display: Expose window_grab_modifiers

Since commit c255031b6d6 we pass scroll-events through to
the compositor if the window_grab_modifiers are pressed;
in order to allow gnome-shell to check for those events,
expose the struct member as a MetaDisplay property.

Also take the opportunity to pick a more generic name, now
that the modifier is no longer used exclusively for mouse
clicks (unless we maintain the notion of scroll events as
button 4 and 5 "clicks").

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1695>

src/core/display.c

@@ -167,6 +167,7 @@ enum
 {
   PROP_0,
 
+  PROP_COMPOSITOR_MODIFIERS,
   PROP_FOCUS_WINDOW
 };
 
@@ -199,6 +200,9 @@ meta_display_get_property(GObject         *object,
 
   switch (prop_id)
     {
+    case PROP_COMPOSITOR_MODIFIERS:
+      g_value_set_flags (value, meta_display_get_compositor_modifiers (display));
+      break;
     case PROP_FOCUS_WINDOW:
       g_value_set_object (value, display->focus_window);
       break;
@@ -512,6 +516,15 @@ meta_display_class_init (MetaDisplayClass *klass)
                   NULL, NULL,
                   G_TYPE_BOOLEAN, 1, G_TYPE_TASK);
 
+  g_object_class_install_property (object_class,
+                                   PROP_COMPOSITOR_MODIFIERS,
+                                   g_param_spec_flags ("compositor-modifiers",
+                                                       "Compositor modifiers",
+                                                       "Modifiers reserved for compositor actions",
+                                                       CLUTTER_TYPE_MODIFIER_TYPE,
+                                                       0,
+                                                       G_PARAM_READABLE));
+
   g_object_class_install_property (object_class,
                                    PROP_FOCUS_WINDOW,
                                    g_param_spec_object ("focus-window",

src/core/events.c

@@ -273,7 +273,7 @@ meta_display_handle_event (MetaDisplay        *display,
     {
       ClutterModifierType grab_mods;
 
-      grab_mods = meta_display_get_window_grab_modifiers (display);
+      grab_mods = meta_display_get_compositor_modifiers (display);
       if ((clutter_event_get_state (event) & grab_mods) != 0)
         {
           bypass_wayland = TRUE;

src/core/keybindings-private.h

@@ -141,8 +141,6 @@ gboolean meta_keybindings_process_event     (MetaDisplay        *display,
                                              MetaWindow         *window,
                                              const ClutterEvent *event);
 
-ClutterModifierType meta_display_get_window_grab_modifiers (MetaDisplay *display);
-
 gboolean meta_prefs_add_keybinding          (const char           *name,
                                              GSettings            *settings,
                                              MetaKeyBindingAction  action,

src/core/keybindings.c

@@ -1227,7 +1227,7 @@ meta_change_button_grab (MetaKeyBindingManager *keys,
 }
 
 ClutterModifierType
-meta_display_get_window_grab_modifiers (MetaDisplay *display)
+meta_display_get_compositor_modifiers (MetaDisplay *display)
 {
   MetaKeyBindingManager *keys = &display->key_binding_manager;
   return keys->window_grab_modifiers;
@@ -1297,15 +1297,20 @@ meta_display_ungrab_window_buttons (MetaDisplay *display,
 }
 
 static void
-update_window_grab_modifiers (MetaKeyBindingManager *keys)
+update_window_grab_modifiers (MetaDisplay *display)
 {
+  MetaKeyBindingManager *keys = &display->key_binding_manager;
   MetaVirtualModifier virtual_mods;
   unsigned int mods;
 
   virtual_mods = meta_prefs_get_mouse_button_mods ();
   devirtualize_modifiers (keys, virtual_mods, &mods);
 
-  keys->window_grab_modifiers = mods;
+  if (keys->window_grab_modifiers != mods)
+    {
+      keys->window_grab_modifiers = mods;
+      g_object_notify (G_OBJECT (display), "compositor-modifiers");
+    }
 }
 
 void
@@ -1378,7 +1383,7 @@ prefs_changed_callback (MetaPreference pref,
             meta_display_ungrab_window_buttons (display, w->xwindow);
           }
 
-        update_window_grab_modifiers (keys);
+        update_window_grab_modifiers (display);
 
         for (l = windows; l; l = l->next)
           {
@@ -4559,7 +4564,7 @@ meta_display_init_keys (MetaDisplay *display)
 
   reload_combos (keys);
 
-  update_window_grab_modifiers (keys);
+  update_window_grab_modifiers (display);
 
   /* Keys are actually grabbed in meta_screen_grab_keys() */
 

src/core/window.c

@@ -6499,7 +6499,7 @@ meta_window_handle_mouse_grab_op_event  (MetaWindow         *window,
     {
     case CLUTTER_BUTTON_PRESS:
       {
-        ClutterModifierType grab_mods = meta_display_get_window_grab_modifiers (window->display);
+        ClutterModifierType grab_mods = meta_display_get_compositor_modifiers (window->display);
 
         /* This is the keybinding or menu case where we've
          * been dragging around the window without the button
@@ -8426,7 +8426,7 @@ meta_window_handle_ungrabbed_event (MetaWindow         *window,
    * care about. Just let the event through.
    */
 
-  grab_mods = meta_display_get_window_grab_modifiers (display);
+  grab_mods = meta_display_get_compositor_modifiers (display);
   event_mods = clutter_event_get_state (event);
   unmodified = (event_mods & grab_mods) == 0;
   source = clutter_event_get_source_device (event);

src/meta/display.h

@@ -170,6 +170,9 @@ guint meta_display_get_keybinding_action (MetaDisplay  *display,
                                           unsigned int  keycode,
                                           unsigned long mask);
 
+META_EXPORT
+ClutterModifierType meta_display_get_compositor_modifiers (MetaDisplay *display);
+
 META_EXPORT
 GSList *meta_display_sort_windows_by_stacking (MetaDisplay *display,
                                                GSList      *windows);