Fluorite has the right identification, though is missing some information.
Holloway's Moths of Borneo series, in this case the combined parts 15 & 16 issued late last year (Malayan Nature Journal58: 1-529) gives the distribution of Grammodes geometrica as "Mediterranean east to Oriental and Australasian tropics". I think it must occur in Taiwan as (if I recall correctly from my ailing memory) it is figured by H-Y Wang in his series of Illustrated Insects of Taiwan.
It's not regularly seen in Hong Kong - just a few records, so could possibly be migratory.