Last active
February 24, 2024 20:13
-
-
Save Zhuinden/ea3189198938bd16c03db628e084a4fa to your computer and use it in GitHub Desktop.
Fragment view binding delegate
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
// https://github.com/Zhuinden/fragmentviewbindingdelegate-kt | |
import android.view.View | |
import androidx.fragment.app.Fragment | |
import androidx.lifecycle.DefaultLifecycleObserver | |
import androidx.lifecycle.Lifecycle | |
import androidx.lifecycle.LifecycleOwner | |
import androidx.lifecycle.Observer | |
import androidx.viewbinding.ViewBinding | |
import kotlin.properties.ReadOnlyProperty | |
import kotlin.reflect.KProperty | |
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) |
@Zhuinden what is the real reason behind val binding = binding
in most cases we directly access binding. is this required ? .
@manju23reddy I debugged a guy's code who had trouble with callbacks of a WebView running on a different thread and this was the fix, so I do do it in my code personally.
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Btw there is an updated version of this gist as a library in https://github.com/Zhuinden/fragmentviewbindingdelegate-kt