Pre-loads a font family and calculates font measurements for the family. This should generally be called in an item's load function so
that font data is loaded in preparation for dynamic font drawing. This will also be called at draw-time, but if the font is already
pre-loaded, this function will do nothing.
Parameters
fontFamily: string
the font family to load. Can be a single font name or a full CSS font stack
(e.g. "'Helvetica', 'Arial', sans-serif")
Pre-loads a font family and calculates font measurements for the family. This should generally be called in an item's load function so that font data is loaded in preparation for dynamic font drawing. This will also be called at draw-time, but if the font is already pre-loaded, this function will do nothing.