cairo:scaled-font (cr)

cr -- a cairo:context-t instance
font -- a cairo:scaled-font-t instance

The cairo:scaled-font function gets the current scaled font for the Cairo context. The (setf cairo:scaled-font) function replaces the current font face, font matrix, and font options in the Cairo context.

Except for some translation, the current transformation matrix CTM of the Cairo context should be the same as that of the cairo:scaled-font-t instance, which can be accessed using the cairo:scaled-font-ctm function.

This object is owned by Cairo. To keep a reference to it, you must call the cairo:scaled-font-reference function. This function always returns a cairo:scaled-font-t instance. If memory cannot be allocated, a special "nil" instance will be returned on which the cairo:scaled-font-status function returns the :no-memory value. Using this "nil" instance will cause its error state to propagate to other objects it is passed to, for example, calling the cairo:scaled-font function with a "nil" font will trigger an error that will shutdown the Cairo context.