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Re: Flow of keystroke messages in a UI

From "Rod Pemberton" <boo@fasdfrewar.cdm>
Newsgroups alt.os.development
Subject Re: Flow of keystroke messages in a UI
Date 2015-12-27 15:51 -0500
Organization Aioe.org NNTP Server
Message-ID <op.yablj4i6yfako5@localhost> (permalink)
References (2 earlier) <murgth$uhm$1@dont-email.me> <op.x50ebanoyfako5@localhost> <mutvnl$9h9$2@dont-email.me> <op.x52adnz7yfako5@localhost> <n5om2t$cuc$1@dont-email.me>

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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:
>> On Mon, 05 Oct 2015 10:01:16 -0400, James Harris
>> <james.harris.1@gmail.com> wrote:
>>> On 05/10/2015 02:27, Rod Pemberton wrote:
>>>> On Sun, 04 Oct 2015 11:36:08 -0400, James Harris
>>>> <james.harris.1@gmail.com> wrote:

>>>>> say you are typing into a text-entry field. You
>>>>> might want:
>>>>>
>>>>> * V and Shift+V to be passed to the text-entry field
>>>>> * Control-V to trigger a Paste operation
>>>>> * Alt+V to be passed to the window to pull down the View menu
>>>>> * Windows+V to start an app
>>>>>
>>>>> That requires the different key combinations to be handled in
>>>>> different places, not just the widget which has focus. The
>>>>> component which receives the keystroke event will differ
>>>>> depending on what the event is.
>>>>> I was asking how a UI should control which events go to which
>>>>> components.
>
> 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 ... :-)

>> Isn't all of this just an issue of how you want to split the keyboard's
>> stream or filter it?
>>
>> I.e., send it forward and filter as it goes, send it backward and filter
>> as it goes, send it directly to the appropriate object or item, allow
>> multiple objects to access or not, etc.
>
> Yes, how to direct keystrokes is a big part of it. As I think you mean,
> the issue is whether to direct them down from general to more-detailed
> or vice versa.

Yes, it looks like that might've been what I meant. ;-)

> 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.)

> Each component could, potentially, get two chances to see and deal
> with the event. It sounds a pain but seems to be necessary.

Well, it would also allow for pre- and post-processing on the
same key.  E.g., key to maximize window passed down, window
maximizes, then low-level mouse hook detects the key and relocates
the mouse pointer to the text field, then key passed back on window
closed or minimization, then higher-level mouse hook detects the key
and restores the original mouse pointer position.

> 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'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.

>>>>> I guess I was asking if and how a GUI's messaging should be
>>>>> set up so that an app could not take over keys that the user might
>>>>> want to use for the GUI's windows.
>>>>
>>>> Perhaps, don't let the app have any access.  I.e., a text field is a
>>>> part of the OS, a widget is a part of the OS, a menu is a part of the
>>>> OS, etc.  If the app can only call a function for each of the menuing
>>>> elements, then the OS keeps control.  You're a strong propoent of
>>>> modularity anyway.  So, this should fit right in with your values. :)
>>>
>>> That sounds good but is it possible for the OS to keep control? Take
>>> the example above. If the OS launches a web browser and passes it things
>>> like Alt+ keystrokes for its own menus how can it prevent the browser
>>> then passing those keystrokes to an app the browser is running?
>>
>> 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?".  Do both
require message-passing? buffering?  Since it's been a while since this
thread was in my head, I don't recollect if I brought this up before.
I haven't reread the thread.


Rod Pemberton

-- 
The idea that sentient beings can be suppressed by a few simple
rules is a farce.  Even so, Isaac Asimov posited such rules for
sentient artificial intelligence.

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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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