W3C home > Mailing lists > Public > public-respimg@w3.org > February 2013

Re: CfC: to publish "The srcset attribute" specification as a First Public Working Draft (FPWD)

From: Nathanael D. Jones <nathanael.jones@gmail.com>
Date: Tue, 5 Feb 2013 21:36:25 +0100
Message-ID: <CAG3DbfW06vVkbr-DAzi3X88y5kSWQqFA8M3nLSU8cnWcCduJYw@mail.gmail.com>
To: Mathew Marquis <mat@matmarquis.com>
Cc: Fred Andrews <fredandw@live.com>, "Paul.Cotton@microsoft.com" <paul.cotton@microsoft.com>, "public-html-admin@w3.org" <public-html-admin@w3.org>, "public-respimg@w3.org" <public-respimg@w3.org>
I think many people were expecting a solution based on element size.

While that may not be a use-case you've aimed to solve, *I think it should
be the *primary* use-case*, as it provides a *simple solution to nearly
every other use-case documented*.

*Here's my full proposal:*


For the record:

I do not believe the advantages of slightly-earlier prefetching outweigh
the benefits of a CSS-based approach. There are many possible optimizations
available to ensure the delay can be reduced to ~40ms for a cache miss
(Probably ~15ms with SPDY), and it is simply not worth the markup
complexity required.

Best regards,
Nathanael Jones

On Tue, Feb 5, 2013 at 1:46 PM, Mathew Marquis <mat@matmarquis.com> wrote:

> On Tuesday, Feb 5, 2013, at 12:30 AM, Fred Andrews wrote:
> Perhaps the problem needs to defined in even simpler terms.
> Given the input string "image_200x100.jpg 1x, image_400x200.jpg 2x"
> and a target image box size of 20x10 or 60x30 or 100x50 or
> 200x100 or 300x150 or 400x200 or 800x400 or 1920x960 device
> pixels please supply a computation that selects the smallest
> image that gives a sharp presentation?
> The answers:
> 20x10: image_200x100.jpg
> 60x20: image_200x100.jpg
> 100x50: image_200x100.jpg
> 200x100: image_200x100.jpg
> 300x150: image_400x200.jpg
> 400x200: image_400x200.jpg
> 800x400: image_400x200.jpg
> 1920x960: image_400x200.jpg
> Another example: given the input string "image_300x150.jpg 1x,
> image_600x300.jpg 2x" and the same target image box sizes?
> Wait, so you’re talking about *contextually-aware* image selection based
> on the size of the containing element? I guess this is the root of the
> confusion—this isn’t a use case we’ve aimed to solve, and there hasn’t been
> call for it. Unfortunately, this use case would also be impossible to
> accommodate: the UA doesn’t have information about the layout available at
> the time the images are [pre]fetched.
> Any flags on either element dealing with sizing or resolution are in
> reference to the client’s *display*, similar to (or using) media queries.
> Choosing the image source size most appropriate for a container always 50%
> of the available screen will require consideration on the part of the
> author, as they must do currently with layout elements and CSS media query
> breakpoints.
> I apologize for the confusion.
> [ snip ]
Received on Tuesday, 5 February 2013 20:37:16 UTC

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