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Re: [css-round-display] Percentages of 'polar-distance' when origin is not the center of the containing block

From: Florian Rivoal <florian@rivoal.net>
Date: Thu, 28 Jan 2016 16:06:04 +0900
Cc: Brad Kemper <brad.kemper@gmail.com>, www-style list <www-style@w3.org>
Message-Id: <13EB6B05-30F4-4C4B-8C63-41817389573C@rivoal.net>
To: Jihye Hong <jh.hong@lge.com>

> On Jan 27, 2016, at 20:43, Jihye Hong <jh.hong@lge.com> wrote:
> 
>> On Jan 22, 2016, at 3:29 AM, Brad Kemper < brad.kemper@gmail.com > wrote:
>>> On Jan 20, 2016, at 11:01 PM, Jihye Hong <jh.hong@lge.com> wrote:
>>> 
>>> There is an action item[1] of CSS Round display from the last F2F
>>> meeting in Sapporo. It is about clarifying 'polar-distance'
>>> percentages when origin is not the center.
>>> 
>>> There could be 2 options for the definition of percentages :
>>> 
>>>   1. relative to the shortest distance between the origin of polar
>>> coordinates and edges of containing block.
>>>   2. relative to the distance from the origin of polar coordinates to
>>> edges of containing block.
>> 
>> #2 is as measured along the ray of the angle, right? That one seems
>> more useful to me (though the language would need to change if we use
>> alignment properties instead of polar origin).
>> 
>>> 
>>> Because of the fact that origin is not the center, the distance
>>> between the origin of polar coordinates and the edge of containing
>>> block vary according to the 'polar-angle' value.
>>> 
>>> In the first option, the 'polar-distance' value given by percentages
>>> is constant no matter which value the 'polar-angle' has.
>>> This case is satisfied with the directional consistency and avoiding
>>> circular dependency.
>> 
>> Can you give an example of when circular dependency is an issue?
> 
> Sorry, I used confusing expression, 'circular' dependency.
> 
> What I want to explain was, using the #2, the calculated value of the
> percentage polar-distance changes depending on the polar-angle value.
> There are some usecases when all the elements in a containing block have
> '50%' for polar-distance properties and the origin of polar coordinates
> isn't center.
> For #1 [1], all the calculated value of the percentage polar-distance of
> elements are same because they have same percentage values.
> But for #2 [2], the calculated distances between the each element and the
> origin point are different.
> 
> I couldn't find any usage of percentage for the property's value which has
> dependency on another properties.
> If there exists cases, then #2 seems to be appropriate, but if not, #1 or
> another way can solve this problem.

I see what you meant. Ultimately, we will need to deal with this dependency
to take care of "polar-distance: ***% contain", so I don't think it makes a huge
difference.

Speaking of which what use cases do we have for using polar-distance with a percentage
and not using contain? I'm wondering if we should make "contain" the default, or
possibly the only behavior for percentages.

 - Florian
Received on Thursday, 28 January 2016 07:06:36 UTC

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