WM: message bus replacement for property notifiers

Use dynamically generated message publish/subscribe
so buttons and manipulators update properly.

This resolves common glitches where manipulators weren't updating
as well as the UI when add-ons exposed properties which
hard coded listeners weren't checking for.

Python can also publish/scribe changes via `bpy.msgbus`.

See D2917

4 files changed, 51 insertions, 3 deletions

diff --git a/source/blender/windowmanager/intern/wm.c b/source/blender/windowmanager/intern/wm.c
index b66bddfa6bf..623a7af5165 100644
--- a/source/blender/windowmanager/intern/wm.c
+++ b/source/blender/windowmanager/intern/wm.c
@@ -56,6 +56,7 @@
 
 #include "WM_api.h"
 #include "WM_types.h"
+#include "WM_message.h"
 #include "wm_window.h"
 #include "wm_event_system.h"
 #include "wm_draw.h"
@@ -396,6 +397,10 @@ void WM_check(bContext *C)
 		wm_window_ghostwindows_ensure(wm);
 	}
 
+	if (wm->message_bus == NULL) {
+		wm->message_bus = WM_msgbus_create();
+	}
+
 	/* case: fileread */
 	/* note: this runs in bg mode to set the screen context cb */
 	if ((wm->initialized & WM_WINDOW_IS_INITIALIZED) == 0) {
@@ -475,7 +480,11 @@ void wm_close_and_free(bContext *C, wmWindowManager *wm)
 	}
 
 	BLI_freelistN(&wm->queue);
-	
+
+	if (wm->message_bus != NULL) {
+		WM_msgbus_destroy(wm->message_bus);
+	}
+
 	BLI_freelistN(&wm->paintcursors);
 
 	WM_drag_free_list(&wm->drags);
diff --git a/source/blender/windowmanager/intern/wm_event_system.c b/source/blender/windowmanager/intern/wm_event_system.c
index aa8180a7df6..b1ec1c009df 100644
--- a/source/blender/windowmanager/intern/wm_event_system.c
+++ b/source/blender/windowmanager/intern/wm_event_system.c
@@ -39,7 +39,6 @@
 #include "DNA_screen_types.h"
 #include "DNA_scene_types.h"
 #include "DNA_windowmanager_types.h"
-#include "DNA_workspace_types.h"
 #include "DNA_userdef_types.h"
 
 #include "MEM_guardedalloc.h"
@@ -77,6 +76,7 @@
 
 #include "WM_api.h"
 #include "WM_types.h"
+#include "WM_message.h"
 #include "wm.h"
 #include "wm_window.h"
 #include "wm_event_system.h"
@@ -242,6 +242,14 @@ void WM_main_remove_notifier_reference(const void *reference)
 				wm_notifier_clear(note);
 			}
 		}
+
+		/* Remap instead. */
+#if 0
+		if (wm->message_bus) {
+			WM_msg_id_remove(wm->message_bus, reference);
+		}
+#endif
+
 	}
 }
 
@@ -261,6 +269,17 @@ void WM_main_remap_editor_id_reference(ID *old_id, ID *new_id)
 			}
 		}
 	}
+
+	wmWindowManager *wm = bmain->wm.first;
+	if (wm && wm->message_bus) {
+		struct wmMsgBus *mbus = wm->message_bus;
+		if (new_id != NULL) {
+			WM_msg_id_update(mbus, old_id, new_id);
+		}
+		else {
+			WM_msg_id_remove(mbus, old_id);
+		}
+	}
 }
 
 static void wm_notifier_clear(wmNotifier *note)
@@ -328,7 +347,9 @@ void wm_event_do_notifiers(bContext *C)
 	
 	if (wm == NULL)
 		return;
-	
+
+	/* disable? - keep for now since its used for window level notifiers. */
+#if 1
 	/* cache & catch WM level notifiers, such as frame change, scene/screen set */
 	for (win = wm->windows.first; win; win = win->next) {
 		Scene *scene = WM_window_get_active_scene(win);
@@ -452,6 +473,16 @@ void wm_event_do_notifiers(bContext *C)
 		
 		MEM_freeN(note);
 	}
+#endif /* if 1 (postpone disabling for in favor of message-bus), eventually. */
+
+	/* Handle message bus. */
+	{
+		for (win = wm->windows.first; win; win = win->next) {
+			CTX_wm_window_set(C, win);
+			WM_msgbus_handle(wm->message_bus, C);
+		}
+		CTX_wm_window_set(C, NULL);
+	}
 
 	wm_event_do_refresh_wm_and_depsgraph(C);
 }
diff --git a/source/blender/windowmanager/intern/wm_files.c b/source/blender/windowmanager/intern/wm_files.c
index c3ae4af1964..7c8059fcda9 100644
--- a/source/blender/windowmanager/intern/wm_files.c
+++ b/source/blender/windowmanager/intern/wm_files.c
@@ -123,6 +123,7 @@
 
 #include "WM_api.h"
 #include "WM_types.h"
+#include "WM_message.h"
 #include "wm.h"
 #include "wm_files.h"
 #include "wm_window.h"
@@ -504,7 +505,11 @@ static void wm_file_read_post(bContext *C, const bool is_startup_file, const boo
 	BLI_callback_exec(CTX_data_main(C), NULL, BLI_CB_EVT_VERSION_UPDATE);
 	BLI_callback_exec(CTX_data_main(C), NULL, BLI_CB_EVT_LOAD_POST);
 
+#if 1
 	WM_event_add_notifier(C, NC_WM | ND_FILEREAD, NULL);
+#else
+	WM_msg_publish_static(CTX_wm_message_bus(C), WM_MSG_STATICTYPE_FILE_READ);
+#endif
 
 	/* report any errors.
 	 * currently disabled if addons aren't yet loaded */
diff --git a/source/blender/windowmanager/intern/wm_init_exit.c b/source/blender/windowmanager/intern/wm_init_exit.c
index 4975e818051..55ed8b2a091 100644
--- a/source/blender/windowmanager/intern/wm_init_exit.c
+++ b/source/blender/windowmanager/intern/wm_init_exit.c
@@ -93,6 +93,7 @@
 
 #include "WM_api.h"
 #include "WM_types.h"
+#include "WM_message.h"
 
 #include "wm_cursors.h"
 #include "wm_event_system.h"
@@ -192,6 +193,8 @@ void WM_init(bContext *C, int argc, const char **argv)
 	 * but keep before file reading, since that may report errors */
 	wm_init_reports(C);
 
+	WM_msgbus_types_init();
+
 	/* get the default database, plus a wm */
 	wm_homefile_read(C, NULL, G.factory_startup, false, true, NULL, NULL);