and simplify some of the calculations that needed to be changed.

Which resulted in one unit test needing to change by one pixel,
let's hope not an indication of a real problem.

Change-Id: Ie56434f35f4e58d21ee6f671392e93dc7542fca3
Reviewed-on: https://gerrit.libreoffice.org/42240Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>