MCGR: Border restoration support

Due to tdf#155362 I added code to be able in case we
would need it to convert a BGradient using added
tooling from having offsets in the GradientSteps
and no border to adapted GradientSteps and border.

This is preferrable due to our GradientStyle_RECT
(and GradientStyle_ELLIPTICAL too) use that 'non-
linear' paint aka move-two-pixels-inside, someone
else called it 'frame-paint'. This does not bode
well with the border being applied 'linear' at the
same time (argh). Thus - while in principle all is
correct when re-importing a GradientStyle_RECT
with a border after export to pptx, it looks
slightly better ('correcter') wen doing so. That is
because when being able to and restoring a border
at least that border part *is* applied linearly.

I took the chance to further apply tooling, move
it to classes involved and instead of awt::Gradient2
use more basegfx::BGradient since it can and does
host tooling. This is also a preparation to be
able to adapt (restore) border in case of turn-
around in ODF where the importing instance is before
MCGR existance and has to handle Start/EndColor.

Needed to take more care with using BGradient instead
of awt::Gradient2 for initialization, also better
dividing/organization of tooling, already preparation
to use for other purposes.

Change-Id: I2d3a4240a5ac6fff9211b46642ee80366dc09e3d
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/152194
Tested-by: Jenkins
Reviewed-by: Armin Le Grand <Armin.Le.Grand@me.com>

0 files changed, 0 insertions, 0 deletions