roughly Dealing with again press in Android 13, the proper approach | by Kaustubh Patange | Feb, 2023 will lid the most recent and most present instruction roughly the world. admission slowly in consequence you perceive skillfully and appropriately. will enlargement your data nicely and reliably
Android is thought for a lot of issues, however lately, platform and API releases, it is principally recognized for its main adjustments. Contemplating how they conspicuously broke the clipboard monitoring performance (OnPrimaryClipChangedListener) be obtainable solely for system apps as of Android Q, surpassing tons of apps that used to depend on this callback are actually deprecated and do not even present up in Google Play searches, making this subject tracker one of many requests out of date of longer length (marked as P1). You’ll be able to actually see within the feedback the place builders of many common apps are asking for a workaround, like placing this variation/characteristic behind a particular Permission like System Overlay, and many others.
OnBackPressedDispatcher was launched someplace round 2019 through androidx.exercise API. This transformation steered transferring away from onBackPressed callback to a brand new listener technique just like ActivityResultContract. Some mentioned this was an excellent change, because it made us transfer away from the exercise override technique and depend on callbacks through listeners, which suggests we are able to now write the backclick logic anyplace, like in Fragments. The one disadvantage is the best way it handles the callback.
To hearken to the again, press add a OnBackPressedCallback. If you happen to look carefully, the callback accepts a constructor parameter enabled which tells whether or not this callback is energetic, i.e. it ought to handledOnBackPressed() technique of this callback to be known as or not. While you add a callback, you create a Cancelable model of this callback that has a cancel technique that removes it from the callback checklist.
There’s one other overload that accepts LifecycleOwner as an argument that principally calls this cancel technique every time the proprietor’s state reaches onStop and re-adds the callback when the state reaches onStart. This implies you do not have to deal with the callback elimination and addition manually.
All callbacks added through addCallback can be executed within the reverse order, if one is dealt with, it ignores the remainder of the string. The essential half right here is that each time the execution of the logic is full, you must set the isEnabled property to false or take away() the callback in order that it may be skipped the subsequent time within the chain. That is what onBackPressedDispatcher does it internally
If there aren’t any callbacks to deal with the return occasion then it’s utilized by default mFallbackOnBackPressed. For androidx.exercise.ComponentActivity name to tremendous.onBackPressed() which implies that the overridden technique of onBackPressed outlined in ComponentActivity is not going to be known as however can be delegated to the platform app.Exercise technique. So in the event you lengthen ComponentActivity & write customized backpress logic by overriding onBackPressed() technique is not going to be known as.
It will solely occur if you choose in to the predictive again gesture launched in Android 13. The best way this works is that your window’s DecorView receives a KEYCODE_BACK which then sends a key occasion to app.Exercise‘s onKeyUp() which then calls the onBackPressed() technique. This supply of occasions is completed by InputStage extra particularly an implementation of InputStage by title ViewPreImeInputStage. If you happen to take a look at line 6271 of ViewRootImpl you may see precisely the way it dispatches the occasion after which traces it again to Exercise’s onKeyUp() technique.
For Android 13, if you go for the predictive again gesture by setting android:enableOnBackInvokedCallback to true on the label NativePreImeInputStage is used Right here, a particular implementation of OnBackInvokedDispatcher known as WindowOnBackInvokedDispatcherthe final of onBackInvokedCallback is invoked as an alternative of sending the occasion to Exercise.
This registerOnBackInvokedCallback() accepts a precedence argument indicating the order by which callbacks can be returned. Whom getTopCallback() returns the final onBackInvokedCallback. As of Android 13, the app.Exercise will document a PRIORITY_SYSTEM callback throughout onCreate(). This callback would not do a lot, however principally ends/minimizes the exercise.
Issues began to fail when it stopped calling Exercise’s onBackPressed()technique. This was an enormous inconvenience as a result of now we won’t carry out any motion throughout back-press earlier than the exercise ends. Earlier than we may try this like,
This, tremendous.onBackPressed() It was an essential name to all dad and mom which in flip ends the exercise. Additionally, be sure to do not name end() anyplace in your OnBackPressedCallback as it can break the predictive again gesture characteristic.
So how can we deal with such a situation?
The above change will work, however some other callbacks added after it will have greater priority. From what I’ve seenandroidx.fragment model 1.3.6 of FragmentManager robotically registers a onBackPressedCallback to take away the present fragment from the backstack, which implies that throughout the back-click, the callback we registered is not going to be known as and as an alternative the callbacks registered by FragmentManagercan be known as So in case you are dealing with shard transactions manually or utilizing a third celebration library the place you must maintain observe of these present shards, you could have to replace your code accordingly.
In my view the easiest way is principally to keep away from onBackPressedDispatcher & depend upon onBackInvokedDispatcher. As you realize, every onBackPressedDispatcher have a onBackInvokedDispatcher. This onBackInvokedDispatcher is liable for calling all onBackPressedCallbacks in descending order (test the second snippet of this text) and from the third snippet, we all know the final onBackInvokedCallback that’s registered with a excessive precedence can be known as (within the default case will probably be the caller onBackPressedCallbacks).
What we are able to do is give our customized implementation a lot greater precedence. Any precedence greater than 0 is okay, since that is the default precedence that the default worth is ready to. onBackInvokedCallback is registered by onBackInvokedDispatcher.
The implementation is easy, after performing the motion we merely delegate to onBackPressed() -> onBackPressedDispatcher.onBackPressed() -> android.app.Exercise.onBackPressed() since there is no such thing as a method to name straightapp.Exercise ‘s onBackPressed() from a deeply nested class as a result of that is how inheritance works.
be sure there is no such thing as a onBackPressedCallbackis current in onBackPressedDispatcher. If this contract is adopted, you’ll be able to attempt onBackPressedDispatcher.onBackPressed() such as you tremendous.onBackPressed() which is able to terminate/decrease the exercise.
Make sure to choose in to the predictive again gesture through the manifest. In case your targetSdk is 34, you’ll be able to skip the subsequent step.
A whole implementation that makes use of onBackPressed() for variations decrease than 13 and onBackInvokedDispatcher for model above 13 it can seem like this,
All you must do now could be lengthen your exercise class with BackPressCompatActivity and calls setOnBackPressListener to return true to false. Returning true will terminate/decrease the exercise.
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Handling back press in Android 13, the correct way | by Kaustubh Patange | Feb, 2023
