如何为导航操作定义默认动画？

Question

我正在使用 Android Studio 3.2 Canary 14 和 The Navigation Architecture Component。有了它，您可以像使用 Intents 一样定义过渡动画。

但是动画被设置为导航图中动作的属性，如下所示：

<fragment
    android:id="@+id/startScreenFragment"
    android:name="com.example.startScreen.StartScreenFragment"
    android:label="fragment_start_screen"
    tools:layout="@layout/fragment_start_screen" >
  <action
    android:id="@+id/action_startScreenFragment_to_findAddressFragment"
    app:destination="@id/findAddressFragment"
    app:enterAnim="@animator/slide_in_right"
    app:exitAnim="@animator/slide_out_left"
    app:popEnterAnim="@animator/slide_in_left"
    app:popExitAnim="@animator/slide_out_right"/>
</fragment>

为图表中的所有操作定义这变得乏味！

有没有办法在动作上定义一组默认动画？

我没有为此使用样式。

Answer 1

R.anim 定义了默认动画（最终）：

nav_default_enter_anim
nav_default_exit_anim
nav_default_pop_enter_anim
nav_default_pop_exit_anim

要更改此行为，您必须使用自定义 NavOptions、

因为这是那些动画被分配给 NavAction.

的地方

可以用 NavOptions.Builder:

分配这些

protected NavOptions getNavOptions() {

    NavOptions navOptions = new NavOptions.Builder()
      .setEnterAnim(R.anim.default_enter_anim)
      .setExitAnim(R.anim.default_exit_anim)
      .setPopEnterAnim(R.anim.default_pop_enter_anim)
      .setPopExitAnim(R.anim.default_pop_exit_anim)
      .build();

    return navOptions;
}

很可能需要创建一个 DefaultNavFragment，扩展 class androidx.navigation.fragment（那里的文档似乎还没有完成）。

因此您可以像这样将这些 NavOptions 传递给 NavHostFragment：

NavHostFragment.findNavController(this).navigate(R.id.your_action_id, null, getNavOptions());

或者...查看该包的 attrs.xml 时；这些动画风格：

<resources>
    <declare-styleable name="NavAction">
        <attr name="enterAnim" format="reference"/>
        <attr name="exitAnim" format="reference"/>
        <attr name="popEnterAnim" format="reference"/>
        <attr name="popExitAnim" format="reference"/>
        ...
    </declare-styleable>
</resources>

这意味着，可以定义相应的样式 - 并将这些定义为主题的一部分...

可以在 styles.xml:

中定义它们

<style name="Theme.Default" parent="Theme.AppCompat.Light.NoActionBar">

    <!-- these should be the correct ones -->
    <item name="NavAction_enterAnim">@anim/default_enter_anim</item>
    <item name="NavAction_exitAnim">@anim/default_exit_anim</item>
    <item name="NavAction_popEnterAnim">@anim/default_pop_enter_anim</item>
    <item name="NavAction_popExitAnim">@anim/default_pop_exit_anim</item>

</style>

也可以在res/anim中定义默认动画：

res/anim/nav_default_enter_anim.xml
res/anim/nav_default_exit_anim.xml
res/anim/nav_default_pop_enter_anim.xml
res/anim/nav_default_pop_exit_anim.xml

Answer 2

如上所述，R.anim 定义了默认动画：

nav_default_enter_anim
nav_default_exit_anim
nav_default_pop_enter_anim
nav_default_pop_exit_anim

但您可以轻松覆盖它们。

只需在您的应用程序模块中创建您自己的四个同名动画资源（澄清一下，其中一个的 id 是 your.package.name.R.anim.nav_default_enter_anim）并编写您想要的动画。

Answer 3

可以使用自定义 androidx.navigation.fragment.Navigator。

我将演示如何覆盖 fragment 导航。这是我们的自定义导航器。注意setAnimations()方法

@Navigator.Name("fragment")
class MyAwesomeFragmentNavigator(
    private val context: Context,
    private val manager: FragmentManager, // Should pass childFragmentManager.
    private val containerId: Int
): FragmentNavigator(context, manager, containerId) {
private val backStack by lazy {
    this::class.java.superclass!!.getDeclaredField("mBackStack").let {
        it.isAccessible = true
        it.get(this) as ArrayDeque<Integer>
    }
}

override fun navigate(destination: Destination, args: Bundle?, navOptions: NavOptions?, navigatorExtras: Navigator.Extras?): NavDestination? {
    if (manager.isStateSaved) {
        logi("Ignoring navigate() call: FragmentManager has already"
                + " saved its state")
        return null
    }
    var className = destination.className
    if (className[0] == '.') {
        className = context.packageName + className
    }
    val frag = instantiateFragment(context, manager,
            className, args)
    frag.arguments = args
    val ft = manager.beginTransaction()

    navOptions?.let { setAnimations(it, ft) }

    ft.replace(containerId, frag)
    ft.setPrimaryNavigationFragment(frag)

    @IdRes val destId = destination.id
    val initialNavigation = backStack.isEmpty()
    // TODO Build first class singleTop behavior for fragments
    val isSingleTopReplacement = (navOptions != null && !initialNavigation
            && navOptions.shouldLaunchSingleTop()
            && backStack.peekLast()?.toInt() == destId)

    val isAdded: Boolean
    isAdded = if (initialNavigation) {
        true
    } else if (isSingleTopReplacement) { // Single Top means we only want one 
instance on the back stack
        if (backStack.size > 1) { // If the Fragment to be replaced is on the FragmentManager's
// back stack, a simple replace() isn't enough so we
// remove it from the back stack and put our replacement
// on the back stack in its place
            manager.popBackStack(
                    generateBackStackName(backStack.size, backStack.peekLast()!!.toInt()),
                    FragmentManager.POP_BACK_STACK_INCLUSIVE)
            ft.addToBackStack(generateBackStackName(backStack.size, destId))
        }
        false
    } else {
        ft.addToBackStack(generateBackStackName(backStack.size + 1, destId))
        true
    }
    if (navigatorExtras is Extras) {
        for ((key, value) in navigatorExtras.sharedElements) {
            ft.addSharedElement(key!!, value!!)
        }
    }
    ft.setReorderingAllowed(true)
    ft.commit()
    // The commit succeeded, update our view of the world
    return if (isAdded) {
        backStack.add(Integer(destId))
        destination
    } else {
        null
    }
}

private fun setAnimations(navOptions: NavOptions, transaction: FragmentTransaction) {
    transaction.setCustomAnimations(
            navOptions.enterAnim.takeIf { it != -1 } ?: android.R.anim.fade_in,
            navOptions.exitAnim.takeIf { it != -1 } ?: android.R.anim.fade_out,
            navOptions.popEnterAnim.takeIf { it != -1 } ?: android.R.anim.fade_in,
            navOptions.popExitAnim.takeIf { it != -1 } ?: android.R.anim.fade_out
    )
}

private fun generateBackStackName(backStackIndex: Int, destId: Int): String? {
    return "$backStackIndex-$destId"
}
}

下一步我们必须将导航器添加到 NavController。这是一个如何设置它的例子：

 override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    val navHostFragment = supportFragmentManager.findFragmentById(R.id.fragmentContainer)!!
    with (findNavController(R.id.fragmentContainer)) {
        navigatorProvider += MyAwesomeFragmentNavigator(this@BaseContainerActivity, navHostFragment.childFragmentManager, R.id.fragmentContainer)
        setGraph(navGraphId)
    }
}

xml 没什么特别的:)

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical">

<fragment
    android:id="@+id/fragmentContainer"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    app:defaultNavHost="true" />
</LinearLayout>

现在图中的每个片段都会有 alpha 转换

Answer 4

我找到了需要扩展 NavHostFragment 的解决方案。它类似于但较少涉及代码。大多数情况下，它需要从标准更改所有 xml defaultNavHost 片段名称：

<fragment
    app:defaultNavHost="true"
    ...
    android:name="androidx.navigation.fragment.NavHostFragment"

至：

<fragment
    app:defaultNavHost="true"
    ...
    android:name="your.app.package.fragments.NavHostFragmentWithDefaultAnimations"

NavHostFragmentWithDefaultAnimations 的代码：

package your.app.package.fragments

import android.content.Context
import android.os.Bundle
import androidx.fragment.app.FragmentManager
import androidx.navigation.*
import androidx.navigation.fragment.FragmentNavigator
import androidx.navigation.fragment.NavHostFragment
import your.app.package.R

// Those are navigation-ui (androidx.navigation.ui) defaults
// used in NavigationUI for NavigationView and BottomNavigationView.
// Set yours here
private val defaultNavOptions = navOptions {
    anim {
        enter = R.animator.nav_default_enter_anim
        exit = R.animator.nav_default_exit_anim
        popEnter = R.animator.nav_default_pop_enter_anim
        popExit = R.animator.nav_default_pop_exit_anim
    }
}

private val emptyNavOptions = navOptions {}

class NavHostFragmentWithDefaultAnimations : NavHostFragment() {

    override fun onCreateNavController(navController: NavController) {
        super.onCreateNavController(navController)
        navController.navigatorProvider.addNavigator(
            // this replaces FragmentNavigator
            FragmentNavigatorWithDefaultAnimations(requireContext(), childFragmentManager, id)
        )
    }

}

/**
 * Needs to replace FragmentNavigator and replacing is done with name in annotation.
 * Navigation method will use defaults for fragments transitions animations.
 */
@Navigator.Name("fragment")
class FragmentNavigatorWithDefaultAnimations(
    context: Context,
    manager: FragmentManager,
    containerId: Int
) : FragmentNavigator(context, manager, containerId) {

    override fun navigate(
        destination: Destination,
        args: Bundle?,
        navOptions: NavOptions?,
        navigatorExtras: Navigator.Extras?
    ): NavDestination? {
        // this will try to fill in empty animations with defaults when no shared element transitions are set
        // https://developer.android.com/guide/navigation/navigation-animate-transitions#shared-element
        val shouldUseTransitionsInstead = navigatorExtras != null
        val navOptions = if (shouldUseTransitionsInstead) navOptions
        else navOptions.fillEmptyAnimationsWithDefaults()
        return super.navigate(destination, args, navOptions, navigatorExtras)
    }

    private fun NavOptions?.fillEmptyAnimationsWithDefaults(): NavOptions =
        this?.copyNavOptionsWithDefaultAnimations() ?: defaultNavOptions

    private fun NavOptions.copyNavOptionsWithDefaultAnimations(): NavOptions =
        let { originalNavOptions ->
            navOptions {
                launchSingleTop = originalNavOptions.shouldLaunchSingleTop()
                popUpTo(originalNavOptions.popUpTo) {
                    inclusive = originalNavOptions.isPopUpToInclusive
                }
                anim {
                    enter =
                        if (originalNavOptions.enterAnim == emptyNavOptions.enterAnim) defaultNavOptions.enterAnim
                        else originalNavOptions.enterAnim
                    exit =
                        if (originalNavOptions.exitAnim == emptyNavOptions.exitAnim) defaultNavOptions.exitAnim
                        else originalNavOptions.exitAnim
                    popEnter =
                        if (originalNavOptions.popEnterAnim == emptyNavOptions.popEnterAnim) defaultNavOptions.popEnterAnim
                        else originalNavOptions.popEnterAnim
                    popExit =
                        if (originalNavOptions.popExitAnim == emptyNavOptions.popExitAnim) defaultNavOptions.popExitAnim
                        else originalNavOptions.popExitAnim
                }
            }
        }

}

您可以在导航图中更改动画 xml 或通过传递 navOptions 在代码中更改动画。要禁用默认动画，请传递动画值为 0 的 navOptions 或传递 navigatorExtras（设置共享转换）。

测试版本：

implementation "androidx.navigation:navigation-fragment-ktx:2.3.1"
implementation "androidx.navigation:navigation-ui-ktx:2.3.1"

Answer 5

这是我的解决方案，它在我的应用程序中运行良好。

public void navigate(int resId, Bundle bundle) {
        NavController navController = getNavController();
        if (navController == null) return;
        NavDestination currentNode;

        NavBackStackEntry currentEntry = navController.getCurrentBackStackEntry();
        if (currentEntry == null) currentNode = navController.getGraph();
        else currentNode = currentEntry.getDestination();

        final NavAction navAction = currentNode.getAction(resId);

        final NavOptions navOptions;
        if (navAction == null || navAction.getNavOptions() == null) navOptions = ExampleUtil.defaultNavOptions;
        else if (navAction.getNavOptions().getEnterAnim() == -1
                && navAction.getNavOptions().getPopEnterAnim() == -1
                && navAction.getNavOptions().getExitAnim() == -1
                && navAction.getNavOptions().getPopExitAnim() == -1) {
            navOptions = new NavOptions.Builder()
                    .setLaunchSingleTop(navAction.getNavOptions().shouldLaunchSingleTop())
                    .setPopUpTo(resId, navAction.getNavOptions().isPopUpToInclusive())
                    .setEnterAnim(ExampleUtil.defaultNavOptions.getEnterAnim())
                    .setExitAnim(ExampleUtil.defaultNavOptions.getExitAnim())
                    .setPopEnterAnim(ExampleUtil.defaultNavOptions.getPopEnterAnim())
                    .setPopExitAnim(ExampleUtil.defaultNavOptions.getPopExitAnim())
                    .build();
        } else navOptions = navAction.getNavOptions();
        navController.navigate(resId, bundle, navOptions);
    }

Answer 6

我已经创建了扩展程序并调用了它，而不是在需要时调用 navigation。

fun NavController.navigateWithDefaultAnimation(directions: NavDirections) {
    navigate(directions, navOptions {
        anim {
            enter = R.anim.anim_fragment_enter_transition
            exit = R.anim.anim_fragment_exit_transition
            popEnter = R.anim.anim_fragment_pop_enter_transition
            popExit = R.anim.anim_fragment_pop_exit_transition
        }
    })
}

findNavController().navigateWithDefaultAnimation(HomeFragmentDirections.homeToProfile())

如何为导航操作定义默认动画？

How do I define default animations for Navigation Actions?

android

android-animation

android-jetpack

android-architecture-navigation