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

From: Brad Kemper <brad.kemper@gmail.com>
Date: Thu, 21 Jan 2016 10:28:50 -0800
Cc: www-style list <www-style@w3.org>
Message-Id: <74147551-42FB-441A-AD92-951C1C2B0329@gmail.com>
To: Jihye Hong <jh.hong@lge.com>

> 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?

> Otherwise, in the second option, the 'polar-distance' value given by
> percentages is affected by the value of 'polar-angle'.
> I think this may be useful for general usecases such as aligning elements in
> the egg-shape.

Agreed. I think you would need to add something about that length depending upon the border-radii (and maybe shape-inside or shape-outside) of the containing block. One would want to be able to follow the curve with many elements (such as clock numerals or minute markers) at the same distance from the curve. 

> Which could be more reasonable definition for 'polar-distance' percentages
> when origin is not the center?
> [1] https://www.w3.org/Style/CSS/Tracker/actions/731
> [2] https://drafts.csswg.org/css-round-display/#polar-distance-property
> Thanks,
> Jihye
Received on Thursday, 21 January 2016 18:29:22 UTC

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