Overlays

include/xkbcommon/xkbcommon.h

@@ -1438,7 +1438,15 @@ enum xkb_state_component {
      *  Use this unless you explicitly care how the state came about. */
     XKB_STATE_LAYOUT_EFFECTIVE = (1 << 7),
     /** LEDs (derived from the other state components). */
-    XKB_STATE_LEDS = (1 << 8)
+    XKB_STATE_LEDS = (1 << 8),
+    /** TODO: doc */
+    XKB_STATE_OVERLAYS_SET = (1 << 9),
+    /** TODO: doc */
+    XKB_STATE_OVERLAYS_LOCKED = (1 << 10),
+    /** TODO: doc */
+    XKB_STATE_OVERLAYS_EFFECTIVE = (1 << 11),
+    /** TODO: doc */
+    XKB_STATE_OVERLAID_KEYS = (1 << 12),
 };
 
 /**
@@ -1502,6 +1510,9 @@ xkb_state_update_mask(struct xkb_state *state,
                       xkb_layout_index_t latched_layout,
                       xkb_layout_index_t locked_layout);
 
+xkb_keycode_t
+xkb_state_key_get_overlay_keycode(struct xkb_state *state, xkb_keycode_t kc);
+
 /**
  * Get the keysyms obtained from pressing a particular key in a given
  * keyboard state.

meson.build

@@ -251,6 +251,7 @@ libxkbcommon_sources = [
     'src/messages-codes.h',
     'src/scanner-utils.h',
     'src/state.c',
+    'src/state.h',
     'src/text.c',
     'src/text.h',
     'src/utf8.c',

src/keymap.c

@@ -82,6 +82,9 @@ xkb_keymap_unref(struct xkb_keymap *keymap)
                 }
                 free(key->groups);
             }
+            if (key->overlays) {
+                free(key->overlays);
+            }
         }
         free(keymap->keys);
     }
@@ -92,6 +95,7 @@ xkb_keymap_unref(struct xkb_keymap *keymap)
         }
         free(keymap->types);
     }
+    free(keymap->incompatible_overlays);
     free(keymap->sym_interprets);
     free(keymap->key_aliases);
     free(keymap->group_names);

src/keymap.h

@@ -120,6 +120,15 @@ enum mod_type {
 };
 #define MOD_REAL_MASK_ALL ((xkb_mod_mask_t) 0x000000ff)
 
+/* TODO: doc */
+#define XKB_MAX_OVERLAYS 8
+
+#if XKB_MAX_OVERLAYS > 8
+    #error "Cannot store overlays indexes"
+#endif
+typedef uint8_t xkb_overlay_index_t;
+typedef uint8_t xkb_overlay_mask_t;
+
 enum xkb_action_type {
     ACTION_TYPE_NONE = 0,
     ACTION_TYPE_MOD_SET,
@@ -165,11 +174,15 @@ enum xkb_action_controls {
     CONTROL_AX_FEEDBACK = (1 << 8),
     CONTROL_BELL = (1 << 9),
     CONTROL_IGNORE_GROUP_LOCK = (1 << 10),
+#define _CONTROL_OVERLAY1_LOG2 11
+#define CONTROL_OVERLAYS (CONTROL_OVERLAY1 | CONTROL_OVERLAY2)
+    CONTROL_OVERLAY1 = (1 << 11),
+    CONTROL_OVERLAY2 = (1 << 12),
     CONTROL_ALL = \
         (CONTROL_REPEAT | CONTROL_SLOW | CONTROL_DEBOUNCE | CONTROL_STICKY | \
          CONTROL_MOUSEKEYS | CONTROL_MOUSEKEYS_ACCEL | CONTROL_AX | \
          CONTROL_AX_TIMEOUT | CONTROL_AX_FEEDBACK | CONTROL_BELL | \
-         CONTROL_IGNORE_GROUP_LOCK)
+         CONTROL_IGNORE_GROUP_LOCK | CONTROL_OVERLAY1 | CONTROL_OVERLAY2)
 };
 
 enum xkb_match_operation {
@@ -201,6 +214,7 @@ struct xkb_controls_action {
     enum xkb_action_type type;
     enum xkb_action_flags flags;
     enum xkb_action_controls ctrls;
+    xkb_overlay_mask_t overlays;
 };
 
 struct xkb_pointer_default_action {
@@ -336,6 +350,9 @@ struct xkb_key {
     xkb_keycode_t keycode;
     xkb_atom_t name;
 
+    xkb_overlay_mask_t overlays_mask;
+    xkb_keycode_t *overlays;
+
     enum xkb_explicit_components explicit;
 
     xkb_mod_mask_t modmap;
@@ -370,6 +387,8 @@ struct xkb_keymap {
     enum xkb_keymap_format format;
 
     enum xkb_action_controls enabled_ctrls;
+    xkb_overlay_index_t num_overlays;
+    xkb_overlay_mask_t *incompatible_overlays;
 
     xkb_keycode_t min_key_code;
     xkb_keycode_t max_key_code;