W3C home > Mailing lists > Public > www-style@w3.org > August 2014

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

From: John Daggett <jdaggett@mozilla.com>
Date: Mon, 18 Aug 2014 18:02:21 -0700 (PDT)
To: fantasai <fantasai.lists@inkedblade.net>
Cc: WWW International <www-international@w3.org>, www-style@w3.org
Message-ID: <1735646555.15446005.1408410141576.JavaMail.zimbra@mozilla.com>

fantasai wrote:

> > Not sure what the intended purpose of this text is but I guess the
> > first question is whether it's necessary or not.
> 
> We got requests to clarify when Arabic joining is broken or not
> broken at an inline boundary. For example, some implementations
> breaking joining even when there's no style change. This is clearly
> bad. As another example, in another implementation joining was
> preserved even when margin/border/padding was nonzero, which created
> problems for a set of inlined list items that were now pretending to
> be all part of the same word.

I don't think it's an easy task to come up with a good definition of whether shaping is broken or not at inline boundaries, at least not one that will actually be useful for implementations to use as a guideline. Better to consider what's optimal and what's not. Breaking at presentational style changes (e.g. color) shouldn't happen. But any property change that affects positioning (e.g. nonzero margin/border/padding) or alters an input to shaping will potentially affect the output of shaping. Whether it does or not will depend on underlying implementation details.

I'm not sure specifying this in great detail helps implementations that really need to understand the scripts that they are dealing with in the first place. Giving them general guidelines to follow is better I think.

Regards,

John Daggett
Mozilla Japan
Received on Tuesday, 19 August 2014 01:02:50 UTC

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