[whatwg] Implementation complexity with elements vs an attribute (responsive images)

[Boris Zbarsky]

On 5/13/12 7:26 AM, David Goss wrote:
> but it'd be irresponsible to just serve an
> <img>  with the high res source to all users, making them wait longer
> for the download even though they can't see the extra quality on their
> screen.

Except when they can, e.g. by printing or moving the display to another 
screen.

Basically, in this case not sending the high-res image is optimizing a 
bit for one common use case while degrading the user experience in other 
use cases.  Maybe that's OK, but that requires a careful analysis of 
user behavior for the particular content involved.  And in particular, 
I'm not sure what I think of labeling content that aims to be usable by 
the user in the widest variety of circumstances as "irresponsible". 
Past examples of us doing that sort of thing led to it being considered 
"irresponsible" to allow website layouts to scale above or below certain 
widths, amongst other current usability disasters.

>> Note that these concerns argue, to a certian extent, *against* reusing a
>> very general syntax that can express constraints that aren't relevant to the
>> actual use cases, or that provide an attractive nuisance that encourages
>> developers to do things that can't be implemented in a performant way.
>
> Dumping<picture>  as it is won't prevent this, as it's already in the
> door in the form of<video>.

<video> has quite different dynamic behavior from <img> and quite 
different author expectations (e.g. authors don't expect videos to be 
preloaded in their entirety, by default; there are other significant 
expectation differences too).

-Boris