W3C home > Mailing lists > Public > public-respimg@w3.org > April 2014

Re: Clarification on what to do when zooming or resizing

From: Yoav Weiss <yoav@yoav.ws>
Date: Wed, 9 Apr 2014 23:26:12 +0200
Message-ID: <CACj=BEhuwuUd3m8U=p7=Jr1xv43QsR1AVXAao-7v3g3CbgcXfQ@mail.gmail.com>
To: Greg Whitworth <gwhit@microsoft.com>
Cc: "Tab Atkins Jr." <jackalmage@gmail.com>, "public-respimg@w3.org" <public-respimg@w3.org>
Hey Greg,

If the media change is only enough so that it would impact which image the
browser would choose inside a single
source-set<http://picture.responsiveimages.org/#source-set>(e.g.
example
7 <http://picture.responsiveimages.org/#examples>), that is entirely UA
defined. Personally, I think these images should be downloaded as extremely
low priority, unless there are indications that the user prefers to save on
bandwidth (user preference, data roaming, battery status, etc).
If the media change impacts the source selection
algorithm<http://picture.responsiveimages.org/#select-image-source>,
then the UA should (but doesn't have to) download the new image. The UA can
probably do that in intervals, to save on re-layouts and intermediate
downloads in case that the user is resizing their browser window.
Regarding zoom, that depends on what kind of zoom and how zoom impact the
viewport dimensions and DPR (unfortunately that's not something everyone
agrees on :/). I don't know what IE does in that aspect.

>From a user's perspective, images in a single source-set are the same image
in varying qualities. If the browser decides to avoid the download, the
user may see quality differences, but the image would still be the same.
Images in different source-sets are supposed to be differently
"art-directed", so providing the user with the wrong image may break the
page's layout or make the image unusable.

I hope that makes it clearer. Feel free to ping me if you have any more
questions.

Cheers :)
Yoav



On Wed, Apr 9, 2014 at 11:00 PM, Greg Whitworth <gwhit@microsoft.com> wrote:

>  Hey guys,
>
>
>
> I don't see anywhere that instructs what a UA should do in the event a
> user zooms or resizes the browser (sorry if I missed it). Should the UA
> kick of a new download for the image that matches the new dimensions, or
> should we only do this at certain times?
>
>
>
> Thanks,
>
> Greg
>
Received on Wednesday, 9 April 2014 21:26:40 UTC

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