[Webkit-unassigned] [Bug 205454] Poor gesture-based animation performance on fullscreen/"notch" iPhones

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=205454

--- Comment #4 from Liam DeBeasi <ldebeasi at gmail.com> ---
I have identified another piece of information that may help track down the source of this issue. I happened to stumble upon this website that shows animations running in a <canvas>: https://ciechanow.ski/gears/

I noticed there are some custom sliders that let you control the animations. It appears as though it is the pointer/touch events that are janky/being throttled, not the animation itself.

Steps to reproduce:

1. Open https://ciechanow.ski/gears/ on a "notch" iPhone.
2. Find the demo right before the "Torque" section. It should have two circles, one yellow and one green.
3. Tap the pause button to prevent the circles from rotating.
4. Drag the slider to see one circle get bigger while the other gets smaller.

You should notice that the custom slider appears to lag as well as the canvas animation.

Upon running a Timeline, it looks like Safari considers the canvas animation to be running at 60+fps (on both my iPhone 11 and iPhone 7). This would lead me to believe that it is the pointer/touch events that are causing this issue, not that the animation itself is slow.

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