Which widget should be scheduled to rebuild upon state change? about flutter_reactive_value HOT 5 CLOSED

Correct, I forgot about that, you can introduce BuildContext anywhere you want in that way for efficiency. I don't think there will be significant performance differences most of the time, because rebuilding is fairly lightweight once the Element tree is built. Also it's good style to keep widgets small in terms of tree size.

I'll update the docs.

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It's the widget that is the BuildContext passed into reactiveValue that is scheduled to be rebuilt. BuildContext is actually an Element, so technically it's the Element, not the Widget, that is rebuilt -- Element is the laid-out view of a widget. The scheduling happens via Element.markMeedsBuild().

This may trigger other elements to be rebuilt too, especially if the size of the Element changes, since constraints are passed down the Element tree and sizes are passed back up. And of course it will trigger a render frame, which (I assume) will only redraw the area of the screen that was marked for rebuilding, but I'm not sure about that.

I should update the docs to make this clearer, sorry!

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Sorry, I reread your question... The Text Widget optimally would be the only one rebuilt, yes. But it has no BuildContext, so there's no way to get a reference to it.

In general you should be breaking large coplex widget trees down into separate widgets, for readability if nothing else, so usually widget trees go only a few layers deep below a BuildContext, and the re-layout should not be horribly wasteful.

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The Builder widget could provide the parents BuildContext exactly where and when you need it.

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@AntonEriksson978 The docs are updated. Thanks for pointing this out, it is an important point!

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