NavEventSnippets as per the Doc

compose/snippets/src/main/java/com/example/compose/snippets/predictiveback/NavEventSnippets.kt

@@ -0,0 +1,138 @@
+/*
+ * Copyright 2026 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.
+ */
+
+@file:Suppress("unused", "UNUSED_VARIABLE")
+
+package com.example.compose.snippets.predictiveback
+
+import androidx.annotation.MainThread
+import androidx.navigationevent.NavigationEvent
+import androidx.navigationevent.NavigationEventHandler
+import androidx.navigationevent.NavigationEventInfo
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.navigationevent.NavigationEventDispatcher
+import androidx.navigationevent.NavigationEventDispatcherOwner
+import androidx.navigationevent.NavigationEventInput
+import androidx.navigationevent.compose.NavigationEventState
+
+@Composable
+private fun HandlingBackEvents() {
+    // [START android_compose_predictiveback_navevent_handler]
+    val myHandler = object: NavigationEventHandler<NavigationEventInfo>(
+        initialInfo = NavigationEventInfo.None,
+        isBackEnabled = true
+    ) {
+        override fun onBackStarted(event: NavigationEvent) {
+            // Prepare for the back event
+        }
+
+        override fun onBackProgressed(event: NavigationEvent) {
+            // Use event.progress for predictive animations
+        }
+
+        // This is the required method for final event handling
+        override fun onBackCompleted() {
+            // Complete the back event
+        }
+
+        override fun onBackCancelled() {
+            // Cancel the back event
+        }
+    }
+    // [END android_compose_predictiveback_navevent_handler]
+}
+
+// [START android_compose_predictiveback_navevent_register_handler]
+@Composable
+fun RegisterHandler(
+    navigationEventDispatcher: NavigationEventDispatcher,
+    myHandler: NavigationEventHandler<*>
+) {
+    DisposableEffect(navigationEventDispatcher, myHandler) {
+        navigationEventDispatcher.addHandler(myHandler)
+        onDispose {
+            myHandler.remove()
+        }
+    }
+}
+// [END android_compose_predictiveback_navevent_register_handler]
+
+
+
+// [START android_compose_predictiveback_navevent_NavigationEventHandler]
+@Composable
+public fun NavigationBackHandler(
+    state: NavigationEventState<out NavigationEventInfo>,
+    isBackEnabled: Boolean = true,
+    onBackCancelled: () -> Unit = {},
+    onBackCompleted: () -> Unit,
+){
+
+}
+// [END android_compose_predictiveback_navevent_NavigationEventHandler]
+
+
+// [START android_compose_predictiveback_navevent_NavigationEvent_dispatcher_owner]
+class MyComponent: NavigationEventDispatcherOwner {
+    override val navigationEventDispatcher: NavigationEventDispatcher =
+        NavigationEventDispatcher()
+}
+// [END android_compose_predictiveback_navevent_NavigationEvent_dispatcher_owner]
+
+
+// [START android_compose_predictiveback_navevent_navigation_event_input]
+public class MyInput : NavigationEventInput() {
+    @MainThread
+    public fun backStarted(event: NavigationEvent) {
+        dispatchOnBackStarted(event)
+    }
+
+    @MainThread
+    public fun backProgressed(event: NavigationEvent) {
+        dispatchOnBackProgressed(event)
+    }
+
+    public fun backCancelled() {
+        dispatchOnBackCancelled()
+    }
+
+    @MainThread
+    public fun backCompleted() {
+        dispatchOnBackCompleted()
+    }
+}
+// [END android_compose_predictiveback_navevent_navigation_event_input]
+
+// TODO: We then need to provide that input to our dispatcher:
+// [START android_compose_predictiveback_navevent_register_input]
+fun setupDispatcher() {
+    val myComponent = MyComponent()
+    val myInput = MyInput()
+
+    // Register the custom input with the dispatcher
+    myComponent.navigationEventDispatcher.addInput(myInput)
+}
+// [END android_compose_predictiveback_navevent_register_input]
+
+// [START android_compose_predictiveback_navevent_dispose]
+fun cleanupDispatcher(myComponent: MyComponent) {
+    // Explicitly remove the dispatcher from the hierarchy when the component is destroyed
+    myComponent.navigationEventDispatcher.dispose()
+}
+// [END android_compose_predictiveback_navevent_dispose]
+
+