From 38634ef5ca80b6e40ff4c0c6e9b799cebdfc910f Mon Sep 17 00:00:00 2001
From: Karim Akra <karimakra512@gmail.com>
Date: Sat, 15 Nov 2025 17:43:51 +0200
Subject: [PATCH] Prevent the game bounds from breaking when resizing the
 window

---
 source/funkin/ui/FullScreenScaleMode.hx | 112 +++++++++++++++++++++++-
 source/funkin/ui/MusicBeatState.hx      |   3 +
 2 files changed, 113 insertions(+), 2 deletions(-)

diff --git a/source/funkin/ui/FullScreenScaleMode.hx b/source/funkin/ui/FullScreenScaleMode.hx
index 6f878c37c..369572350 100644
--- a/source/funkin/ui/FullScreenScaleMode.hx
+++ b/source/funkin/ui/FullScreenScaleMode.hx
@@ -4,10 +4,13 @@ import flixel.tweens.FlxEase;
 import flixel.tweens.FlxTween;
 import flixel.math.FlxPoint;
 import flixel.util.FlxAxes;
+import flixel.util.FlxHorizontalAlign;
+import flixel.util.FlxVerticalAlign;
 import flixel.FlxG;
 import openfl.display.Bitmap;
 import openfl.display.BitmapData;
 import funkin.util.MathUtil;
+import funkin.graphics.FunkinCamera;
 
 class FullScreenScaleMode extends flixel.system.scaleModes.BaseScaleMode
 {
@@ -95,6 +98,15 @@ class FullScreenScaleMode extends flixel.system.scaleModes.BaseScaleMode
   @:noCompletion
   private static var cutoutBitmaps:Array<Bitmap> = [null, null];
 
+  @:noCompletion
+  private static var mustAwait:Bool = false;
+
+  @:noCompletion
+  private static var awaitedSize:FlxPoint = FlxPoint.get(0, 0);
+
+  @:noCompletion
+  private static var finishingAwait:Bool = false;
+
   /**
    * Constructor for `FullScreenScaleMode`.
    *
@@ -119,6 +131,62 @@ class FullScreenScaleMode extends flixel.system.scaleModes.BaseScaleMode
    */
   override public function onMeasure(Width:Int, Height:Int):Void
   {
+    if (mustAwait)
+    {
+      onMeasureAwait(Width, Height);
+    }
+    else
+    {
+      onMeasureInstant(Width, Height);
+      mustAwait = true;
+    }
+  }
+
+  /**
+   * Locks the game to the current aspect ratio and assignes the requested resolution as awaited for later.
+   * @param Width The width of the screen.
+   * @param Height The height of the screen.
+   */
+  public function onMeasureAwait(Width:Int, Height:Int):Void
+  {
+    horizontalAlign = CENTER;
+    verticalAlign = CENTER;
+
+    updateGameSize(FlxG.width, FlxG.height);
+    updateDeviceSize(Width, Height);
+    updateDeviceCutout(Width, Height);
+    #if mobile
+    updateDeviceNotch(funkin.mobile.util.ScreenUtil.getNotchRect());
+    #end
+    updateScaleOffset();
+    updateGamePosition();
+
+    awaitedSize.set(Width, Height);
+  }
+
+  /**
+   * Unlock the game resolution and swap into the awaited one.
+   */
+  public function onMeasurePostAwait():Void
+  {
+    if (awaitedSize.x == 0 && awaitedSize.y == 0) return;
+
+    horizontalAlign = enabled ? LEFT : CENTER;
+    verticalAlign = enabled ? TOP : CENTER;
+    onMeasureInstant(Math.ceil(awaitedSize.x), Math.ceil(awaitedSize.y));
+    FlxG.cameras.reset(new FunkinCamera('default'));
+
+    awaitedSize.set(0, 0);
+  }
+
+  /**
+   * Instantly apply the measured resolution to the game
+   * @param Width The width of the screen.
+   * @param Height The height of the screen.
+   */
+  public function onMeasureInstant(Width:Int, Height:Int):Void
+  {
+    finishingAwait = true;
     untyped FlxG.width = FlxG.initialWidth;
     untyped FlxG.height = FlxG.initialHeight;
 
@@ -132,6 +200,8 @@ class FullScreenScaleMode extends flixel.system.scaleModes.BaseScaleMode
     updateGamePosition();
 
     adjustGameSize();
+
+    finishingAwait = false;
   }
 
   /**
@@ -265,12 +335,50 @@ class FullScreenScaleMode extends flixel.system.scaleModes.BaseScaleMode
 
   override public function updateScaleOffset():Void
   {
-    scale.x = ratioAxis == X ? logicalSize.x / FlxG.width : deviceSize.x / FlxG.width;
-    scale.y = ratioAxis == Y ? logicalSize.y / FlxG.height : deviceSize.y / FlxG.height;
+    if (finishingAwait)
+    {
+      scale.x = ratioAxis == X ? logicalSize.x / FlxG.width : deviceSize.x / FlxG.width;
+      scale.y = ratioAxis == Y ? logicalSize.y / FlxG.height : deviceSize.y / FlxG.height;
+    }
+    else
+    {
+      scale.x = deviceSize.x / FlxG.width;
+      scale.y = deviceSize.y / FlxG.height;
+
+      if (scale.x > scale.y) scale.x = scale.y;
+      else
+        scale.y = scale.x;
+    }
     updateOffsetX();
     updateOffsetY();
   }
 
+  override function updateOffsetX():Void
+  {
+    offset.x = switch (horizontalAlign)
+    {
+      case FlxHorizontalAlign.LEFT:
+        0;
+      case FlxHorizontalAlign.CENTER:
+        Math.ceil(finishingAwait ? (deviceSize.x - gameSize.x) : (deviceSize.x - (gameSize.x * scale.x)) * 0.5);
+      case FlxHorizontalAlign.RIGHT:
+        deviceSize.x - gameSize.x;
+    }
+  }
+
+  override function updateOffsetY():Void
+  {
+    offset.y = switch (verticalAlign)
+    {
+      case FlxVerticalAlign.TOP:
+        0;
+      case FlxVerticalAlign.CENTER:
+        Math.ceil(finishingAwait ? (deviceSize.y - gameSize.y) : (deviceSize.y - (gameSize.y * scale.y)) * 0.5);
+      case FlxVerticalAlign.BOTTOM:
+        deviceSize.y - gameSize.y;
+    }
+  }
+
   #if mobile
   private function updateDeviceNotch(notch:lime.math.Rectangle):Void
   {
diff --git a/source/funkin/ui/MusicBeatState.hx b/source/funkin/ui/MusicBeatState.hx
index b7953af9f..fe8fefb55 100644
--- a/source/funkin/ui/MusicBeatState.hx
+++ b/source/funkin/ui/MusicBeatState.hx
@@ -14,6 +14,7 @@ import funkin.modding.module.ModuleHandler;
 import funkin.util.SortUtil;
 import funkin.util.WindowUtil;
 import funkin.input.Controls;
+import funkin.ui.FullScreenScaleMode;
 #if mobile
 import funkin.graphics.FunkinCamera;
 import funkin.mobile.ui.FunkinHitbox;
@@ -55,6 +56,8 @@ class MusicBeatState extends FlxTransitionableState implements IEventHandler
 
   public function new()
   {
+    if (FullScreenScaleMode.instance != null) FullScreenScaleMode.instance.onMeasurePostAwait();
+
     super();
 
     initCallbacks();