(finally) managed to get a working way to check caps lock

Author: stringfromjava

source/InitState.hx

@@ -74,7 +74,7 @@ class InitState extends FlxState
 		FlxG.autoPause = false;
 
 		// Set the stage and scaling modes
-		Lib.current.stage.align = "tl";
+		Lib.current.stage.align = 'tl';
 		Lib.current.stage.scaleMode = StageScaleMode.NO_SCALE;
 
 		// Disable the binds for increasing/decreasing/muting
@@ -91,7 +91,7 @@ class InitState extends FlxState
 
 		// Disable the right-click context menu for HTML5
 		#if html5
-		Browser.document.addEventListener("contextmenu", (e) ->
+		Browser.document.addEventListener('contextmenu', (e) ->
 		{
 			e.preventDefault();
 		});
@@ -103,6 +103,19 @@ class InitState extends FlxState
 		CacheUtil.vcrMario85Shader = new VCRMario85Shader();
 		#end
 		CacheUtil.grainShader = new GrainShader();
+
+		// Configure the event listener for detecting caps lock
+		// if the target is set to HTML5
+		#if html5
+		untyped __js__('
+			window.__haxe_capslock__ = false;
+			document.addEventListener("keydown", function (e) {
+				if (e.getModifierState) {
+					window.__haxe_capslock__ = e.getModifierState("CapsLock");
+				}
+			});
+		');
+		#end
 	}
 
 	function addBackgroundProcesses():Void
@@ -172,15 +185,6 @@ class InitState extends FlxState
 		});
 		#end
 
-		// Enable/disable caps lock
-		FlxG.stage.addEventListener(KeyboardEvent.KEY_DOWN, (_) ->
-		{
-			if (FlxG.keys.justPressed.CAPSLOCK)
-			{
-				CacheUtil.capsLockEnabled = !CacheUtil.capsLockEnabled;
-			}
-		});
-
 		// Do shit like saving the user's data when the game closes
 		Application.current.window.onClose.add(() ->
 		{

source/starcore/backend/util/CacheUtil.hx

@@ -55,10 +55,5 @@ final class CacheUtil
 	 */
 	public static var grainShader:GrainShader;
 
-	/**
-	 * Is caps lock enabled?
-	 */
-	public static var capsLockEnabled:Bool = false; // TODO: Find a better way to do this...
-
 	function new() {}
 }

source/starcore/backend/util/FlixelUtil.hx

@@ -23,6 +23,21 @@ import flixel.sound.filters.effects.FlxSoundReverbEffect;
 import js.Browser;
 #end
 
+// Directly inject C++ code for 
+// detecting if caps lock is enabled
+// on Windows/C++ builds
+#if cpp
+@:headerCode('
+    extern "C" bool hx_isCapsLockOn();
+')
+@:cppFileCode('
+    #include <windows.h>
+    extern "C" bool hx_isCapsLockOn() {
+        return (GetKeyState(VK_CAPITAL) & 0x0001) != 0;
+    }
+')
+#end
+
 /**
  * Utility class for handling objects and components specific to Flixel.
  */
@@ -393,6 +408,47 @@ final class FlixelUtil
 		}
 	}
 
+	/**
+	 * Gets if caps lock is enabled.
+	 * Only works on HTML5, Windows/C++, macOS and Linux builds.
+	 * 
+	 * @return If caps lock is enabled.
+	 */
+	public static inline function getCapsLockedEnabled():Bool
+	{
+		#if html5
+		return untyped __js__('window.__haxe_capslock__');
+		#elseif cpp // This includes Windows builds
+		return untyped __cpp__('hx_isCapsLockOn()');
+		#elseif mac
+		try
+		{
+			var proc = new sys.io.Process("bash", ["-c", "osascript -e 'tell application \"System Events\" to get caps lock'"]);
+			var result = proc.stdout.readLine();
+			proc.close();
+			return result == "true";
+		}
+		catch (e:Dynamic)
+		{
+			return false;
+		}
+		#elseif linux
+		try
+		{
+			var proc = new sys.io.Process("bash", ["-c", "xset q | grep Caps"]);
+			var output = proc.stdout.readAll().toString();
+			proc.close();
+			return output.indexOf("on") != -1;
+		}
+		catch (e:Dynamic)
+		{
+			return false;
+		}
+		#else
+		return false;
+		#end
+	}
+
 	/**
 	 * Tweens an `FlxTypedGroup<FlxSprite>`'s members with ease.
 	 * 

source/starcore/menus/MainMenuState.hx

@@ -1,5 +1,6 @@
 package starcore.menus;
 
+import starcore.ui.TextBox;
 import starcore.play.PlayState;
 import flixel.FlxG;
 import flixel.FlxSprite;

source/starcore/ui/TextBox.hx

@@ -9,7 +9,6 @@ import flixel.util.FlxColor;
 import flixel.util.FlxTimer;
 import openfl.ui.MouseCursor;
 import starcore.backend.data.Constants;
-import starcore.backend.util.CacheUtil;
 import starcore.backend.util.DataUtil;
 import starcore.backend.util.FlixelUtil;
 
@@ -106,6 +105,7 @@ class TextBox extends FlxSpriteGroup
 		displayText = new FlxText();
 		displayText.text = textHint;
 		displayText.color = FlxColor.BLACK;
+		trace(font);
 		displayText.font = font;
 		displayText.size = size;
 		displayText.fieldWidth = width;
@@ -208,7 +208,7 @@ class TextBox extends FlxSpriteGroup
 		{
 			if (currentJustPressedKeys.contains(key) || canHoldLetter)
 			{
-				var shift:Bool = ((!CacheUtil.capsLockEnabled) ? FlxG.keys.pressed.SHIFT : !FlxG.keys.pressed.SHIFT);
+				var shift:Bool = ((!FlixelUtil.getCapsLockedEnabled()) ? FlxG.keys.pressed.SHIFT : !FlxG.keys.pressed.SHIFT);
 				if (type != STRING && shift)
 				{
 					// Prevent the user from adding a new character