Make sdl_keymod_to_hid_modifiers() more readable

app/src/hid_keyboard.c

@@ -142,6 +142,20 @@ const unsigned char REPORT_DESC[REPORT_DESC_SIZE]  = {
     0xC0
 };
 
+/**
+ * HID keyboard events are sequence-based, every time keyboard state changes
+ * it sends an array of currently pressed keys, the host is responsible for
+ * compare events and determine which key becomes pressed and which key becomes
+ * released. In order to convert SDL_KeyboardEvent to HID events, we first use
+ * an array of keys to save each keys' state. And when a SDL_KeyboardEvent was
+ * emitted, we updated our state, this is done by hid_keyboard_update_state(),
+ * and then we use a loop to generate HID events, the sequence of array elements
+ * is unimportant and when too much keys pressed at the same time (more than
+ * report count), we should generate phantom state. This is done by
+ * hid_keyboard_get_hid_event(). Don't forget that modifiers should be updated
+ * too, even for phantom state.
+ */
+
 // See "SDL2/SDL_scancode.h".
 // Maybe SDL_Keycode is used by most people,
 // but SDL_Scancode is taken from USB HID protocol so I perfer this.
@@ -152,19 +166,31 @@ static unsigned char modifiers = HID_KEYBOARD_MODIFIER_NONE;
 
 inline static unsigned char sdl_keymod_to_hid_modifiers(SDL_Keymod mod) {
     unsigned char modifiers = HID_KEYBOARD_MODIFIER_NONE;
-    // That's why you should not write code drunked.
-    // SDL_Keymod:    NONE NONE NONE NONE RGUI LGUI RALT LALT RCTRL LCTRL NONE   NONE  NONE  NONE RSHIFT LSHIFT
-    // SDL hex:                           0800 0400 0200 0100 0080  0040                          0002   0001
-    // HID modifiers:                                         RGUI  RALT  RSHIFT RCTRL LGUI  LALT LSHIFT LCTRL
-    // HID hex:                                               80    40    20     10    08    04   02     01
-    modifiers |= ((mod & KMOD_LCTRL) >> 6);
-    modifiers |= ((mod & KMOD_LSHIFT) << 1);
-    modifiers |= ((mod & KMOD_LALT) >> 6);
-    modifiers |= ((mod & KMOD_LGUI) >> 7);
-    modifiers |= ((mod & KMOD_RCTRL) >> 3);
-    modifiers |= ((mod & KMOD_RSHIFT) << 4);
-    modifiers |= ((mod & KMOD_RALT) >> 3);
-    modifiers |= ((mod & KMOD_RGUI) >> 4);
+    // Not so cool, but more readable, and does not rely on actual value.
+    if (mod & KMOD_LCTRL) {
+        modifiers |= HID_KEYBOARD_MODIFIER_LEFT_CONTROL;
+    }
+    if (mod & KMOD_LSHIFT) {
+        modifiers |= HID_KEYBOARD_MODIFIER_LEFT_SHIFT;
+    }
+    if (mod & KMOD_LALT) {
+        modifiers |= HID_KEYBOARD_MODIFIER_LEFT_ALT;
+    }
+    if (mod & KMOD_LGUI) {
+        modifiers |= HID_KEYBOARD_MODIFIER_LEFT_GUI;
+    }
+    if (mod & KMOD_RCTRL) {
+        modifiers |= HID_KEYBOARD_MODIFIER_RIGHT_CONTROL;
+    }
+    if (mod & KMOD_RSHIFT) {
+        modifiers |= HID_KEYBOARD_MODIFIER_RIGHT_SHIFT;
+    }
+    if (mod & KMOD_RALT) {
+        modifiers |= HID_KEYBOARD_MODIFIER_RIGHT_ALT;
+    }
+    if (mod & KMOD_RGUI) {
+        modifiers |= HID_KEYBOARD_MODIFIER_RIGHT_GUI;
+    }
     return modifiers;
 }
 

app/src/input_manager.c

@@ -330,6 +330,7 @@ input_manager_process_text_input(struct input_manager *im,
     if (im->use_hid_over_aoa) {
         return;
     }
+
     if (is_shortcut_mod(im, SDL_GetModState())) {
         // A shortcut must never generate text events
         return;