Recomposition in compose - does it go through each...

# compose

[ritesh]

Recomposition in compose - does it go through each node(composable) in the tree and checks if that nodes needs to be updated or not based on last state from slot table?

[ritesh]

@Composable
fun MainScreen(viewModel:Vm){
  // live-data in vm
  when (viewModel.response.observeAsState().value) {
    //   
  }

  ScreenContent(
    sate = viewModel.emailState.collectAsState().value,
    onValueChanged: viewModel::valueChanged
  )

}

@Composable
fun ScreenContent(
  state:SomeState,
  onValueChanged:(String) -> Unit
){
  TextField(value = state.text, onValueChange = onValueChanged)
}

Why MainScreen Composable, is called(recomposed/invalidated) again when ScreenContent is changed. I believe only ScreenContent should be recomposed in this case.

[Adam Powell]

ScreenContent isn't what's reading the .value of the snapshot state objects being invalidated, MainScreen is

[ritesh]

Thanks Adam, i was under the assumption that re-composition is based on parameters passed down in the tree hierarchy, and if there is a difference from last state, only that composable will re-compose, not the parent node.

[Adam Powell]

a parameter's value is controlled by the caller. For a parameter to change the caller must run to pass a new value

[ritesh]

a parameter's value is controlled by the caller. For a parameter to change the caller must run to pass a new value

also, this article by Zach cleared my doubts related to node invalidation