Android: Improve handling of portrait mode

android/app/src/cpp/android_host_interface.cpp

@@ -723,3 +723,10 @@ DEFINE_JNI_ARGS_METHOD(void, AndroidHostInterface_saveState, jobject obj, jboole
   AndroidHostInterface* hi = AndroidHelpers::GetNativeClass(env, obj);
   hi->RunOnEmulationThread([hi, global, slot]() { hi->SaveState(global, slot); });
 }
+
+DEFINE_JNI_ARGS_METHOD(void, AndroidHostInterface_setDisplayAlignment, jobject obj, jint alignment)
+{
+  AndroidHostInterface* hi = AndroidHelpers::GetNativeClass(env, obj);
+  hi->RunOnEmulationThread([hi, alignment]() { hi->GetDisplay()->SetDisplayAlignment(static_cast<HostDisplay::Alignment>(alignment)); });
+}
+

android/app/src/main/AndroidManifest.xml

@@ -18,7 +18,8 @@
             android:configChanges="orientation|keyboardHidden|screenSize"
             android:label="@string/title_activity_emulation"
             android:parentActivityName=".MainActivity"
-            android:theme="@style/FullscreenTheme">
+            android:theme="@style/FullscreenTheme"
+            android:immersive="true">
             <meta-data
                 android:name="android.support.PARENT_ACTIVITY"
                 android:value="com.github.stenzek.duckstation.MainActivity" />

android/app/src/main/java/com/github/stenzek/duckstation/AndroidHostInterface.java

@@ -9,6 +9,10 @@ import android.widget.Toast;
 import com.google.android.material.snackbar.Snackbar;
 
 public class AndroidHostInterface {
+    public final static int DISPLAY_ALIGNMENT_TOP_OR_LEFT = 0;
+    public final static int DISPLAY_ALIGNMENT_CENTER = 1;
+    public final static int DISPLAY_ALIGNMENT_RIGHT_OR_BOTTOM = 2;
+
     private long mNativePointer;
     private Context mContext;
 
@@ -57,6 +61,8 @@ public class AndroidHostInterface {
 
     public native void applySettings();
 
+    public native void setDisplayAlignment(int alignment);
+
     static {
         System.loadLibrary("duckstation-native");
     }

android/app/src/main/java/com/github/stenzek/duckstation/EmulationActivity.java

@@ -2,12 +2,14 @@ package com.github.stenzek.duckstation;
 
 import android.annotation.SuppressLint;
 
+import androidx.annotation.NonNull;
 import androidx.appcompat.app.ActionBar;
 import androidx.appcompat.app.AlertDialog;
 import androidx.appcompat.app.AppCompatActivity;
 
 import android.content.Intent;
 import android.content.SharedPreferences;
+import android.content.res.Configuration;
 import android.os.Bundle;
 import android.os.Handler;
 import android.util.Log;
@@ -102,6 +104,7 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
         // Once we get a surface, we can boot.
         if (AndroidHostInterface.getInstance().isEmulationThreadRunning()) {
             AndroidHostInterface.getInstance().surfaceChanged(holder.getSurface(), format, width, height);
+            updateOrientation();
             return;
         }
 
@@ -110,6 +113,7 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
         final String bootSaveStatePath = getIntent().getStringExtra("saveStatePath");
 
         AndroidHostInterface.getInstance().startEmulationThread(this, holder.getSurface(), bootPath, resumeState, bootSaveStatePath);
+        updateOrientation();
     }
 
     @Override
@@ -227,6 +231,27 @@ public class EmulationActivity extends AppCompatActivity implements SurfaceHolde
         showSystemUI();
     }
 
+    @Override
+    public void onConfigurationChanged(@NonNull Configuration newConfig) {
+        super.onConfigurationChanged(newConfig);
+        updateOrientation(newConfig.orientation);
+    }
+
+    private void updateOrientation() {
+        final int orientation = getResources().getConfiguration().orientation;
+        updateOrientation(orientation);
+    }
+
+    private void updateOrientation(int newOrientation) {
+        if (!AndroidHostInterface.getInstance().isEmulationThreadRunning())
+            return;
+
+        if (newOrientation == Configuration.ORIENTATION_PORTRAIT)
+            AndroidHostInterface.getInstance().setDisplayAlignment(AndroidHostInterface.DISPLAY_ALIGNMENT_TOP_OR_LEFT);
+        else
+            AndroidHostInterface.getInstance().setDisplayAlignment(AndroidHostInterface.DISPLAY_ALIGNMENT_CENTER);
+    }
+
     /**
      * Some older devices needs a small delay between UI widget updates
      * and a change of the status and navigation bar.