Move static n*Pixel* into properties container

Change-Id: I37d932ceabf50ffad2953d32309a668dbde1469f
Reviewed-on: https://gerrit.libreoffice.org/12485
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>