[haiku-bugs] Re: [Haiku] #2053: returning B_SKIP_MESSAGE in my filter let capslocks get through anyway
- From: "leavengood" <trac@xxxxxxxxxxxx>
- Date: Thu, 02 Aug 2012 01:55:43 -0000
#2053: returning B_SKIP_MESSAGE in my filter let capslocks get through anyway
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Reporter: stpere | Owner: leavengood
Type: bug | Status: in-progress
Priority: normal | Milestone: R1
Component: Servers/input_server | Version: R1/pre-alpha1
Resolution: | Keywords:
Blocked By: | Blocking:
Has a Patch: 0 | Platform: All
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Comment (by leavengood):
Continuing my work on old tickets, I've looked into this more. As korli
says, the keyboard device manages the modifiers within itself and also
sends the B_MODIFIERS_CHANGED message which gets forwarded to filters by
the input_server. But by the time the filters get the message, it is too
late to stop the modifiers from being changed. Also I think in general Be
did not design this as the sort of message that can be stopped, it is just
informative.
In addition, the key down message which would turn on caps lock (or other
locks) cannot be intercepted or stopped before the modifiers are changed.
This is because the modifier handling is done before the key down
handling, and in addition there is not currently any way to stop the
keyboard device from getting a key press (which is probably a good thing.)
Given that the behavior wanted in this ticket is actually not bad
(avoiding accidental Caps Lock by requiring left shift held), I'd be up
for adding it as an optional feature. But since some people may not like
that, I also think this is possible to accomplish with the current system.
While looking around the source code to figure this out, I found the
set_keyboard_locks function in InterfaceDefs.h. I think that instead of
trying to stop the caps lock from being turned on, you can just
immediately turn it off with set_keyboard_locks if shift was not pressed.
I imagine it would happen so fast that the keyboard caps lock light might
not even turn on. In addition you could track the modifiers in your filter
and block B_MODIFIERS_CHANGED if nothing has changed except caps lock.
Given that stpere is now a Haiku committer I'll leave that exercise up to
you :)
I'll leave this ticket open for now, but please try this and let me know
if it works so we can close this.
--
Ticket URL: <http://dev.haiku-os.org/ticket/2053#comment:6>
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