Re: [css3-values] Physical length units

On Mon, Feb 20, 2012 at 12:34 PM, Lea Verou <leaverou@gmail.com> wrote:

> On 20/2/12 01:08, Robert O'Callahan wrote:
>
>> No, that's a surefire way to write pages that are unusable across
>> different kinds of devices.
>>
>> The only use-cases for truemm are when you need content matching the size
>> of some real-world object, e.g. a ruler, or a life-size image, or a human
>> fingertip. That's it.
>>
>> Ask yourself, "do I really want this content to be the same physical size
>> on a phone and a wall projector?" If the answer is yes, use truemm,
>> otherwise don't.
>>
> A wall projector is a special case anyway.


Why?


> Even in the use cases you mentioned, you probably wouldn't want those
> objects to be that small on a projector as well.


Why not? A projected ruler, or projected life-size diagram, or projected
touch interface, could all be very useful.

But you would want them to have a consistent size across desktop screens
> and phones. Special cases like projectors is why we have media queries (and
> why the resolution media query should continue being about physical dpi).


I don't think it makes sense to insist that true physical units are very
important, but only for some blessed set of devices.

I don't think it makes sense for authors to create documents using truemm
and then rely on complex media queries to make it render OK in the range of
devices the author happens to think of at the time.

Anyway, for all but the use-cases I mentioned, I don't think you want
content to be the same physical size even just considering phones and large
desktop screens. I certainly don't!

Rob
-- 
“You have heard that it was said, ‘Love your neighbor and hate your enemy.’
But I tell you, love your enemies and pray for those who persecute you,
that you may be children of your Father in heaven. ... If you love those
who love you, what reward will you get? Are not even the tax collectors
doing that? And if you greet only your own people, what are you doing more
than others?" [Matthew 5:43-47]