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

Re: src-n viewport-url alternatives

From: Marcos Caceres <w3c@marcosc.com>
Date: Fri, 18 Oct 2013 16:44:35 +0100
To: John Mellor <johnme@chromium.org>, "Tab Atkins Jr." <jackalmage@gmail.com>
Cc: "public-respimg@w3.org" <public-respimg@w3.org>
Message-ID: <1B332E85505B4D73A22A1E7C1F9A0E21@marcosc.com>
Hi John and Tab,  
Would be very useful to have your input hereā€¦ thanks!  


On Friday, October 18, 2013 at 12:56 PM, David Newton wrote:

> For me, and I suspect others, the viewport-url microsyntax is one of the more confusing parts the src-n proposal. It's clever, for sure, but it took me a long time to understand it (and I'm still not 100% convinced I do). I thought it would be a good idea to discuss what we're getting with viewport-url and if there are any better possible alternatives.
>  
> So, what does viewport-url get us?
>  
> 1) viewport switching
> 2) the browser can use it to automatically calculate DPR switching stuff (1x, 1.5x, 2x, etc.)
> 3) the browser can use it to decide if a viewport change requires a new download, or if a larger, previously-cached image can be used
>  
> (1) and (2) can be solved with media queries that are already part of src-n, though admittedly a bit more verbosely and with a bit more math. Despite those obstacles, it's a syntax that's familiar to devs, and one I suspect they'll use more often than viewport-url. If they do, though, they lose the caching advantage of (3).
>  
> In order to properly figure out if a cached image can be used, the browser must know whether a newly requested source has the same content/art direction as a cached version, and if the newly requested source is bigger or smaller than a newly requested version. Yesterday on IRC I came up with a syntax (https://gist.github.com/nwtn/7032904) that groups art direction styles to provide this info to browsers, so that (3) is still possible when doing viewport- and DPR-switching using media queries.
>  
> I don't yet know if I think this is a good idea, but my gut tells me it's more readable and writeable for devs, despite its verbosity. What do you think? Or, do you have any other good viewport-url alternatives?
>  
> Dave  
Received on Friday, 18 October 2013 15:45:00 UTC

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