Android: Fix CheatsActivity d-pad navigation

Special shoutout to Android for not having RTL compatible
variants of nextFocusRight and nextFocusLeft.

Ideally we would have some way to block the user from using
the d-pad to switch between the two panes when in portrait mode,
or make the list pane act as if it's to the left of the details
pane rather than the right when the details pane is open, but I
don't know of a good way to do this. SlidingPaneLayout doesn't
really seem to have been implemented with d-pad navigation in mind.
Thankfully, landscape is the most important use case for gamepads.

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/cheats/ui/CheatDetailsFragment.java

@@ -73,13 +73,12 @@ public class CheatDetailsFragment extends Fragment
     mViewModel.getIsEditing().observe(getViewLifecycleOwner(), this::onIsEditingUpdated);
 
     mButtonDelete.setOnClickListener(this::onDeleteClicked);
-    mButtonEdit.setOnClickListener((v) -> mViewModel.setIsEditing(true));
-    mButtonCancel.setOnClickListener((v) ->
-    {
-      mViewModel.setIsEditing(false);
-      onSelectedCheatUpdated(mCheat);
-    });
+    mButtonEdit.setOnClickListener(this::onEditClicked);
+    mButtonCancel.setOnClickListener(this::onCancelClicked);
     mButtonOk.setOnClickListener(this::onOkClicked);
+
+    CheatsActivity.setOnFocusChangeListenerRecursively(view,
+            (v, hasFocus) -> activity.onDetailsViewFocusChange(hasFocus));
   }
 
   private void clearEditErrors()
@@ -98,6 +97,19 @@ public class CheatDetailsFragment extends Fragment
     builder.show();
   }
 
+  private void onEditClicked(View view)
+  {
+    mViewModel.setIsEditing(true);
+    mButtonOk.requestFocus();
+  }
+
+  private void onCancelClicked(View view)
+  {
+    mViewModel.setIsEditing(false);
+    onSelectedCheatUpdated(mCheat);
+    mButtonDelete.requestFocus();
+  }
+
   private void onOkClicked(View view)
   {
     clearEditErrors();
@@ -118,6 +130,7 @@ public class CheatDetailsFragment extends Fragment
           mViewModel.notifySelectedCheatChanged();
           mViewModel.setIsEditing(false);
         }
+        mButtonEdit.requestFocus();
         break;
       case Cheat.TRY_SET_FAIL_NO_NAME:
         mEditName.setError(getString(R.string.cheats_error_no_name));

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/cheats/ui/CheatListFragment.java

@@ -36,7 +36,7 @@ public class CheatListFragment extends Fragment
     CheatsActivity activity = (CheatsActivity) requireActivity();
     CheatsViewModel viewModel = new ViewModelProvider(activity).get(CheatsViewModel.class);
 
-    recyclerView.setAdapter(new CheatsAdapter(getViewLifecycleOwner(), viewModel));
+    recyclerView.setAdapter(new CheatsAdapter(activity, viewModel));
     recyclerView.setLayoutManager(new LinearLayoutManager(activity));
     recyclerView.addItemDecoration(new DividerItemDecoration(activity, null));
   }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/cheats/ui/CheatWarningFragment.java

@@ -37,6 +37,10 @@ public class CheatWarningFragment extends Fragment implements View.OnClickListen
 
     Button settingsButton = view.findViewById(R.id.button_settings);
     settingsButton.setOnClickListener(this);
+
+    CheatsActivity activity = (CheatsActivity) requireActivity();
+    CheatsActivity.setOnFocusChangeListenerRecursively(view,
+            (v, hasFocus) -> activity.onListViewFocusChange(hasFocus));
   }
 
   @Override

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/cheats/ui/CheatsActivity.java

@@ -5,8 +5,12 @@ package org.dolphinemu.dolphinemu.features.cheats.ui;
 import android.content.Context;
 import android.content.Intent;
 import android.os.Bundle;
+import android.view.View;
+import android.view.ViewGroup;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.AppCompatActivity;
+import androidx.core.view.ViewCompat;
 import androidx.lifecycle.ViewModelProvider;
 import androidx.slidingpanelayout.widget.SlidingPaneLayout;
 
@@ -18,6 +22,7 @@ import org.dolphinemu.dolphinemu.ui.TwoPaneOnBackPressedCallback;
 import org.dolphinemu.dolphinemu.ui.main.MainPresenter;
 
 public class CheatsActivity extends AppCompatActivity
+        implements SlidingPaneLayout.PanelSlideListener
 {
   private static final String ARG_GAME_ID = "game_id";
   private static final String ARG_REVISION = "revision";
@@ -29,6 +34,11 @@ public class CheatsActivity extends AppCompatActivity
   private CheatsViewModel mViewModel;
 
   private SlidingPaneLayout mSlidingPaneLayout;
+  private View mCheatList;
+  private View mCheatDetails;
+
+  private View mCheatListLastFocus;
+  private View mCheatDetailsLastFocus;
 
   public static void launch(Context context, String gameId, int revision, boolean isWii)
   {
@@ -59,6 +69,13 @@ public class CheatsActivity extends AppCompatActivity
     setContentView(R.layout.activity_cheats);
 
     mSlidingPaneLayout = findViewById(R.id.sliding_pane_layout);
+    mCheatList = findViewById(R.id.cheat_list);
+    mCheatDetails = findViewById(R.id.cheat_details);
+
+    mCheatListLastFocus = mCheatList;
+    mCheatDetailsLastFocus = mCheatDetails;
+
+    mSlidingPaneLayout.addPanelSlideListener(this);
 
     getOnBackPressedDispatcher().addCallback(this,
             new TwoPaneOnBackPressedCallback(mSlidingPaneLayout));
@@ -77,6 +94,25 @@ public class CheatsActivity extends AppCompatActivity
     mViewModel.saveIfNeeded(mGameId, mRevision);
   }
 
+  @Override
+  public void onPanelSlide(@NonNull View panel, float slideOffset)
+  {
+  }
+
+  @Override
+  public void onPanelOpened(@NonNull View panel)
+  {
+    boolean rtl = ViewCompat.getLayoutDirection(panel) == ViewCompat.LAYOUT_DIRECTION_RTL;
+    mCheatDetailsLastFocus.requestFocus(rtl ? View.FOCUS_LEFT : View.FOCUS_RIGHT);
+  }
+
+  @Override
+  public void onPanelClosed(@NonNull View panel)
+  {
+    boolean rtl = ViewCompat.getLayoutDirection(panel) == ViewCompat.LAYOUT_DIRECTION_RTL;
+    mCheatListLastFocus.requestFocus(rtl ? View.FOCUS_RIGHT : View.FOCUS_LEFT);
+  }
+
   private void onSelectedCheatChanged(Cheat selectedCheat)
   {
     boolean cheatSelected = selectedCheat != null;
@@ -88,6 +124,30 @@ public class CheatsActivity extends AppCompatActivity
             SlidingPaneLayout.LOCK_MODE_UNLOCKED : SlidingPaneLayout.LOCK_MODE_LOCKED_CLOSED);
   }
 
+  public void onListViewFocusChange(boolean hasFocus)
+  {
+    if (hasFocus)
+    {
+      mCheatListLastFocus = mCheatList.findFocus();
+      if (mCheatListLastFocus == null)
+        throw new NullPointerException();
+
+      mSlidingPaneLayout.close();
+    }
+  }
+
+  public void onDetailsViewFocusChange(boolean hasFocus)
+  {
+    if (hasFocus)
+    {
+      mCheatDetailsLastFocus = mCheatDetails.findFocus();
+      if (mCheatDetailsLastFocus == null)
+        throw new NullPointerException();
+
+      mSlidingPaneLayout.open();
+    }
+  }
+
   private void openDetailsView(boolean open)
   {
     if (open)
@@ -100,4 +160,20 @@ public class CheatsActivity extends AppCompatActivity
     settings.loadSettings(null, mGameId, mRevision, mIsWii);
     return settings;
   }
+
+  public static void setOnFocusChangeListenerRecursively(@NonNull View view,
+          View.OnFocusChangeListener listener)
+  {
+    view.setOnFocusChangeListener(listener);
+
+    if (view instanceof ViewGroup)
+    {
+      ViewGroup viewGroup = (ViewGroup) view;
+      for (int i = 0; i < viewGroup.getChildCount(); i++)
+      {
+        View child = viewGroup.getChildAt(i);
+        setOnFocusChangeListenerRecursively(child, listener);
+      }
+    }
+  }
 }

Source/Android/app/src/main/java/org/dolphinemu/dolphinemu/features/cheats/ui/CheatsAdapter.java

@@ -20,25 +20,27 @@ import java.util.ArrayList;
 
 public class CheatsAdapter extends RecyclerView.Adapter<CheatItemViewHolder>
 {
+  private final CheatsActivity mActivity;
   private final CheatsViewModel mViewModel;
 
-  public CheatsAdapter(LifecycleOwner owner, CheatsViewModel viewModel)
+  public CheatsAdapter(CheatsActivity activity, CheatsViewModel viewModel)
   {
+    mActivity = activity;
     mViewModel = viewModel;
 
-    mViewModel.getCheatAddedEvent().observe(owner, (position) ->
+    mViewModel.getCheatAddedEvent().observe(activity, (position) ->
     {
       if (position != null)
         notifyItemInserted(position);
     });
 
-    mViewModel.getCheatChangedEvent().observe(owner, (position) ->
+    mViewModel.getCheatChangedEvent().observe(activity, (position) ->
     {
       if (position != null)
         notifyItemChanged(position);
     });
 
-    mViewModel.getCheatDeletedEvent().observe(owner, (position) ->
+    mViewModel.getCheatDeletedEvent().observe(activity, (position) ->
     {
       if (position != null)
         notifyItemRemoved(position);
@@ -55,12 +57,15 @@ public class CheatsAdapter extends RecyclerView.Adapter<CheatItemViewHolder>
     {
       case CheatItem.TYPE_CHEAT:
         View cheatView = inflater.inflate(R.layout.list_item_cheat, parent, false);
+        addViewListeners(cheatView);
         return new CheatViewHolder(cheatView);
       case CheatItem.TYPE_HEADER:
         View headerView = inflater.inflate(R.layout.list_item_header, parent, false);
+        addViewListeners(headerView);
         return new HeaderViewHolder(headerView);
       case CheatItem.TYPE_ACTION:
         View actionView = inflater.inflate(R.layout.list_item_submenu, parent, false);
+        addViewListeners(actionView);
         return new ActionViewHolder(actionView);
       default:
         throw new UnsupportedOperationException();
@@ -86,6 +91,12 @@ public class CheatsAdapter extends RecyclerView.Adapter<CheatItemViewHolder>
     return getItemAt(position).getType();
   }
 
+  private void addViewListeners(View view)
+  {
+    CheatsActivity.setOnFocusChangeListenerRecursively(view,
+            (v, hasFocus) -> mActivity.onListViewFocusChange(hasFocus));
+  }
+
   private CheatItem getItemAt(int position)
   {
     // Patches

Source/Android/app/src/main/res/layout-ldrtl/list_item_cheat.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<androidx.constraintlayout.widget.ConstraintLayout
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/root"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:focusable="true"
+    android:nextFocusLeft="@id/checkbox">
+
+    <TextView
+        android:id="@+id/text_name"
+        android:layout_width="0dp"
+        android:layout_height="wrap_content"
+        style="@style/TextAppearance.AppCompat.Headline"
+        android:textSize="16sp"
+        tools:text="Hyrule Field Speed Hack"
+        android:layout_margin="@dimen/spacing_large"
+        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintEnd_toStartOf="@id/checkbox"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent" />
+
+    <CheckBox
+        android:id="@+id/checkbox"
+        android:layout_width="48dp"
+        android:layout_height="64dp"
+        app:layout_constraintStart_toEndOf="@id/text_name"
+        app:layout_constraintEnd_toEndOf="parent"
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintBottom_toBottomOf="parent"
+        android:gravity="center"
+        android:focusable="true"
+        android:nextFocusRight="@id/root" />
+
+</androidx.constraintlayout.widget.ConstraintLayout>

Source/Android/app/src/main/res/layout/list_item_cheat.xml

@@ -6,7 +6,8 @@
     android:id="@+id/root"
     android:layout_width="match_parent"
     android:layout_height="wrap_content"
-    android:focusable="true">
+    android:focusable="true"
+    android:nextFocusRight="@id/checkbox">
 
     <TextView
         android:id="@+id/text_name"
@@ -30,6 +31,7 @@
         app:layout_constraintTop_toTopOf="parent"
         app:layout_constraintBottom_toBottomOf="parent"
         android:gravity="center"
-        android:focusable="true" />
+        android:focusable="true"
+        android:nextFocusLeft="@id/root" />
 
 </androidx.constraintlayout.widget.ConstraintLayout>