keyboard bell woes (ignores xset)

Jeremy Huddleston jeremyhu at apple.com
Tue Mar 16 16:37:31 PDT 2010


I started looking into this because a user reported that XQuartz was still beeping in his xterm even though he uses 'xset -b' ... it turns out that xterm is using XkbBell() rather than XBell().  Even with 'xset -b', the audible bell is still calling DDXRingBell() with volume = 50...

I made a reduced test case that does:

XBell(dpy, 0);            // No beep with 'xset -b'
XkbBell(dpy, 0, 0, None); // Beep with vol=50 with 'xset -b'

shouldn't these be the same?


On Mar 16, 2010, at 15:30, Peter Hutterer wrote:

> On Tue, Mar 16, 2010 at 01:12:54PM -0700, Jeremy Huddleston wrote:
>> Actually, as I read this again, I noticed that it is behaving as per the spec:
>> 
>> XBell(dpy, 100) with base = 0:
>> base - [(base * percent) / 100] + percent = 0 - 0 + 100 = 100
>> 
>> XBell(dpy, 100) with base = 100:
>> base - [(base * percent) / 100] + percent = 100 - 100 + 100 = 100
>> 
>> So... this just seems a bit deceptive... if 'xset -b' is supposed to mute
>> the keyboard bell, why was XBell() designed to work around this?
> 
> I think you need to ask the question the other way round - why does 
> xset -b provide a functionality that XBell() can route around. I'm pretty
> sure XBell() was there first :)
> 
> Looks like to really disable the bell for core requests you need to call
> XkbSetControls() with the XkbAudibleBellMask. That way it can only be
> overridden by a forced XkbBell() request, not by any core requests.
> xset at this point doesn't do xkb but I don't se why it couldn't.
> 
> Cheers,
>  Peter
> 
> 
>> On Mar 16, 2010, at 11:47, Jeremy Huddleston wrote:
>> 
>>> I turn off the bell using 'xset -b' :
>>> ~ $ xset -q | grep bell
>>> bell percent:  0    bell pitch:  400    bell duration:  100
>>> 
>>> but when I do XBell(dpy, 100), the bell still rings at volume 100.
>>> 
>>> #0  DDXRingBell (volume=100, pitch=400, duration=100) at quartzAudio.c:223
>>> #1  0x0000000100138ba2 in CoreKeyboardBell (volume=100, pDev=0x115b708e0, arg=0x115b71100, something=0) at devices.c:498
>>> #2  0x0000000100105114 in XkbHandleBell (force=0 '\0', eventOnly=0 '\0', kbd=0x115b708e0, percent=100 'd', pCtrl=0x115b71100, class=0 '\0', name=0, pWin=0x0, pClient=0x115e11c00) at xkbEvents.c:514
>>> 
>>> Shouldn't the bell percent set by 'xset' be multiplied by the volume passed to XBell?  From XBell(3):
>>> 
>>> """
>>>      The XBell function rings the bell on the keyboard on the specified display, if possible.  The specified
>>>      volume is relative to the base volume for the keyboard.  If the value for the percent argument is not in
>>>      the range -100 to 100 inclusive, a BadValue error results.  The volume at which the bell rings when the
>>>      percent argument is nonnegative is:
>>> 
>>>             base - [(base * percent) / 100] + percent
>>> 
>>>      The volume at which the bell rings when the percent argument is negative is:
>>> 
>>>             base + [(base * percent) / 100]
>>> """
>>> 
>>> --Jeremy
> 
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