(PECL cairo >= 0.1.0)
CairoContext::deviceToUserDistance -- cairo_device_to_user_distance — Transform a distance
面向对象风格 (method):
$x
   , float $y
    )过程化风格:
   Transform a distance vector from device space to user space. This function is similar to
    CairoContext::deviceToUser() or cairo_device_to_user()
   except that the translation components of the inverse Cairo Transformation Matrix will be
   ignored when transforming (x,y).
  
context
     A valid CairoContext object created with CairoContext::__construct() or cairo_create()
x
     X component of a distance vector
y
     Y component of a distance vector
Returns an array with the x and y values of a distance vector in the user-space