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Groups > alt.os.development > #9066

Re: Flow of keystroke messages in a UI

From James Harris <james.harris.1@gmail.com>
Newsgroups alt.os.development
Subject Re: Flow of keystroke messages in a UI
Date 2016-01-03 12:08 +0000
Organization A noiseless patient Spider
Message-ID <n6b2r2$jj9$1@dont-email.me> (permalink)
References (3 earlier) <op.x50ebanoyfako5@localhost> <mutvnl$9h9$2@dont-email.me> <op.x52adnz7yfako5@localhost> <n5om2t$cuc$1@dont-email.me> <op.yablj4i6yfako5@localhost>

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On 27/12/2015 20:51, Rod Pemberton wrote:
> On Sun, 27 Dec 2015 07:40:17 -0500, James Harris
> <james.harris.1@gmail.com> wrote:
>
>> On 06/10/2015 02:57, Rod Pemberton wrote:

...

>> Sorry for delayed replies.  I have been caught up with other things
>> and have done very little on this.
>
> That's OK.  After three months, I just assumed you were hit by one
> of those city buses.  But, I didn't feel any permanent disturbance
> in the force, so I assumed you were OK ... :-)

[OT] A quick summary: Three main issues have distracted me from the 
normal IT stuff: 1) A dispute with the local council about a so-called 
traffic infraction. 2) The issue of UK independence from the European 
Union - resulting in time spent on Twitter and looking at setting up a 
new web site and delivery system - not done yet. 3) Selling my old Aga 
cooker. When it was dismantled it resulted in large quantities of dust 
being spread around the house and getting onto floors, surfaces and into 
clothes, towels etc. Some of it is still invisibly present in the air 
despite lots of cleaning. I cannot confirm without a specialist's 
analysis but it is worrying as the dust likely contains asbestos.

The bottom line is being distracted with other things and not having 
much time left to think about the normal IT issues we discuss here.

...


>> One of the few things I have worked out since my last post is that
>> I would need to support both: down first to the most specific then,
>> if not handled, back up.
>
> Ok.
>
> (FYI.  By "down first," did you mean sent directly to the first, or
> passed down through others to the first?  I've assumed the latter here.)

I meant "down" as in "drill down" from general to specific. Events would 
have to flow down to target widgets then back up. Any container or the 
final widget could stop the event propagating further. The HTML DOM 
works that way so there is a precedent.

 
http://stackoverflow.com/questions/4616694/what-is-event-bubbling-and-capturing

...


>> IIRC it turned out that in a browser environment Mozilla initially
>> supported flowing down from general to specific and Microsoft supported
>> flowing up from specific to general. Some people call the two forms of
>> event flow "capture" and "bubble" respectively.
>
> Interesting terminology.  Which do you think works better?

I think both mechanisms are needed. I don't think either of the terms is 
very good.

> I've used both.  IE for a decade.  MF for a few years now.  At the
> moment, I don't recollect much functional difference.  Both seemed
> to be responsive to the user.  Maybe, I'll recall something later.
>
> Obviously, there is no point in wasting processor time to do things
> which may be unneeded.  So, I'd personally go with whichever is more
> direct, unless there is an important reason to choose something more
> complicated.

IIRC, at least in JavaScript, a widget/container has two chances to 
capture an event: on the way down and on the way back up, and that the 
JavaScript event registration call assumes "up" by default.

...

>>> Does the OS control all the ways the "app the browser is running" can
>>> use those keys?  If yes, i.e., if the OS controls the input boxes/fields
>>> even though the app is using them, then there is nothing more to do.
>>> If no, then the stream would need to be filtered or split so that the
>> "app the browser is running" won't receive them.
>>
>> That's valid. I don't know yet whether it is feasible that the OS would
>> always have full control or not, but that would be preferable.
>>
>
> If that's so, then I think the next question is: "Is the app required to
> request input from the OS or does the OS send it to the app?".

AIUI, with an event-driven program the widgets typically tell the UI 
what they are interested in and then the UI tells the registered 
functions when one of those events occurs. But the app could also have a 
main loop which receives every event and decides itself where to direct 
it or what to do with it.

 > Do both require message-passing? buffering?

I don't know about "require" but I think message passing is a good model 
for this.

James

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Thread

Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-02 11:42 +0100
  Re: Flow of keystroke messages in a UI Bernhard Schornak <schornak@web.de> - 2015-10-02 20:43 +0200
    Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-04 15:23 +0100
      Re: Flow of keystroke messages in a UI Bernhard Schornak <schornak@web.de> - 2015-10-05 17:38 +0200
  Re: Flow of keystroke messages in a UI "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-10-02 17:17 -0400
    Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-04 16:36 +0100
      Re: Flow of keystroke messages in a UI "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-10-04 21:27 -0400
        Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-05 15:01 +0100
          Re: Flow of keystroke messages in a UI "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-10-05 21:57 -0400
            Re: halting Adobe Flash videos with Mozilla Firefox, was [Re: Flow of keystroke messages in a UI] "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-10-26 04:35 -0400
            Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-12-27 12:40 +0000
              Re: Flow of keystroke messages in a UI "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-12-27 15:51 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-03 12:08 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-03 14:55 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-13 17:58 +0000
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-15 11:32 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-16 03:29 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-16 13:44 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-16 12:55 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-16 19:55 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-18 07:39 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-18 22:45 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-19 22:28 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-27 13:27 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-27 17:20 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-28 11:03 +0000
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-22 17:43 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-01-23 13:17 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-27 13:42 +0000
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-04-08 09:14 +0100
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-02-14 09:56 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-14 09:11 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-02-14 15:58 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-15 05:55 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-02-15 15:57 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-16 05:33 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-02-24 06:16 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-24 18:03 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-02-28 06:25 +0000
                Re: Flow of keystroke messages in a UI "Alexei A. Frounze" <alexfrunews@gmail.com> - 2016-02-28 00:21 -0800
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-02-28 08:45 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-28 20:40 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-03-02 14:49 +0000
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-02 21:50 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-03-05 06:09 +0000
                OT politics was Re: Flow of keystroke messages in a UI "Kerr Mudd-John" <admin@127.0.0.1> - 2016-03-05 12:40 +0000
                Re: OT politics was Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-05 20:11 -0500
                Re: OT politics, was [Re: Flow of keystroke messages in a UI] Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-05 20:11 -0500
                Re: OT politics, was [Re: Flow of keystroke messages in a UI] James Harris <james.harris.1@gmail.com> - 2016-03-17 16:35 +0000
                Re: OT politics, was [Re: Flow of keystroke messages in a UI] Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-17 21:02 -0400
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-24 20:09 -0500
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-02-25 14:55 +0000
                Re: Flow of keystroke messages in a UI "Alexei A. Frounze" <alexfrunews@gmail.com> - 2016-02-16 03:56 -0800
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-17 04:21 -0500
                Re: Flow of keystroke messages in a UI "Alexei A. Frounze" <alexfrunews@gmail.com> - 2016-02-24 02:12 -0800
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-24 18:03 -0500
                Re: Flow of keystroke messages in a UI "Alexei A. Frounze" <alexfrunews@gmail.com> - 2016-02-28 02:53 -0800
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-02-28 20:15 -0500
                Re: Flow of keystroke messages in a UI "Alexei A. Frounze" <alexfrunews@gmail.com> - 2016-03-27 20:37 -0700
                Re: Flow of keystroke messages in a UI Rod Pemberton <NoHaveNotOne@bcczxcfre.cmm> - 2016-03-28 18:23 -0400
                Re: Flow of keystroke messages in a UI "Alexei A. Frounze" <alexfrunews@gmail.com> - 2016-03-27 21:10 -0700
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-15 14:34 +0000
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2016-01-15 15:10 +0000
        Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-05 15:39 +0100
  Re: Flow of keystroke messages in a UI "wolfgang kern" <nowhere@never.at> - 2015-10-03 12:48 +0200
    Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-04 17:00 +0100
      Re: Flow of keystroke messages in a UI "wolfgang kern" <nowhere@never.at> - 2015-10-04 23:32 +0200
        Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-05 14:05 +0100
          Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-05 15:17 +0100
            Re: Flow of keystroke messages in a UI "wolfgang kern" <nowhere@never.at> - 2015-10-06 10:35 +0200
              Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-06 16:28 +0100
                Re: Flow of keystroke messages in a UI "wolfgang kern" <nowhere@never.at> - 2015-10-06 19:14 +0200
                Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-10-06 20:02 +0100
          Re: Flow of keystroke messages in a UI "wolfgang kern" <nowhere@never.at> - 2015-10-06 10:46 +0200
            Re: Flow of keystroke messages in a UI "Rod Pemberton" <boo@fasdfrewar.cdm> - 2015-10-07 01:16 -0400
            Re: Flow of keystroke messages in a UI James Harris <james.harris.1@gmail.com> - 2015-12-27 12:50 +0000
              Re: Flow of keystroke messages in a UI "wolfgang kern" <nowhere@never.at> - 2015-12-27 23:22 +0100

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