Propagate BackHandler#enabled changing in Treehouse

cashapp · Nov 13, 2023 · 34941f6 · 34941f6
1 parent ea3fc40
commit 34941f6
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Showing 6 changed files with 36 additions and 13 deletions.
diff --git a/redwood-treehouse-guest/src/commonMain/kotlin/app/cash/redwood/treehouse/treehouseCompose.kt b/redwood-treehouse-guest/src/commonMain/kotlin/app/cash/redwood/treehouse/treehouseCompose.kt
@@ -27,6 +27,7 @@ import app.cash.redwood.ui.OnBackPressedDispatcher
 import app.cash.redwood.ui.UiConfiguration
 import app.cash.zipline.ZiplineScope
 import app.cash.zipline.ZiplineScoped
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.plus
 
@@ -135,15 +136,21 @@ private fun ZiplineTreehouseUi.Host.asOnBackPressedDispatcher() = object : OnBac
 }
 
 private fun OnBackPressedCallback.asService() = object : OnBackPressedCallbackService {
-  override var isEnabled: Boolean
-    get() = this@asService.isEnabled
-    set(value) {
-      this@asService.isEnabled = value
+  override val isEnabled = MutableStateFlow(this@asService.isEnabled)
+
+  init {
+    enabledChangedCallback = {
+      isEnabled.value = this@asService.isEnabled
     }
+  }
 
   override fun handleOnBackPressed() {
     this@asService.handleOnBackPressed()
   }
+
+  override fun close() {
+    enabledChangedCallback = null
+  }
 }
 
 private object NullOnBackPressedDispatcherService : OnBackPressedDispatcherService {

diff --git a/...i/src/androidMain/kotlin/app/cash/redwood/treehouse/composeui/TreehouseContent.android.kt b/...i/src/androidMain/kotlin/app/cash/redwood/treehouse/composeui/TreehouseContent.android.kt
@@ -30,9 +30,13 @@ internal actual fun platformOnBackPressedDispatcher(): RedwoodOnBackPressedDispa
     object : RedwoodOnBackPressedDispatcher {
       override fun addCallback(onBackPressedCallback: RedwoodOnBackPressedCallback): Cancellable {
         val androidOnBackPressedCallback = onBackPressedCallback.toAndroid()
+        onBackPressedCallback.enabledChangedCallback = {
+          androidOnBackPressedCallback.isEnabled = onBackPressedCallback.isEnabled
+        }
         delegate.addCallback(androidOnBackPressedCallback)
         return object : Cancellable {
           override fun cancel() {
+            onBackPressedCallback.enabledChangedCallback = null
             androidOnBackPressedCallback.remove()
           }
         }

diff --git a/...od-treehouse-host/src/commonMain/kotlin/app/cash/redwood/treehouse/TreehouseAppContent.kt b/...od-treehouse-host/src/commonMain/kotlin/app/cash/redwood/treehouse/TreehouseAppContent.kt
@@ -35,6 +35,7 @@ import kotlinx.coroutines.flow.StateFlow
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.job
 import kotlinx.coroutines.launch
+import kotlinx.coroutines.suspendCancellableCoroutine
 
 private class State<A : AppService>(
   val viewState: ViewState,
@@ -457,20 +458,29 @@ private class ViewContentCodeBinding<A : AppService>(
     onBackPressedCallbackService: OnBackPressedCallbackService,
   ): CancellableService {
     dispatchers.checkZipline()
-    val cancellable = onBackPressedDispatcher.addCallback(
-      object : OnBackPressedCallback(onBackPressedCallbackService.isEnabled) {
+    val cancellableJob = bindingScope.launch(dispatchers.zipline) {
+      val onBackPressedCallback = object : OnBackPressedCallback(onBackPressedCallbackService.isEnabled.value) {
         override fun handleOnBackPressed() {
           bindingScope.launch(dispatchers.zipline) {
             onBackPressedCallbackService.handleOnBackPressed()
           }
         }
-      },
-    )
+      }
+      val cancellable = onBackPressedDispatcher.addCallback(onBackPressedCallback)
+      launch {
+        onBackPressedCallbackService.isEnabled.collect {
+          onBackPressedCallback.isEnabled = it
+        }
+      }
+      suspendCancellableCoroutine { continuation ->
+        continuation.invokeOnCancellation { cancellable.cancel() }
+      }
+    }
 
     return object : CancellableService {
       override fun cancel() {
         dispatchers.checkZipline()
-        cancellable.cancel()
+        cancellableJob.cancel()
       }
 
       override fun close() {

diff --git a/...treehouse-host/src/commonTest/kotlin/app/cash/redwood/treehouse/FakeZiplineTreehouseUi.kt b/...treehouse-host/src/commonTest/kotlin/app/cash/redwood/treehouse/FakeZiplineTreehouseUi.kt
@@ -24,6 +24,7 @@ import app.cash.redwood.protocol.PropertyChange
 import app.cash.redwood.protocol.PropertyTag
 import app.cash.redwood.protocol.WidgetTag
 import app.cash.redwood.ui.UiConfiguration
+import kotlinx.coroutines.flow.MutableStateFlow
 import kotlinx.coroutines.flow.StateFlow
 import kotlinx.serialization.json.JsonPrimitive
 
@@ -62,7 +63,7 @@ class FakeZiplineTreehouseUi(
 
   fun addBackHandler(isEnabled: Boolean): CancellableService {
     val result = host.addOnBackPressedCallback(object : OnBackPressedCallbackService {
-      override var isEnabled = isEnabled
+      override var isEnabled = MutableStateFlow(isEnabled)
 
       override fun handleOnBackPressed() {
         eventLog += "$name.onBackPressed()"

diff --git a/redwood-treehouse/api/zipline-api.toml b/redwood-treehouse/api/zipline-api.toml
@@ -69,8 +69,8 @@ functions = [
   # fun handleOnBackPressed(): kotlin.Unit
   "NjIN59uX",
 
-  # var isEnabled: kotlin.Boolean
-  "yKh+yo1c",
+  # val isEnabled: kotlinx.coroutines.flow.StateFlow<kotlin.Boolean>
+  "TAJYS/cz",
 ]
 
 [app.cash.redwood.treehouse.OnBackPressedDispatcherService]

diff --git a/...reehouse/src/commonMain/kotlin/app/cash/redwood/treehouse/OnBackPressedCallbackService.kt b/...reehouse/src/commonMain/kotlin/app/cash/redwood/treehouse/OnBackPressedCallbackService.kt
@@ -18,11 +18,12 @@ package app.cash.redwood.treehouse
 import app.cash.redwood.ui.OnBackPressedCallback
 import app.cash.zipline.ZiplineService
 import kotlin.native.ObjCName
+import kotlinx.coroutines.flow.StateFlow
 
 /** Redwood's [OnBackPressedCallback] but implementing [ZiplineService]. */
 @ObjCName("OnBackPressedCallbackService", exact = true)
 public interface OnBackPressedCallbackService : ZiplineService {
-  public var isEnabled: Boolean
+  public val isEnabled: StateFlow<Boolean>
 
   public fun handleOnBackPressed()
 }