[whatwg] Resolutions meta tag proposal

Aryeh Gregor Simetrical+w3c at gmail.com
Fri Jul 2 10:22:00 PDT 2010

On Fri, Jul 2, 2010 at 8:39 AM, Aral Balkan <aral at aralbalkan.com> wrote:
> I just submitted a proposal for a new meta tag to flag that
> high-resolution images are available and should be loaded in place of
> low-resolution ones for users with high-PPI displays (like the new
> iPhone 4's Retina display).
> Please see:
> http://wiki.whatwg.org/wiki/MetaExtensions#Proposals

I don't know what the right solution is for this problem (other than
"use SVG" :) ), but I don't think your proposal is workable.
Inevitably, some images will be available in different sizes and some
not, but your proposed meta tag will affect all images on the page.
Also, the author needs to be able to control the names of the resized
images to fit their needs -- on a site allowing user-uploaded images,
for instance, you might not be able to guarantee that there isn't
already a file named flower at 2x.jpg in the directory.

The most natural way to do something like this is probably along the
lines of content negotiation, but as we all know, that doesn't work
well in practice because it's hard for authors to set up.  Ideally,
you could have the browser include a Resolution: header or something
like that, saying what resolution it expects to see, and then the web
server should automatically try resizing the image to match (using
appropriate caching).  But this is too hard to deploy and control.

So I don't have any really good ideas.

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