From e32ab161ae2bb8096f4b8f7c91c4ca481a2b2ecb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Julian=20Offenh=C3=A4user?= <offenhaeuser@protonmail.com>
Date: Mon, 20 Mar 2023 20:45:36 +0100
Subject: [PATCH] WindowServer: Fix alt shortcut navigation for non-default
 keymaps

Some keymaps will bind key presses with the alt modifier to characters
other than the unmodified one, in which case you couldn't activate the
alt shortcuts in the menu bar before.

We now ask the current keymap for the code point that is mapped to the
pressed (unmodified) key instead.
---
 Userland/Services/WindowServer/CMakeLists.txt |  2 +-
 Userland/Services/WindowServer/Window.cpp     | 39 ++++++++++++-------
 Userland/Services/WindowServer/main.cpp       |  6 +--
 3 files changed, 30 insertions(+), 17 deletions(-)

diff --git a/Userland/Services/WindowServer/CMakeLists.txt b/Userland/Services/WindowServer/CMakeLists.txt
index ed975c387ea..77875a349f6 100644
--- a/Userland/Services/WindowServer/CMakeLists.txt
+++ b/Userland/Services/WindowServer/CMakeLists.txt
@@ -45,5 +45,5 @@ set(GENERATED_SOURCES
 )
 
 serenity_bin(WindowServer)
-target_link_libraries(WindowServer PRIVATE LibCore LibFileSystem LibGfx LibThreading LibIPC LibMain)
+target_link_libraries(WindowServer PRIVATE LibCore LibFileSystem LibKeyboard LibGfx LibThreading LibIPC LibMain)
 serenity_install_headers(Services/WindowServer)
diff --git a/Userland/Services/WindowServer/Window.cpp b/Userland/Services/WindowServer/Window.cpp
index cee941835d4..3ca05386131 100644
--- a/Userland/Services/WindowServer/Window.cpp
+++ b/Userland/Services/WindowServer/Window.cpp
@@ -19,6 +19,7 @@
 #include <LibCore/Account.h>
 #include <LibCore/ProcessStatisticsReader.h>
 #include <LibCore/SessionManagement.h>
+#include <LibKeyboard/CharacterMap.h>
 
 namespace WindowServer {
 
@@ -516,20 +517,32 @@ void Window::handle_keydown_event(KeyEvent const& event)
         return;
     }
     if (event.modifiers() == Mod_Alt && event.code_point() && m_menubar.has_menus()) {
-        Menu* menu_to_open = nullptr;
-        m_menubar.for_each_menu([&](Menu& menu) {
-            if (to_ascii_lowercase(menu.alt_shortcut_character()) == to_ascii_lowercase(event.code_point())) {
-                menu_to_open = &menu;
-                return IterationDecision::Break;
-            }
-            return IterationDecision::Continue;
-        });
+        // When handling alt shortcuts, we only care about the key that has been pressed in addition
+        // to alt, not the code point that has been mapped to alt+[key], so we have to look up the
+        // scancode directly from the "unmodified" character map.
+        auto character_map_or_error = Keyboard::CharacterMap::fetch_system_map();
+        if (!character_map_or_error.is_error()) {
+            auto& character_map = character_map_or_error.value();
 
-        if (menu_to_open) {
-            frame().open_menubar_menu(*menu_to_open);
-            if (!menu_to_open->is_empty())
-                menu_to_open->set_hovered_index(0);
-            return;
+            // The lowest byte serves as our index into the character table.
+            auto index = event.scancode() & 0xff;
+            u32 character = to_ascii_lowercase(character_map.character_map_data().map[index]);
+
+            Menu* menu_to_open = nullptr;
+            m_menubar.for_each_menu([&](Menu& menu) {
+                if (to_ascii_lowercase(menu.alt_shortcut_character()) == character) {
+                    menu_to_open = &menu;
+                    return IterationDecision::Break;
+                }
+                return IterationDecision::Continue;
+            });
+
+            if (menu_to_open) {
+                frame().open_menubar_menu(*menu_to_open);
+                if (!menu_to_open->is_empty())
+                    menu_to_open->set_hovered_index(0);
+                return;
+            }
         }
     }
     m_client->async_key_down(m_window_id, (u32)event.code_point(), (u32)event.key(), event.modifiers(), (u32)event.scancode());
diff --git a/Userland/Services/WindowServer/main.cpp b/Userland/Services/WindowServer/main.cpp
index 6b0176e1fb4..c71efa5f760 100644
--- a/Userland/Services/WindowServer/main.cpp
+++ b/Userland/Services/WindowServer/main.cpp
@@ -25,7 +25,7 @@ RefPtr<Core::ConfigFile> g_config;
 
 ErrorOr<int> serenity_main(Main::Arguments)
 {
-    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc sigaction exec tty"));
+    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc getkeymap sigaction exec tty"));
     TRY(Core::System::unveil("/res", "r"));
     TRY(Core::System::unveil("/tmp", "cw"));
     TRY(Core::System::unveil("/etc/WindowServer.ini", "rwc"));
@@ -42,7 +42,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
     act.sa_flags = SA_NOCLDWAIT;
     act.sa_handler = SIG_IGN;
     TRY(Core::System::sigaction(SIGCHLD, &act, nullptr));
-    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc exec tty"));
+    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc getkeymap exec tty"));
 
     WindowServer::g_config = TRY(Core::ConfigFile::open("/etc/WindowServer.ini", Core::ConfigFile::AllowWriting::Yes));
     auto theme_name = WindowServer::g_config->read_entry("Theme", "Name", "Default");
@@ -73,7 +73,7 @@ ErrorOr<int> serenity_main(Main::Arguments)
 
     WindowServer::EventLoop loop;
 
-    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc exec"));
+    TRY(Core::System::pledge("stdio video thread sendfd recvfd accept rpath wpath cpath unix proc getkeymap exec"));
 
     // First check which screens are explicitly configured
     {