W3C home > Mailing lists > Public > www-style@w3.org > February 2012

Re: [css3-values] Physical length units

From: Felix Miata <mrmazda@earthlink.net>
Date: Wed, 22 Feb 2012 20:44:16 -0500
Message-ID: <4F4599F0.6070000@earthlink.net>
To: www-style@w3.org
On 2012/02/23 00:54 (GMT) Linss, Peter composed:

> 1) CSS px units are now defined as 96px per 1in. That's not going to
> change. Neither is the ratio between 'in' and 'cm'.

> 2) CSS has physical length units, and always has. They're called 'in',
> 'cm', 'pt' and the like.

Those are unfortunate misnomers as long as they are presumptively logical 
rather than physical as dictated by the 96px=1in specification.

> If they don't get rendered at all times at 1in = 1 inch, that's a UA issue

Until UAs hard-coded 96px=1in, those who needed 1 logical inch to equal 1 
physical inch could configure for that to be the case. And, using only the 
latest browser versions, they still can, except for the portion of the screen 
within the confines of a current version browser's viewport.

Those using older versions of some browsers, and those using only suitably 
styled pages (sized in mozmm units) loaded into the latest Gecko browsers, 
still can have accuracy across 100% of their non-96ppi displays.

> There's quite often no good way for the UA to know the
> exact physical properties of the screen that's being used to view the
> content.

It needn't know. It apparently long sufficed for them to assume correctness 
no matter how incorrect the DE's purported DPI actually was, and leave it to 
the users who need or want accuracy to appropriately configure the DEs to 
that end. That the most popular DE's make no provision to configure accuracy, 
or that displays might provide erroneous information that stymies automatic 
configuration, is not justification to prevent everyone not using a display 
that actually happens to have a 96 ppi density from having accuracy if needed 
or wanted.
-- 
"The wise are known for their understanding, and pleasant
words are persuasive." Proverbs 16:21 (New Living Translation)

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Felix Miata  ***  http://fm.no-ip.com/
Received on Thursday, 23 February 2012 01:44:38 GMT

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