Fix issue 23527: Exception: RenderViewport exceeded its maximum numb… #30809
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chunhtai
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Apr 9, 2019
goderbauer
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goderbauer
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nit: Maybe even better: precisionErrorTolerance?
…er of layout cycles
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* master: (209 commits) Allow mouse hover to only respond to some mouse events but not all. (flutter#30886) Fix issue 23527: Exception: RenderViewport exceeded its maximum number of layout cycles (flutter#30809) Keep hover annotation layers in sync with the mouse detector. (flutter#30829) Use identical instead of '==' in a constant expression. (flutter#30921) Add toggle for debugProfileWidgetBuilds (flutter#30867) Revert "Manual engine roll with disabled service authentication codes (flutter#30919)" (flutter#30930) Manual engine roll with disabled service authentication codes (flutter#30919) Baseline Aligned Row (flutter#30746) [Material] Fix showDialog crasher caused by old contexts (flutter#30754) Let `sliver.dart` `_createErrorWidget` work with other Widgets (flutter#30880) Add more dialog doc cross-reference (flutter#30887) Allow downloading of desktop embedding artifacts (flutter#30648) CupertinoDatePicker initialDateTime accounts for minuteInterval (flutter#30862) add golden tests for CupertinoDatePicker (flutter#30828) Simplify toImage future handling (flutter#30876) Fixed Table flex column layout error flutter#30437 (flutter#30470) Fix iTunes Transporter quirk (flutter#30883) Bump Android build tools to 28.0.3 in Dockerfile (flutter#30832) Update the upload key which seems to have trouble for some reason (flutter#30871) Check for invalid elevations (flutter#30215) ...
Hixie
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Apr 12, 2019
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| static const double _epsilon = 1e-10; | ||
| /// The epsilon of tolerable double precision error. | ||
| static const double precisionErrorTolerance = 1e-10; |
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we really shouldn't expose this in our public API. This kind of thing is a hack at best.
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I am happy to revert this is this is not preferable. This issue has been happened in a lot different place. There is another bug in performlayout I am trying to fix . https://github.com/flutter/flutter/pull/30979/files
I think it is better to have a central place to define this constant. That is why I exposed this to public api.
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I guess it's better to expose it and use it consistently than to have it in many places...
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…er of layout cycles
Description
this is caused by double precision error. If we have certain height of widget in sliver list, the way we calculate layout offset of children will introduce some double precision error. Later when we scroll all the way to top, we will try to correct the error by shifting the scroll offset even if it is so tiny and does not really need to be corrected (~2e-14).
Most of the time it is correctable, but some times it fail to do so due to precision error in double operation
for example iphone 6s
corrected_scrollofset = scrolloffset + correction
if scrolloffset = 258.8489087697789 and correction = 0.00000000000002842170943040401
Then the scrolloffset does not change after correction due to precision error.
258.8489087697789 + 0.00000000000002842170943040401 = 258.8489087697789
Thus, it stuck on an infinite update loop.
Related Issues
#23527
Tests
I added the following tests:
https://github.com/chunhtai/flutter/blob/465ade89e57a6d8fffc34094d327bcbb99ee8f7c/packages/flutter/test/rendering/slivers_block_test.dart#L298
Checklist
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[x]). This will ensure a smooth and quick review process.///).flutter analyze --flutter-repo) does not report any problems on my PR.Breaking Change
Does your PR require Flutter developers to manually update their apps to accommodate your change?