[Sample] Hook up back button on Android

sample/android/src/main/kotlin/dev/chrisbanes/haze/sample/android/ExoPlayerSample.kt

@@ -55,12 +55,11 @@ fun ExoPlayerSample(navigator: Navigator) {
     AndroidView(
       factory = { ctx ->
         // For Haze to work with video players, they need to be configured to use a TextureView.
-        // For ExoPlayer that needs to be done via a layout file.
-        val view = LayoutInflater.from(ctx)
-          .inflate(R.layout.exoplayer, null) as PlayerView
-        view.apply {
-          player = exoPlayer
-        }
+        // When using ExoPlayer's PlayerView, that needs to be done via a layout attribute.
+        LayoutInflater.from(ctx).inflate(R.layout.exoplayer, null) as PlayerView
+      },
+      update = { playerView ->
+        playerView.player = exoPlayer
       },
       modifier = Modifier
         .fillMaxSize()
@@ -77,4 +76,5 @@ fun ExoPlayerSample(navigator: Navigator) {
   }
 }
 
-private const val BIG_BUCK_BUNNY = "https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4"
+private const val BIG_BUCK_BUNNY =
+  "https://commondatastorage.googleapis.com/gtv-videos-bucket/sample/BigBuckBunny.mp4"

sample/android/src/main/kotlin/dev/chrisbanes/haze/sample/android/MainActivity.kt

@@ -5,8 +5,11 @@ package dev.chrisbanes.haze.sample.android
 
 import android.os.Bundle
 import androidx.activity.ComponentActivity
+import androidx.activity.compose.BackHandler
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
+import androidx.compose.runtime.remember
+import dev.chrisbanes.haze.sample.Navigator
 import dev.chrisbanes.haze.sample.Sample
 import dev.chrisbanes.haze.sample.Samples
 
@@ -16,8 +19,13 @@ class MainActivity : ComponentActivity() {
     super.onCreate(savedInstanceState)
 
     setContent {
+      val navigator = remember { Navigator() }
+
+      BackHandler { navigator.navigateUp() }
+
       Samples(
         appTitle = title.toString(),
+        navigator = navigator,
         samples = Samples + AndroidSamples,
       )
     }

sample/shared/src/commonMain/kotlin/dev/chrisbanes/haze/sample/Navigator.kt

@@ -0,0 +1,24 @@
+// Copyright 2024, Christopher Banes and the Haze project contributors
+// SPDX-License-Identifier: Apache-2.0
+
+package dev.chrisbanes.haze.sample
+
+import androidx.compose.runtime.mutableStateListOf
+
+class Navigator {
+
+  private val backStack = mutableStateListOf<Sample>()
+
+  val currentSample: Sample?
+    get() = backStack.lastOrNull()
+
+  fun navigateTo(sample: Sample) {
+    backStack.add(sample)
+  }
+
+  fun navigateUp() {
+    if (backStack.isNotEmpty()) {
+      backStack.removeLast()
+    }
+  }
+}

sample/shared/src/commonMain/kotlin/dev/chrisbanes/haze/sample/Samples.kt

@@ -10,11 +10,7 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
-import androidx.compose.material.icons.Icons
-import androidx.compose.material.icons.filled.ArrowBack
 import androidx.compose.material3.ExperimentalMaterial3Api
-import androidx.compose.material3.Icon
-import androidx.compose.material3.IconButton
 import androidx.compose.material3.ListItem
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Scaffold
@@ -24,10 +20,7 @@ import androidx.compose.material3.darkColorScheme
 import androidx.compose.material3.lightColorScheme
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
-import androidx.compose.runtime.getValue
-import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
-import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.platform.testTag
 import coil3.ImageLoader
@@ -61,10 +54,6 @@ data class Sample(
   val content: @Composable (Navigator) -> Unit,
 )
 
-fun interface Navigator {
-  fun navigateUp()
-}
-
 @Composable
 fun SamplesTheme(
   useDarkColors: Boolean = isSystemInDarkTheme(),
@@ -80,6 +69,7 @@ fun SamplesTheme(
 @Composable
 fun Samples(
   appTitle: String,
+  navigator: Navigator = remember { Navigator() },
   samples: List<Sample> = Samples,
 ) {
   setSingletonImageLoaderFactory { context ->
@@ -111,14 +101,8 @@ fun Samples(
   }
 
   SamplesTheme {
-    var currentSample by remember { mutableStateOf<Sample?>(null) }
-
-    val navigator = remember {
-      Navigator { currentSample = null }
-    }
-
     Crossfade(
-      targetState = currentSample,
+      targetState = navigator.currentSample,
       modifier = Modifier.testTagsAsResourceId(true),
     ) { sample ->
       if (sample != null) {
@@ -127,18 +111,7 @@ fun Samples(
         Scaffold(
           topBar = {
             TopAppBar(
-              title = { Text(text = currentSample?.title ?: appTitle) },
-              navigationIcon = {
-                if (currentSample != null) {
-                  IconButton(onClick = { currentSample = null }) {
-                    @Suppress("DEPRECATION")
-                    Icon(
-                      imageVector = Icons.Default.ArrowBack,
-                      contentDescription = "Navigate back",
-                    )
-                  }
-                }
-              },
+              title = { Text(text = appTitle) },
               modifier = Modifier.fillMaxWidth(),
             )
           },
@@ -153,7 +126,7 @@ fun Samples(
                 modifier = Modifier
                   .fillMaxWidth()
                   .testTag(sample.title)
-                  .clickable { currentSample = sample },
+                  .clickable { navigator.navigateTo(sample) },
               )
             }
           }