/68941. This mail is about an 
additional 'position' problem.

MS Office uses for the ellipse a size of width=43200 and height=43200 in 
the shape internal coordinate system. It sets the viewbox so, that it is 
a bounding rectangle to the current sector. Thereby left/top of this 
rectangle becomes the origin.

Currently LibreOffice uses an ellipse size of width=21600 and 
height=21600 and a viewbox="0 0 21600 21600", so that the viewbox 
includes the entire ellipse.

Both in LibreOffice and Word the outer position (e.g. "horizontal 5cm 
from left page edge") is relative to the viewbox (which is the frame 
rectangle in LibreOffice).

The result of this is, that in case the bounding rectangle of the sector 
has a different left/top position than the bounding rectangle of the 
full ellipse, the shape gets a different position in Word than in 
LibreOffice. That breaks layout.

It is not possible to change the outer position to set the sector to the 
original position, because that might result in positions outside the 
page. But that is not possible for text documents.

I consider to change the import so, that the viewbox only includes the 
current sector not the entire ellipse. What do you think?

Kind regards
Regina