Screen Edges Advanced

_W = display.contentWidth -- Virtual width
_H = display.contentHeight -- Virtual height
_T = display.screenOriginY -- Top
_L = display.screenOriginX -- Left
_R = display.viewableContentWidth - _L -- Right
_B = display.viewableContentHeight - _T -- Bottom

virtual_actual_width = _R - _L -- Screen width in virtual coordinate system
virtual_actual_height = _B - _T -- Screen height in virtual coordinate system

screen_width = display.pixelWidth -- Device native width
screen_height = display.pixelHeight -- Device native height