UI: disable triggering drawer via gesture; enable alert dialog on back navigation inside conversation and benchmark

examples/llama.android/app/src/main/java/com/example/llama/revamp/MainActivity.kt

@@ -2,30 +2,40 @@ package com.example.llama.revamp
 
 import android.os.Bundle
 import androidx.activity.ComponentActivity
+import androidx.activity.OnBackPressedCallback
+import androidx.activity.OnBackPressedDispatcher
+import androidx.activity.compose.BackHandler
+import androidx.activity.compose.LocalOnBackPressedDispatcherOwner
 import androidx.activity.compose.setContent
 import androidx.compose.foundation.layout.fillMaxSize
+import androidx.compose.material3.DrawerState
 import androidx.compose.material3.DrawerValue
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Surface
 import androidx.compose.material3.rememberDrawerState
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.collectAsState
+import androidx.compose.runtime.derivedStateOf
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.runtime.setValue
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.platform.LocalLifecycleOwner
 import androidx.lifecycle.viewmodel.compose.viewModel
 import androidx.navigation.NavType
 import androidx.navigation.compose.NavHost
 import androidx.navigation.compose.composable
+import androidx.navigation.compose.currentBackStackEntryAsState
 import androidx.navigation.compose.rememberNavController
 import androidx.navigation.navArgument
 import com.example.llama.revamp.engine.InferenceEngine
 import com.example.llama.revamp.navigation.AppDestinations
 import com.example.llama.revamp.navigation.NavigationActions
+import com.example.llama.revamp.ui.components.AppNavigationDrawer
 import com.example.llama.revamp.ui.components.UnloadModelConfirmationDialog
 import com.example.llama.revamp.ui.screens.BenchmarkScreen
 import com.example.llama.revamp.ui.screens.ConversationScreen
@@ -71,6 +81,11 @@ fun AppContent() {
 
     val engineState by viewModel.engineState.collectAsState()
 
+    // Track if model is loaded for gesture handling
+    val isModelLoaded = remember(engineState) {
+        viewModel.isModelLoaded()
+    }
+
     val navigationActions = remember(navController) {
         NavigationActions(navController)
     }
@@ -79,6 +94,65 @@ fun AppContent() {
     var showUnloadDialog by remember { mutableStateOf(false) }
     var pendingNavigation by remember { mutableStateOf<(() -> Unit)?>(null) }
 
+    // Get current route
+    val navBackStackEntry by navController.currentBackStackEntryAsState()
+    val currentRoute by remember {
+        derivedStateOf { navBackStackEntry?.destination?.route }
+    }
+
+    // Determine if current route requires model unloading
+    val routeNeedsModelUnloading by remember(currentRoute) {
+        derivedStateOf {
+            currentRoute == AppDestinations.CONVERSATION_ROUTE ||
+                currentRoute == AppDestinations.BENCHMARK_ROUTE ||
+                currentRoute == AppDestinations.MODE_SELECTION_ROUTE
+        }
+    }
+
+    // Get local back dispatcher
+    val backDispatcher = LocalOnBackPressedDispatcherOwner.current?.onBackPressedDispatcher
+    val lifecycleOwner = LocalLifecycleOwner.current
+
+    // Helper function to handle back press with model unloading check
+    val handleBackWithModelCheck = {
+        if (viewModel.isModelLoaded()) {
+            showUnloadDialog = true
+            pendingNavigation = { navController.popBackStack() }
+            true // Mark as handled
+        } else {
+            navController.popBackStack()
+            true // Mark as handled
+        }
+    }
+
+    // Register a system back handler for screens that need unload confirmation
+    DisposableEffect(lifecycleOwner, backDispatcher, currentRoute, isModelLoaded) {
+        val callback = object : OnBackPressedCallback(
+            // Only enable for screens that need model unloading confirmation
+            routeNeedsModelUnloading && isModelLoaded
+        ) {
+            override fun handleOnBackPressed() {
+                handleBackWithModelCheck()
+            }
+        }
+
+        backDispatcher?.addCallback(lifecycleOwner, callback)
+
+        // Remove the callback when the effect leaves the composition
+        onDispose {
+            callback.remove()
+        }
+    }
+
+    // Compose BackHandler for added protection (this handles Compose-based back navigation)
+    BackHandler(
+        enabled = routeNeedsModelUnloading &&
+            isModelLoaded &&
+            drawerState.currentValue == DrawerValue.Closed
+    ) {
+        handleBackWithModelCheck()
+    }
+
     // Observe back button
     LaunchedEffect(navController) {
         navController.addOnDestinationChangedListener { _, destination, _ ->
@@ -94,7 +168,12 @@ fun AppContent() {
         }
     }
 
-    // Main Content
+    // Main Content with navigation drawer wrapper
+    AppNavigationDrawer(
+        drawerState = drawerState,
+        navigationActions = navigationActions,
+        modelLoaded = isModelLoaded
+    ) {
         NavHost(
             navController = navController,
             startDestination = AppDestinations.MODEL_SELECTION_ROUTE
@@ -129,12 +208,7 @@ fun AppContent() {
                     },
                     onBackPressed = {
                         // Need to unload model before going back
-                    if (viewModel.isModelLoaded()) {
+                        handleBackWithModelCheck()
-                        showUnloadDialog = true
-                        pendingNavigation = { navController.popBackStack() }
-                    } else {
-                        navController.popBackStack()
-                    }
                     },
                     drawerState = drawerState,
                     navigationActions = navigationActions
@@ -146,12 +220,7 @@ fun AppContent() {
                 ConversationScreen(
                     onBackPressed = {
                         // Need to unload model before going back
-                    if (viewModel.isModelLoaded()) {
+                        handleBackWithModelCheck()
-                        showUnloadDialog = true
-                        pendingNavigation = { navController.popBackStack() }
-                    } else {
-                        navController.popBackStack()
-                    }
                     },
                     drawerState = drawerState,
                     navigationActions = navigationActions,
@@ -164,12 +233,7 @@ fun AppContent() {
                 BenchmarkScreen(
                     onBackPressed = {
                         // Need to unload model before going back
-                    if (viewModel.isModelLoaded()) {
+                        handleBackWithModelCheck()
-                        showUnloadDialog = true
-                        pendingNavigation = { navController.popBackStack() }
-                    } else {
-                        navController.popBackStack()
-                    }
                     },
                     onRerunPressed = {
                         viewModel.rerunBenchmark()
@@ -208,6 +272,7 @@ fun AppContent() {
                 )
             }
         }
+    }
 
     // Model unload confirmation dialog
     if (showUnloadDialog) {

examples/llama.android/app/src/main/java/com/example/llama/revamp/ui/components/AppScaffold.kt

@@ -62,10 +62,6 @@ fun AppScaffold(
     // Formatted memory usage
     val memoryText = "${memoryUsage.availableGb}GB available"
 
-    AppNavigationDrawer(
-        drawerState = drawerState,
-        navigationActions = navigationActions
-    ) {
     Scaffold(
         topBar = {
             SystemStatusTopBar(
@@ -85,5 +81,4 @@ fun AppScaffold(
         },
         content = content
     )
-    }
 }

examples/llama.android/app/src/main/java/com/example/llama/revamp/ui/components/NavigationDrawer.kt

@@ -1,5 +1,6 @@
 package com.example.llama.revamp.ui.components
 
+import androidx.activity.compose.BackHandler
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.Spacer
@@ -7,10 +8,13 @@ import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.height
 import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.width
 import androidx.compose.material.icons.Icons
 import androidx.compose.material.icons.filled.Home
 import androidx.compose.material.icons.filled.Settings
+import androidx.compose.material3.Divider
 import androidx.compose.material3.DrawerState
+import androidx.compose.material3.DrawerValue
 import androidx.compose.material3.HorizontalDivider
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
@@ -19,9 +23,14 @@ import androidx.compose.material3.ModalNavigationDrawer
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.derivedStateOf
+import androidx.compose.runtime.getValue
+import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberCoroutineScope
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.dp
 import com.example.llama.revamp.navigation.NavigationActions
@@ -29,19 +38,45 @@ import kotlinx.coroutines.launch
 
 /**
  * App navigation drawer that provides access to different sections of the app.
+ * Gesture opening is disabled when a model is loaded to prevent accidental navigation,
+ * but gesture dismissal is always enabled.
  */
 @Composable
 fun AppNavigationDrawer(
     drawerState: DrawerState,
     navigationActions: NavigationActions,
+    modelLoaded: Boolean = false,
     content: @Composable () -> Unit
 ) {
     val coroutineScope = rememberCoroutineScope()
+    val configuration = LocalConfiguration.current
+
+    // Calculate drawer width (60% of screen width)
+    val drawerWidth = (configuration.screenWidthDp * 0.6).dp
+
+    // Determine if gestures should be enabled
+    // Always enable when drawer is open (to allow dismissal)
+    // Only enable when model is not loaded (to prevent accidental opening)
+    val gesturesEnabled by remember(drawerState.currentValue, modelLoaded) {
+        derivedStateOf {
+            drawerState.currentValue == DrawerValue.Open || !modelLoaded
+        }
+    }
+
+    // Handle back button to close drawer if open
+    BackHandler(enabled = drawerState.currentValue == DrawerValue.Open) {
+        coroutineScope.launch {
+            drawerState.close()
+        }
+    }
 
     ModalNavigationDrawer(
         drawerState = drawerState,
+        gesturesEnabled = gesturesEnabled,
         drawerContent = {
-            ModalDrawerSheet {
+            ModalDrawerSheet(
+                modifier = Modifier.width(drawerWidth)
+            ) {
                 DrawerContent(
                     onHomeClicked = {
                         coroutineScope.launch {