Avoid recording empty voice messages during an ongoing call.

app/src/main/java/org/thoughtcrime/securesms/audio/AudioRecordingHandler.kt

@@ -8,4 +8,5 @@ interface AudioRecordingHandler {
   fun onRecordSaved()
   fun onRecordMoved(offsetX: Float, absoluteX: Float)
   fun onRecordPermissionRequired()
+  fun onRecorderAlreadyInUse()
 }

app/src/main/java/org/thoughtcrime/securesms/components/InputPanel.java

@@ -568,6 +568,11 @@ public class InputPanel extends ConstraintLayout
     if (listener != null) listener.onRecorderPermissionRequired();
   }
 
+  @Override
+  public void onRecorderAlreadyInUse() {
+    if (listener != null) listener.onRecorderAlreadyInUse();
+  }
+
   @Override
   public void onRecordPressed() {
     if (listener != null) listener.onRecorderStarted();
@@ -815,6 +820,7 @@ public class InputPanel extends ConstraintLayout
     void onRecorderFinished();
     void onRecorderCanceled(boolean byUser);
     void onRecorderPermissionRequired();
+    void onRecorderAlreadyInUse();
     void onEmojiToggle();
     void onLinkPreviewCanceled();
     void onStickerSuggestionSelected(@NonNull StickerRecord sticker);

app/src/main/java/org/thoughtcrime/securesms/components/MicrophoneRecorderView.java

@@ -3,6 +3,7 @@ package org.thoughtcrime.securesms.components;
 import android.Manifest;
 import android.content.Context;
 import android.graphics.PorterDuff;
+import android.media.AudioManager;
 import android.util.AttributeSet;
 import android.view.MotionEvent;
 import android.view.View;
@@ -19,6 +20,7 @@ import android.widget.ImageView;
 
 import androidx.annotation.NonNull;
 import androidx.annotation.Nullable;
+import androidx.core.content.ContextCompat;
 
 import org.thoughtcrime.securesms.R;
 import org.thoughtcrime.securesms.audio.AudioRecordingHandler;
@@ -40,12 +42,16 @@ public final class MicrophoneRecorderView extends FrameLayout implements View.On
   private @Nullable AudioRecordingHandler handler;
   private @NonNull  State                 state = State.NOT_RUNNING;
 
+  private final AudioManager audioManager;
+
   public MicrophoneRecorderView(Context context) {
     super(context);
+    this.audioManager = ContextCompat.getSystemService(context, AudioManager.class);
   }
 
   public MicrophoneRecorderView(Context context, AttributeSet attrs) {
     super(context, attrs);
+    this.audioManager = ContextCompat.getSystemService(context, AudioManager.class);
   }
 
   @Override
@@ -110,10 +116,16 @@ public final class MicrophoneRecorderView extends FrameLayout implements View.On
 
   @Override
   public boolean onTouch(View v, final MotionEvent event) {
+    boolean isMicPossiblyInUse = false;
+    if (audioManager != null) {
+      isMicPossiblyInUse = audioManager.getMode() == AudioManager.MODE_IN_COMMUNICATION || audioManager.getMode() == AudioManager.MODE_IN_CALL;
+    }
     switch (event.getAction()) {
       case MotionEvent.ACTION_DOWN:
         if (!Permissions.hasAll(getContext(), Manifest.permission.RECORD_AUDIO)) {
           if (handler != null) handler.onRecordPermissionRequired();
+        } else if (isMicPossiblyInUse) {
+          if (handler != null) handler.onRecorderAlreadyInUse();
         } else if (state == State.NOT_RUNNING) {
           state = State.RUNNING_HELD;
           floatingRecordButton.display(event.getX(), event.getY());

app/src/main/java/org/thoughtcrime/securesms/conversation/v2/ConversationFragment.kt

@@ -4202,6 +4202,10 @@ class ConversationFragment :
         .execute()
     }
 
+    override fun onRecorderAlreadyInUse() {
+      toast(R.string.ConversationFragment_cannot_record_voice_message_during_call)
+    }
+
     override fun onEmojiToggle() {
       container.toggleInput(MediaKeyboardFragmentCreator, composeText, showSoftKeyOnHide = true)
     }

app/src/main/res/values/strings.xml

@@ -546,6 +546,8 @@
     <string name="ConversationActivity__invite_to_signal">Invite to Signal</string>
     <!-- Snackbar message shown after dismissing the full screen sms export megaphone indicating we\'ll do it again soon -->
     <string name="ConversationActivity__you_will_be_reminded_again_soon">You will be reminded again soon.</string>
+    <!-- Toast message shown when trying to record a voice message during an ongoing call -->
+    <string name="ConversationFragment_cannot_record_voice_message_during_call">Cannot record voice message during call.</string>
 
     <!-- Title for dialog shown when first sending formatted text -->
     <string name="SendingFormattingTextDialog_title">Sending formatted text</string>