Merge pull request #12 from NordicPlayground/bugfix/simple-destinations

Navigating to simple destinations fixed

Author: philips77

app/src/main/java/no/nordicsemi/android/common/test/MainActivity.kt

@@ -37,6 +37,7 @@ import dagger.hilt.android.AndroidEntryPoint
 import no.nordicsemi.android.common.navigation.NavigationView
 import no.nordicsemi.android.common.test.main.MainDestination
 import no.nordicsemi.android.common.test.scanner.ScannerDestination
+import no.nordicsemi.android.common.test.simple.HelloDestination
 import no.nordicsemi.android.common.theme.NordicActivity
 import no.nordicsemi.android.common.theme.NordicTheme
 
@@ -48,7 +49,7 @@ class MainActivity : NordicActivity() {
 
         setContent {
             NordicTheme {
-                NavigationView(MainDestination + ScannerDestination)
+                NavigationView(MainDestination + ScannerDestination + HelloDestination)
             }
         }
     }

app/src/main/java/no/nordicsemi/android/common/test/main/page/BasicViewsPage.kt

@@ -26,6 +26,7 @@ import no.nordicsemi.android.common.navigation.NavigationResult
 import no.nordicsemi.android.common.navigation.Navigator
 import no.nordicsemi.android.common.test.R
 import no.nordicsemi.android.common.test.scanner.Scanner
+import no.nordicsemi.android.common.test.simple.Hello
 import no.nordicsemi.android.common.theme.NordicTheme
 import no.nordicsemi.android.common.theme.view.PagerViewItem
 import no.nordicsemi.android.common.theme.view.RssiIcon
@@ -40,7 +41,8 @@ val BasicsPage = PagerViewItem("Basics") {
 
     BasicViewsScreen(
         device = device?.let { DeviceInfo(it) },
-        onOpenScanner = { vm.openScanner() }
+        onOpenScanner = { vm.openScanner() },
+        onOpenSimple = { vm.openSimple() },
     )
 }
 
@@ -69,6 +71,10 @@ class BasicPageViewModel @Inject constructor(
         // This is Mesh Proxy Service UUID
         navigator.navigateTo(Scanner, ParcelUuid(UUID.fromString("00001828-0000-1000-8000-00805F9B34FB")))
     }
+
+    fun openSimple() {
+        navigator.navigateTo(Hello)
+    }
 }
 
 @SuppressLint("MissingPermission")
@@ -84,6 +90,7 @@ data class DeviceInfo(
 private fun BasicViewsScreen(
     device: DeviceInfo?,
     onOpenScanner: () -> Unit,
+    onOpenSimple: () -> Unit,
 ) {
     Column(
         modifier = Modifier
@@ -92,6 +99,12 @@ private fun BasicViewsScreen(
         verticalArrangement = Arrangement.spacedBy(16.dp),
         horizontalAlignment = Alignment.CenterHorizontally,
     ) {
+        Button(
+            onClick = onOpenSimple
+        ) {
+            Text(text = stringResource(id = R.string.action_simple))
+        }
+
         Button(
             onClick = onOpenScanner
         ) {
@@ -249,7 +262,8 @@ private fun ContentPreview() {
     NordicTheme {
         BasicViewsScreen(
             device = null,
-            onOpenScanner = {}
+            onOpenScanner = {},
+            onOpenSimple = {},
         )
     }
 }

app/src/main/java/no/nordicsemi/android/common/test/simple/Simple.kt

@@ -0,0 +1,71 @@
+package no.nordicsemi.android.common.test.simple
+
+import androidx.compose.foundation.layout.*
+import androidx.compose.material3.Button
+import androidx.compose.material3.ExperimentalMaterial3Api
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.ui.Alignment
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.tooling.preview.Preview
+import androidx.compose.ui.unit.dp
+import androidx.hilt.navigation.compose.hiltViewModel
+import no.nordicsemi.android.common.navigation.createSimpleDestination
+import no.nordicsemi.android.common.navigation.defineDestination
+import no.nordicsemi.android.common.navigation.viewmodel.SimpleNavigationViewModel
+import no.nordicsemi.android.common.test.R
+import no.nordicsemi.android.common.theme.NordicTheme
+import no.nordicsemi.android.common.theme.view.NordicAppBar
+
+/**
+ * This is an example of a simple destination.
+ *
+ * A simple destination does not take any parameters and does not return any result.
+ */
+val Hello = createSimpleDestination("hello")
+
+val HelloDestination = defineDestination(Hello) {
+    val vm: SimpleNavigationViewModel = hiltViewModel()
+
+    HelloScreen(
+        modifier = Modifier.fillMaxWidth(),
+        onNavigateUp = { vm.navigateUp() }
+    )
+}
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun HelloScreen(
+    onNavigateUp: () -> Unit,
+    modifier: Modifier = Modifier,
+) {
+    Column(
+        modifier = modifier,
+    ) {
+        NordicAppBar(
+            text = stringResource(id = R.string.hello),
+            onNavigationButtonClick = onNavigateUp,
+        )
+
+        Column(
+            modifier = Modifier.fillMaxSize(),
+            verticalArrangement = Arrangement.spacedBy(16.dp, Alignment.CenterVertically),
+            horizontalAlignment = Alignment.CenterHorizontally,
+        ) {
+            Text(text = stringResource(id = R.string.hello))
+
+            Button(onClick = onNavigateUp) {
+                Text(text = stringResource(id = R.string.action_dialog))
+            }
+        }
+    }
+}
+
+@Preview
+@Composable
+private fun SimpleContentPreview() {
+    NordicTheme {
+        HelloScreen(onNavigateUp = {})
+    }
+}

app/src/main/res/values/strings.xml

@@ -62,13 +62,17 @@
     <string name="wizard_step_inactive">Inactive</string>
     <string name="wizard_text_inactive">This is not yet available</string>
 
+    <string name="action_simple">Say Hello</string>
     <string name="action_scanner">Open Scanner</string>
     <string name="action_no_op">Button</string>
     <string name="action_disabled">Disabled</string>
     <string name="action_destroy">Destroy</string>
+    <string name="action_dialog">Open Dialog</string>
 
     <string name="option">Important option</string>
 
+    <string name="hello">Hello!</string>
+
     <string name="warning_title">No parachute</string>
     <string name="warning_text">It\'s too late to do anything.</string>
     <string name="warning_normal">Try anyway</string>

navigation/src/main/java/no/nordicsemi/android/common/navigation/Navigator.kt

@@ -19,14 +19,21 @@ interface Navigator {
     fun <R> resultFrom(from: DestinationId<*, R>): Flow<NavigationResult<R>>
 
     /**
-     * Requests navigation to the given destination. An optional parameter can be passed.
+     * Requests navigation to the given destination. An required parameter must be passed.
      *
      * @param to The destination to navigate to.
      * @param args An optional argument to pass to the destination. The argument will be saved
      * in [SavedStateHandle], therefore it must be savable to a [Bundle].
      */
     fun <A> navigateTo(to: DestinationId<A, *>, args: @RawValue A)
 
+    /**
+     * Requests navigation to the given destination which takes no input parameter.
+     *
+     * @param to The destination to navigate to.
+     */
+    fun navigateTo(to: DestinationId<Unit, *>) = navigateTo(to, Unit)
+
     /**
      * Navigates up to previous destination, or finishes the Activity.
      */
@@ -70,4 +77,12 @@ fun <A> SavedStateHandle.getOrNull(destination: DestinationId<A?, *>): A? =
  * @param destination The current destination.
  */
 fun <A> SavedStateHandle.get(destination: DestinationId<A & Any, *>): A =
-    get(destination.name) ?: error("Destination '${destination.name}' requires a non-nullable argument")
+    get(destination.name) ?: error("Destination '${destination.name}' requires a non-nullable argument")
+
+/**
+ * Returns the argument for the current destination.
+ *
+ * @param destination The current destination.
+ */
+fun SavedStateHandle.get(destination: DestinationId<Unit, *>): Nothing =
+    error("Destination '${destination.name}' does not have an argument")

navigation/src/main/java/no/nordicsemi/android/common/navigation/internal/NavigationExecutor.kt

@@ -18,7 +18,7 @@ internal data class NavigationTarget<A>(
     val destination: DestinationId<A, *>,
     val args: @RawValue A
 ) {
-    fun toBundle() = bundleOf(destination.name to args)
+    fun toBundle() = if (args is Unit) bundleOf() else bundleOf(destination.name to args)
 }
 
 internal sealed class NavigationResultState

navigation/src/main/java/no/nordicsemi/android/common/navigation/viewmodel/SimpleNavigationViewModel.kt

@@ -19,16 +19,20 @@ open class SimpleNavigationViewModel @Inject constructor(
     /**
      * Returns the parameter of the current destination, or null, if hasn't been set.
      */
-    fun <A> nullableParameterOf(destinationId: DestinationId<A?, *>): A? {
-        return savedStateHandle.getOrNull(destinationId)
-    }
+    fun <A> nullableParameterOf(destinationId: DestinationId<A?, *>): A? =
+        savedStateHandle.getOrNull(destinationId)
 
     /**
      * Returns the parameter of the current destination, or null, if hasn't been set.
      */
-    fun <A> parameterOf(destinationId: DestinationId<A & Any, *>): A {
-        return savedStateHandle.get(destinationId)
-    }
+    fun <A> parameterOf(destinationId: DestinationId<A & Any, *>): A =
+        savedStateHandle.get(destinationId)
+
+    /**
+     * Returns the parameter of the current destination, or null, if hasn't been set.
+     */
+    fun parameterOf(destinationId: DestinationId<Unit, *>): Nothing =
+        savedStateHandle.get(destinationId)
 
     /**
      * Returns the parameter of the current destination, or null, if hasn't been set.