Add left/right sliding animations to the navbar

app/src/main/java/org/torproject/android/OrbotActivity.kt

@@ -16,6 +16,7 @@ import androidx.activity.result.contract.ActivityResultContracts
 import androidx.core.content.ContextCompat
 import androidx.localbroadcastmanager.content.LocalBroadcastManager
 import androidx.navigation.NavController
+import androidx.navigation.NavOptions
 import androidx.navigation.findNavController
 import androidx.navigation.ui.setupWithNavController
 
@@ -85,6 +86,42 @@ class OrbotActivity : BaseActivity() {
 
         bottomNavigationView.menu.findItem(R.id.connectFragment).isChecked = true
 
+        val navOptionsLeftToRight = NavOptions.Builder()
+            .setEnterAnim(R.anim.slide_in_right)
+            .setExitAnim(R.anim.slide_out_left)
+            .setPopEnterAnim(R.anim.slide_in_right)
+            .setPopExitAnim(R.anim.slide_out_left)
+            .build()
+
+        val navOptionsRightToLeft = NavOptions.Builder()
+            .setEnterAnim(R.anim.slide_in_left)
+            .setExitAnim(R.anim.slide_out_right)
+            .setPopEnterAnim(R.anim.slide_in_left)
+            .setPopExitAnim(R.anim.slide_out_right)
+            .build()
+
+        var lastSelectedItemId = R.id.connectFragment
+
+        bottomNavigationView.setOnItemSelectedListener { item ->
+            if (item.itemId == lastSelectedItemId) {
+                return@setOnItemSelectedListener true
+            }
+
+            val navOptions = if (item.itemId > lastSelectedItemId) {
+                navOptionsLeftToRight
+            } else {
+                navOptionsRightToLeft
+            }
+            lastSelectedItemId = item.itemId
+
+            when (item.itemId) {
+                R.id.connectFragment -> navController.navigate(R.id.connectFragment, null, navOptions)
+                R.id.kindnessFragment -> navController.navigate(R.id.kindnessFragment, null, navOptions)
+                R.id.moreFragment -> navController.navigate(R.id.moreFragment, null, navOptions)
+            }
+            true
+        }
+
         with(LocalBroadcastManager.getInstance(this)) {
             registerReceiver(
                 orbotServiceBroadcastReceiver, IntentFilter(OrbotConstants.LOCAL_ACTION_STATUS)

app/src/main/res/anim/slide_in_left.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate
+        android:fromXDelta="-100%"
+        android:toXDelta="0%"
+        android:duration="300"/>
+</set>

app/src/main/res/anim/slide_in_right.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate
+        android:fromXDelta="100%"
+        android:toXDelta="0%"
+        android:duration="300"/>
+</set>

app/src/main/res/anim/slide_out_left.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate
+        android:fromXDelta="0%"
+        android:toXDelta="-100%"
+        android:duration="300"/>
+</set>

app/src/main/res/anim/slide_out_right.xml

@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="utf-8"?>
+<set xmlns:android="http://schemas.android.com/apk/res/android">
+    <translate
+        android:fromXDelta="0%"
+        android:toXDelta="100%"
+        android:duration="300"/>
+</set>

app/src/main/res/layout/activity_orbot.xml

@@ -23,6 +23,7 @@
             android:id="@+id/bottom_navigation"
             android:layout_width="match_parent"
             android:layout_height="wrap_content"
+            android:background="@android:color/black"
             app:layout_constraintStart_toStartOf="parent"
             app:layout_constraintEnd_toEndOf="parent"
             app:layout_constraintBottom_toBottomOf="parent"