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Fine-tune fling velocity #11772
Description
There's a slight difference in velocity reported by iOS's pan gesture recognizer's velocityInView vs our own VelocityTracker. Flutter's calculation is ~20% faster.
On Android, the velocity tracker is distinct from the gesture callbacks, but our flings are a bit slower.
Probably better to have a platform agnostic velocity and correct the difference in the friction simulations.
Activity
Hixie commentedon Aug 29, 2017
I've tentatively put this at post-1.0 but we can bring this back if people notice.
xster commentedon Aug 29, 2017
Agreed. I think it's lower prio than the last 4 we dealt with so far.
eseidelGoogle commentedon Apr 6, 2018
This came up in a review from an internal team today. I presume this shows up in:
https://github.com/flutter/scroll_overlay
eseidelGoogle commentedon Aug 31, 2018
@xster do we know if this is still an issue? Has anyone played with scroll_overlay recently to tune our physics further?
xster commentedon Aug 31, 2018
As of last time I checked in spring, it is still and issue. This and #13171 are the 2 remaining scrolling related issues I know of.
I left them deprioritized and not slated for Q3-Q4 since I don't think they're noticeable enough. Let me know if that should change or if anyone is blocked on it.
molon commentedon Apr 10, 2019
It's still and issue.
I feel
ListViewhas too much friction when deceleration on iOS.But
https://github.com/xster/flutter-test/tree/master/t95_ios_settings_pageperforms well.Is this my illusion?
I went deep into the source code, and they all used the same
ScrollPhysic.Really don't know why.
eseidelGoogle commentedon Apr 10, 2019
https://github.com/flutter/platform_tests contains a project one can use to test ListView against an iOS scroll physics if you'd like to confirm.
molon commentedon Apr 11, 2019
Very useful tests.
Three problems can be clearly seen from the test:
As a iOS developer.
Based on my development experience, we hardly need a
CupertinoUI.But something is important:
AppBar+PreferredSizeto implement it.t95_ios_settings_page, It's also a little weird.Few users like a
CupertinoUI. Because design should be diverse.But most users hard to tolerate app with inconsistent interactions.
So I still prefer to use
MaterialAppand I'm not going to useCupertinoApp.I guess there will be a lot of iOS developers like me.
So I suggest that Flutter should pay more attention to interactions instead of
CupertinoUI.xster commentedon Apr 11, 2019
Users building custom designs is indeed our vision though we've recently focused on building an extensive set of Cupertino widgets based on our quarterly survey results. Note also that the Material/Cupertino interest ratio is also skewed between China and the rest of the market.
I do agree this is important however. We just haven't fine tuned it because no one noticed so far :) (as mentioned above). It shouldn't be difficult to do and it's in our plans for Q2. You can also send us a PR based on that comparison test.
1 remaining item
LongCatIsLooong commentedon Jun 26, 2020
Looked into this (prompted by #59623).
UIPanGestureRecognizeruses a far smaller sample size to calculate the velocity.Reduce damping in iOS scrollbehavior for list with differently sized …
github-actions commentedon Aug 17, 2021
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