Experimental full screen scale mode for mobile

source/Main.hx

@@ -118,6 +118,7 @@ class Main extends Sprite
 
     #if mobile
     FlxG.signals.gameResized.add(resizeGame);
+    FlxG.scaleMode = new flixel.system.scaleModes.FullScreenScaleMode();
     #end
 
     var game:FlxGame = new FlxGame(gameWidth, gameHeight, initialState, Preferences.framerate, Preferences.framerate, skipSplash, startFullscreen);

source/flixel/system/scaleModes/FullScreenScaleMode.hx

@@ -0,0 +1,122 @@
+package flixel.system.scaleModes;
+
+import flixel.system.scaleModes.BaseScaleMode;
+import flixel.math.FlxPoint;
+import flixel.util.FlxAxes;
+import flixel.FlxG;
+#if android
+import android.os.Build;
+import android.Tools;
+#end
+
+class FullScreenScaleMode extends BaseScaleMode
+{
+  public static var windowScale:FlxPoint = FlxPoint.get(1, 1);
+  public static var cutoutSize:FlxPoint = FlxPoint.get(0, 0);
+  // x is game ratio, y is window ratio.
+  public static var ratio:FlxPoint = FlxPoint.get(-1, -1);
+  public static var ratioAxis:FlxAxes = X;
+  public static var enabled(default, set):Bool;
+
+  public function new(enable:Bool = true)
+  {
+    super();
+    enabled = enable;
+  }
+
+  override public function onMeasure(Width:Int, Height:Int):Void
+  {
+    FlxG.width = FlxG.initialWidth;
+    FlxG.height = FlxG.initialHeight;
+
+    updateGameSize(Width, Height);
+    updateDeviceSize(Width, Height);
+    updateCutoutSize(Width, Height);
+    updateScaleOffset();
+    updateGamePosition();
+    if ((cutoutSize.x > 0 || cutoutSize.y > 0) && enabled)
+    {
+      // trace('\nresized the game!\nDevice Size: ${deviceSize}\nGame Size: ${gameSize}\nCutout Size: ${cutoutSize}');
+      fillScreen();
+    }
+  }
+
+  override function updateGameSize(Width:Int, Height:Int):Void
+  {
+    ratio.x = FlxG.width / FlxG.height;
+    ratio.y = Width / Height;
+
+    ratioAxis = ratio.y < ratio.x ? Y : X;
+
+    // trace('ratio axis: ' + ratioAxis);
+
+    if (ratioAxis == Y)
+    {
+      gameSize.x = Width;
+      gameSize.y = Math.floor(gameSize.x / ratio.x);
+    }
+    else
+    {
+      gameSize.y = Height;
+      gameSize.x = Math.floor(gameSize.y * ratio.x);
+    }
+  }
+
+  public function updateCutoutSize(Width:Float, Height:Float)
+  {
+    cutoutSize.set(0, 0);
+
+    if (ratioAxis == Y)
+    {
+      cutoutSize.y = Height - gameSize.y;
+    }
+    else
+    {
+      cutoutSize.x = Width - gameSize.x;
+    }
+  }
+
+  public function fillScreen()
+  {
+    if (ratioAxis == Y)
+    {
+      gameSize.y += cutoutSize.y;
+      FlxG.height = Math.floor(gameSize.y / scale.y);
+    }
+    else
+    {
+      gameSize.x += cutoutSize.x;
+      FlxG.width = Math.floor(gameSize.x / scale.x);
+    }
+
+    windowScale.set(FlxG.width / FlxG.initialWidth, FlxG.height / FlxG.initialHeight);
+    // trace('resized game with size $gameSize and scale ${scale}');
+    // trace('flixel width: ${FlxG.width} - flixel height: ${FlxG.height}');
+    // trace('current window scale is $windowScale');
+  }
+
+  @:noCompletion
+  private static function set_enabled(Value:Bool):Bool
+  {
+    // No idea what to do about this for iOS
+    #if android
+    if (!(VERSION.SDK_INT >= VERSION_CODES.P || Tools.isTablet()))
+    {
+      Value = false;
+    }
+    #end
+
+    if (Value == true)
+    {
+      FlxG.scaleMode.horizontalAlign = LEFT;
+      FlxG.scaleMode.verticalAlign = TOP;
+    }
+    else
+    {
+      FlxG.scaleMode.horizontalAlign = CENTER;
+      FlxG.scaleMode.verticalAlign = CENTER;
+    }
+
+    return enabled = Value;
+  }
+}

source/funkin/ui/mainmenu/MainMenuState.hx

@@ -67,7 +67,7 @@ class MainMenuState extends MusicBeatState
     var bg:FlxSprite = new FlxSprite(Paths.image('menuBG'));
     bg.scrollFactor.x = 0;
     bg.scrollFactor.y = 0.17;
-    bg.setGraphicSize(Std.int(bg.width * 1.2));
+    bg.setGraphicSize(Std.int(FlxG.width * 1.2));
     bg.updateHitbox();
     bg.screenCenter();
     add(bg);