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

From: Brad Kemper <brad.kemper@gmail.com>
Date: Mon, 23 May 2011 21:30:27 -0700
Cc: Tab Atkins Jr. <jackalmage@gmail.com>, www-style list <www-style@w3.org>
Message-Id: <D7276899-2465-41BF-B264-63C18A72DF47@gmail.com>
To: Sylvain Galineau <sylvaing@microsoft.com>

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.
Received on Tuesday, 24 May 2011 04:30:58 UTC

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