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RE: [css3-images] Is the dppx unit needed?

From: Sylvain Galineau <sylvaing@microsoft.com>
Date: Tue, 24 May 2011 14:40:27 +0000
To: Brad Kemper <brad.kemper@gmail.com>
CC: Tab Atkins Jr. <jackalmage@gmail.com>, www-style list <www-style@w3.org>
Message-ID: <3C4041FF83E1E04A986B6DC50F017829027B55@TK5EX14MBXC297.redmond.corp.microsoft.com>

[Brad Kemper:]
> On May 23, 2011, at 8:30 PM, Sylvain Galineau wrote:
> 
> > [Tab Atkins:]
> >> I'm rewriting the section on the <resolution> type in the Images spec
> >> <http://dev.w3.org/csswg/css3-images/#resolution-units> to actually
> >> explain what the unit does right now.  While writing an example, I
> >> was struck by the fact that the dppx unit seems unnecessary, given
> >> that we now have a guaranteed 96:1 ratio of 'px' per 'in'.
> >>
> >> Everything I know of that talks about image resolution uses dpi or
> >> dpcm only.  I don't think I've ever seen anything equivalent to dppx.
> >> Plus, 'dppx' is a hard unit to pronounce.  ^_^
> >>
> >> I suspect that dppx was created back when we couldn't actually say
> >> that images were 96dpi by default, because the CSS 'in' wasn't tied
> >> to a specific number of CSS 'px'.  Could I just drop it, and set the
> >> initial value of 'image-resolution' to 96dpi?
> >>
> >> ~TJ
> > I was going to ask as the dppx unit seemed to be a way to redefine CSS
> pixels.
> > What was(were) the use-case(s) ?
> 
> DPI and its metric cousin are good enough for me. I suppose that since
> dppx = dpi/96, someone maybe would want a non-fractional result, in which
> case dppx could make that easier to pick the right number. But I don't
> think that it is too big a deal to just do the math in that case and pick
> something suitable.

If that was a use-case I don't understand any of it.
Received on Tuesday, 24 May 2011 14:41:02 GMT

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