Jetpack compose 如何等待动画结束答案

【问题标题】：Jetpack compose how to wait for animation endsJetpack compose 如何等待动画结束
【发布时间】：2021-08-05 21:15:24
【问题描述】：

我通过 AnimatedVisibility (slideInVertically/SlideOut) 制作了简单的动画。当我按下“nextScreenButton”时，我通过 navController 进行新导航。过渡立即完成，因此没有时间退出动画。如何让等到动画结束

我可以为动画时间输入一些延迟，但这不是一个好方法。

代码：

      Scaffold() {
        AnimatedVisibility(
            //Boolean State for open animation 
            OpenChooseProfilePageAnim.value,
            
            initiallyVisible= false,
            enter = slideInVertically(
                initialOffsetY = { fullHeight -> fullHeight },
                animationSpec = tween(
                    durationMillis = 3000,
                    easing = LinearOutSlowInEasing
                )
            ),
            exit = slideOutVertically(
                targetOffsetY = { fullHeight -> fullHeight },
                animationSpec = tween(
                    durationMillis = 3000,
                    easing = LinearOutSlowInEasing
                )
            )
        ) {
            ConstraintLayout() {
                Card() {
                    Column() {
                        
                        //Some other Composable items
                        
                        //Composable button
                        NextScreenButton() {
                            //calling navigation here
                        }
                    }
                }
            }
        }
    }

求帮助。

NextScreenButton 代码：

    fun navigateToMainListPage(navController: NavController) {
        //change State of visibility for "AnimatedVisibility"
        AnimationsState.OpenChooseProfilePageAnim.value = false
        //navigate to another route in NavHost
        navController.navigate(ROUTE_MAIN_LIST)
    }

导航主机：


    @Composable
    fun LoginGroupNavigation(startDestination: String) {
        val navController = rememberNavController()
        NavHost(navController, startDestination = startDestination) {
            composable(LoginScreens.LoginScreen.route) {
                LoginMainPage(navController)
            }
            composable(LoginScreens.EnteringPhoneNumScreen.route,
                arguments = listOf(navArgument("title") { type = NavType.StringType },
            )) {
                val title =  it.arguments?.getString("title") ?: ""
                EnterPhoneNumberForSmsPage(
                    navController = navController,
                    title
                )
            }
    //more composable screens

【问题讨论】：

标签： android android-animation android-jetpack-compose

【解决方案1】：

这里是这样做的主要思想：

   val animVisibleState = remember { MutableTransitionState(false) }
    .apply { targetState = true }

//Note: Once the exit transition is finished,
//the content composable will be removed from the tree, 
//and disposed.
//Both currentState and targetState will be false for 
//visibleState.
if (!animVisibleState.targetState &&
    !animVisibleState.currentState
) {
    //navigate to another route in NavHost
    navController.navigate(ROUTE_MAIN_LIST)
    return
}


AnimatedVisibility(
    visibleState = animVisibleState,
    enter = fadeIn(
        animationSpec = tween(durationMillis = 200)
    ),
    exit = fadeOut(
        animationSpec = tween(durationMillis = 200)
    )
) {
    NextButton() {
        //start exit animation
        animVisibleState.targetState = false
    }

}

【讨论】：

【解决方案2】：

在 Navigation 2.4.0-alpha05 中引入了 Crossfade 作为导航的默认过渡。使用最新版本的 Navigation 2.4.0-alpha06，您可以通过 Accompanist 添加自定义过渡

【讨论】：