W3C home > Mailing lists > Public > public-fx@w3.org > July to September 2010

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

From: Dr. Olaf Hoffmann <Dr.O.Hoffmann@gmx.de>
Date: Sat, 14 Aug 2010 21:03:32 +0200
To: public-fx@w3.org, www-style@w3.org
Message-Id: <201008142103.33110.Dr.O.Hoffmann@gmx.de>
Doug Schepers:
> 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?
>
> 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.
>

At least on all my computers (Linux) the resolution is reported properly to
the X11 log - available for any program, therefore it should be no problem
to use this information as I can do it to determine, whether a program 
does it right or wrong in the SVG sense of a maximum deviation of
less than a device pixel ;o)
I think, it should be sufficient for a program to believe in what the
X server assumes, that this is correct might be the problem of
the X server or that of the monitor. Therefore to test an SVG viewer 
one has to test against the assumption of the X server, not
against a ruler. A test against a ruler is more useful to prove the
assumption of the X server -  the guess from the X server is ok for my
monitors.

I think, the problematic point is, that some (many?) authors do not 
understand the problem enough to fix it easily and those will 
typically not be able to add an additional information about what to 
do to fix their problem automatically. 
CSS (and SVG) have already a lot of units, CSS3 drafts
even more to avoid the problem to mix absolute and relative units.
Well, if some authors do not use such options, this causes obviously
problems at some end. 
But indeed, something, that can be called a solution of this 'author
understanding units' problem is something, that allows both use cases,
some scaling with device pixels/resolution and absolute units.
A mixture will be never completely under control of the author...

Olaf
Received on Saturday, 14 August 2010 19:04:08 GMT

This archive was generated by hypermail 2.2.0+W3C-0.50 : Saturday, 14 August 2010 19:04:08 GMT