Out of curiosity will we be able to hook into the predictive

Question

Out of curiosity will we be able to hook into the predictive back animation system in compose

Stylianos Gakis · Answer

Not sure exactly what that means but considering that the androidx navigation which is for compose does support the predictive back gestures then I suppose the answer is yes Isn t it all basically working around the OnBackPressedDispatcher which you can retrieve in compose using LocalOnBackPressedDispatcherOwner

andrew · Answer

I mean the animation that you get between activities and Android 14 I know it s already technically supported under the hood

andrew · Answer

I e you can peek behind to the previous activity

Stylianos Gakis · Answer

Yes but since androidx navigation for compose already does this atm I am not sure what you mean by hook into the predictive back animation system in compose It s probably me misunderstanding you here thinking face

andrew · Answer

See the screenshot above I was in another screen in settings but swiping back allows me to peek the previous screen

andrew · Answer

Are they two separate composables

andrew · Answer

i e no activities

Stylianos Gakis · Answer

~Gimme a sec to triple check everything so that I am not lying to you~ sweat smile I was in fact lying to you

andrew · Answer

Because this looks exactly like the activity transition stuck out tongue

Stylianos Gakis · Answer

Yeah I now remembered that we do still have some pesky activities lying around in this flow in our app so I may be showing the wrong thing And that I could be wrong this entire time Gimme a sec dizzy face

andrew · Answer

Gotcha because that transition is what I d like to see between two composables using any arbitrary navigation library

andrew · Answer

However I just realized we re intercepting the event with the listener

andrew · Answer

So this might need to be performed manually

Stylianos Gakis · Answer

I was just very confidently incorrect here skull and crossbones face with open eyes and hand over mouth We are using androidx navigation and I had seen this behavior before in our app so in my brain I was like yes it works But I forgot that that transition was still between activities right now

Ian Lake · Answer

It was <https developer android com jetpack androidx releases activity 1 8 0 alpha01|Activity 1 8 0 alpha01> that added Android 14 s new progress APIs to `OnBackPressedCallback` instances that s what allows your app to get the gesture start callback and react to finger movements to do that Predictive animation

Ian Lake · Answer

There s three bits remaining to be done 1 `BackHandler` is going to be getting this same ability to get start and progress events which will mean any composable or navigation library can interact with Predictive Back in app progress on Android 14+ 2 `AnimatedContent` and friends are going to get new APIs to handle this in between state e g instead of just a `targetState` it would let you update the `progress` between two states this is what you d actually do with the progress callbacks `BackHandler` gives you 3 `NavHost` will update its `BackHandler` to call the new APIs on `AnimatedContent` thus giving you predictive back animations based on the transitions you ve set for free

andrew · Answer

This is exciting Thank you for the update Ian

andrew · Answer

Glad to hear it gets first class support

Stylianos Gakis · Answer

What s the status on some `AnimatedContent` which supports setting a progress too Is there some issue that we can track or some work that is already happening atm Feels like that is the biggest of the pieces missing in this puzzle right

Alex Vanyo · Answer

1 and 2 can be achieved from the Activity 1 8 APIs with a bit of work to a pretty nice effect This is nothing official though just me independently experimenting with the APIs

andrew · Answer

That is awesome sunglasses sunglasses

andrew · Answer

Imagine with official API support

Ian Lake · Answer

1 is just convenience at the Activity Compose layer the underlying layer is indeed already there And yep if you pick a different layer than AnimatedContent the underlying Compose animation APIs can already be driven by gestures

andrew · Answer

I figure as much but having high level APIs for convenience makes it accessible for everyone too I definitely don t mind digging for now seeing that it is in fact possible

Alex Vanyo · Answer

The version of 1 I m using is and part of my implementation of 2 is