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Re: [css3-marquee] Comments on Terminology and marquee-direction

From: Bert Bos <bert@w3.org>
Date: Tue, 15 Jul 2008 11:40:32 +0200
Message-Id: <200807151140.32491.bert@w3.org>
To: www-style@w3.org

fantasai wrote:
> Bert Bos wrote:

>> But why 'writing-mode'? 'Writing-mode' is too wide, it includes 
>> 'direction', which doesn't affect this definition.
> 
> Then remove the comment about what property it might be controlled by.
> I would rather not be over-precise here.

I try to say as little as possible in normative text, but I like to give 
some extra clues in notes. But I've removed the mention of any 
properties by name.


> CSS3 is likely to introduce other kinds of boxes, to which 'overflow'
> may or may not apply. Also it's possible that 'overflow' will soon
> apply to table-row-group elements. Not all of these boxes have line
> boxes that we can refer to, but they would if they were "display:
> block" 
> and had text content. That's why I think you should add that
> parenthetical. 
> To make sure that all boxes can be classified.

I've added "if its 'display' property were set to ''block'' and its 
content set to text." That's good enough for this module, but it is 
wrong in general, because it says that 'inline' boxes have a writing 
mode, too.

> 
> Also, going forward, it's likely that this Terminology section will be
> useful to other specs (such as multi-col, which also needs these 
terms)
> that advance to CR before CSS3 Text Layout is ready.

It's probably fine for multi-col, because that also only deals with 
blocks. But it is not so reader-friendly to make the multi-col module 
refer to the marquee module for some of its terminology.


> I am only suggesting to define "top-bottom" writing mode, which is
> what 
> we have in English.

OK, that makes sense. If I use the term top-bottom, I no longer need 
horizontal and vertical, which makes the text a bit shorter again.

> 
>>> marquee-direction
>>> -----------------
>>>
>>> The table here is only correct if we don't later add the ability to
>>> reverse-stack line boxes for horizontal and right-left writing modes
>>> or the ability to forward-stack line boxes for left-right writing
>>> mode. By reverse-stacking, what I mean is that the lines stack like
>>> they do in Mongolian, where if you took the box and turned it 90deg
>>> the English would either be laid out stacking top-to-bottom but with
>>> each line upside down or with the lines right-side-up but stacking
>>> bottom-to-top.
>>
>> Reverse stacking line boxes in CSS? If we ever add a thing like that, 
>> we'll have time enough to update the marquee module.
> 
> left-right writing mode reverse-stacks line boxes by default, because
> that's how English embedded in Mongolian reads. What will make your
> table wrong as-written is adding an option to forward-stack line boxes
> in left-right writing mode.

OK, so lr is "reverse" only from the point of view of English. That 
means that rl is reverse from the point of view of Mongolian. Fine.

We'll see if it is a good idea to add more properties to a module, Text 
Layout, that is already so difficult to understand, but as long as the 
properties don't put the first line box *between* the second and third, 
there is no problem for the marquee properties:

     1  2  3        3  2  1        3  2  1
     1  2  3        3  2  1        3  2  1
     1  2  3        3  2  1        3  2  1
     1  2  3        3  2  1        3  2  1
     1  2  3        3  2  1        3  2  1
     1  2  3        3  2  1        3  2  1
     1  2  3        3  2  1        3  2  1
     1  2  3        3  2  1        3  2  1

       lr         reverse lr         rl

but for the purposes of Marquee, the last two are the same:

     "left-right"  "right-left"  "right-left"

The marquee animation has to move in one of four directions. If this 
module doesn't define which direction that is, what does?

I can add the bottom-top to the table, for completeness sake, but other 
than that, the table is complete. No matter how many as yet unspecified 
properties reverse or restore the line stacking order, the result is 
always one of these four.



Bert
-- 
   Bert Bos                                ( W 3 C ) http://www.w3.org/
   http://www.w3.org/people/bos                               W3C/ERCIM
   bert@w3.org                             2004 Rt des Lucioles / BP 93
   +33 (0)4 92 38 76 92            06902 Sophia Antipolis Cedex, France
Received on Tuesday, 15 July 2008 09:41:12 GMT

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