PredictiveBack [pattern] v0.1.0

On Android 13+ predictive back lets users peek at the destination during the back-gesture: as the user drags from the screen edge, the OS shows a preview of where they'll land. If the app intercepts back via the legacy OnBackPressedCallback synchronously, the gesture loses its preview animation. Use PredictiveBackHandler (compose-foundation 1.7+) or Compose Navigation's built-in support — both wire into the gesture progress so screen content can animate as the user drags.

Label

Implement predictive-back via PredictiveBackHandler / Compose Navigation

Problem

An app uses BackHandler { closeBottomSheet() } to dismiss a sheet on back press. With predictive back, the user expects to see the underlying screen during the drag — but the app intercepts before the OS can preview, so the gesture flickers or freezes. Worse, on the user's release, the sheet may dismiss but no transition was shown.

Solution

    Use the predictive variant which gives a Flow of gesture progress:

      PredictiveBackHandler(enabled = isOpen) { progress: Flow<BackEventCompat> ->
        try {
          progress.collect { event ->
            // event.progress  : 0f..1f drag progress
            // event.swipeEdge : LEFT or RIGHT
            sheetOffset.snapTo(event.progress)
          }
          // user committed — finish the dismiss
          onDismiss()
        } catch (_: CancellationException) {
          // user cancelled — animate back to fully open
          sheetOffset.animateTo(0f)
        }
      }

    For Compose Navigation (Nav3 / Nav-Compose 2.8+) predictive back is
    handled automatically for the standard NavHost transitions; opt in
    by setting `enablePredictiveBack = true` in the Activity and using
    the default forward/back animations.
  

PredictiveBack [pattern] v0.1.0

On Android 13+ predictive back lets users peek at the destination during the back-gesture: as the user drags from the screen edge, the OS shows a preview of where they'll land. If the app intercepts back via the legacy OnBackPressedCallback synchronously, the gesture loses its preview animation. Use PredictiveBackHandler (compose-foundation 1.7+) or Compose Navigation's built-in support — both wire into the gesture progress so screen content can animate as the user drags.

Label

Implement predictive-back via PredictiveBackHandler / Compose Navigation

Problem

An app uses BackHandler { closeBottomSheet() } to dismiss a sheet on back press. With predictive back, the user expects to see the underlying screen during the drag — but the app intercepts before the OS can preview, so the gesture flickers or freezes. Worse, on the user's release, the sheet may dismiss but no transition was shown.

Solution

    Use the predictive variant which gives a Flow of gesture progress:

      PredictiveBackHandler(enabled = isOpen) { progress: Flow<BackEventCompat> ->
        try {
          progress.collect { event ->
            // event.progress  : 0f..1f drag progress
            // event.swipeEdge : LEFT or RIGHT
            sheetOffset.snapTo(event.progress)
          }
          // user committed — finish the dismiss
          onDismiss()
        } catch (_: CancellationException) {
          // user cancelled — animate back to fully open
          sheetOffset.animateTo(0f)
        }
      }

    For Compose Navigation (Nav3 / Nav-Compose 2.8+) predictive back is
    handled automatically for the standard NavHost transitions; opt in
    by setting `enablePredictiveBack = true` in the Activity and using
    the default forward/back animations.
  

Label

Implement predictive-back via PredictiveBackHandler / Compose Navigation

Problem

An app uses BackHandler { closeBottomSheet() } to dismiss a sheet on back press. With predictive back, the user expects to see the underlying screen during the drag — but the app intercepts before the OS can preview, so the gesture flickers or freezes. Worse, on the user's release, the sheet may dismiss but no transition was shown.

Solution

    Use the predictive variant which gives a Flow of gesture progress:

      PredictiveBackHandler(enabled = isOpen) { progress: Flow<BackEventCompat> ->
        try {
          progress.collect { event ->
            // event.progress  : 0f..1f drag progress
            // event.swipeEdge : LEFT or RIGHT
            sheetOffset.snapTo(event.progress)
          }
          // user committed — finish the dismiss
          onDismiss()
        } catch (_: CancellationException) {
          // user cancelled — animate back to fully open
          sheetOffset.animateTo(0f)
        }
      }

    For Compose Navigation (Nav3 / Nav-Compose 2.8+) predictive back is
    handled automatically for the standard NavHost transitions; opt in
    by setting `enablePredictiveBack = true` in the Activity and using
    the default forward/back animations.