VML import: handle <v:imagedata gain="..." blacklevel="...">
Map it to (the UNO API of) GraphicDrawMode::Watermark, similar to what
the binary import does in SvxMSDffManager::ImportGraphic() and how the
drawingML import does it in
oox::drawingml::GraphicProperties::pushToPropMap().
On export, the drawingML export is used, and that already maps
GraphicDrawMode::Watermark to <a:lum bright="70000" contrast="-70000">.
(cherry picked from commit
90556b6df0f6378fb60d7dee18b2f5d275ece530)
Conflicts:
oox/qa/unit/vml.cxx
Change-Id: I33986a03bf3d3863da5c5b1f0a2e0da0fa595c9e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/126949
Tested-by: Jenkins CollaboraOffice <jenkinscollaboraoffice@gmail.com>
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>