From e977975008efe6d8df8d31f6f046d37b5d73d9ae Mon Sep 17 00:00:00 2001
From: Zi Ree <zi.ree@phoenixviewer.com>
Date: Sun, 2 Oct 2022 15:54:26 +0200
Subject: [PATCH] FIRE-32123 - Attempt to fix Right-ALT cam on non AltGr
 keyboards while still keeping AltGr on AltGr keyboards working

---
 indra/llwindow/llkeyboardsdl2.cpp |  6 ++---
 indra/llwindow/llwindowsdl2.cpp   | 37 +++++++++++++++++++++++++++++--
 2 files changed, 38 insertions(+), 5 deletions(-)

diff --git a/indra/llwindow/llkeyboardsdl2.cpp b/indra/llwindow/llkeyboardsdl2.cpp
index 402feed1d5..594818869e 100644
--- a/indra/llwindow/llkeyboardsdl2.cpp
+++ b/indra/llwindow/llkeyboardsdl2.cpp
@@ -148,7 +148,7 @@ void LLKeyboardSDL::resetMaskKeys()
 		mKeyLevel[KEY_CONTROL] = TRUE;
 	}
 
-	if(mask & KMOD_LALT)
+	if(mask & KMOD_ALT)
 	{
 		mKeyLevel[KEY_ALT] = TRUE;
 	}
@@ -170,7 +170,7 @@ MASK LLKeyboardSDL::updateModifiers(const U32 mask)
 		out_mask |= MASK_CONTROL;
 	}
 
-	if(mask & KMOD_LALT)
+	if(mask & KMOD_ALT)
 	{
 		out_mask |= MASK_ALT;
 	}
@@ -252,7 +252,7 @@ MASK LLKeyboardSDL::currentMask(BOOL for_mouse_event)
 		result |= MASK_SHIFT;
 	if (mask & KMOD_CTRL)
 		result |= MASK_CONTROL;
-	if (mask & KMOD_LALT)
+	if (mask & KMOD_ALT)
 		result |= MASK_ALT;
 
 	// For keyboard events, consider Meta keys equivalent to Control
diff --git a/indra/llwindow/llwindowsdl2.cpp b/indra/llwindow/llwindowsdl2.cpp
index c1f99e39f9..cd5d3b362e 100644
--- a/indra/llwindow/llwindowsdl2.cpp
+++ b/indra/llwindow/llwindowsdl2.cpp
@@ -1779,11 +1779,40 @@ void LLWindowSDL::gatherInput()
 	static U64 previousTextinputTime = 0;
     SDL_Event event;
 
+	// mask to apply to the keyup/keydown modifiers to handle AltGr keys correctly
+	static U32 altGrMask = 0x00;
+
     // Handle all outstanding SDL events
     while (SDL_PollEvent(&event))
     {
         switch (event.type)
         {
+			case SDL_SYSWMEVENT:
+			{
+				XEvent e = event.syswm.msg->msg.x11.event;
+				if (e.type == KeyPress || e.type == KeyRelease)
+				{
+					// XLookupKeysym doesn't work here because of the weird way the "index" is
+					// tied to the e->state and we don't get the necessary information at this
+					// point, so we use the more expensive XLookupString which apparently knows
+					// all of the secrets inside XKeyEvent. -Zi
+
+					KeySym ks;
+					static char str[256+1];
+					XLookupString((XKeyEvent *) &e, str, 256, &ks, nullptr);
+
+					if (ks == XK_ISO_Level3_Shift)
+					{
+						altGrMask = KMOD_RALT;
+					}
+					else if (ks == XK_Alt_R)
+					{
+						altGrMask = 0x00;
+					}
+				}
+				break;
+			}
+
 			case SDL_MOUSEWHEEL:
 				if( event.wheel.y != 0 )
 					mCallbacks->handleScrollWheel(this, -event.wheel.y);
@@ -1803,6 +1832,10 @@ void LLWindowSDL::gatherInput()
 			{
 				auto string = utf8str_to_utf16str( event.text.text );
 				mKeyModifiers = gKeyboard->currentMask( FALSE );
+				if (altGrMask)
+				{
+					mKeyModifiers &= ~MASK_ALT;
+				}
 				mInputType = "textinput";
 				for( auto key: string )
 				{
@@ -1821,7 +1854,7 @@ void LLWindowSDL::gatherInput()
 
             case SDL_KEYDOWN:
 				mKeyVirtualKey = event.key.keysym.sym;
-				mKeyModifiers = event.key.keysym.mod;
+				mKeyModifiers = event.key.keysym.mod & (~altGrMask);
 				mInputType = "keydown";
 
 				// treat all possible Enter/Return keys the same
@@ -1863,7 +1896,7 @@ void LLWindowSDL::gatherInput()
 
             case SDL_KEYUP:
 				mKeyVirtualKey = event.key.keysym.sym;
-				mKeyModifiers = event.key.keysym.mod;
+				mKeyModifiers = event.key.keysym.mod & (~altGrMask);
 				mInputType = "keyup";
 
 				// treat all possible Enter/Return keys the same