Fix Slow Event Log Scrolling for large # of events - #4175
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kenzieschmoll
approved these changes
Jun 7, 2022
CoderDake
marked this pull request as ready for review
June 8, 2022 15:36
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| _TableState<T> createState() => _TableState<T>(rowItemExtent: rowItemExtent); | ||
| } | ||
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| class _TableState<T> extends State<_Table<T>> with AutoDisposeMixin { | ||
| _TableState({this.rowItemExtent}); |
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never pass parameters into state objects. You can access the widget class member from the state object via widget.rowItemExtent
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this is a good life lesson thank you :)
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I'm surprised the no-logic in createState lint didn't warn about this.
kenzieschmoll
approved these changes
Jun 8, 2022
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Details
Fixes #3238
It is a known issue that ListItem.builder lists can have performance issues when scrolling large lists.
The reasoning for this is that the height of each item needs to be calculated when scrolling along a list. So the list being scrolled can't just skip to the new location.
If the height of each row is the same, this performance hit can be avoided by telling the ListView the height of each row ahead of time.
This is done by setting the
itemExtent.In our case the height of each row height is the same and should be
defaultRowHeightThis also benefits the scrolling speed on the profiler page
Demos
Original Behaviour
d6idd65lgkw540ta28177tc2.mp4
Fixed Behaviour
tlxo4iyurw5c28sdchmg59av.mp4
Pre-launch Checklist
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