#cairo_user_data_key_t is used for attaching user data to cairo
data structures. The actual contents of the struct is never used,
and there is no need to initialize the object; only the unique
address of a #cairo_data_key_t object is used. Typically, you
would just use the address of a static #cairo_data_key_t object.
#cairo_user_data_key_t is used for attaching user data to cairo data structures. The actual contents of the struct is never used, and there is no need to initialize the object; only the unique address of a #cairo_data_key_t object is used. Typically, you would just use the address of a static #cairo_data_key_t object.