| /* |
| * Copyright (C) 2017 The Android Open Source Project |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); |
| * you may not use this file except in compliance with the License. |
| * You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| package com.google.r4a.examples.explorerapp.common.adapters |
| |
| import android.content.Context |
| import android.os.Bundle |
| import android.support.annotation.NavigationRes |
| import android.support.v4.app.Fragment |
| import android.util.AttributeSet |
| import android.view.LayoutInflater |
| import android.view.View |
| import android.view.ViewGroup |
| import android.widget.FrameLayout |
| |
| import androidx.navigation.NavController |
| import androidx.navigation.NavGraph |
| import androidx.navigation.NavHost |
| import androidx.navigation.Navigation |
| import androidx.navigation.Navigator |
| import androidx.navigation.fragment.FragmentNavigator |
| import androidx.navigation.fragment.R |
| import com.google.r4a.Ambient |
| |
| /** |
| * NOTE(lmr): This is a stripped down version of NavHostFragment that essentially doesn't really do anything extra |
| * except that it allows for the NavController to be passed to it instead of created privately. ComposeActivity ends |
| * up needing this inversion. When we build ComposeNavigator we can get rid of this... but potentially we should add |
| * the setter to |
| */ |
| class MyNavHostFragment : Fragment(), NavHost { |
| |
| var controller: NavController? = null |
| var reference: CompositionReference? = null |
| |
| // State that will be saved and restored |
| private var mDefaultNavHost: Boolean = false |
| |
| /** |
| * Returns the [navigation controller][NavController] for this navigation host. |
| * This method will return null until this host fragment's [.onCreate] |
| * has been called and it has had an opportunity to restore from a previous instance state. |
| * |
| * @return this host's navigation controller |
| * @throws IllegalStateException if called before [.onCreate] |
| */ |
| override fun getNavController(): NavController = controller!! |
| |
| override fun onAttach(context: Context?) { |
| super.onAttach(context) |
| // TODO This feature should probably be a first-class feature of the Fragment system, |
| // but it can stay here until we can add the necessary attr resources to |
| // the fragment lib. |
| if (mDefaultNavHost) { |
| requireFragmentManager().beginTransaction() |
| .setPrimaryNavigationFragment(this) |
| .commit() |
| } |
| } |
| |
| override fun onCreate(savedInstanceState: Bundle?) { |
| super.onCreate(savedInstanceState) |
| val context = requireContext() |
| |
| controller = NavController(context) |
| controller!!.navigatorProvider.addNavigator(createFragmentNavigator()) |
| |
| var navState: Bundle? = null |
| if (savedInstanceState != null) { |
| navState = savedInstanceState.getBundle(KEY_NAV_CONTROLLER_STATE) |
| if (savedInstanceState.getBoolean(KEY_DEFAULT_NAV_HOST, false)) { |
| mDefaultNavHost = true |
| requireFragmentManager().beginTransaction() |
| .setPrimaryNavigationFragment(this) |
| .commit() |
| } |
| } |
| |
| if (navState != null) { |
| // Navigation controller state overrides arguments |
| controller!!.restoreState(navState) |
| } else { |
| // controller!!.setGraph() |
| } |
| } |
| |
| /** |
| * Create the FragmentNavigator that this NavHostFragment will use. By default, this uses |
| * [FragmentNavigator], which replaces the entire contents of the NavHostFragment. |
| * |
| * |
| * This is only called once in [.onCreate] and should not be called directly by |
| * subclasses. |
| * @return a new instance of a FragmentNavigator |
| */ |
| private fun createFragmentNavigator(): Navigator<out FragmentNavigator.Destination> { |
| return FragmentNavigator(requireContext(), childFragmentManager, id) |
| } |
| |
| override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, |
| savedInstanceState: Bundle?): View? { |
| val frameLayout = FrameLayout(inflater.context) |
| // When added via XML, this has no effect (since this FrameLayout is given the ID |
| // automatically), but this ensures that the View exists as part of this Fragment's View |
| // hierarchy in cases where the NavHostFragment is added programmatically as is required |
| // for child fragment transactions |
| frameLayout.id = id |
| return frameLayout |
| } |
| |
| override fun onViewCreated(view: View, savedInstanceState: Bundle?) { |
| super.onViewCreated(view, savedInstanceState) |
| if (view !is ViewGroup) { |
| throw IllegalStateException("created host view $view is not a ViewGroup") |
| } |
| // When added via XML, the parent is null and our view is the root of the NavHostFragment |
| // but when added programmatically, we need to set the NavController on the parent - i.e., |
| // the View that has the ID matching this NavHostFragment. |
| val rootView = if (view.getParent() != null) view.getParent() as View else view |
| Navigation.setViewNavController(rootView, controller) |
| } |
| |
| override fun onSaveInstanceState(outState: Bundle) { |
| super.onSaveInstanceState(outState) |
| val navState = controller!!.saveState() |
| if (navState != null) { |
| outState.putBundle(KEY_NAV_CONTROLLER_STATE, navState) |
| } |
| if (mDefaultNavHost) { |
| outState.putBoolean(KEY_DEFAULT_NAV_HOST, true) |
| } |
| } |
| |
| companion object { |
| private val KEY_NAV_CONTROLLER_STATE = "android-support-nav:fragment:navControllerState" |
| private val KEY_DEFAULT_NAV_HOST = "android-support-nav:fragment:defaultHost" |
| } |
| } |
