Hi folks Is there a way to customize back button behavior wi kotlinlang #compose

? I want to make a list with multiple selection like in the GMail app. On back button press navigation-compose goes to the previous destination, but I want it to unselect all selected items. I did it with a boolean optional argument

"items?selected={selected}"

, but I think it really smells. I suppose it's better to override the default behavior of back button, but I just can't find a solution. Or is there a better approach to the problem?

Ian Lake

11/21/2020, 1:43 AM

You'd want to add your own

OnBackPressedCallback

ala https://kotlinlang.slack.com/archives/CJLTWPH7S/p1604158427082300

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We've talked about making this part of Compose here: https://kotlinlang.slack.com/archives/CJLTWPH7S/p1604266607160300 (and that has a link to the issue you can star)

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Denis

11/21/2020, 2:24 AM

Thanks a lot, Ian! The @Vinay Gaba’s message you shared lead me to his full implementation of

BackButtonHandler

that works perfectly for me. Vinay, thank you for it!

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Oh, and there's https://github.com/vinaygaba/Learn-Jetpack-Compose-By-Example/blob/master/app/src/main/java/com/example/jetpackcompose/state/backpress/BackButtonHandler.kt and https://github.com/vinaygaba/Learn-Jetpack-Compose-By-Example/blob/master/app/src/main/java/com/example/jetpackcompose/state/backpress/BackPressActivity.kt. I was focused on navigation-compose and didn't look at anything else.

Vinay Gaba

11/21/2020, 2:33 AM

@Denis The implementation in Showcase is correct - https://github.com/airbnb/Showkase/blob/9301d3dc49fa3174b813931a332d56c5565ea8ad/showkase/src/main/java/com/airbnb/android/showkase/ui/BackButtonHandler.kt#L48. I’ll update the example in Learn Jetpack Compose repo as it uses a less than ideal approach that is also being discussed in the thread that Ian pointed to.

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