This method is exported so package users can generate their own rules
cf_field_to_gtable( cf_field, xview, gridobj, unlocked, has_rownames, has_colnames )
A cf_field object. This is like a rule, but with the computed colour values. It usually maps one-to-one to a CSS field.
A data frame with the columns to be printed and rows filtered
The tableGrob object
A logical matrix of cells unlocked (that can still be modified by further rules).
Whether or not the gridobj has a first column with row names
Whether or not the gridobj has a first row with column names
A list with two elements: gridobj and unlocked (with updated values)