Intent to Ship: HTMLImageElement's srcset attribute (DPR switching)
Yoav Weiss
Primary eng (and PM) emails
Spec
http://whatwg.org/html#attr-img-srcset
Summary
The `srcset` attribute enables authors to adapt image resources to the device'sdisplay characteristics. This intent refers to the DPR switching parts (the 'x' descriptor), which have rough consensus around them.
Motivation
New device form factors and screen DPRs are added to the market on a regular basis. Serving the same image resources to all devices (which may display them in differing dimensions and at different DPRs) is wasteful, and hurts Web performance.
This feature will start resolving this problem, by enabling Web authors to specify multiple resources, with varying DPR qualities, and let the browser pick the resource that matches the device's capabilities.
This feature is also a subset of the picture element specification.
Compatibility Risk
Low.
The feature is implemented in WebKit (but not yet shipped). It's intended to be implemented soon in Gecko as part of the picture element implementation. It is not yet implemented in IE.
The feature's syntax include an inherent fallback mechanism for authors, where non-supporting browsers will simply fetch the resource specified in the `src` attribute. (resulting in a sub-optimal, but fully-functional image)
Ongoing technical constraints
None.
Link to “Intent to Implement” blink-dev discussion
https://groups.google.com/a/chromium.org/d/msg/blink-dev/SVQxmsJRa9c/qfd55y_86HEJ
Is this feature supported on all five Blink platforms (Windows, Mac, Linux, Chrome OS and Android)?
Yes.
OWP launch tracking bug?
http://crbug.com/296891Yes.
Requesting approval to ship?
Yes.
Adam Barth
Ilya Grigorik
I'm glad we're making progress on responsive images and have figured out how to ship various parts incrementally. Thanks for driving the discussion in the WhatWG and other forums.
Darin Fisher
LGTM
