Re: [AD] New gfx api

[Chris <kcat@xxxxxxxxxx>]

Peter Wang wrote:
> I don't know how else to say it.  You don't have to handle any queues if 
> you don't want to.  There is a key[]-like mechanism already -- you just 
> can't access it without going through some synchronisation.  Similarly 
> for the mouse and joystick APIs.

Well, I guess I'll just have to wait and see the final implementaion 
then. I'm just getting more confused. Unless this is how you mean:

OS sends an event to Allegro (key pressed/released, mouse moved, etc). 
Allegro converts the OS event into an Allegro event. Allegro handles the 
event internally (updates the mouse position, key[]-mechanism, etc), 
then passes it to a user-installed event handler.

Is that close?

> > > And how is the key[] array any different?  It's still "polling" in 
> > > that sense.
> >
> > But with a key[] array, it's updated away from the main 
> > program/thread. So if I dereference the key array, wait a second, then 
> > dereference again it'll show the current keyboard state along with 
> > whatever changes happened within that second, not the last time you 
> > "took the snap shot". 
>
> Ok, so you don't like the one extra step.

Not that I have to do the one extra step, but the overhead associated 
with it I don't really care for.

> > If I have to continually refresh the keyboard state, it'll just bring 
> > more work into the main program. I'd prefer the main program not have 
> > to worry about refreshing the keyboard (or mouse or other device) 
> > state.. it should be done automatically.
>
> I know key[] is convenient for many programs, but passing information 
> between threads through global variables without any synchronisation is 
> just a bad idea.  I just couldn't think of a mechanism which is both 
> thread-safe _and_ as convenient.

As long as the variable is volatile and not read in the main thread, I 
don't see anything wrong with updating it in a seperate thread. At 
worst, the old data is "ghosted" in the main thread for a few nano 
seconds (if that).

- Kitty Cat