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RE: [css-text] Shaping Isolation and Layout Separation of Inlines

From: Stephen Zilles <szilles@adobe.com>
Date: Fri, 15 Aug 2014 04:19:48 +0000
To: fantasai <fantasai.lists@inkedblade.net>, 'WWW International' <www-international@w3.org>, "www-style@w3.org" <www-style@w3.org>
Message-ID: <2af17d7e62094100a179e57fa3990561@BN1PR02MB183.namprd02.prod.outlook.com>
This seems like a reasonable approach given the comments received on this list. More detail below
Steve  Z

> -----Original Message-----
> From: fantasai [mailto:fantasai.lists@inkedblade.net]
> Sent: Thursday, August 14, 2014 7:02 PM
> To: 'WWW International'; www-style@w3.org
> Subject: [css-text] Shaping Isolation and Layout Separation of Inlines
> 
> Proposal:
> 
>    Shaping is not broken across an inline element boundary unless:
> 
>      1. one of margin/border/padding are non-zero
> 
>      2. vertical-align is not 'baseline'
[SZ] It would seem to make more sense to say, "when the two elements to be shapeed have different vertical alignments". This is less specific to which baseline aligns and focuses more on the alignment of the elements.
> 
>      3. it is a bidi isolation boundary
> 
>    Note: This means that color changes, font changes, letterspacing
>    changes, etc. have no effect on shaping. Shaping might not result
>    in the glyphs joining correctly, but will nonetheless choose the
>    correct form of the letter (initial, medial, final, isolated).
[SZ] This would be more easily understood if it said, "Shaping will choose the correct form of the letter (initial, medial, final, isolated), but it might not result in the glyphs joining correctly."
> 
> Rationale:
[SZ] I had trouble understanding these bullets until I realize that they are matched to the rules above. Perhaps, saying "Rationale (for the above rules using the same numbering):"
> 
>    1. This provides visual separation. Authors will not expect
>       text across such a boundary to combine.
>        -> A sample use case is inlinifying a list.
> 
>    2. This provides visual separation. Authors will not expect
>       text across such a boundary to combine, nor is it useful.
>        -> A sample use case is superscripts or subscripts.
> 
>    3. This describes a logical separation. I can think of no
>       use case where a bidi isolation boundary would not also
>       coincide with a shaping isolation boundary.
> 
> Thoughts?
[SZ]  With respect to John D's comment and the comments on this list earlier, I think that it was established that font change should not stop joining even if it might make the result unpleasant. I think that simple rules that work most of the time are better than trying ot be capture every small case.
> 
> ~fantasai and TJ
> 

Received on Friday, 15 August 2014 04:20:18 UTC

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