Ricetta delle animazioni

Questa ricetta mostra come sostituire le animazioni predefinite a livello di NavDisplay e di singola destinazione.

Come funziona

Il componibile NavDisplay accetta i parametri transitionSpec, popTransitionSpec e predictivePopTransitionSpec per definire le animazioni per la navigazione in avanti, indietro e con il gesto Indietro predittivo, rispettivamente. Queste animazioni verranno applicate a tutte le destinazioni per impostazione predefinita.

In questo esempio, utilizziamo slideInHorizontally e slideOutHorizontally per creare un'animazione di scorrimento per la navigazione in avanti e indietro.

È anche possibile eseguire l'override di queste animazioni per una destinazione specifica fornendo un transitionSpec e un popTransitionSpec diversi al componente componibile entry. In questa ricetta, ScreenC ha un'animazione di scorrimento verticale personalizzata.

package com.example.nav3recipes.animations


import android.os.Bundle
import androidx.activity.ComponentActivity
import androidx.activity.compose.setContent
import androidx.compose.animation.EnterTransition
import androidx.compose.animation.ExitTransition
import androidx.compose.animation.core.tween
import androidx.compose.animation.slideInHorizontally
import androidx.compose.animation.slideInVertically
import androidx.compose.animation.slideOutHorizontally
import androidx.compose.animation.slideOutVertically
import androidx.compose.animation.togetherWith
import androidx.compose.material3.Button
import androidx.compose.material3.Text
import androidx.lifecycle.compose.dropUnlessResumed
import androidx.navigation3.runtime.NavKey
import androidx.navigation3.runtime.entryProvider
import androidx.navigation3.runtime.metadata
import androidx.navigation3.runtime.rememberNavBackStack
import androidx.navigation3.ui.NavDisplay
import com.example.nav3recipes.content.ContentGreen
import com.example.nav3recipes.content.ContentMauve
import com.example.nav3recipes.content.ContentOrange
import com.example.nav3recipes.ui.setEdgeToEdgeConfig
import kotlinx.serialization.Serializable


@Serializable
private data object ScreenA : NavKey

@Serializable
private data object ScreenB : NavKey

@Serializable
private data object ScreenC : NavKey


class AnimatedActivity : ComponentActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        setEdgeToEdgeConfig()
        super.onCreate(savedInstanceState)
        setContent {

            val backStack = rememberNavBackStack(ScreenA)

            NavDisplay(
                backStack = backStack,
                onBack = { backStack.removeLastOrNull() },
                entryProvider = entryProvider {
                    entry<ScreenA> {
                        ContentOrange("This is Screen A") {
                            Button(onClick = dropUnlessResumed { backStack.add(ScreenB) }) {
                                Text("Go to Screen B")
                            }
                        }
                    }
                    entry<ScreenB> {
                        ContentMauve("This is Screen B") {
                            Button(onClick = dropUnlessResumed { backStack.add(ScreenC) }) {
                                Text("Go to Screen C")
                            }
                        }
                    }
                    entry<ScreenC>(
                        metadata = metadata {
                            // Slide new content up, keeping the old content in place underneath
                            put(NavDisplay.TransitionKey) {
                                slideInVertically(
                                    initialOffsetY = { it },
                                    animationSpec = tween(1000)
                                ) togetherWith ExitTransition.KeepUntilTransitionsFinished
                            }

                            // Slide old content down, revealing the new content in place underneath
                            put(NavDisplay.PopTransitionKey) {
                                EnterTransition.None togetherWith
                                        slideOutVertically(
                                            targetOffsetY = { it },
                                            animationSpec = tween(1000)
                                        )
                            }

                            // Slide old content down, revealing the new content in place underneath
                            put(NavDisplay.PredictivePopTransitionKey) {
                                EnterTransition.None togetherWith
                                        slideOutVertically(
                                            targetOffsetY = { it },
                                            animationSpec = tween(1000)
                                        )
                            }
                        }
                    ) {
                        ContentGreen("This is Screen C")
                    }
                },
                transitionSpec = {
                    // Slide in from right when navigating forward
                    slideInHorizontally(
                        initialOffsetX = { it },
                        animationSpec = tween(1000)
                    ) togetherWith slideOutHorizontally(
                        targetOffsetX = { -it },
                        animationSpec = tween(1000)
                    )
                },
                popTransitionSpec = {
                    // Slide in from left when navigating back
                    slideInHorizontally(
                        initialOffsetX = { -it },
                        animationSpec = tween(1000)
                    ) togetherWith slideOutHorizontally(
                        targetOffsetX = { it },
                        animationSpec = tween(1000)
                    )
                },
                predictivePopTransitionSpec = {
                    // Slide in from left when navigating back
                    slideInHorizontally(
                        initialOffsetX = { -it },
                        animationSpec = tween(1000)
                    ) togetherWith slideOutHorizontally(
                        targetOffsetX = { it },
                        animationSpec = tween(1000)
                    )
                }
            )
        }
    }
}