Function is_rtl 

pub fn is_rtl() -> bool

Whether the app is being rendered right-to-left (docs/localization) — a convenience over layout_direction. The layout engine already mirrors widget placement under an RTL locale, but a canvas draws in its own coordinate space, so a custom drawing that has a reading direction (a battery that drains one way, an arrow, a progress sweep) can call this to mirror itself. Fixed for the life of the process, like layout_direction.