init static method
Implementation
static void init(BuildContext context, {required Size designSize}) {
final media = MediaQuery.of(context);
_screenWidth = media.size.width;
_screenHeight = media.size.height;
_textScaleFactor = media.textScaler.scale(1.0);
_scaleWidthFactor = _screenWidth / designSize.width;
_scaleHeightFactor = _screenHeight / designSize.height;
_initialized = true;
}