W3C home > Mailing lists > Public > www-style@w3.org > August 2010

Re: [css21][css3][svg] SVG and unit-less length values

From: Tab Atkins Jr. <jackalmage@gmail.com>
Date: Sat, 14 Aug 2010 10:27:25 -0700
Message-ID: <AANLkTi=Lo-6GXctB3=Vzc6R=+rgvR8MLRewuK-NVZCyU@mail.gmail.com>
To: Doug Schepers <schepers@w3.org>
Cc: "Dr. Olaf Hoffmann" <Dr.O.Hoffmann@gmx.de>, public-fx@w3.org, www-style@w3.org
On Sat, Aug 14, 2010 at 9:56 AM, Doug Schepers <schepers@w3.org> wrote:
> Hi, Folks-
> I was under the impression that it was not possible to render real-world
> units to uncalibrated monitors, and that most monitors are uncalibrated; am
> I mistaken or confused (maybe thinking of color calibration), or has that
> changed?

That is also true, more or less.  I'm not an expert at the arcane
details of the information exposed by various system APIs, but yeah, I
believe that at least a significant amount of the time you can't get
"true" information about the physical dimensions of the monitor, so
rendering a "true inch" is logically impossible for *any* program that
doesn't self-calibrate with a "hold a ruler up to the screen"-type

> Wouldn't it be possible to meet both use-cases by adding a property,
> something like 'unit-space':'realteive*|absolute', where the default is to
> use these abstracted units (for necessary bugwards compatibility), and the
> 'absolute' option would do its best to render the physical size as
> indicated?  This would be something like dealing with transforms or
> viewboxes.

That's been proposed, as has a parallel set of "true" physical units
that aren't tied to the definition of a pixel.

The basic issue is simply a question of how much anyone *cares*.
There doesn't seem to be much evidence that the current state of
affairs is bad enough to fix.  After all, the "bugwards compatibility"
that we're adding is simply a reflection of what every browser has
done for years; it's correcting the spec to match reality, not coming
up with something new.  If it was really a problem, we'd see authors
complaining about it.

So, since this is an issue that (a) only affects a limited class of
devices right now, and will disappear *completely* in the relatively
near future, and (b) authors don't seem to care about in the first
place, it doesn't seem like it's worthwhile to care about it.  As far
as I've been able to tell, the only concern that anyone has expressed
over it has been aesthetic, not practical.

Received on Saturday, 14 August 2010 17:28:21 UTC

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