XR: Add runtime window area for XR events

This adds an offscreen View3D window area for the VR view in order to
execute XR events/operators in the proper context. The area is created
as runtime data before XR events are dispatched and set as the active
area during XR event handling.

Since the area is runtime-only, it will not be saved in files and since
the area is offscreen, it will not interfere with regular window areas.
The area is removed with the rest of the XR runtime data on exit, file
read, or when stopping the VR session.

Note: This also adds internal types (EVT_DATA_XR, EVT_XR_ACTION) and
structs (wmXrActionData) for XR events.

Reviewed By: Severin

Differential Revision: https://developer.blender.org/D12472

3 files changed, 75 insertions, 7 deletions

diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index 833c9accf95..d5456482d67 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -2001,6 +2001,68 @@ void ED_area_init(wmWindowManager *wm, wmWindow *win, ScrArea *area)
   }
 }
 
+static void area_offscreen_init(wmWindowManager *wm, ScrArea *area)
+{
+  area->type = BKE_spacetype_from_id(area->spacetype);
+
+  if (area->type == NULL) {
+    area->spacetype = SPACE_VIEW3D;
+    area->type = BKE_spacetype_from_id(area->spacetype);
+  }
+
+  LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
+    region->type = BKE_regiontype_from_id_or_first(area->type, region->regiontype);
+  }
+}
+
+ScrArea *ED_area_offscreen_create(wmWindowManager *wm, wmWindow *win, eSpace_Type space_type)
+{
+  ScrArea *area = MEM_callocN(sizeof(*area), __func__);
+  area->spacetype = space_type;
+
+  screen_area_spacelink_add(WM_window_get_active_scene(win), area, space_type);
+  area_offscreen_init(wm, area);
+
+  return area;
+}
+
+static void area_offscreen_exit(wmWindowManager *wm, wmWindow *win, ScrArea *area)
+{
+  if (area->type && area->type->exit) {
+    area->type->exit(wm, area);
+  }
+
+  LISTBASE_FOREACH (ARegion *, region, &area->regionbase) {
+    if (region->type && region->type->exit) {
+      region->type->exit(wm, region);
+    }
+
+    WM_event_modal_handler_region_replace(win, region, NULL);
+    WM_draw_region_free(region, true);
+
+    MEM_SAFE_FREE(region->headerstr);
+
+    if (region->regiontimer) {
+      WM_event_remove_timer(wm, win, region->regiontimer);
+      region->regiontimer = NULL;
+    }
+
+    if (wm->message_bus) {
+      WM_msgbus_clear_by_owner(wm->message_bus, region);
+    }
+  }
+
+  WM_event_modal_handler_area_replace(win, area, NULL);
+}
+
+void ED_area_offscreen_free(wmWindowManager *wm, wmWindow *win, ScrArea *area)
+{
+  area_offscreen_exit(wm, win, area);
+
+  BKE_screen_area_free(area);
+  MEM_freeN(area);
+}
+
 static void region_update_rect(ARegion *region)
 {
   region->winx = BLI_rcti_size_x(&region->winrct) + 1;
diff --git a/source/blender/editors/screen/screen_edit.c b/source/blender/editors/screen/screen_edit.c
index 1c068fdd6e4..02b1e002d86 100644
--- a/source/blender/editors/screen/screen_edit.c
+++ b/source/blender/editors/screen/screen_edit.c
@@ -574,6 +574,17 @@ bool screen_area_close(struct bContext *C, bScreen *screen, ScrArea *area)
   return screen_area_join_ex(C, screen, sa2, area, true);
 }
 
+void screen_area_spacelink_add(Scene *scene, ScrArea *area, eSpace_Type space_type)
+{
+  SpaceType *stype = BKE_spacetype_from_id(space_type);
+  SpaceLink *slink = stype->create(area, scene);
+
+  area->regionbase = slink->regionbase;
+
+  BLI_addhead(&area->spacedata, slink);
+  BLI_listbase_clear(&slink->regionbase);
+}
+
 /* ****************** EXPORTED API TO OTHER MODULES *************************** */
 
 /* screen sets cursor based on active region */
@@ -1023,13 +1034,7 @@ static void screen_global_area_refresh(wmWindow *win,
   }
   else {
     area = screen_area_create_with_geometry(&win->global_areas, rect, space_type);
-    SpaceType *stype = BKE_spacetype_from_id(space_type);
-    SpaceLink *slink = stype->create(area, WM_window_get_active_scene(win));
-
-    area->regionbase = slink->regionbase;
-
-    BLI_addhead(&area->spacedata, slink);
-    BLI_listbase_clear(&slink->regionbase);
+    screen_area_spacelink_add(WM_window_get_active_scene(win), area, space_type);
 
     /* Data specific to global areas. */
     area->global = MEM_callocN(sizeof(*area->global), __func__);
diff --git a/source/blender/editors/screen/screen_intern.h b/source/blender/editors/screen/screen_intern.h
index 04ee62b1631..47229e5e2b5 100644
--- a/source/blender/editors/screen/screen_intern.h
+++ b/source/blender/editors/screen/screen_intern.h
@@ -94,6 +94,7 @@ eScreenDir area_getorientation(ScrArea *sa_a, ScrArea *sa_b);
 void area_getoffsets(
     ScrArea *sa_a, ScrArea *sa_b, const eScreenDir dir, int *r_offset1, int *r_offset2);
 bool screen_area_close(struct bContext *C, bScreen *screen, ScrArea *area);
+void screen_area_spacelink_add(struct Scene *scene, ScrArea *area, eSpace_Type space_type);
 struct AZone *ED_area_actionzone_find_xy(ScrArea *area, const int xy[2]);
 
 /* screen_geometry.c */