Request for Mozilla Position on an Emerging Web Specification

• Specification Title: Viewport Segment API

• Specification or proposal URL:
  CSS : https://drafts.csswg.org/css-env-1/#viewport-segments and https://www.w3.org/TR/mediaqueries-5/#mf-horizontal-viewport-segments
  JavaScript : https://wicg.github.io/visual-viewport/#dom-visualviewport-segments (Proposal to merge it into VisualViewport here)

• Explainer URL: https://github.com/WICG/visual-viewport/blob/gh-pages/segments-explainer/SEGMENTS-EXPLAINER.md

Other information

The Viewport Segments API allows developers to adapt their website/webapp layout to target foldable devices. The viewport segments defines the position and dimensions of a logically separate region of the viewport. Viewport segments are created when the viewport is split by one or more hardware features (such as a fold or a hinge between separate displays) that act as a divider; segments are the regions of the viewport that can be treated as logically distinct by the author.

As this time this API applies only to Android and Windows OSes. Android provides the necessary OS APIs over here. Windows doesn't have an official API yet but instead relies on OEMs implementing the following specification in their middleware pre-installed software.

This API is to complimentary of the Device Posture API which also helps targeting foldable devices (Mozilla position requested over here).

This API is enabled by default on Samsung Internet.
This API is enabled by on some Android devices with Microsoft Edge.

TAG review here and here.