keybindings: Add support for resolving from multiple layouts

Add the infrastructure to resolve keybinding symbols from multiple
layouts. It is still unused, but will be, when the primary layout does
not have the required latin keysyms in it.

https://bugzilla.gnome.org/show_bug.cgi?id=787016

src/core/keybindings-private.h

@@ -89,6 +89,13 @@ typedef struct
   gboolean      builtin:1;
 } MetaKeyPref;
 
+typedef struct _MetaKeyBindingKeyboardLayout
+{
+  struct xkb_keymap *keymap;
+  xkb_layout_index_t index;
+  xkb_level_index_t n_levels;
+} MetaKeyBindingKeyboardLayout;
+
 typedef struct
 {
   MetaBackend *backend;
@@ -108,7 +115,11 @@ typedef struct
   MetaResolvedKeyCombo iso_next_group_combo[2];
   int n_iso_next_group_combos;
 
-  xkb_level_index_t keymap_num_levels;
+  /*
+   * A primary layout, and an optional secondary layout that is
+   * not yet used.
+   */
+  MetaKeyBindingKeyboardLayout active_layouts[2];
 
   /* Alt+click button grabs */
   ClutterModifierType window_grab_modifiers;

src/core/keybindings.c

@@ -57,6 +57,9 @@
 #define SCHEMA_MUTTER_KEYBINDINGS "org.gnome.mutter.keybindings"
 #define SCHEMA_MUTTER_WAYLAND_KEYBINDINGS "org.gnome.mutter.wayland.keybindings"
 
+#define META_KEY_BINDING_PRIMARY_LAYOUT 0
+#define META_KEY_BINDING_SECONDARY_LAYOUT 1
+
 static gboolean add_builtin_keybinding (MetaDisplay          *display,
                                         const char           *name,
                                         GSettings            *settings,
@@ -339,6 +342,27 @@ get_keycodes_for_keysym_iter (struct xkb_keymap *keymap,
     }
 }
 
+static void
+add_keysym_keycodes_from_layout (int                           keysym,
+                                 MetaKeyBindingKeyboardLayout *layout,
+                                 GArray                       *keycodes)
+{
+  xkb_level_index_t layout_level;
+
+  for (layout_level = 0; layout_level < layout->n_levels; layout_level++)
+    {
+      FindKeysymData search_data = (FindKeysymData) {
+        .keycodes = keycodes,
+        .keysym = keysym,
+        .layout = layout->index,
+        .level = layout_level
+      };
+      xkb_keymap_key_for_each (layout->keymap,
+                               get_keycodes_for_keysym_iter,
+                               &search_data);
+    }
+}
+
 /* Original code from gdk_x11_keymap_get_entries_for_keyval() in
  * gdkkeys-x11.c */
 static void
@@ -346,9 +370,7 @@ get_keycodes_for_keysym (MetaKeyBindingManager  *keys,
                          int                     keysym,
                          MetaResolvedKeyCombo   *resolved_combo)
 {
-  struct xkb_keymap *keymap;
+  unsigned int i;
-  xkb_layout_index_t layout_index;
-  xkb_level_index_t layout_level;
   GArray *keycodes;
   int keycode;
 
@@ -362,19 +384,14 @@ get_keycodes_for_keysym (MetaKeyBindingManager  *keys,
       goto out;
     }
 
-  keymap = meta_backend_get_keymap (keys->backend);
+  for (i = 0; i < G_N_ELEMENTS (keys->active_layouts); i++)
-  layout_index = meta_backend_get_keymap_layout_group (keys->backend);
-
-  for (layout_level = 0; layout_level < keys->keymap_num_levels; layout_level++)
     {
-      FindKeysymData search_data = (FindKeysymData) {
+      MetaKeyBindingKeyboardLayout *layout = &keys->active_layouts[i];
-        .keycodes = keycodes,
+
-        .keysym = keysym,
+      if (!layout->keymap)
-        .layout = layout_index,
+        continue;
-        .level = layout_level
+
-      };
+      add_keysym_keycodes_from_layout (keysym, layout, keycodes);
-      xkb_keymap_key_for_each (keymap, get_keycodes_for_keysym_iter,
-                               &search_data);
     }
 
  out:
@@ -384,29 +401,44 @@ get_keycodes_for_keysym (MetaKeyBindingManager  *keys,
                                     keycodes->len == 0 ? TRUE : FALSE);
 }
 
+typedef struct _CalculateLayoutLevelsState
+{
+  struct xkb_keymap *keymap;
+  xkb_layout_index_t layout_index;
+
+  xkb_level_index_t out_n_levels;
+} CalculateLayoutLevelState;
+
 static void
-determine_keymap_num_levels_iter (struct xkb_keymap *keymap,
+calculate_n_layout_levels_iter (struct xkb_keymap *keymap,
                                 xkb_keycode_t      keycode,
                                 void              *data)
 {
-  xkb_level_index_t *num_levels = data;
+  CalculateLayoutLevelState *state = data;
-  xkb_layout_index_t i;
+  xkb_level_index_t n_levels;
 
-  for (i = 0; i < xkb_keymap_num_layouts_for_key (keymap, keycode); i++)
+  n_levels = xkb_keymap_num_levels_for_key (keymap,
-    {
+                                            keycode,
-      xkb_level_index_t level = xkb_keymap_num_levels_for_key (keymap, keycode, i);
+                                            state->layout_index);
-      if (level > *num_levels)
+
-        *num_levels = level;
+  state->out_n_levels = MAX (n_levels, state->out_n_levels);
-    }
 }
 
-static void
+static xkb_level_index_t
-determine_keymap_num_levels (MetaKeyBindingManager *keys)
+calculate_n_layout_levels (struct xkb_keymap *keymap,
-{
+                           xkb_layout_index_t layout_index)
-  struct xkb_keymap *keymap = meta_backend_get_keymap (keys->backend);
 
-  keys->keymap_num_levels = 0;
+{
-  xkb_keymap_key_for_each (keymap, determine_keymap_num_levels_iter, &keys->keymap_num_levels);
+  CalculateLayoutLevelState state = {
+    .keymap = keymap,
+    .layout_index = layout_index,
+
+    .out_n_levels = 0
+  };
+
+  xkb_keymap_key_for_each (keymap, calculate_n_layout_levels_iter, &state);
+
+  return state.out_n_levels;
 }
 
 static void
@@ -590,12 +622,44 @@ binding_reload_combos_foreach (gpointer key,
   index_binding (keys, binding);
 }
 
+static void
+clear_active_keyboard_layouts (MetaKeyBindingManager *keys)
+{
+  unsigned int i;
+
+  for (i = 0; i < G_N_ELEMENTS (keys->active_layouts); i++)
+    {
+      MetaKeyBindingKeyboardLayout *layout = &keys->active_layouts[i];
+
+      g_clear_pointer (&layout->keymap, xkb_keymap_unref);
+      *layout = (MetaKeyBindingKeyboardLayout) { 0 };
+    }
+}
+
+static void
+reload_active_keyboard_layouts (MetaKeyBindingManager *keys)
+{
+  struct xkb_keymap *keymap;
+  xkb_layout_index_t layout_index;
+
+  clear_active_keyboard_layouts (keys);
+
+  keymap = meta_backend_get_keymap (keys->backend);
+  layout_index = meta_backend_get_keymap_layout_group (keys->backend);
+
+  keys->active_layouts[META_KEY_BINDING_PRIMARY_LAYOUT] = (MetaKeyBindingKeyboardLayout) {
+    .keymap = xkb_keymap_ref (keymap),
+    .index = layout_index,
+    .n_levels = calculate_n_layout_levels (keymap, layout_index),
+  };
+}
+
 static void
 reload_combos (MetaKeyBindingManager *keys)
 {
   g_hash_table_remove_all (keys->key_bindings_index);
 
-  determine_keymap_num_levels (keys);
+  reload_active_keyboard_layouts (keys);
 
   resolve_key_combo (keys,
                      &keys->overlay_key_combo,
@@ -1196,6 +1260,8 @@ meta_display_shutdown_keys (MetaDisplay *display)
 
   g_hash_table_destroy (keys->key_bindings_index);
   g_hash_table_destroy (keys->key_bindings);
+
+  clear_active_keyboard_layouts (keys);
 }
 
 /* Grab/ungrab, ignoring all annoying modifiers like NumLock etc. */