Function lv_theme_default_init 

pub unsafe extern "C" fn lv_theme_default_init(
    disp: *mut lv_display_t,
    color_primary: lv_color_t,
    color_secondary: lv_color_t,
    dark: bool,
    font: *const lv_font_t,
) -> *mut lv_theme_t

Initialize the theme @param disp pointer to display @param color_primary the primary color of the theme @param color_secondary the secondary color for the theme @param dark @param font pointer to a font to use. @return a pointer to reference this theme later