Intent to Implement: Frame Timing API
Paul Irish
Primary eng emails
m...@google.com, vmp...@chromium.org, nd...@chromium.org
Spec
Summary
This specification defines an interface to help web developers measure the rendering performance of their applications in the wild. The API provides frame performance data, as experienced by the end user on their device, to facilitate smoothness measurements (i.e. Frames per Second and Time to Frame). This is done by capturing events for main frame and impl (compositor) thread actions, and exposing them to JavaScript via the Performance Timeline.
Motivation
Motivation is dealt with in more depth at: github.com/w3c/frame-timing/wiki/Explainer
Currently, the only way to get information like this is to call requestAnimationFrame in a tight loop, and count how often you get callbacks. This increases load on the system unnecessarily, and is not entirely accurate.
Compatibility Risk
Low. We’re still iterating on the fine points of the spec language and shape of the API (see open issues at: github.com/w3c/frame-timing/issues), and the intent to implement is to help us inform these decisions through hands-on implementation experience. The feedback from Mozilla and IE teams has been positive so far -- no blocking issues that we’re aware of.
Ongoing technical constraints
None.
Will this feature be supported on all six Blink platforms (Windows, Mac, Linux, Chrome OS, Android, and Android WebView)?
Yes.
OWP launch tracking bug?
Link to entry on the feature dashboard
chromestatus.com/features/5558926443544576
Requesting approval to ship?
No.
.
Alex Russell
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Rick Byers
Philip Jägenstedt
Key quote from https://github.com/w3c/frame-timing/wiki/Explainer:
"Because of these subtleties, the browser will never have enough information about your app to make intelligent decisions as to what any given visual change implies, nor how it should be meaningfully measured. Instead, the Frame Timing API gives you the raw data you need to build a custom picture of your app’s performance characteristics during periods of interest, like transitions or interactions."
Philip
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