minor sample app improvements

+<vector xmlns:android="http://schemas.android.com/apk/res/android"
+    android:width="24dp"
+    android:height="24dp"
+    android:viewportWidth="24"
+    android:viewportHeight="24"
+    android:tint="?attr/colorControlNormal">
+  <path
+      android:fillColor="@android:color/white"
+      android:pathData="M12,2C6.47,2 2,6.47 2,12s4.47,10 10,10 10,-4.47 10,-10S17.53,2 12,2zM17,15.59L15.59,17 12,13.41 8.41,17 7,15.59 10.59,12 7,8.41 8.41,7 12,10.59 15.59,7 17,8.41 13.41,12 17,15.59z"/>
+</vector>

@@ -12,6 +12,7 @@ import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.lazy.LazyRow
 import androidx.compose.material.*
+import androidx.compose.material.ripple.rememberRipple
 import androidx.compose.runtime.*
 import androidx.compose.runtime.livedata.observeAsState
 import androidx.compose.ui.Alignment
@@ -98,6 +99,7 @@ class CallActivity : AppCompatActivity() {
                 videoEnabled,
                 flipButtonEnabled,
                 screencastEnabled,
+                onExitClick = { finish() }
             )
         }
     }
@@ -122,6 +124,7 @@ class CallActivity : AppCompatActivity() {
         videoEnabled: Boolean = true,
         flipButtonEnabled: Boolean = true,
         screencastEnabled: Boolean = false,
+        onExitClick: () -> Unit = {},
     ) {
         AppTheme(darkTheme = true) {
             ConstraintLayout(
@@ -187,8 +190,13 @@ class CallActivity : AppCompatActivity() {
                     horizontalArrangement = Arrangement.SpaceEvenly,
                     verticalAlignment = Alignment.Bottom,
                 ) {
+                    val controlSize = 40.dp
+                    val controlPadding = 4.dp
                     Surface(
                         onClick = { viewModel.setMicEnabled(!micEnabled) },
+                        indication = rememberRipple(false),
+                        modifier = Modifier.size(controlSize)
+                            .padding(controlPadding)
                     ) {
                         val resource =
                             if (micEnabled) R.drawable.outline_mic_24 else R.drawable.outline_mic_off_24
@@ -200,6 +208,9 @@ class CallActivity : AppCompatActivity() {
                     }
                     Surface(
                         onClick = { viewModel.setCameraEnabled(!videoEnabled) },
+                        indication = rememberRipple(false),
+                        modifier = Modifier.size(controlSize)
+                            .padding(controlPadding)
                     ) {
                         val resource =
                             if (videoEnabled) R.drawable.outline_videocam_24 else R.drawable.outline_videocam_off_24
@@ -211,6 +222,9 @@ class CallActivity : AppCompatActivity() {
                     }
                     Surface(
                         onClick = { viewModel.flipCamera() },
+                        indication = rememberRipple(false),
+                        modifier = Modifier.size(controlSize)
+                            .padding(controlPadding)
                     ) {
                         Icon(
                             painterResource(id = R.drawable.outline_flip_camera_android_24),
@@ -226,6 +240,9 @@ class CallActivity : AppCompatActivity() {
                                 viewModel.stopScreenCapture()
                             }
                         },
+                        indication = rememberRipple(false),
+                        modifier = Modifier.size(controlSize)
+                            .padding(controlPadding)
                     ) {
                         val resource =
                             if (screencastEnabled) R.drawable.baseline_cast_connected_24 else R.drawable.baseline_cast_24
@@ -235,6 +252,18 @@ class CallActivity : AppCompatActivity() {
                             tint = Color.White,
                         )
                     }
+                    Surface(
+                        onClick = { onExitClick() },
+                        indication = rememberRipple(false),
+                        modifier = Modifier.size(controlSize)
+                            .padding(controlPadding)
+                    ) {
+                        Icon(
+                            painterResource(id = R.drawable.ic_baseline_cancel_24),
+                            contentDescription = "Flip Camera",
+                            tint = Color.White,
+                        )
+                    }
                 }
             }
         }

@@ -151,6 +151,8 @@ class CallActivity : AppCompatActivity() {
             )
         }
 
+        binding.exit.setOnClickListener { finish() }
+
         // Grab audio focus for video call
         val audioManager = getSystemService(AUDIO_SERVICE) as AudioManager
         with(audioManager) {

@@ -103,5 +103,13 @@
             android:background="?android:attr/selectableItemBackground"
             android:padding="@dimen/control_padding"
             android:src="@drawable/baseline_cast_24" />
+
+        <ImageView
+            android:id="@+id/exit"
+            android:layout_width="@dimen/control_size"
+            android:layout_height="@dimen/control_size"
+            android:background="?android:attr/selectableItemBackground"
+            android:padding="@dimen/control_padding"
+            android:src="@drawable/ic_baseline_cancel_24" />
     </LinearLayout>
 </androidx.constraintlayout.widget.ConstraintLayout>