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Re: Making pt a non-physical unit

From: Robert O'Callahan <robert@ocallahan.org>
Date: Thu, 14 Jan 2010 21:45:52 +1300
Message-ID: <11e306601001140045g7b27090dj50782ddb9b7eb4b@mail.gmail.com>
To: Giuseppe Bilotta <giuseppe.bilotta@gmail.com>
Cc: David Singer <singer@apple.com>, www-style <www-style@w3.org>
On Thu, Jan 14, 2010 at 9:05 PM, Giuseppe Bilotta <
giuseppe.bilotta@gmail.com> wrote:

> The question is, should the UA be left at guessing when the 'true'
> unit can/should be used, or should this be left in the hands of the
> designer?


The latter.


> In the latter case, do we want to introduce truein, truemm,
> etc or would it be enough to have some kind of at-rule or directive
> that specifies that lengths are true, physical lengths rather than
> logical?
>

> In the latter case, I was thinking about something along the lines of
> a directive reference-length that takes a unit of measure as argument.
> This would default to reference-length: px; for screen media,
> reference-length: in for print media.
> This could be extended to a syntax reference-length: css-length =
> true-length. For example, reference-length: 1in = 12in would mean that
> everything should be rendered so that 1 CSS inch covers a foot on the
> actual medium (to the best of the UA knowledge), while preserving the
> relationships between (CSS) px, pt, in, mm etc.
> Notice that for a computer monitor with a dpi known to the UA,
> reference-length: 1px = 1px (shortened to reference-length: px) and
> reference-length: 1in = 1in (shortened to reference-length: in) would
> give different results, as in the former case you'd get 1px = 1
> monitor pixel, while in the latter you'd have 1px = 1/96 physical
> inch.
>
> How does _this_ sound?
>

That sounds more complicated than just creating new units.

Rob
-- 
"He was pierced for our transgressions, he was crushed for our iniquities;
the punishment that brought us peace was upon him, and by his wounds we are
healed. We all, like sheep, have gone astray, each of us has turned to his
own way; and the LORD has laid on him the iniquity of us all." [Isaiah
53:5-6]
Received on Thursday, 14 January 2010 08:46:20 GMT

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