Updates Navigation approach with new guidance (#347)

Author: Manuel Vivo

app/build.gradle.kts

@@ -85,7 +85,6 @@ dependencies {
 
     implementation(project(":core:ui"))
     implementation(project(":core:designsystem"))
-    implementation(project(":core:navigation"))
 
     implementation(project(":sync:work"))
     implementation(project(":sync:sync-test"))
@@ -104,6 +103,8 @@ dependencies {
     implementation(libs.androidx.compose.runtime)
     implementation(libs.androidx.compose.runtime.tracing)
     implementation(libs.androidx.compose.material3.windowSizeClass)
+    implementation(libs.androidx.hilt.navigation.compose)
+    implementation(libs.androidx.navigation.compose)
     implementation(libs.androidx.window.manager)
     implementation(libs.androidx.profileinstaller)
 
@@ -118,4 +119,4 @@ configurations.configureEach {
         // Temporary workaround for https://issuetracker.google.com/174733673
         force("org.objenesis:objenesis:2.6")
     }
-}
+}

app/src/androidTest/java/com/google/samples/apps/nowinandroid/ui/NiaAppStateTest.kt

@@ -82,9 +82,9 @@ class NiaAppStateTest {
         }
 
         assertEquals(3, state.topLevelDestinations.size)
-        assertTrue(state.topLevelDestinations[0].destination.contains("for_you"))
-        assertTrue(state.topLevelDestinations[1].destination.contains("bookmarks"))
-        assertTrue(state.topLevelDestinations[2].destination.contains("interests"))
+        assertTrue(state.topLevelDestinations[0].name.contains("for_you", true))
+        assertTrue(state.topLevelDestinations[1].name.contains("bookmarks", true))
+        assertTrue(state.topLevelDestinations[2].name.contains("interests", true))
     }
 
     @Test

app/src/main/java/com/google/samples/apps/nowinandroid/navigation/NiaNavHost.kt

@@ -20,15 +20,14 @@ import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.navigation.NavHostController
 import androidx.navigation.compose.NavHost
-import com.google.samples.apps.nowinandroid.core.navigation.NiaNavigationDestination
-import com.google.samples.apps.nowinandroid.feature.author.navigation.AuthorDestination
-import com.google.samples.apps.nowinandroid.feature.author.navigation.authorGraph
-import com.google.samples.apps.nowinandroid.feature.bookmarks.navigation.bookmarksGraph
-import com.google.samples.apps.nowinandroid.feature.foryou.navigation.ForYouDestination
-import com.google.samples.apps.nowinandroid.feature.foryou.navigation.forYouGraph
+import com.google.samples.apps.nowinandroid.feature.author.navigation.authorScreen
+import com.google.samples.apps.nowinandroid.feature.author.navigation.navigateToAuthor
+import com.google.samples.apps.nowinandroid.feature.bookmarks.navigation.bookmarksScreen
+import com.google.samples.apps.nowinandroid.feature.foryou.navigation.forYouNavigationRoute
+import com.google.samples.apps.nowinandroid.feature.foryou.navigation.forYouScreen
 import com.google.samples.apps.nowinandroid.feature.interests.navigation.interestsGraph
-import com.google.samples.apps.nowinandroid.feature.topic.navigation.TopicDestination
-import com.google.samples.apps.nowinandroid.feature.topic.navigation.topicGraph
+import com.google.samples.apps.nowinandroid.feature.topic.navigation.navigateToTopic
+import com.google.samples.apps.nowinandroid.feature.topic.navigation.topicScreen
 
 /**
  * Top-level navigation graph. Navigation is organized as explained at
@@ -40,32 +39,27 @@ import com.google.samples.apps.nowinandroid.feature.topic.navigation.topicGraph
 @Composable
 fun NiaNavHost(
     navController: NavHostController,
-    onNavigateToDestination: (NiaNavigationDestination, String) -> Unit,
     onBackClick: () -> Unit,
     modifier: Modifier = Modifier,
-    startDestination: String = ForYouDestination.route
+    startDestination: String = forYouNavigationRoute
 ) {
     NavHost(
         navController = navController,
         startDestination = startDestination,
         modifier = modifier,
     ) {
-        forYouGraph()
-        bookmarksGraph()
+        forYouScreen()
+        bookmarksScreen()
         interestsGraph(
-            navigateToTopic = {
-                onNavigateToDestination(
-                    TopicDestination, TopicDestination.createNavigationRoute(it)
-                )
+            navigateToTopic = { topicId ->
+                navController.navigateToTopic(topicId)
             },
-            navigateToAuthor = {
-                onNavigateToDestination(
-                    AuthorDestination, AuthorDestination.createNavigationRoute(it)
-                )
+            navigateToAuthor = { authorId ->
+                navController.navigateToAuthor(authorId)
             },
             nestedGraphs = {
-                topicGraph(onBackClick)
-                authorGraph(onBackClick)
+                topicScreen(onBackClick)
+                authorScreen(onBackClick)
             }
         )
     }

app/src/main/java/com/google/samples/apps/nowinandroid/navigation/TopLevelDestination.kt

@@ -17,17 +17,36 @@
 package com.google.samples.apps.nowinandroid.navigation
 
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon
-import com.google.samples.apps.nowinandroid.core.navigation.NiaNavigationDestination
+import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.DrawableResourceIcon
+import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.ImageVectorIcon
+import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
+import com.google.samples.apps.nowinandroid.feature.bookmarks.R as bookmarksR
+import com.google.samples.apps.nowinandroid.feature.foryou.R as forYouR
+import com.google.samples.apps.nowinandroid.feature.interests.R as interestsR
 
 /**
  * Type for the top level destinations in the application. Each of these destinations
  * can contain one or more screens (based on the window size). Navigation from one screen to the
  * next within a single destination will be handled directly in composables.
  */
-data class TopLevelDestination(
-    override val route: String,
-    override val destination: String,
+enum class TopLevelDestination(
     val selectedIcon: Icon,
     val unselectedIcon: Icon,
     val iconTextId: Int
-) : NiaNavigationDestination
+) {
+    FOR_YOU(
+        selectedIcon = DrawableResourceIcon(NiaIcons.Upcoming),
+        unselectedIcon = DrawableResourceIcon(NiaIcons.UpcomingBorder),
+        iconTextId = forYouR.string.for_you
+    ),
+    BOOKMARKS(
+        selectedIcon = DrawableResourceIcon(NiaIcons.Bookmarks),
+        unselectedIcon = DrawableResourceIcon(NiaIcons.BookmarksBorder),
+        iconTextId = bookmarksR.string.saved
+    ),
+    INTERESTS(
+        selectedIcon = ImageVectorIcon(NiaIcons.Grid3x3),
+        unselectedIcon = ImageVectorIcon(NiaIcons.Grid3x3),
+        iconTextId = interestsR.string.interests
+    )
+}

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaApp.kt

@@ -52,7 +52,6 @@ import com.google.samples.apps.nowinandroid.core.designsystem.component.NiaNavig
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.DrawableResourceIcon
 import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.ImageVectorIcon
 import com.google.samples.apps.nowinandroid.core.designsystem.theme.NiaTheme
-import com.google.samples.apps.nowinandroid.feature.foryou.navigation.ForYouDestination
 import com.google.samples.apps.nowinandroid.navigation.NiaNavHost
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination
 
@@ -69,7 +68,9 @@ fun NiaApp(
     NiaTheme {
         val background: @Composable (@Composable () -> Unit) -> Unit =
             when (appState.currentDestination?.route) {
-                ForYouDestination.route -> { content -> NiaGradientBackground(content = content) }
+                TopLevelDestination.FOR_YOU.name -> { content ->
+                    NiaGradientBackground(content = content)
+                }
                 else -> { content -> NiaBackground(content = content) }
             }
 
@@ -85,7 +86,7 @@ fun NiaApp(
                     if (appState.shouldShowBottomBar) {
                         NiaBottomBar(
                             destinations = appState.topLevelDestinations,
-                            onNavigateToDestination = appState::navigate,
+                            onNavigateToDestination = appState::navigateToTopLevelDestination,
                             currentDestination = appState.currentDestination
                         )
                     }
@@ -103,7 +104,7 @@ fun NiaApp(
                     if (appState.shouldShowNavRail) {
                         NiaNavRail(
                             destinations = appState.topLevelDestinations,
-                            onNavigateToDestination = appState::navigate,
+                            onNavigateToDestination = appState::navigateToTopLevelDestination,
                             currentDestination = appState.currentDestination,
                             modifier = Modifier.safeDrawingPadding()
                         )
@@ -112,7 +113,6 @@ fun NiaApp(
                     NiaNavHost(
                         navController = appState.navController,
                         onBackClick = appState::onBackClick,
-                        onNavigateToDestination = appState::navigate,
                         modifier = Modifier
                             .padding(padding)
                             .consumedWindowInsets(padding)
@@ -132,8 +132,7 @@ private fun NiaNavRail(
 ) {
     NiaNavigationRail(modifier = modifier) {
         destinations.forEach { destination ->
-            val selected =
-                currentDestination?.hierarchy?.any { it.route == destination.route } == true
+            val selected = currentDestination.isTopLevelDestinationInHierarchy(destination)
             NiaNavigationRailItem(
                 selected = selected,
                 onClick = { onNavigateToDestination(destination) },
@@ -168,8 +167,7 @@ private fun NiaBottomBar(
 ) {
     NiaNavigationBar {
         destinations.forEach { destination ->
-            val selected =
-                currentDestination?.hierarchy?.any { it.route == destination.route } == true
+            val selected = currentDestination.isTopLevelDestinationInHierarchy(destination)
             NiaNavigationBarItem(
                 selected = selected,
                 onClick = { onNavigateToDestination(destination) },
@@ -195,3 +193,8 @@ private fun NiaBottomBar(
         }
     }
 }
+
+private fun NavDestination?.isTopLevelDestinationInHierarchy(destination: TopLevelDestination) =
+    this?.hierarchy?.any {
+        it.route?.contains(destination.name, true) ?: false
+    } ?: false

app/src/main/java/com/google/samples/apps/nowinandroid/ui/NiaAppState.kt

@@ -28,19 +28,16 @@ import androidx.navigation.NavGraph.Companion.findStartDestination
 import androidx.navigation.NavHostController
 import androidx.navigation.compose.currentBackStackEntryAsState
 import androidx.navigation.compose.rememberNavController
+import androidx.navigation.navOptions
 import androidx.tracing.trace
-import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.DrawableResourceIcon
-import com.google.samples.apps.nowinandroid.core.designsystem.icon.Icon.ImageVectorIcon
-import com.google.samples.apps.nowinandroid.core.designsystem.icon.NiaIcons
-import com.google.samples.apps.nowinandroid.core.navigation.NiaNavigationDestination
 import com.google.samples.apps.nowinandroid.core.ui.TrackDisposableJank
-import com.google.samples.apps.nowinandroid.feature.bookmarks.R as bookmarksR
-import com.google.samples.apps.nowinandroid.feature.bookmarks.navigation.BookmarksDestination
-import com.google.samples.apps.nowinandroid.feature.foryou.R as forYouR
-import com.google.samples.apps.nowinandroid.feature.foryou.navigation.ForYouDestination
-import com.google.samples.apps.nowinandroid.feature.interests.R as interestsR
-import com.google.samples.apps.nowinandroid.feature.interests.navigation.InterestsDestination
+import com.google.samples.apps.nowinandroid.feature.bookmarks.navigation.navigateToBookmarks
+import com.google.samples.apps.nowinandroid.feature.foryou.navigation.navigateToForYou
+import com.google.samples.apps.nowinandroid.feature.interests.navigation.navigateToInterestsGraph
 import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination
+import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination.BOOKMARKS
+import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination.FOR_YOU
+import com.google.samples.apps.nowinandroid.navigation.TopLevelDestination.INTERESTS
 
 @Composable
 fun rememberNiaAppState(
@@ -72,61 +69,35 @@ class NiaAppState(
     /**
      * Top level destinations to be used in the BottomBar and NavRail
      */
-    val topLevelDestinations: List<TopLevelDestination> = listOf(
-        TopLevelDestination(
-            route = ForYouDestination.route,
-            destination = ForYouDestination.destination,
-            selectedIcon = DrawableResourceIcon(NiaIcons.Upcoming),
-            unselectedIcon = DrawableResourceIcon(NiaIcons.UpcomingBorder),
-            iconTextId = forYouR.string.for_you
-        ),
-        TopLevelDestination(
-            route = BookmarksDestination.route,
-            destination = BookmarksDestination.destination,
-            selectedIcon = DrawableResourceIcon(NiaIcons.Bookmarks),
-            unselectedIcon = DrawableResourceIcon(NiaIcons.BookmarksBorder),
-            iconTextId = bookmarksR.string.saved
-        ),
-        TopLevelDestination(
-            route = InterestsDestination.route,
-            destination = InterestsDestination.destination,
-            selectedIcon = ImageVectorIcon(NiaIcons.Grid3x3),
-            unselectedIcon = ImageVectorIcon(NiaIcons.Grid3x3),
-            iconTextId = interestsR.string.interests
-        )
-    )
+    val topLevelDestinations: List<TopLevelDestination> = TopLevelDestination.values().asList()
 
     /**
-     * UI logic for navigating to a particular destination in the app. The NavigationOptions to
-     * navigate with are based on the type of destination, which could be a top level destination or
-     * just a regular destination.
+     * UI logic for navigating to a top level destination in the app. Top level destinations have
+     * only one copy of the destination of the back stack, and save and restore state whenever you
+     * navigate to and from it.
      *
-     * Top level destinations have only one copy of the destination of the back stack, and save and
-     * restore state whenever you navigate to and from it.
-     * Regular destinations can have multiple copies in the back stack and state isn't saved nor
-     * restored.
-     *
-     * @param destination: The [NiaNavigationDestination] the app needs to navigate to.
-     * @param route: Optional route to navigate to in case the destination contains arguments.
+     * @param topLevelDestination: The destination the app needs to navigate to.
      */
-    fun navigate(destination: NiaNavigationDestination, route: String? = null) {
-        trace("Navigation: ${destination.route}") {
-            if (destination is TopLevelDestination) {
-                navController.navigate(route ?: destination.route) {
-                    // Pop up to the start destination of the graph to
-                    // avoid building up a large stack of destinations
-                    // on the back stack as users select items
-                    popUpTo(navController.graph.findStartDestination().id) {
-                        saveState = true
-                    }
-                    // Avoid multiple copies of the same destination when
-                    // reselecting the same item
-                    launchSingleTop = true
-                    // Restore state when reselecting a previously selected item
-                    restoreState = true
+    fun navigateToTopLevelDestination(topLevelDestination: TopLevelDestination) {
+        trace("Navigation: ${topLevelDestination.name}") {
+            val topLevelNavOptions = navOptions {
+                // Pop up to the start destination of the graph to
+                // avoid building up a large stack of destinations
+                // on the back stack as users select items
+                popUpTo(navController.graph.findStartDestination().id) {
+                    saveState = true
                 }
-            } else {
-                navController.navigate(route ?: destination.route)
+                // Avoid multiple copies of the same destination when
+                // reselecting the same item
+                launchSingleTop = true
+                // Restore state when reselecting a previously selected item
+                restoreState = true
+            }
+
+            when (topLevelDestination) {
+                FOR_YOU -> navController.navigateToForYou(topLevelNavOptions)
+                BOOKMARKS -> navController.navigateToBookmarks(topLevelNavOptions)
+                INTERESTS -> navController.navigateToInterestsGraph(topLevelNavOptions)
             }
         }
     }

build-logic/convention/src/main/kotlin/AndroidFeatureConventionPlugin.kt

@@ -44,7 +44,6 @@ class AndroidFeatureConventionPlugin : Plugin<Project> {
                 add("implementation", project(":core:designsystem"))
                 add("implementation", project(":core:data"))
                 add("implementation", project(":core:common"))
-                add("implementation", project(":core:navigation"))
                 add("implementation", project(":core:domain"))
 
                 add("testImplementation", project(":core:testing"))
@@ -68,4 +67,4 @@ class AndroidFeatureConventionPlugin : Plugin<Project> {
             }
         }
     }
-}
+}

core/navigation/build.gradle.kts …winandroid/core/decoder/StringDecoder.ktcore/navigation/build.gradle.kts renamed to core/common/src/main/java/com/google/samples/apps/nowinandroid/core/decoder/StringDecoder.kt core/navigation/build.gradle.kts renamed to core/common/src/main/java/com/google/samples/apps/nowinandroid/core/decoder/StringDecoder.kt

@@ -13,19 +13,9 @@
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
-// TODO: Remove once https://youtrack.jetbrains.com/issue/KTIJ-19369 is fixed
-@Suppress("DSL_SCOPE_VIOLATION")
-plugins {
-    id("nowinandroid.android.library")
-    id("nowinandroid.android.library.jacoco")
-    id("nowinandroid.android.hilt")
-}
 
-android {
-    namespace = "com.google.samples.apps.nowinandroid.core.navigation"
-}
+package com.google.samples.apps.nowinandroid.core.decoder
 
-dependencies {
-    api(libs.androidx.hilt.navigation.compose)
-    api(libs.androidx.navigation.compose)
-}
+interface StringDecoder {
+    fun decodeString(encodedString: String): String
+}

core/common/src/main/java/com/google/samples/apps/nowinandroid/core/decoder/UriDecoder.kt

@@ -0,0 +1,24 @@
+/*
+ * Copyright 2022 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
+ *
+ *     https://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.samples.apps.nowinandroid.core.decoder
+
+import android.net.Uri
+import javax.inject.Inject
+
+class UriDecoder @Inject constructor() : StringDecoder {
+    override fun decodeString(encodedString: String): String = Uri.decode(encodedString)
+}