OpenContainer jank due to multiple frames of shader compilation #76180
Description
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Hello! Thanks for taking a time to look into the issue of jank with animations on iOS using the Metal shader API. It's an issue that a lot of folks have reported as per major threads here:
and I wanted to try and help by giving a clear example as per the guideline for this jank here:
#74833
System info
Device: iPhone 12 mini
Source code
Demo lib is available here:
https://github.com/danReynolds/iosjank
It is a barebones flutter create app with a single dart file modified:
https://github.com/danReynolds/iosjank/blob/master/lib/main.dart
The animation it uses is from the OpenContainer component supplied by flutter here:
https://github.com/flutter/packages/blob/master/packages/animations/lib/src/open_container.dart
Video
A video of the jank is available here:
https://photos.google.com/share/AF1QipOIN6m7QjsVUf63zeMXriQW0pg_npG3e0mwBnzV_TojsNzN4kEpXzFiKC6vVRrUzg?key=Wk96RzBNdnFTRF8xTDVkV08yRGFlZHdxMktSUWRR
note how the animation of the floating button lags the first couple times on open/close.
Trace
A trace is available here: https://drive.google.com/file/d/1RhWnX_zytL_1KWjHtOxx0Ji_3Z-idRw3/view?usp=sharing
which was recorded as per the instructions here: https://medium.com/flutter/profiling-flutter-applications-using-the-timeline-a1a434964af3#a499
In Summary
I hope this example illustrates how the issue of iOS jank with Metal is pervasive in the most basic of apps with performant animations provided by the Flutter library itself. If there is anything more I can provide to help debug this issue I will do whatever it takes, so please let me know.
This is the biggest issue facing my organization's Flutter application and both our org and devs from other companies I've spoken to are considering moving away from Flutter if this problem is not resolved soon or given a timeline for being resolved in upcoming releases. I don't mean to be overly harsh, it's just a fact that we need robust performance on iOS in order for our application to succeed as a product.
Overall I've greatly enjoyed working with Flutter and would love to keep using and evangelizing it in the future. Thanks to everyone involved with this project. ❤️