使用导航组件bottomnavmenu在android工具栏中自定义后退图标

Question

在使用导航组件和底部导航菜单时，我想在工具栏中使用自己的后退图标。

我已经尝试了所有可能的解决方案，但仍然显示默认的后退图标。

当我写作时

binding.toolbar.setNavigationIcon(R.drawable.ic_arrow_back)

在 onCreate MainActivity 然后显示该图标，但是当我导航到下一个屏幕时，它使用默认值。

我添加了 onDestinationListener

val destinationChangedListener =
        NavController.OnDestinationChangedListener { controller, destination, arguments ->

            when(destination.id){
                R.id.subCategoriesFragment -> {
                    // Nothing is working
                    supportActionBar?.setHomeButtonEnabled(true)
                    supportActionBar?.setHomeAsUpIndicator(R.drawable.ic_arrow_back)
                    binding.toolbar.setNavigationIcon(R.drawable.ic_arrow_back)
                }
                else -> {
                    binding.toolbar.navigationIcon = null
                }
            }
        }

静止工具栏显示默认图标。

我正在使用谷歌的导航扩展来管理所有底部菜单的后台。

扩展代码如下。

/**
 * Manages the various graphs needed for a [BottomNavigationView].
 *
 * This sample is a workaround until the Navigation Component supports multiple back stacks.
 */
fun BottomNavigationView.setupWithNavController(
    navGraphIds: List<Int>,
    fragmentManager: FragmentManager,
    containerId: Int,
    intent: Intent
): LiveData<NavController> {

    // Map of tags
    val graphIdToTagMap = SparseArray<String>()
    // Result. Mutable live data with the selected controlled
    val selectedNavController = MutableLiveData<NavController>()

    var firstFragmentGraphId = 0

    // First create a NavHostFragment for each NavGraph ID
    navGraphIds.forEachIndexed { index, navGraphId ->
        val fragmentTag = getFragmentTag(index)

        // Find or create the Navigation host fragment
        val navHostFragment = obtainNavHostFragment(
            fragmentManager,
            fragmentTag,
            navGraphId,
            containerId
        )

        // Obtain its id
        val graphId = navHostFragment.navController.graph.id

        if (index == 0) {
            firstFragmentGraphId = graphId
        }

        // Save to the map
        graphIdToTagMap[graphId] = fragmentTag

        // Attach or detach nav host fragment depending on whether it's the selected item.
        if (this.selectedItemId == graphId) {
            // Update livedata with the selected graph
            selectedNavController.value = navHostFragment.navController
            attachNavHostFragment(fragmentManager, navHostFragment, index == 0)
        } else {
            detachNavHostFragment(fragmentManager, navHostFragment)
        }
    }

    // Now connect selecting an item with swapping Fragments
    var selectedItemTag = graphIdToTagMap[this.selectedItemId]
    val firstFragmentTag = graphIdToTagMap[firstFragmentGraphId]
    var isOnFirstFragment = selectedItemTag == firstFragmentTag

    // When a navigation item is selected
    setOnNavigationItemSelectedListener { item ->
        LocalBroadcastManager.getInstance(context).sendBroadcast(Intent(SELECTED_RESELETED_ITEM).apply {
            putExtra("item", item.itemId)
        })
        // Don't do anything if the state is state has already been saved.
        if (fragmentManager.isStateSaved) {
            false
        } else {
            val newlySelectedItemTag = graphIdToTagMap[item.itemId]
            if (selectedItemTag != newlySelectedItemTag) {
                // Pop everything above the first fragment (the "fixed start destination")
                fragmentManager.popBackStack(firstFragmentTag,
                    FragmentManager.POP_BACK_STACK_INCLUSIVE)
                val selectedFragment = fragmentManager.findFragmentByTag(newlySelectedItemTag)
                    as NavHostFragment

                // Exclude the first fragment tag because it's always in the back stack.
                if (firstFragmentTag != newlySelectedItemTag) {
                    // Commit a transaction that cleans the back stack and adds the first fragment
                    // to it, creating the fixed started destination.
                    fragmentManager.beginTransaction()
                        .setCustomAnimations(
                            R.anim.nav_default_enter_anim,
                            R.anim.nav_default_exit_anim,
                            R.anim.nav_default_pop_enter_anim,
                            R.anim.nav_default_pop_exit_anim)
                        .attach(selectedFragment)
                        .setPrimaryNavigationFragment(selectedFragment)
                        .apply {
                            // Detach all other Fragments
                            graphIdToTagMap.forEach { _, fragmentTagIter ->
                                if (fragmentTagIter != newlySelectedItemTag) {
                                    detach(fragmentManager.findFragmentByTag(firstFragmentTag)!!)
                                }
                            }
                        }
                        .addToBackStack(firstFragmentTag)
                        .setReorderingAllowed(true)
                        .commit()
                }
                selectedItemTag = newlySelectedItemTag
                isOnFirstFragment = selectedItemTag == firstFragmentTag
                selectedNavController.value = selectedFragment.navController
                true
            } else {
                false
            }
        }
    }

    // Optional: on item reselected, pop back stack to the destination of the graph
    setupItemReselected(graphIdToTagMap, fragmentManager)

    // Handle deep link
    setupDeepLinks(navGraphIds, fragmentManager, containerId, intent)

    // Finally, ensure that we update our BottomNavigationView when the back stack changes
    fragmentManager.addOnBackStackChangedListener {
        if (!isOnFirstFragment && !fragmentManager.isOnBackStack(firstFragmentTag)) {
            this.selectedItemId = firstFragmentGraphId
        }

        // Reset the graph if the currentDestination is not valid (happens when the back
        // stack is popped after using the back button).
        selectedNavController.value?.let { controller ->
            if (controller.currentDestination == null) {
                controller.navigate(controller.graph.id)
            }
        }
    }
    return selectedNavController
}

private fun BottomNavigationView.setupDeepLinks(
    navGraphIds: List<Int>,
    fragmentManager: FragmentManager,
    containerId: Int,
    intent: Intent
) {
    navGraphIds.forEachIndexed { index, navGraphId ->
        val fragmentTag = getFragmentTag(index)

        // Find or create the Navigation host fragment
        val navHostFragment = obtainNavHostFragment(
            fragmentManager,
            fragmentTag,
            navGraphId,
            containerId
        )
        // Handle Intent
        if (navHostFragment.navController.handleDeepLink(intent)
                && selectedItemId != navHostFragment.navController.graph.id) {
            this.selectedItemId = navHostFragment.navController.graph.id
        }
    }
}

private fun BottomNavigationView.setupItemReselected(
    graphIdToTagMap: SparseArray<String>,
    fragmentManager: FragmentManager
) {
    setOnNavigationItemReselectedListener { item ->
        LocalBroadcastManager.getInstance(context).sendBroadcast(Intent(SELECTED_RESELETED_ITEM).apply {
            putExtra("item", item.itemId)
        })
        val newlySelectedItemTag = graphIdToTagMap[item.itemId]
        val selectedFragment = fragmentManager.findFragmentByTag(newlySelectedItemTag)
            as NavHostFragment
        val navController = selectedFragment.navController
        // Pop the back stack to the start destination of the current navController graph
        navController.popBackStack(
            navController.graph.startDestination, false
        )
    }
}

private fun detachNavHostFragment(
    fragmentManager: FragmentManager,
    navHostFragment: NavHostFragment
) {
    fragmentManager.beginTransaction()
        .detach(navHostFragment)
        .commitNow()
}

private fun attachNavHostFragment(
    fragmentManager: FragmentManager,
    navHostFragment: NavHostFragment,
    isPrimaryNavFragment: Boolean
) {
    fragmentManager.beginTransaction()
        .attach(navHostFragment)
        .apply {
            if (isPrimaryNavFragment) {
                setPrimaryNavigationFragment(navHostFragment)
            }
        }
        .commitNow()

}

private fun obtainNavHostFragment(
    fragmentManager: FragmentManager,
    fragmentTag: String,
    navGraphId: Int,
    containerId: Int
): NavHostFragment {
    // If the Nav Host fragment exists, return it
    val existingFragment = fragmentManager.findFragmentByTag(fragmentTag) as NavHostFragment?
    existingFragment?.let { return it }

    // Otherwise, create it and return it.
    val navHostFragment = NavHostFragment.create(navGraphId)
    fragmentManager.beginTransaction()
        .add(containerId, navHostFragment, fragmentTag)
        .commitNow()
    return navHostFragment
}

private fun FragmentManager.isOnBackStack(backStackName: String): Boolean {
    val backStackCount = backStackEntryCount
    for (index in 0 until backStackCount) {
        if (getBackStackEntryAt(index).name == backStackName) {
            return true
        }
    }
    return false
}

private fun getFragmentTag(index: Int) = "bottomNavigation#$index"

谁能帮忙，我如何使用我自己的后退图标。

Answer 1

导航组件的开发者没有提供改变图标的​​方法。

但这可以通过下一种方式实现：

1. 在您的项目中创建一个包：“androidx.navigation.ui”
2. 创建 ModifiedAbstractAppBarOnDestinationChangedListener：

package androidx.navigation.ui;

import android.animation.ObjectAnimator;
import android.animation.ValueAnimator;
import android.content.Context;
import android.graphics.drawable.Drawable;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.StringRes;
import androidx.appcompat.graphics.drawable.DrawerArrowDrawable;
import androidx.customview.widget.Openable;
import androidx.navigation.FloatingWindow;
import androidx.navigation.NavController;
import androidx.navigation.NavDestination;

import java.lang.ref.WeakReference;
import java.util.Set;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * The abstract OnDestinationChangedListener for keeping any type of app bar updated.
 * This handles both updating the title and updating the Up Indicator, transitioning between
 * the drawer icon and up arrow as needed.
 * @hide
 */
public abstract class ModifiedAbstractAppBarOnDestinationChangedListener
        implements NavController.OnDestinationChangedListener {
    private final Context mContext;
    private final Set<Integer> mTopLevelDestinations;
    @Nullable
    private final WeakReference<Openable> mOpenableLayoutWeakReference;
    private DrawerArrowDrawable mArrowDrawable;
    private ValueAnimator mAnimator;

    ModifiedAbstractAppBarOnDestinationChangedListener(@NonNull Context context,
                                                       @NonNull AppBarConfiguration configuration) {
        mContext = context;
        mTopLevelDestinations = configuration.getTopLevelDestinations();
        Openable openableLayout = configuration.getOpenableLayout();
        if (openableLayout != null) {
            mOpenableLayoutWeakReference = new WeakReference<>(openableLayout);
        } else {
            mOpenableLayoutWeakReference = null;
        }
    }

    protected abstract void setTitle(CharSequence title);

    protected abstract void setNavigationIcon(Drawable icon, @StringRes int contentDescription, int destinationId);

    @Override
    public void onDestinationChanged(@NonNull NavController controller,
                                     @NonNull NavDestination destination, @Nullable Bundle arguments) {
        if (destination instanceof FloatingWindow) {
            return;
        }
        Openable openableLayout = mOpenableLayoutWeakReference != null
                ? mOpenableLayoutWeakReference.get()
                : null;
        if (mOpenableLayoutWeakReference != null && openableLayout == null) {
            controller.removeOnDestinationChangedListener(this);
            return;
        }
        int id = destination.getId();
        CharSequence label = destination.getLabel();
        if (label != null) {
            // Fill in the data pattern with the args to build a valid URI
            StringBuffer title = new StringBuffer();
            Pattern fillInPattern = Pattern.compile("\\{(.+?)\\}");
            Matcher matcher = fillInPattern.matcher(label);
            while (matcher.find()) {
                String argName = matcher.group(1);
                if (arguments != null && arguments.containsKey(argName)) {
                    matcher.appendReplacement(title, "");
                    //noinspection ConstantConditions
                    title.append(arguments.get(argName).toString());
                } else {
                    throw new IllegalArgumentException("Could not find " + argName + " in "
                            + arguments + " to fill label " + label);
                }
            }
            matcher.appendTail(title);
            setTitle(title);
        }
        boolean isTopLevelDestination = NavigationUI.matchDestinations(destination,
                mTopLevelDestinations);
        if (openableLayout == null && isTopLevelDestination) {
            setNavigationIcon(null, 0, id);
        } else {
            setActionBarUpIndicator(openableLayout != null && isTopLevelDestination, id);
        }
    }

    private void setActionBarUpIndicator(boolean showAsDrawerIndicator, int destinationId) {
        boolean animate = true;
        if (mArrowDrawable == null) {
            mArrowDrawable = new DrawerArrowDrawable(mContext);
            // We're setting the initial state, so skip the animation
            animate = false;
        }
        setNavigationIcon(mArrowDrawable, showAsDrawerIndicator
                ? R.string.nav_app_bar_open_drawer_description
                : R.string.nav_app_bar_navigate_up_description,
                destinationId);
        float endValue = showAsDrawerIndicator ? 0f : 1f;
        if (animate) {
            float startValue = mArrowDrawable.getProgress();
            if (mAnimator != null) {
                mAnimator.cancel();
            }
            mAnimator = ObjectAnimator.ofFloat(mArrowDrawable, "progress",
                    startValue, endValue);
            mAnimator.start();
        } else {
            mArrowDrawable.setProgress(endValue);
        }
    }
}

1. 创建 ModifiedToolbarOnDestinationChangedListener 并添加使用 getModifiedIcon(drawable, destinationId) 方法更改或替换可绘制图标的功能：

package androidx.navigation.ui;

import android.graphics.drawable.Drawable;
import android.os.Bundle;

import androidx.annotation.NonNull;
import androidx.annotation.Nullable;
import androidx.annotation.StringRes;
import androidx.appcompat.widget.Toolbar;
import androidx.navigation.NavController;
import androidx.navigation.NavDestination;
import androidx.transition.TransitionManager;

import java.lang.ref.WeakReference;

/**
 * The OnDestinationChangedListener specifically for keeping a Toolbar updated.
 * This handles both updating the title and updating the Up Indicator, transitioning between
 * the drawer icon and up arrow as needed.
 * @hide
 */
public class ModifiedToolbarOnDestinationChangedListener extends
        ModifiedAbstractAppBarOnDestinationChangedListener {
    private final WeakReference<Toolbar> mToolbarWeakReference;

    public ModifiedToolbarOnDestinationChangedListener(
            @NonNull Toolbar toolbar, @NonNull AppBarConfiguration configuration) {
        super(toolbar.getContext(), configuration);
        mToolbarWeakReference = new WeakReference<>(toolbar);
    }

    @Override
    public void onDestinationChanged(@NonNull NavController controller,
                                     @NonNull NavDestination destination, @Nullable Bundle arguments) {
        Toolbar toolbar = mToolbarWeakReference.get();
        if (toolbar == null) {
            controller.removeOnDestinationChangedListener(this);
            return;
        }
        super.onDestinationChanged(controller, destination, arguments);
    }

    @Override
    protected void setTitle(CharSequence title) {
        mToolbarWeakReference.get().setTitle(title);
    }

    @Override
    protected void setNavigationIcon(Drawable icon, @StringRes int contentDescription, int destinationId) {
        Toolbar toolbar = mToolbarWeakReference.get();
        if (toolbar != null) {
            Drawable modifiedIcon = getModifiedIcon(icon, destinationId);
            boolean useTransition = modifiedIcon == null && toolbar.getNavigationIcon() != null;
            toolbar.setNavigationIcon(modifiedIcon);
            toolbar.setNavigationContentDescription(contentDescription);
            if (useTransition) {
                TransitionManager.beginDelayedTransition(toolbar);
            }
        }
    }

    @Nullable
    protected Drawable getModifiedIcon(@Nullable Drawable drawable, int destinationId) {
       return drawable;
    }

}

1. 使用修改后的类设置导航组件并根据destinationId更改可绘制图标：

    fun setupWithNavController(toolbar: Toolbar, navController: NavController, configuration: AppBarConfiguration) {
        val listener = object : ModifiedToolbarOnDestinationChangedListener(toolbar, configuration) {
            override fun getModifiedIcon(drawable: Drawable?, destinationId: Int): Drawable? {
                // Return the drawable in depend on destinationId
                if (drawable is DrawerArrowDrawable){
                    drawable.color = Icon.getInstance().iconsColor
                }
                return drawable
            }
        }
        navController.addOnDestinationChangedListener(listener)
        toolbar.setNavigationOnClickListener { NavigationUI.navigateUp(navController, configuration) }
    }