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Re: [css-writing-modes] Should a combined white space at the end of a line be removed?

From: fantasai <fantasai.lists@inkedblade.net>
Date: Tue, 14 Aug 2018 14:16:14 -0700
To: Yuki Sekiguchi <yuki.sekiguchi@access-company.com>, www-style@w3.org
Message-ID: <709a026b-7ec4-0d9a-2785-90cd74bb6f06@inkedblade.net>
On 08/13/2018 11:59 PM, Yuki Sekiguchi wrote:
> Hi,
> 
> I checked the following on Safari/Chrome/Firefox for macOS.
> http://jsbin.com/nocidux/edit?html,output
> <style>
>    #tcy {
>      border: solid 1px red;
>      text-combine-upright: all;
>      -webkit-text-combine: horizontal;
>    }
> </style>
> <div style="writing-mode: vertical-rl">
>    <span id="tcy"> </span>
> </div>
> 
> Safari shows the combined white space at the end of the line, but Chrome and Firefox don't show it.
> 
> Should the combined white space at the end of a line be removed?
> 
> It looks like Chrome and Firefox remove the combined white space to follow CSS 3 Text.
> https://drafts.csswg.org/css-text-3/#white-space-phase-2
>  > A sequence of collapsible spaces at the end of a line (ignoring any intervening inline box 
> boundaries) is removed.
> 
> However, Safari doesn't remove the combined white space because it should be considered as the 
> Object Replacement Character
> https://www.w3.org/TR/css-writing-modes-3/#text-combine-layout
>  > For other text layout purposes, ... the resulting composition is treated as a single glyph 
> representing the Object Replacement Character U+FFFC.
> 
> I guess that Chrome and Firefox consider White Space Processing as line breaking and follow:
>  > For line breaking before and after the composition, it is treated as a regular inline with its 
> actual contents.
> 
> I'm not sure if the removing is line breaking because the removing is done after line breaking.
> 
> Which is correct?

Wow, I don't know. From the specs you quote, it seems like Safari
is correct, but I'm not sure it makes sense.

It seems to me we did not consider what happens if there is white
space at the start/end of tate-chu-yoko in general, e.g.
   text <span id="tcy">tcy </span> text
Maybe such white space should always be trimmed? Probably the best
thing is to combine TCY before white space collapsing, and then
additionally trim the white space at the start/end of the TCY.

What do you think should happen?

~fantasai
Received on Tuesday, 14 August 2018 21:16:39 UTC

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