Function rect_axis_visibility_rect 

pub fn rect_axis_visibility_rect(
    side: Side,
    rect: &RectF,
    axis: &AxisOptions,
) -> RectF

Axis line/tick interaction bounds when the axis runs on one edge of an arbitrary rectangle. The colourbar uses this with its painted strip rectangle, so a shortened, aligned, or freely offset strip and its axis chrome cannot acquire different interaction geometry.