Use TopAppBar on all RegV5 screens.

feature/registration/src/main/java/org/signal/registration/screens/RegistrationScaffold.kt

@@ -16,13 +16,18 @@ import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.imePadding
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.layout.wrapContentHeight
+import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Surface
 import androidx.compose.material3.Text
+import androidx.compose.material3.TopAppBarDefaults
+import androidx.compose.material3.TopAppBarScrollBehavior
+import androidx.compose.material3.rememberTopAppBarState
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.layout.SubcomposeLayout
+import androidx.compose.ui.platform.LocalResources
 import androidx.compose.ui.text.style.TextAlign
 import androidx.compose.ui.unit.Dp
 import androidx.compose.ui.unit.dp
@@ -30,6 +35,8 @@ import androidx.compose.ui.unit.sp
 import org.signal.core.ui.WindowBreakpoint
 import org.signal.core.ui.compose.AllDevicePreviews
 import org.signal.core.ui.compose.Previews
+import org.signal.core.ui.getWindowSizeClass
+import org.signal.core.ui.isHeightCompact
 import org.signal.core.ui.rememberWindowBreakpoint
 
 object RegistrationScaffold {
@@ -132,6 +139,19 @@ object RegistrationScaffold {
     }
   }
 
+  @OptIn(ExperimentalMaterial3Api::class)
+  @Composable
+  fun rememberTopBarScrollBehavior(): TopAppBarScrollBehavior {
+    val isHeightCompact = LocalResources.current.getWindowSizeClass().isHeightCompact
+    val topAppBarState = rememberTopAppBarState()
+
+    return if (isHeightCompact) {
+      TopAppBarDefaults.enterAlwaysScrollBehavior(state = topAppBarState)
+    } else {
+      TopAppBarDefaults.pinnedScrollBehavior(state = topAppBarState)
+    }
+  }
+
   @Composable
   fun FooterSurface(
     isContentScrolledUnder: Boolean,

feature/registration/src/main/java/org/signal/registration/screens/countrycode/CountryCodePickerScreen.kt

@@ -28,6 +28,7 @@ import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextField
 import androidx.compose.material3.TextFieldDefaults
+import androidx.compose.material3.TopAppBarScrollBehavior
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
@@ -56,6 +57,7 @@ import org.signal.core.ui.compose.Dividers
 import org.signal.core.ui.compose.IconButtons.IconButton
 import org.signal.core.ui.compose.LargeFontPreviews
 import org.signal.core.ui.compose.Previews
+import org.signal.core.ui.compose.Scaffolds
 import org.signal.core.ui.compose.SignalIcons
 import org.signal.registration.R
 import org.signal.registration.screens.OnePaneRegistrationScaffold
@@ -85,58 +87,40 @@ private fun OnePaneLayout(
   state: CountryCodeState,
   onEvent: (CountryCodePickerScreenEvents) -> Unit
 ) {
+  val topBarScrollBehavior = RegistrationScaffold.rememberTopBarScrollBehavior()
+
   OnePaneRegistrationScaffold(
     modifier = Modifier.fillMaxSize(),
     params = layoutParams,
     topBar = {
-      Row(
-        modifier = Modifier.fillMaxWidth().padding(horizontal = 12.dp, vertical = 8.dp),
-        verticalAlignment = Alignment.CenterVertically
-      ) {
-        IconButton(
-          onClick = { onEvent(CountryCodePickerScreenEvents.Dismissed) }
-        ) {
-          Icon(
-            imageVector = SignalIcons.X.imageVector,
-            contentDescription = stringResource(R.string.CountryCodeSelectScreen__close)
-          )
-        }
-        Text(
-          stringResource(R.string.CountryCodeSelectScreen__your_country),
-          style = MaterialTheme.typography.titleLarge,
-          modifier = Modifier.attachDebugLogHelper()
-        )
-      }
+      TopAppBar(
+        scrollBehavior = topBarScrollBehavior,
+        onCloseClick = { onEvent(CountryCodePickerScreenEvents.Dismissed) }
+      )
     }
   ) {
     CountryList(state, onEvent)
   }
 }
 
+@OptIn(ExperimentalMaterial3Api::class)
 @Composable
 private fun TwoPaneLayout(
   params: RegistrationScaffold.Params.TwoPane,
   state: CountryCodeState,
   onEvent: (CountryCodePickerScreenEvents) -> Unit
 ) {
+  val topBarScrollBehavior = RegistrationScaffold.rememberTopBarScrollBehavior()
+
   TwoPaneRegistrationScaffold(
     modifier = Modifier.fillMaxSize(),
-    topBar = {
-      Row(
-        modifier = Modifier.fillMaxWidth(),
-        verticalAlignment = Alignment.CenterVertically
-      ) {
-        IconButton(
-          onClick = { onEvent(CountryCodePickerScreenEvents.Dismissed) }
-        ) {
-          Icon(
-            imageVector = SignalIcons.X.imageVector,
-            contentDescription = stringResource(R.string.CountryCodeSelectScreen__close)
-          )
-        }
-      }
-    },
     params = params,
+    topBar = {
+      TopAppBar(
+        scrollBehavior = topBarScrollBehavior,
+        onCloseClick = { onEvent(CountryCodePickerScreenEvents.Dismissed) }
+      )
+    },
     firstPane = { paddingValues ->
       Column(
         modifier = Modifier
@@ -146,7 +130,7 @@ private fun TwoPaneLayout(
       ) {
         Text(
           stringResource(R.string.CountryCodeSelectScreen__your_country),
-          style = MaterialTheme.typography.titleLarge,
+          style = MaterialTheme.typography.headlineMedium,
           modifier = Modifier.attachDebugLogHelper()
         )
       }
@@ -164,6 +148,22 @@ private fun TwoPaneLayout(
   )
 }
 
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun TopAppBar(
+  scrollBehavior: TopAppBarScrollBehavior,
+  onCloseClick: () -> Unit
+) {
+  Scaffolds.DefaultTopAppBar(
+    title = "",
+    titleContent = { _, _ -> },
+    onNavigationClick = onCloseClick,
+    navigationIcon = SignalIcons.X.imageVector,
+    navigationContentDescription = stringResource(R.string.CountryCodeSelectScreen__close),
+    scrollBehavior = scrollBehavior
+  )
+}
+
 @Composable
 private fun CountryList(state: CountryCodeState, onEvent: (CountryCodePickerScreenEvents) -> Unit) {
   val listState = rememberLazyListState()

feature/registration/src/main/java/org/signal/registration/screens/phonenumber/PhoneNumberEntryScreen.kt

@@ -24,11 +24,13 @@ import androidx.compose.foundation.text.KeyboardActions
 import androidx.compose.foundation.text.KeyboardOptions
 import androidx.compose.foundation.verticalScroll
 import androidx.compose.material3.CircularProgressIndicator
+import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.MaterialTheme
 import androidx.compose.material3.Text
 import androidx.compose.material3.TextField
 import androidx.compose.material3.TextFieldDefaults
+import androidx.compose.material3.TopAppBarScrollBehavior
 import androidx.compose.runtime.Composable
 import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
@@ -41,6 +43,7 @@ import androidx.compose.ui.draw.clip
 import androidx.compose.ui.focus.FocusRequester
 import androidx.compose.ui.focus.focusRequester
 import androidx.compose.ui.graphics.vector.ImageVector
+import androidx.compose.ui.input.nestedscroll.nestedScroll
 import androidx.compose.ui.platform.LocalResources
 import androidx.compose.ui.platform.testTag
 import androidx.compose.ui.res.stringResource
@@ -57,6 +60,7 @@ import org.signal.core.ui.compose.Dialogs
 import org.signal.core.ui.compose.DropdownMenus
 import org.signal.core.ui.compose.IconButtons.IconButton
 import org.signal.core.ui.compose.Previews
+import org.signal.core.ui.compose.Scaffolds
 import org.signal.registration.R
 import org.signal.registration.screens.OnePaneRegistrationScaffold
 import org.signal.registration.screens.RegistrationScaffold
@@ -64,6 +68,7 @@ import org.signal.registration.screens.TwoPaneRegistrationScaffold
 import org.signal.registration.screens.attachDebugLogHelper
 import org.signal.registration.screens.phonenumber.PhoneNumberEntryState.OneTimeEvent
 import org.signal.registration.test.TestTags
+import org.signal.core.ui.R as CoreR
 
 /**
  * Phone number entry screen
@@ -120,51 +125,7 @@ fun PhoneNumberScreen(
   }
 }
 
-@Composable
-fun TopbarMenu() {
-  Row(
-    modifier = Modifier.fillMaxWidth(),
-    horizontalArrangement = Arrangement.End
-  ) {
-    Box {
-      val menuController = remember { DropdownMenus.MenuController() }
-      IconButton(
-        onClick = { menuController.show() }
-      ) {
-        Icon(
-          imageVector = ImageVector.vectorResource(org.signal.core.ui.R.drawable.symbol_more_vertical_24),
-          contentDescription = stringResource(R.string.RegistrationActivity_open_menu)
-        )
-      }
-
-      DropdownMenus.Menu(
-        controller = menuController,
-        offsetX = 24.dp,
-        offsetY = 0.dp
-      ) {
-        DropdownMenus.Item(
-          text = {
-            Text(text = stringResource(R.string.RegistrationActivity_use_proxy))
-          },
-          onClick = {
-            // TODO: Implement use proxy
-            menuController.hide()
-          }
-        )
-        DropdownMenus.Item(
-          text = {
-            Text(text = stringResource(R.string.RegistrationActivity_link_device))
-          },
-          onClick = {
-            // TODO: Implement link device
-            menuController.hide()
-          }
-        )
-      }
-    }
-  }
-}
-
+@OptIn(ExperimentalMaterial3Api::class)
 @Composable
 private fun OnePaneLayout(
   params: RegistrationScaffold.Params.OnePane,
@@ -175,16 +136,16 @@ private fun OnePaneLayout(
   val selectedCountryEmoji = state.countryEmoji
 
   val scrollState = rememberScrollState()
+  val topBarScrollBehavior = RegistrationScaffold.rememberTopBarScrollBehavior()
 
   OnePaneRegistrationScaffold(
     params = params,
-    topBar = {
-      TopbarMenu()
-    },
+    topBar = { TopAppBar(scrollBehavior = topBarScrollBehavior) },
     content = { paddingValues ->
       Column(
         modifier = Modifier
           .fillMaxSize()
+          .nestedScroll(topBarScrollBehavior.nestedScrollConnection)
           .verticalScroll(scrollState)
           .padding(paddingValues)
       ) {
@@ -224,6 +185,7 @@ private fun OnePaneLayout(
   )
 }
 
+@OptIn(ExperimentalMaterial3Api::class)
 @Composable
 private fun TwoPaneLayout(
   params: RegistrationScaffold.Params.TwoPane,
@@ -233,18 +195,19 @@ private fun TwoPaneLayout(
   val selectedCountry = state.countryName
   val selectedCountryEmoji = state.countryEmoji
 
-  val scrollState = rememberScrollState()
+  val firstPaneScrollState = rememberScrollState()
+  val secondPaneScrollState = rememberScrollState()
+  val topBarScrollBehavior = RegistrationScaffold.rememberTopBarScrollBehavior()
 
   TwoPaneRegistrationScaffold(
     params = params,
-    topBar = {
-      TopbarMenu()
-    },
+    topBar = { TopAppBar(scrollBehavior = topBarScrollBehavior) },
     firstPane = { paddingValues ->
       Column(
         modifier = Modifier
           .weight(1f)
-          .verticalScroll(scrollState)
+          .nestedScroll(topBarScrollBehavior.nestedScrollConnection)
+          .verticalScroll(firstPaneScrollState)
           .padding(paddingValues)
       ) {
         Description()
@@ -254,7 +217,8 @@ private fun TwoPaneLayout(
       Column(
         modifier = Modifier
           .weight(1f)
-          .verticalScroll(scrollState)
+          .nestedScroll(topBarScrollBehavior.nestedScrollConnection)
+          .verticalScroll(secondPaneScrollState)
           .padding(paddingValues)
       ) {
         CountryPicker(
@@ -281,7 +245,7 @@ private fun TwoPaneLayout(
     },
     footer = {
       RegistrationScaffold.FooterSurface(
-        isContentScrolledUnder = scrollState.canScrollForward
+        isContentScrolledUnder = firstPaneScrollState.canScrollForward || secondPaneScrollState.canScrollForward
       ) {
         NextButton(state, onEvent)
       }
@@ -289,6 +253,54 @@ private fun TwoPaneLayout(
   )
 }
 
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+fun TopAppBar(
+  scrollBehavior: TopAppBarScrollBehavior
+) {
+  Scaffolds.DefaultTopAppBar(
+    title = "",
+    titleContent = { _, _ -> },
+    onNavigationClick = { },
+    navigationIcon = null,
+    scrollBehavior = scrollBehavior,
+    actions = {
+      val menuController = remember { DropdownMenus.MenuController() }
+
+      IconButton(
+        onClick = { menuController.show() },
+        modifier = Modifier.padding(horizontal = 8.dp)
+      ) {
+        Icon(
+          imageVector = ImageVector.vectorResource(CoreR.drawable.symbol_more_vertical_24),
+          contentDescription = stringResource(R.string.RegistrationActivity_open_menu)
+        )
+      }
+
+      DropdownMenus.Menu(
+        controller = menuController,
+        offsetX = 24.dp,
+        offsetY = 0.dp
+      ) {
+        DropdownMenus.Item(
+          text = { Text(text = stringResource(R.string.RegistrationActivity_use_proxy)) },
+          onClick = {
+            TODO("Handle use proxy")
+            menuController.hide()
+          }
+        )
+        DropdownMenus.Item(
+          text = { Text(text = stringResource(R.string.RegistrationActivity_link_device)) },
+          onClick = {
+            TODO("Handle link device")
+            menuController.hide()
+          }
+        )
+      }
+    }
+  )
+}
+
 @Composable
 private fun Description() {
   Text(