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Re: [css3-mediaqueries] Is 'resolution' in terms of device pixels or CSS pixels?

From: Brad Kemper <brkemper@comcast.net>
Date: Mon, 7 Apr 2008 08:00:08 -0700
Cc: "L. David Baron" <dbaron@dbaron.org>, www-style@w3.org
Message-Id: <B7D7F0AA-28B1-4115-88BA-838C9DC1C72F@comcast.net>
To: Anne van Kesteren <annevk@opera.com>


On Apr 7, 2008, at 5:11 AM, Anne van Kesteren wrote:

>
> On Mon, 07 Apr 2008 06:00:08 +0200, L. David Baron  
> <dbaron@dbaron.org> wrote:
>> The 'resolution' media feature has two new units, 'dpi' and 'dpcm'.
>> Are these "dots" supposed to be device pixels or CSS pixels?
>
> I'm not sure.
>> (I'm not sure what the use cases for this feature are.  One that I
>> could come up with is switching which images to serve (to save
>> bandwidth) for images whose sizes are specified in physical units.
>> For this use case device pixels would be better.  However, I'm not
>> sure what other use cases people have.)
>
> I would not be against dropping this feature.

It does make sense to keep it if you think about something like an  
iPhone, that has high resolution and a width of 480 device pixels. On  
something like that, because the resolution is so high, I'm going to  
want to use fairly large font sizes, so that you don't have to squint  
to read it. But on something else, like a 72 dpi monitor, I might want  
to use smaller font sizes instead, since the pixels will be larger,  
and therefore the text will appear larger. By using smaller text on a  
low res monitor, I can fit more on the screen, and it does not appear  
to be that small because the pixels are all huge.


>
>> http://www.w3.org/TR/2007/CR-css3-mediaqueries-20070606/#units is
>> clear that 'px' always mean CSS pixels,

That seems odd to me. I'm curious to know the reasoning behind that.


>> but I don't see anywhere
>> that defines 'dpi' and 'dpcm'.  (I'd lean towards saying the current
>> spec suggests that it's device pixels, but I don't think it's
>> clear.)
>
> Would device pixels be better here?
>
>
> -- 
> Anne van Kesteren
> <http://annevankesteren.nl/>
> <http://www.opera.com/>
>
Received on Monday, 7 April 2008 15:00:59 GMT

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