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

From: fantasai <fantasai.lists@inkedblade.net>
Date: Wed, 16 Jul 2008 09:01:24 -0700
Message-ID: <487E1B54.2010000@inkedblade.net>
To: Bert Bos <bert@w3.org>
CC: www-style@w3.org

Bert Bos wrote:
> 
> 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.

(Well, they do. If their writing mode is different from their containing
block, they become inline-boxes.)

>>
>>>> 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.

Your diagram is wrong. It's not the direction of stacking that changes
for reverse lr, but the line boxes are effectively rotated 180deg. The
order is still left-to-right. So the direction for marquee-block doesn't
change, but the direction for marquee-line does. That is where your table,
as written, would be wrong.

~fantasai
Received on Wednesday, 16 July 2008 16:02:26 GMT

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