Fix: RangeBase should not write coerced values back when DataContext is changing

[timunie]

What does the pull request do?

solves an issue where the bound value was changed when data context was changed or cleared

What is the current behavior?

coerced value was written back to the datacontext which is a recent regression

What is the updated/expected behavior with this PR?

regression doesn't happen anymore

How was the solution implemented (if it's not obvious)?

added a bool flag skipping the coerce if the datacontext is beeing changed

Checklist

• Added unit tests (if possible)?
• Added XML documentation to any related classes?
• Consider submitting a PR to https://github.com/AvaloniaUI/Documentation with user documentation

Breaking changes

Obsoletions / Deprecations

Fixed issues

Fixes #11870

fyi @ahopper : I tested this branch with your sample and it was solved for me. I'd be happy if you can verify this PR.

@grokys Hope you don't mind I took a look into it. If the fix is wrong, feel free to cherry-pick the Unit-Test.

[robloo]

My instinct is this is a general issue and should probably be addressed at a lower level.

1. Avalonia has DataContext switching differences from WPF (there are issues for it some place)
2. Coercion still might not work correctly in all edge cases (again, some issues for coercion might still be open)

[avaloniaui-team]

You can test this PR using the following package version. 11.0.999-cibuild0037044-beta. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[ahopper]

This control has always had the issue that the order you set the properties in XAML matters, if the value comes first it will be clamped to the defaults before the desired min and max are set. There seem to be issues with coercion at both ends of the lifetime.

[ahopper]

An alternative solution might just be to make the default Minimum and Maximum values min and max double values.

[timunie]

An alternative solution might just be to make the default Minimum and Maximum values min and max double values.

probably an idea for now. But the underlaying issue should be solved anyway.

[avaloniaui-team]

You can test this PR using the following package version. 11.0.999-cibuild0038248-beta. (feed url: https://nuget-feed-all.avaloniaui.net/v3/index.json) [PRBUILDID]

[ahopper]

@timunie I'm currently using a hybrid of this pr and big default min max values in my app with no issues, the big limits are belt and braces and probably not needed.

[timunie]

We need to wait for @maxkatz6 to check and merge this PR. Currently his workload is different 😉

[maxkatz6]

ISupportInitialize could help with XAML order, but not with DataContext reloading. Will keep this as a hack for now...