Intent to Ship: PointerEvent.getCoalescedEvents
Navid Zolghadr
Contact emails
nzol...@chromium.org, dtap...@chromium.org
Spec
https://w3c.github.io/pointerevents/extension.html
Summary
An API to return all the coalesced events of the received events in javascript. This API enables apps like drawing app to draw smoother curves using the precise history of points.
Intent to implement discussion.
Motivation
Coalescing already happens inside the input pipeline when the main thread is busy. In order to provide granularity to applications it is necessary to provide an enhanced API.
Likewise it is desired to align some input events with the document lifecycle; i.e. firing events just before rAF. In this model the frequency at which events are delivered to javascript is decreased causing an increase in coalesced events. The loss of precision is an undesirable side effect and this API overcomes that.
The Android platform already follows something similar aligning events to a vsync signal and provides an API in its SDK to retrieve prior events consumed by the touch driver.
Interoperability risk
Firefox: Public support
Edge: They were okay with this as well in the working group meetings.
Safari: No public signals
Web developers: Positive (discussions in PEWG at TPAC 2016)
Compatibility risk
This is a new API and by itself it is not a breaking change.
Ongoing technical constraints
There were some discussions in the design doc and we have prototyped a few solutions to get some idea about difficulties but there was no particularly blocking issue at this point.
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux,
Chrome OS, Android, and Android WebView)? Yes
OWP launch tracking bug
https://crbug.com/656781
Link to entry on the Chrome Platform Status
https://www.chromestatus.com/features/5853451217010688
Requesting approval to ship
Yes (to enable by default for M58).
Rick Byers
TAMURA, Kent
Software Engineer, Google
