Backport: Allow for mapping scancodes to current layout

Co-authored-by: Frixuu <kontakt@lukasz.xyz>

core/bind/core_bind.cpp

@@ -572,6 +572,10 @@ String _OS::keyboard_get_layout_name(int p_index) const {
 	return OS::get_singleton()->keyboard_get_layout_name(p_index);
 }
 
+uint32_t _OS::keyboard_get_scancode_from_physical(uint32_t p_scancode) const {
+	return OS::get_singleton()->keyboard_get_scancode_from_physical(p_scancode);
+}
+
 String _OS::get_model_name() const {
 	return OS::get_singleton()->get_model_name();
 }
@@ -1354,6 +1358,7 @@ void _OS::_bind_methods() {
 	ClassDB::bind_method(D_METHOD("keyboard_set_current_layout", "index"), &_OS::keyboard_set_current_layout);
 	ClassDB::bind_method(D_METHOD("keyboard_get_layout_language", "index"), &_OS::keyboard_get_layout_language);
 	ClassDB::bind_method(D_METHOD("keyboard_get_layout_name", "index"), &_OS::keyboard_get_layout_name);
+	ClassDB::bind_method(D_METHOD("keyboard_get_scancode_from_physical", "scancode"), &_OS::keyboard_get_scancode_from_physical);
 
 	ClassDB::bind_method(D_METHOD("can_draw"), &_OS::can_draw);
 	ClassDB::bind_method(D_METHOD("is_userfs_persistent"), &_OS::is_userfs_persistent);

core/bind/core_bind.h

@@ -263,6 +263,7 @@ public:
 	void keyboard_set_current_layout(int p_index);
 	String keyboard_get_layout_language(int p_index) const;
 	String keyboard_get_layout_name(int p_index) const;
+	uint32_t keyboard_get_scancode_from_physical(uint32_t p_scancode) const;
 
 	String get_model_name() const;
 

core/os/os.cpp

@@ -215,6 +215,10 @@ int OS::get_virtual_keyboard_height() const {
 	return 0;
 }
 
+uint32_t OS::keyboard_get_scancode_from_physical(uint32_t p_scancode) const {
+	return p_scancode;
+}
+
 void OS::set_cursor_shape(CursorShape p_shape) {
 }
 

core/os/os.h

@@ -411,6 +411,7 @@ public:
 
 	// returns height of the currently shown virtual keyboard (0 if keyboard is hidden)
 	virtual int get_virtual_keyboard_height() const;
+	virtual uint32_t keyboard_get_scancode_from_physical(uint32_t p_scancode) const;
 
 	virtual void set_cursor_shape(CursorShape p_shape);
 	virtual CursorShape get_cursor_shape() const;

doc/classes/OS.xml

@@ -709,6 +709,14 @@
 				[b]Note:[/b] This method is implemented on Linux, macOS and Windows.
 			</description>
 		</method>
+		<method name="keyboard_get_scancode_from_physical" qualifiers="const">
+			<return type="int" />
+			<argument index="0" name="scancode" type="int" />
+			<description>
+				Converts a physical (US QWERTY) [code]scancode[/code] to one in the active keyboard layout.
+				[b]Note:[/b] This method is implemented on Linux, macOS and Windows.
+			</description>
+		</method>
 		<method name="keyboard_set_current_layout">
 			<return type="void" />
 			<argument index="0" name="index" type="int" />

platform/osx/os_osx.h

@@ -263,6 +263,7 @@ public:
 	virtual void keyboard_set_current_layout(int p_index);
 	virtual String keyboard_get_layout_language(int p_index) const;
 	virtual String keyboard_get_layout_name(int p_index) const;
+	virtual uint32_t keyboard_get_scancode_from_physical(uint32_t p_scancode) const;
 
 	virtual void move_window_to_foreground();
 

platform/osx/os_osx.mm

@@ -932,11 +932,8 @@ static bool isNumpadKey(unsigned int key) {
 	return false;
 }
 
-// Translates a OS X keycode to a Godot keycode
-//
-static int translateKey(unsigned int key) {
 // Keyboard symbol translation table
-	static const unsigned int table[128] = {
+static const unsigned int _osx_to_godot_table[128] = {
 	/* 00 */ KEY_A,
 	/* 01 */ KEY_S,
 	/* 02 */ KEY_D,
@@ -1067,10 +1064,22 @@ static int translateKey(unsigned int key) {
 	/* 7f */ KEY_UNKNOWN,
 };
 
+// Translates a OS X keycode to a Godot keycode
+static int translateKey(unsigned int key) {
 	if (key >= 128)
 		return KEY_UNKNOWN;
 
-	return table[key];
+	return _osx_to_godot_table[key];
+}
+
+// Translates a Godot keycode back to a OSX keycode
+static unsigned int unmapKey(int key) {
+	for (int i = 0; i <= 126; i++) {
+		if (_osx_to_godot_table[i] == key) {
+			return i;
+		}
+	}
+	return 127;
 }
 
 struct _KeyCodeMap {
@@ -3207,6 +3216,17 @@ String OS_OSX::keyboard_get_layout_name(int p_index) const {
 	return kbd_layouts[p_index].name;
 }
 
+uint32_t OS_OSX::keyboard_get_scancode_from_physical(uint32_t p_scancode) const {
+	if (p_scancode == KEY_PAUSE) {
+		return p_scancode;
+	}
+
+	unsigned int modifiers = p_scancode & KEY_MODIFIER_MASK;
+	unsigned int scancode_no_mod = p_scancode & KEY_CODE_MASK;
+	unsigned int osx_scancode = unmapKey((uint32_t)scancode_no_mod);
+	return (uint32_t)(remapKey(osx_scancode, 0) | modifiers);
+}
+
 void OS_OSX::process_events() {
 	while (true) {
 		NSEvent *event = [NSApp

platform/windows/key_mapping_windows.cpp

@@ -347,6 +347,16 @@ unsigned int KeyMappingWindows::get_keysym(unsigned int p_code) {
 	return KEY_UNKNOWN;
 }
 
+unsigned int KeyMappingWindows::get_scancode(unsigned int p_keycode) {
+	for (int i = 0; _scancode_to_keycode[i].keysym != KEY_UNKNOWN; i++) {
+		if (_scancode_to_keycode[i].keysym == p_keycode) {
+			return _scancode_to_keycode[i].keycode;
+		}
+	}
+
+	return 0;
+}
+
 unsigned int KeyMappingWindows::get_scansym(unsigned int p_code, bool p_extended) {
 	unsigned int keycode = KEY_UNKNOWN;
 	for (int i = 0; _scancode_to_keycode[i].keysym != KEY_UNKNOWN; i++) {

platform/windows/key_mapping_windows.h

@@ -42,6 +42,7 @@ class KeyMappingWindows {
 
 public:
 	static unsigned int get_keysym(unsigned int p_code);
+	static unsigned int get_scancode(unsigned int p_keycode);
 	static unsigned int get_scansym(unsigned int p_code, bool p_extended);
 	static bool is_extended_key(unsigned int p_code);
 };

platform/windows/os_windows.cpp

@@ -3307,6 +3307,42 @@ String OS_Windows::keyboard_get_layout_language(int p_index) const {
 	return String(buf).substr(0, 2);
 }
 
+uint32_t OS_Windows::keyboard_get_scancode_from_physical(uint32_t p_scancode) const {
+	unsigned int modifiers = p_scancode & KEY_MODIFIER_MASK;
+	uint32_t scancode_no_mod = (uint32_t)(p_scancode & KEY_CODE_MASK);
+
+	if (scancode_no_mod == KEY_PRINT ||
+			scancode_no_mod == KEY_KP_ADD ||
+			scancode_no_mod == KEY_KP_5 ||
+			(scancode_no_mod >= KEY_0 && scancode_no_mod <= KEY_9)) {
+		return p_scancode;
+	}
+
+	unsigned int scancode = KeyMappingWindows::get_scancode(scancode_no_mod);
+	if (scancode == 0) {
+		return p_scancode;
+	}
+
+	HKL current_layout = GetKeyboardLayout(0);
+	UINT vk = MapVirtualKeyEx(scancode, MAPVK_VSC_TO_VK, current_layout);
+	if (vk == 0) {
+		return p_scancode;
+	}
+
+	UINT char_code = MapVirtualKeyEx(vk, MAPVK_VK_TO_CHAR, current_layout) & 0x7FFF;
+	// Unlike a similar Linux/BSD check which matches full Latin-1 range,
+	// we limit these to ASCII to fix some layouts, including Arabic ones
+	if (char_code >= 32 && char_code <= 127) {
+		// Godot uses 'braces' instead of 'brackets'
+		if (char_code == KEY_BRACKETLEFT || char_code == KEY_BRACKETRIGHT) {
+			char_code += 32;
+		}
+		return (uint32_t)(char_code | modifiers);
+	}
+
+	return (uint32_t)(KeyMappingWindows::get_keysym(vk) | modifiers);
+}
+
 String _get_full_layout_name_from_registry(HKL p_layout) {
 	String id = "SYSTEM\\CurrentControlSet\\Control\\Keyboard Layouts\\" + String::num_int64((int64_t)p_layout, 16, false).lpad(8, "0");
 	String ret;

platform/windows/os_windows.h

@@ -532,6 +532,7 @@ public:
 	virtual void keyboard_set_current_layout(int p_index);
 	virtual String keyboard_get_layout_language(int p_index) const;
 	virtual String keyboard_get_layout_name(int p_index) const;
+	virtual uint32_t keyboard_get_scancode_from_physical(uint32_t p_scancode) const;
 
 	virtual void enable_for_stealing_focus(ProcessID pid);
 	virtual void move_window_to_foreground();

platform/x11/key_mapping_x11.cpp

@@ -310,6 +310,18 @@ unsigned int KeyMappingX11::get_scancode(unsigned int p_code) {
 	return keycode;
 }
 
+unsigned int KeyMappingX11::get_xlibcode(unsigned int p_keysym) {
+	unsigned int code = 0;
+	for (int i = 0; _scancode_to_keycode[i].keysym != KEY_UNKNOWN; i++) {
+		if (_scancode_to_keycode[i].keysym == p_keysym) {
+			code = _scancode_to_keycode[i].keycode;
+			break;
+		}
+	}
+
+	return code;
+}
+
 unsigned int KeyMappingX11::get_keycode(KeySym p_keysym) {
 	// kinda bruteforce.. could optimize.
 

platform/x11/key_mapping_x11.h

@@ -45,6 +45,7 @@ class KeyMappingX11 {
 
 public:
 	static unsigned int get_keycode(KeySym p_keysym);
+	static unsigned int get_xlibcode(unsigned int p_keysym);
 	static unsigned int get_scancode(unsigned int p_code);
 	static KeySym get_keysym(unsigned int p_code);
 	static unsigned int get_unicode_from_keysym(KeySym p_keysym);

platform/x11/os_x11.cpp

@@ -4100,6 +4100,24 @@ String OS_X11::keyboard_get_layout_name(int p_index) const {
 	return ret;
 }
 
+uint32_t OS_X11::keyboard_get_scancode_from_physical(uint32_t p_scancode) const {
+	unsigned int modifiers = p_scancode & KEY_MODIFIER_MASK;
+	unsigned int scancode_no_mod = p_scancode & KEY_CODE_MASK;
+	unsigned int xkeycode = KeyMappingX11::get_xlibcode((uint32_t)scancode_no_mod);
+	KeySym xkeysym = XkbKeycodeToKeysym(x11_display, xkeycode, 0, 0);
+	if (xkeysym >= 'a' && xkeysym <= 'z') {
+		xkeysym -= ('a' - 'A');
+	}
+
+	uint32_t key = KeyMappingX11::get_keycode(xkeysym);
+	// If not found, fallback to QWERTY.
+	// This should match the behavior of the event pump
+	if (key == 0) {
+		return p_scancode;
+	}
+	return (uint32_t)(key | modifiers);
+}
+
 void OS_X11::update_real_mouse_position() {
 	Window root_return, child_return;
 	int root_x, root_y, win_x, win_y;

platform/x11/os_x11.h

@@ -361,6 +361,7 @@ public:
 	virtual void keyboard_set_current_layout(int p_index);
 	virtual String keyboard_get_layout_language(int p_index) const;
 	virtual String keyboard_get_layout_name(int p_index) const;
+	virtual uint32_t keyboard_get_scancode_from_physical(uint32_t p_scancode) const;
 
 	void update_real_mouse_position();
 	OS_X11();