Yaru layout index controller

[d-loose]

WIP
Adds YaruLayoutIndexController YaruPageController that controls

• YaruMasterDetailPage
  • YaruLandscapeLayout
  • YaruPortraitLayout
• YaruCompactLayout

Pull request checklist

• This PR does not introduce visual changes, or
  • I ran flutter test --update-goldens and committed the changes if there were any, or
  • I added before/after/light/dark screenshots if the visual changes I made were not covered by golden tests.

    	Before	After
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[jpnurmi]

naming idea: YaruPageController 🙂

[d-loose]

Naming things is always the hardest part :D

[jpnurmi]

I wish YaruCompactLayout would be named something like YaruNavigationPage to be consistent with YaruMasterDetailPage and YaruNavigationRail but it would break the software app once again... 🤔

[Feichtmeier]

Breaking software is not the problem
I just thought about a future where we might want to readd the layout builder and the bottom bar again
But then this could also be done inside the app so feel free to rename it ;P

[jpnurmi]

Sorry for repeatedly hijacking random PRs. 🙂 Let's continue the discussion here:

• Rename YaruCompactLayout? #416

[jpnurmi]

my head hearts with all these layouts, indexes, controllers, and listeners but i think it looks good now 👍

[jpnurmi]

now that we always have a controller instance, we could let AnimatedBuilder take care of rebuilds:

AnimatedBuilder(
  animation: _pageController,
  builder: (context, child) => YaruFooBarPageOrLayout(
    index: _pageController.index
  ),
),

this way, we could get rid of the manual add/removeListener() and setState() calls.

Despite the name, AnimatedBuilder is not limited to Animations. Any subtype of Listenable (such as ChangeNotifier and ValueNotifier) can be used with an AnimatedBuilder to rebuild only certain parts of a widget when the Listenable notifies its listeners. This technique is a performance improvement that allows rebuilding only specific widgets leaving others untouched.

[d-loose]

Do we want to keep YaruPortraitLayout and YaruLandscapeLayout available as stand-alone layout widgets with their own controllers? Using the AnimatedBuilder like this in YaruMasterDetailPage would make YaruPortraitLayout and YaruLandscapeLayout stateless and dependent on a parent widget that handles interactions.

[jpnurmi]

We should be free to change YaruPortraitLayout and YaruLandscapeLayout as we wish. They are not exported in lib/yaru_widgets.dart because they are supposed to be internal implementation details. Do you think they would be valuable as public classes?

[d-loose]

Maybe there are situations where you wouldn't want the layout to change, but I guess this can be controlled by setting the breakpoint to zero or infinity.
But I like the idea of moving all control to the MD page, it simplifies things a lot.

[jpnurmi]

Is this good to go as it is now? We could leave using AnimatedBuilder and the consequent changes as a separate step.

[d-loose]

Yes, should be good to go - let's do it in a separate PR. There are still some things to consider with the AnimatedBuilder (navigator in YaruPortraitLayout, YaruLandscapeLayout needs to be stateful to manage pane resizing)

[jpnurmi]

Ok, sounds good! LGTM 👍

Thanks for working on this and sorry it got more laborious than anticipated... :)

[d-loose]

Better to do it right than deal with annoying issues later - thanks again for the feedback!