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class FragmentViewBindingDelegate<T : ViewBinding>( | |
val fragment: Fragment, | |
val viewBindingFactory: (View) -> T | |
) : ReadOnlyProperty<Fragment, T> { | |
private var binding: T? = null | |
init { | |
fragment.lifecycle.addObserver(object : DefaultLifecycleObserver { | |
val viewLifecycleOwnerLiveDataObserver = | |
Observer<LifecycleOwner?> { | |
val viewLifecycleOwner = it ?: return@Observer | |
viewLifecycleOwner.lifecycle.addObserver(object : DefaultLifecycleObserver { | |
override fun onDestroy(owner: LifecycleOwner) { | |
binding = null | |
} | |
}) | |
} | |
override fun onCreate(owner: LifecycleOwner) { | |
fragment.viewLifecycleOwnerLiveData.observeForever( | |
viewLifecycleOwnerLiveDataObserver | |
) | |
} | |
override fun onDestroy(owner: LifecycleOwner) { | |
fragment.viewLifecycleOwnerLiveData.removeObserver( | |
viewLifecycleOwnerLiveDataObserver | |
) | |
} | |
}) | |
} | |
override fun getValue(thisRef: Fragment, property: KProperty<*>): T { | |
val binding = binding | |
if (binding != null) { | |
return binding | |
} | |
val lifecycle = fragment.viewLifecycleOwner.lifecycle | |
if (!lifecycle.currentState.isAtLeast(Lifecycle.State.INITIALIZED)) { | |
throw IllegalStateException("Should not attempt to get bindings when Fragment views are destroyed.") | |
} | |
return viewBindingFactory(thisRef.requireView()).also { this.binding = it } | |
} | |
} | |
fun <T : ViewBinding> Fragment.viewBinding(viewBindingFactory: (View) -> T) = | |
FragmentViewBindingDelegate(this, viewBindingFactory) | |
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