Intent to Prototype: Auto Sizes for Lazy Loaded Images with Srcset
Traian Captan
Contact emails
tca...@chromium.orgExplainer
https://github.com/whatwg/html/issues/4654Specification
https://github.com/whatwg/html/pull/8008Summary
Auto Sizes allows developers to omit the sizes attribute (or set it to sizes=auto) for lazy loaded image elements with srcset. For this use case the image's width should be provided. The browser will use the layout width of the image in order to select the source url from the srcset.
Blink component
Blink>ImageMotivation
The layout size information in sizes is redundant with layout information in CSS, but for images that are critical to initial paint it's necessary to have the information in the HTML. For lazy-loaded images, CSS will usually be available before the image load begins. The browser could take the actual width of the image as specified in CSS, and use that as if it was the image's sizes.
Initial public proposal
https://github.com/whatwg/html/issues/4654Search tags
sizes, sizes=auto, autosizes, srcsetTAG review
TAG review status
Not applicableRisks
Interoperability and Compatibility
None since all major browsers (Chrome, Safari and Firefox) indicate that they would be willing to implement it.
Gecko: Positive (https://github.com/mozilla/standards-positions/issues/650)
WebKit: Positive (https://github.com/WebKit/standards-positions/issues/9)
Web developers: No signals
Other signals:
WebView application risks
Does this intent deprecate or change behavior of existing APIs, such that it has potentially high risk for Android WebView-based applications?
Debuggability
Is this feature fully tested by web-platform-tests?
YesFlag name
ImgAutoSizesRequires code in //chrome?
FalseTracking bug
https://bugs.chromium.org/p/chromium/issues/detail?id=1359051Estimated milestones
| DevTrial on desktop | 116 |
| DevTrial on Android | 116 |