Area reacting to events

[nbrr]

How can we proceed if we want a non-trivial area to react to an event? I'm thinking about something like a directional pad: you want a different direction to be triggered depending on where you tap it. We could keep in memory those items with a map similar to that used for blitting, e.g. the d-pad event zone would be described by 4 bmaps:

00100 00000 00000 00000
00100 00000 00000 00000
00000 00000 11000 00011
00000 00100 00000 00000
00000 00100 00000 00000

For example when there is a tap one could determine if it falls on the relevant area (add top-left coordinates to the bmaps) and check if it is expected to react.