動畫食譜

這項食譜說明如何在 NavDisplay 層級和個別目的地層級覆寫預設動畫。

運作方式

NavDisplay 可組合函式會採用 transitionSpec、popTransitionSpec 和 predictivePopTransitionSpec 參數，分別定義向前、向後和預測返回導覽的動畫。這些動畫預設會套用至所有目的地。

在本範例中，我們使用 slideInHorizontally 和 slideOutHorizontally 建立滑動動畫，用於向前和向後導覽。

您也可以為特定目的地覆寫這些動畫，方法是為 entry 可組合函式提供不同的 transitionSpec 和 popTransitionSpec。在本食譜中，ScreenC 具有自訂的垂直滑動動畫。

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)
                    )
                }
            )
        }
    }
}