when there is no chart background and the document mode is to use a dark color for the document color. The intent of this function is to get a color that can be seen against the background. So: a) Always get the background the text is to be rendered on. b) We can consult svtools::FONTCOLOR as a potential foreground color, but reject it if it will not contrast against the background Change-Id: If441050423750fdf0a12f07dd686daf8f7e8b165 Reviewed-on: https://gerrit.libreoffice.org/c/core/+/197109 Reviewed-by: Caolán McNamara <caolan.mcnamara@collabora.com> Tested-by: Jenkins