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September 2020 - Code Heath, Animation Timelines, Smoothness Metrics, Animation event handlers and more!

September  2020

Chrome Interactions Highlights

Archives: go/interactions-team-highlights

Code health

kevers@ presented a graph to show the progress of bug fixing.

  • In this sprint we closed a lot of bugs, but more were opened than closed.

  • We now have breakdowns by priority. Nice to see that we did not lose ground on P0s or P1s.

xidachen@ removed the usage of setTimeout in animations layout test, and replaced them with rAF.

  • setTimeout can easily cause flakiness, especially on debug bots.

  • Animations are driven by animation frames, using rAF leads to more robust tests.

Mutable timelines

kevers@ has been working on scroll timelines and the above demo showcases mutable timelines, which are required for supporting css animation-timeline.

  • The demo illustrates updating the animation timeline via the web-animation API.

  • Presently it is behind the scroll-timeline feature flag.

kevers@ showed another fun demo for scroll timelines, which uses scroll position to drive a paint worklet animation..

Smoothness metrics

xidachen@ improved fps meter by making it account for page loading.

  • The fps meter will reset itself at first contentful paint (which is regarded as loading completed).

  • The stats before first contentful paint will be discarded when we report to UMA.

Animation event handlers

gtsteel@ landed the implementation for ontrasition* event handler properties. Along with that, gtsteel@ also fixed animationcancel event so that it doesn’t fire after animationend.

Zooming no longer breaks transitions

gtsteel@ fixed a bug where zooming would cause transition event listeners to fire.

  • Previously, we compared zoomed values when starting transitions, then transitionend based on computed value.

  • Now we calculate and compare computed values (as per spec) if zoom changed.

Web tests ⇒ WPT

liviutinta@ shared a sheet that lists input related layout tests that we would like to move to wpt/. The spreadsheet also tracks the progress. 

WebDriver Actions API Spec

lanwei@ has landed spec change that adds wheel input to the webdriver action API.

Chrome Interactions Highlights | September 2020