From: Andrew Dunbar (hippietrail@yahoo.com)
Date: Tue Apr 23 2002 - 22:54:03 EDT
--- Paul Rohr <paul@abisource.com> wrote: > At 05:15
PM 4/23/02 +0100, Andrew Dunbar wrote:
> > --- Karl Ove Hufthammer <huftis@bigfoot.com>
> wrote: >
> >"Tomas Frydrych" <tomas@frydrych.uklinux.net> wrote
> >> in
> >> news:3CC58433.16110.B1F416@localhost:
> >>
> >> > I think in the case of the Arabic ligature,
> these
> >> have to be
> >> > treated as two characters, i.e., pressing
> >> backspace after the
> >> > second one leaves you with the first one. This
> >> case is not a
> >> > real issue, because internally the ligature is
> >> stored as two
> >> > separate characters, ligature is just a way of
> >> displaying in
> >> > them in a way that looks better,
> >>
> >> But how does selection works? Are the glyphs
> >> 'decomposed' to allow
> >> selection (which causes a reflow), and religated
> >> when you move the
> >> selection?
> >
> >Selection should select the entire ligature.
>
> Really? For the sake of a consistent user
> experience, shouldn't the
> following operations all have the same extent?
To the user, backspacing is different to selecting.
The user expects backspace to undo the key he just
pressed. He never expects it to undo two keypresses!
The user expects to select what he can see. He never
expects to select half a ligature. It's also
difficult to display graphically a half-selected
ligature and difficult for the user to understand
the display when we do come up with a way to do it.
I just tested Arabic selection in MSIE here:
http://www.aljazeera.net/ and selecting a lam+alef
ligature by keyboard or by mouse works as I've said.
> - backspace
> - extend selection one unit (shift-left arrow)
> - extend selection one unit (via the mouse)
If we were selecting with the keys there might be some
expectation for, say, shift-left to select just the
last keypress. But people don't mix typing,
backspacing and mouse selection on one word as they're
entering it.
> If backspace is going to decompose the ligature,
> then you're setting a UI
> expectation that the portions of that character are
> discrete units, so you
> also should be able to select, format, copy, and
> paste at the same level of
> granularity.
Maybe for an English language user. For Arabic users
they will expect it to work the way they are used to.
-- Okay I just tested MSWord too and it does do both
backspacing and selection by codepoint. For selection
it actually does it for both keyboard (incremental)
selection and mouse selection. I find it very
difficult to use with the mouse and reasonably
difficult to use with the keyboard. I prefer the way
MSIE works. So even MS are not consistent ):
> Thus, please make a case for one of the following:
>
> - backspace/selection are ligature-centric OR
> - backspace/selection are character-centric
>
> I'm not buying the argument that they should be
> different. Ick.
Well we should definitely not make both ligature-
centric. Making selection character-centric is a lot
of extra work IMHO...
> >Otherwise
> >we need a selection that can highlight half of a
> >ligature and I think this is too much to ask for
> too
> >little gain.
>
> Yep. That's what we'd need to implement. Doing the
> math for this may not
> be too hard, though. Two simple suggestions:
>
> 1. Take the width of the ligature and divide by the
> number of characters it
> represents. This might not be pretty, but the
> overall effect should be
> self-explanatory.
Umm no because you're assuming ligatures always have
two halves being on the left and the right. This is
not so! lam+alef do work this way, others such as
anything involving mim, or lam+jim have the two halves
displayed vertically. For Indian languages it gets
even more complicated. A vowel can actually have a
part drawn on the left of the consonant and a part
drawn on the right. I don't even know if the fonts
encode information that would make highlighting these
cases possible...
> 2. Take the widths of the "standalone" glyphs, and
> use them to
> proportionally subdivide the width of the
> ligature. However, I'm not
> sure whether the results would be "good enough"
> in real life. You'd
> have to test.
That wouldn't work at all. For example, alef is only
one pixel wide, lam and lam+alef are about the same
width.
> >I think MSWord does do it though ):
>
> OK, so this suggests that the local equivalent of
> the church secretary
> (gosh, what an American concept that is) already has
> an expectation about
> what it means for selections to Just Work here.
I thought so but after just testing MSIE and MSWord
(without an Arabic keyboard) I'm not sure. I think
we need to ask Arabic users - and if we don't have
any we should do what takes the least effort since if
we put in lots of effort and get it wrong it will be
a waste.
> Paul
>
> PS: How did this discussion move from the selection
> thread to the undo
> thread? Argh! All these posts are hard enough to
> keep track of as it is.
Once it's all been thrashed out, somebody can go
through them all and put the relevant bits in a
summary doc. I'd do it myself if I didn't have to
relay on cybercafes.
Andrew Dunbar.
=====
http://linguaphile.sourceforge.net http://www.abisource.com
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