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Scroll inertia cancel for iPadOS
Send a PointerScrollInertiaCancel event when the user touches the trackpad. Done in two ways, as one only works on real iPad devices, and the other only works when in emulation on an Apple Silicon Mac.
Part of https://github.com/flutter/flutter/issues/106979
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@moffatman thanks for the contribution, looks like there's still a few minor updates needed (mostly comments and clarifications) to get this through.
@moffatman thanks for the contribution, looks like there's still a few minor updates needed (mostly comments and clarifications) to get this through.
Yep, will be addressing it soon. I was looking into a way to avoid having to guess with magic numbers at all, but it hasn't panned out.
@hellohuanlin
I updated the numbers after some further data collection. I took the excel line-of-best-fit and subtracted an additional 200ms to account for all outlier data points (we want to bias towards reducing "false positives"/unwanted scroll-cancel events). I think the reason that the numbers are not a direct relationship is because I am using the UIGestureRecognizer velocity, whereas a proper UIScrollView would have a different velocity tracking formula.
This is quite an edge case (flutter-based app running on iPad emulation in a Mac), so this is best-effort basis.
@moffatman what's the relation between this PR and https://github.com/flutter/flutter/pull/108298? Is this PR ready for another review? And do you need my review on the other PR?
@hellohuanlin The other PR is kind of related, they both need to estimate the macOS scrolling curve, and improve scroll experience on Mac. But they don't depend on each other in any way. This one is now ready for review, if you want you can look at the other one as well, but not necessary.
