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Re: [css-shapes][css-masking] <box>, <box+> and <box++>

From: Alan Stearns <stearns@adobe.com>
Date: Fri, 3 Jan 2014 22:35:38 +0000
To: Dirk Schulze <dschulze@adobe.com>, Tab Atkins Jr. <jackalmage@gmail.com>
CC: www-style list <www-style@w3.org>
Message-ID: <CEEC7B18.35776%stearns@adobe.com>
On 12/22/13, 4:27 AM, "Dirk Schulze" <dschulze@adobe.com> wrote:

>
>On Dec 20, 2013, at 10:10 PM, Tab Atkins Jr. <jackalmage@gmail.com> wrote:
>
>> On Fri, Dec 20, 2013 at 11:13 AM, Alan Stearns <stearns@adobe.com>
>>wrote:
>>> The <box> value is defined in CSS Backgrounds and Borders [1] to have
>>> three possible values (border-box, padding-box and content-box) for the
>>> background-clip property.
>>> 
>>> I’m adding margin-box to the <box> values in CSS Shapes [2]. This
>>>value is
>>> useful in shape-outside, but not useful for background-clip.
>>> 
>>> Dirk just added bounding-box (as a separate value) to clip-path [3].
>>>That
>>> value makes sense for that property, but isn’t terribly useful for
>>> shape-outside or background-clip. Should bounding-box be added to
>>><box> in
>>> CSS Masking, or stay separate?
>>> 
>>> Is there any issue with my adding margin-box to the <box> production
>>>when
>>> that value isn’t useful for background-clip? Is there anything special
>>>I
>>> should be doing with the <box> definition in CSS Shapes to reference
>>>the
>>> definition in CSS Backgrounds and Borders?
>> 
>> Hm, we can't just expand <box>.  margin-box doesn't work if the
>> element has collapsible margins (which shape-outside prevents, I
>> think?).  bounding-box does, but as you note, it's not really useful
>> for shapes or background-clip.  Plus, box-sizing basically uses <box>,
>> it just hasnt' been updated to actually use that grammar nonterminal
>> and instead lists the values explicitly.
>> 
>> I think the best solution is to just use <box> and manually add the
>> extra values you need in each situation.  If it's more convenient,
>> define a subterm like "<shape-box> = <box> | margin-box;", etc.
>
>For what it’s worth, I thought about supporting all boxes from
>shape-outside on clip-path as well (including margin-box). I think it
>would be good to define <shape-box>.

<shape-box> is now defined.

Thanks,

Alan

Received on Friday, 3 January 2014 22:36:21 UTC

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