sign problem with shear angle in transform matrix

[Regina Henschel]

Hi all,

the matrix, which is product by TRGetBaseGeometry and which is available 
as property "Transformation" in macros, is mathematically wrong, because 
the shear element has a wrong sign. What to do?
A) Convert the matrix into a mathematically correct one, where it is 
needed, e.g. in case it will be multiplied by another matrix.
B) Change core to use the mathematically correct matrix.
C) Other idea?

I've used approach A for now. See 
https://cgit.freedesktop.org/libreoffice/core/commit/?id=f44140bebb9c493d97ba5aef26c9692c53a6b93f 
and my new patch in https://gerrit.libreoffice.org/#/c/core/+/86244/
I think, because the property "Transformation" might be used by existing 
macros, it would not be good to change its content. Another reason is, 
that option B would require large changes (some work in Armins aw080), 
so that it should at least be accompanied by an expert developer.

Before I continue, I want to know, whether you think it is OK to use 
option A.

The attachment has an example to reproduce the problem.

Kind regards
Regina
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