StateBinder is a tiny library for view state management.
If you use the MVI pattern or any other pattern using the concept of states to develop your applications, you may have encountered the problem of frequently updating widgets, which leads to poor performance especially when you perform frequent screen state updates. StateBinder eliminates redundant view rendering when the state changes.
dependencies {
impelentation 'com.olegsheliakin:statebinder:latest'
}- Create State class for View:
data class MainState(
val label: String,
val errorText: String?
) : State- Create StateBinder:
private val stateBinder: StateBinder<MainState> = StateBinder.create()- Bind state's properties to actions:
stateBinder.apply {
bind(MainState::label) {
tvLabel.text = it
}
bindNullable(MainState::errorText) {
etText.error = it
}
}Actions will be called only when properties change.
-
Create ViewModel/Presenter or any other class that is responsible for changing and emitting State:
class MainViewModel : ViewModel() { private val internalState = MutableLiveData<MainState>() val state: LiveData<MainState> = internalState init { internalState.value = MainState("", null) } fun loadText() { internalState.value = MainState("Text", null) } fun initError() { internalState.value = MainState("", "Error") } }
-
Update state by calling:
stateBinder.newState(newState)class MainFragment : Fragment() {
private val viewModel: MainViewModel by lazy {
return@lazy ViewModelProviders.of(this@MainFragment)[MainViewModel::class.java]
}
//creates StateBinder
private val stateBinder: StateBinder<MainState> = StateBinder.create()
override fun onCreateView(
inflater: LayoutInflater, container: ViewGroup?,
savedInstanceState: Bundle?
): View? {
return inflater.inflate(R.layout.fragment_main, container, false)
}
override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
super.onViewCreated(view, savedInstanceState)
//refreshes the current state when view is created
stateBinder.applyCurrentState()
//binds properties to actions
stateBinder.apply {
bind(MainState::label) {
tvLabel.text = it
}
bindNullable(MainState::errorText) {
etText.error = it
}
}
//observes MainState
viewModel.state.observe(viewLifecycleOwner, Observer {
it?.let(stateBinder::newState)
})
}
}The MIT License (MIT)
=====================
Copyright © 2019 Oleg Sheliakin
Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the “Software”), to deal in the Software without
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copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
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The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
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OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
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