Re: [pygame] Re: loss of rapidly repeated keypresses (from a barcode gun keyboard)

[James Paige <Bob@xxxxxxxxxxxxxxxxxxx>]

On Wed, Dec 02, 2009 at 03:07:30PM -0600, Luke Paireepinart wrote:
>      3) Reading the SDL Mailing list, I learned that event loss when the
>      event queue is full is already a topic of discussion for SDL1.3
> 
>    I wouldn't think this is the issue you're running into, otherwise you'd
>    lose other characters too.  It sounds like there's some debouncing code in
>    the SDL keyboard input handler, which probably shouldn't be there...

Yes, that is right. "1234567890" never drops a single event, but 
"1111111111" almost always drops all but one or two events... although 
this behavior is strangely inconsistent. In my stripped-down mimimal 
test app, the events are lost almost 100% of the time. In my actual full 
aplication, the events are only ever lost on the first scan. Weird.

>    I'm sure you've already thought of this, but you could always just open
>    /dev/keyboard or whatever and manually post keyboard events yourself, or
>    just use the keyboard data directly...

I have no idea where to look for the usb keyboard device associated with 
the barcode scanner... and even if I could find it, I am fairly certain 
that my app would have to be running as root if I wanted to read 
directly fom it, so that would be unacceptable :(

>    And you could even roll this in to
>    a module so other people could use it too.  Might be hard to make it
>    cross-platform though and it sucks to have to completely throw out SDL's
>    keyboard event handling.  Also I don't know how you'd keep SDL from
>    posting repeated events, I guess you'd just create your custom events
>    under a different event ID and just watch for that ID instead.

Re-implementing my application in pygtk or wxpython sounds like a hell 
of a lot less work :)

>      4) I also discovered, while searching for a workaround, an SDL mailing
>      list post from Sam Lantinga last January mentioning a "simple callback
>      mechanism for SDL events that bypasses the event queue". Does anybody
>      know if there is a pygame way to make event callbacks?
> 
>    I don't know, but I'd guess it would be possible with Pygame-Ctypes.  But
>    I think Alex is no longer maintaining that module in preference to his
>    Pyglet module.

I did a quick test with Pyglet, and it suffers from the same problem. I 
take that to mean that using sdl event callbacks does not work around 
this problem.

---
James Paige