Add InputEventKey.location to tell left from right

This adds a new enum `KeyLocation` and associated property
`InputEventKey.location`, which indicates the left/right location of key
events which may come from one of two physical keys, eg. Shift, Ctrl.

It also adds simulation of missing Shift KEYUP events for Windows.
When multiple Shifts are held down at the same time, Windows natively
only sends a KEYUP for the last one to be released.

6 files changed, 35 insertions, 9 deletions

diff --git a/platform/ios/display_server_ios.h b/platform/ios/display_server_ios.h
index 3d19222fa8..3fdcc07f0b 100644
--- a/platform/ios/display_server_ios.h
+++ b/platform/ios/display_server_ios.h
@@ -119,7 +119,7 @@ public:
 
 	// MARK: Keyboard
 
-	void key(Key p_key, char32_t p_char, Key p_unshifted, Key p_physical, NSInteger p_modifier, bool p_pressed);
+	void key(Key p_key, char32_t p_char, Key p_unshifted, Key p_physical, NSInteger p_modifier, bool p_pressed, KeyLocation p_location);
 	bool is_keyboard_active() const;
 
 	// MARK: Motion
diff --git a/platform/ios/display_server_ios.mm b/platform/ios/display_server_ios.mm
index c31f503605..c660dc5697 100644
--- a/platform/ios/display_server_ios.mm
+++ b/platform/ios/display_server_ios.mm
@@ -247,7 +247,7 @@ void DisplayServerIOS::touches_canceled(int p_idx) {
 
 // MARK: Keyboard
 
-void DisplayServerIOS::key(Key p_key, char32_t p_char, Key p_unshifted, Key p_physical, NSInteger p_modifier, bool p_pressed) {
+void DisplayServerIOS::key(Key p_key, char32_t p_char, Key p_unshifted, Key p_physical, NSInteger p_modifier, bool p_pressed, KeyLocation p_location) {
 	Ref<InputEventKey> ev;
 	ev.instantiate();
 	ev->set_echo(false);
@@ -270,6 +270,7 @@ void DisplayServerIOS::key(Key p_key, char32_t p_char, Key p_unshifted, Key p_ph
 	ev->set_key_label(p_unshifted);
 	ev->set_physical_keycode(p_physical);
 	ev->set_unicode(fix_unicode(p_char));
+	ev->set_location(p_location);
 	perform_event(ev);
 }
 
diff --git a/platform/ios/key_mapping_ios.h b/platform/ios/key_mapping_ios.h
index 6cc61175bb..8874da3024 100644
--- a/platform/ios/key_mapping_ios.h
+++ b/platform/ios/key_mapping_ios.h
@@ -41,6 +41,7 @@ class KeyMappingIOS {
 public:
 	static void initialize();
 	static Key remap_key(CFIndex p_keycode);
+	static KeyLocation key_location(CFIndex p_keycode);
 };
 
 #endif // KEY_MAPPING_IOS_H
diff --git a/platform/ios/key_mapping_ios.mm b/platform/ios/key_mapping_ios.mm
index d2c84884d1..61f28aa84b 100644
--- a/platform/ios/key_mapping_ios.mm
+++ b/platform/ios/key_mapping_ios.mm
@@ -38,6 +38,7 @@ struct HashMapHasherKeys {
 };
 
 HashMap<CFIndex, Key, HashMapHasherKeys> keyusage_map;
+HashMap<CFIndex, KeyLocation, HashMapHasherKeys> location_map;
 
 void KeyMappingIOS::initialize() {
 	if (@available(iOS 13.4, *)) {
@@ -172,6 +173,15 @@ void KeyMappingIOS::initialize() {
 		keyusage_map[0x029D] = Key::GLOBE; // "Globe" key on smart connector / Mac keyboard.
 		keyusage_map[UIKeyboardHIDUsageKeyboardLANG1] = Key::JIS_EISU;
 		keyusage_map[UIKeyboardHIDUsageKeyboardLANG2] = Key::JIS_KANA;
+
+		location_map[UIKeyboardHIDUsageKeyboardLeftAlt] = KeyLocation::LEFT;
+		location_map[UIKeyboardHIDUsageKeyboardRightAlt] = KeyLocation::RIGHT;
+		location_map[UIKeyboardHIDUsageKeyboardLeftControl] = KeyLocation::LEFT;
+		location_map[UIKeyboardHIDUsageKeyboardRightControl] = KeyLocation::RIGHT;
+		location_map[UIKeyboardHIDUsageKeyboardLeftShift] = KeyLocation::LEFT;
+		location_map[UIKeyboardHIDUsageKeyboardRightShift] = KeyLocation::RIGHT;
+		location_map[UIKeyboardHIDUsageKeyboardLeftGUI] = KeyLocation::LEFT;
+		location_map[UIKeyboardHIDUsageKeyboardRightGUI] = KeyLocation::RIGHT;
 	}
 }
 
@@ -184,3 +194,13 @@ Key KeyMappingIOS::remap_key(CFIndex p_keycode) {
 	}
 	return Key::NONE;
 }
+
+KeyLocation KeyMappingIOS::key_location(CFIndex p_keycode) {
+	if (@available(iOS 13.4, *)) {
+		const KeyLocation *location = location_map.getptr(p_keycode);
+		if (location) {
+			return *location;
+		}
+	}
+	return KeyLocation::UNSPECIFIED;
+}
diff --git a/platform/ios/keyboard_input_view.mm b/platform/ios/keyboard_input_view.mm
index bc6eb63ed5..8b614662b7 100644
--- a/platform/ios/keyboard_input_view.mm
+++ b/platform/ios/keyboard_input_view.mm
@@ -116,8 +116,8 @@
 
 - (void)deleteText:(NSInteger)charactersToDelete {
 	for (int i = 0; i < charactersToDelete; i++) {
-		DisplayServerIOS::get_singleton()->key(Key::BACKSPACE, 0, Key::BACKSPACE, Key::NONE, 0, true);
-		DisplayServerIOS::get_singleton()->key(Key::BACKSPACE, 0, Key::BACKSPACE, Key::NONE, 0, false);
+		DisplayServerIOS::get_singleton()->key(Key::BACKSPACE, 0, Key::BACKSPACE, Key::NONE, 0, true, KeyLocation::UNSPECIFIED);
+		DisplayServerIOS::get_singleton()->key(Key::BACKSPACE, 0, Key::BACKSPACE, Key::NONE, 0, false, KeyLocation::UNSPECIFIED);
 	}
 }
 
@@ -137,8 +137,8 @@
 			key = Key::SPACE;
 		}
 
-		DisplayServerIOS::get_singleton()->key(key, character, key, Key::NONE, 0, true);
-		DisplayServerIOS::get_singleton()->key(key, character, key, Key::NONE, 0, false);
+		DisplayServerIOS::get_singleton()->key(key, character, key, Key::NONE, 0, true, KeyLocation::UNSPECIFIED);
+		DisplayServerIOS::get_singleton()->key(key, character, key, Key::NONE, 0, false, KeyLocation::UNSPECIFIED);
 	}
 }
 
diff --git a/platform/ios/view_controller.mm b/platform/ios/view_controller.mm
index 1f55670b68..6f6c04c2c8 100644
--- a/platform/ios/view_controller.mm
+++ b/platform/ios/view_controller.mm
@@ -78,13 +78,15 @@
 				us = u32lbl[0];
 			}
 
+			KeyLocation location = KeyMappingIOS::key_location(press.key.keyCode);
+
 			if (!u32text.is_empty() && !u32text.begins_with("UIKey")) {
 				for (int i = 0; i < u32text.length(); i++) {
 					const char32_t c = u32text[i];
-					DisplayServerIOS::get_singleton()->key(fix_keycode(us, key), c, fix_key_label(us, key), key, press.key.modifierFlags, true);
+					DisplayServerIOS::get_singleton()->key(fix_keycode(us, key), c, fix_key_label(us, key), key, press.key.modifierFlags, true, location);
 				}
 			} else {
-				DisplayServerIOS::get_singleton()->key(fix_keycode(us, key), 0, fix_key_label(us, key), key, press.key.modifierFlags, true);
+				DisplayServerIOS::get_singleton()->key(fix_keycode(us, key), 0, fix_key_label(us, key), key, press.key.modifierFlags, true, location);
 			}
 		}
 	}
@@ -110,7 +112,9 @@
 				us = u32lbl[0];
 			}
 
-			DisplayServerIOS::get_singleton()->key(fix_keycode(us, key), 0, fix_key_label(us, key), key, press.key.modifierFlags, false);
+			KeyLocation location = KeyMappingIOS::key_location(press.key.keyCode);
+
+			DisplayServerIOS::get_singleton()->key(fix_keycode(us, key), 0, fix_key_label(us, key), key, press.key.modifierFlags, false, location);
 		}
 	}
 }