Re: [AD] ex_joystick_hotplugging.c

[Peter Hull <peterhull90@xxxxxxxxxx>]

On OSX it should be possible to use IOServiceAddMatchingNotification
to register a callback when a device is added/removed. It might not be
that exact function; I have used that one to match a particular
VID/PID device but in this case we would want it to trigger on
anything in the HID class.

Pete


On Sun, Aug 22, 2010 at 7:54 AM, Peter Wang <novalazy@xxxxxxxxxx> wrote:
> On 2010-08-21, Trent Gamblin <trent@xxxxxxxxxx> wrote:
>> On 2010-08-21, at 6:39 PM, Peter Wang wrote:
>> > Hi,
>> >
>> > I still think it's a bad idea that al_get_num_joysticks can now
>> > invalidate existing ALLEGRO_JOYSTICK structures.
>>
>> Yeah, I agree.
>>
>> > curr_joy is invalid at this point.
>> >
>> > It crashes when I unplug a joystick.  (I will fix it while fixing some
>> > issues with the linux joystick driver)
>>
>> Alright. I wanted to get it into SVN because I have
>> other commitments that aren't going to leave me much
>> time to tune this how I'd like right now. I think the
>> issues are pretty minor and shouldn't be too hard to
>> fix.
>
> Ok.  The Linux joystick driver is much improved now.
> The other drivers seem to require similar changes.
>
>
> I think we should not require Allegro programs to put in extra effort to
> cope with hotplugging.  Anything that requires the program to remember
> an old id/index/whatever, in addition to ALLEGRO_JOYSTICK handles, is
> too much work.  I have a feeling most programs wouldn't bother.
>
> Rather, ALLEGRO_JOYSTICK handles should persist after reconfiguration,
> and they should continue to refer to the same physical devices (which
> are still plugged in).  No re-getting of handles required.
>
> Handles for devices which have been unplugged should *also* persist, so
> nothing will crash.  Inactive handles should be reused when devices are
> plugged in.  That would make this common situation just work:
> if I pull out device A during a game and plug in device B, I probably
> wanted to use device B in place of device A.  Since the old
> ALLEGRO_JOYSTICK handle is valid, a program that doesn't do anything
> special will work as expected.
>
> We can add a function:
>    bool al_get_joystick_active(ALLEGRO_JOYSTICK *joy);
> to tell if the handle has a physical device associated with it.
>
> Comments?
>
> Peter
>
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