libobs: Always try to update transform in current thread

Due to the recent change in which scene items now only update their
transforms during the next frame's tick, snapping sources would
sometimes jitter and have incorrect snapping.  This fixes that issue by
reverting to the behavior of updating the transform immediately rather
than deferring the update to the next frame tick, but only on non-group
items.

This should not be done on items that are sub-items of groups because we
rely on the obs_scene_item::update_transform variable to update the
parent group's transform in addition.

libobs/obs-scene.c

@@ -1768,11 +1768,19 @@ bool obs_sceneitem_selected(const obs_sceneitem_t *item)
 	return item ? item->selected : false;
 }
 
+#define do_update_transform(item) \
+	do { \
+		if (!item->parent || item->parent->is_group) \
+			os_atomic_set_bool(&item->update_transform, true); \
+		else \
+			update_item_transform(item, false); \
+	} while (false)
+
 void obs_sceneitem_set_pos(obs_sceneitem_t *item, const struct vec2 *pos)
 {
 	if (item) {
 		vec2_copy(&item->pos, pos);
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -1780,7 +1788,7 @@ void obs_sceneitem_set_rot(obs_sceneitem_t *item, float rot)
 {
 	if (item) {
 		item->rot = rot;
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -1788,7 +1796,7 @@ void obs_sceneitem_set_scale(obs_sceneitem_t *item, const struct vec2 *scale)
 {
 	if (item) {
 		vec2_copy(&item->scale, scale);
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -1796,7 +1804,7 @@ void obs_sceneitem_set_alignment(obs_sceneitem_t *item, uint32_t alignment)
 {
 	if (item) {
 		item->align = alignment;
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -1892,7 +1900,7 @@ void obs_sceneitem_set_bounds_type(obs_sceneitem_t *item,
 {
 	if (item) {
 		item->bounds_type = type;
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -1901,7 +1909,7 @@ void obs_sceneitem_set_bounds_alignment(obs_sceneitem_t *item,
 {
 	if (item) {
 		item->bounds_align = alignment;
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -1909,7 +1917,7 @@ void obs_sceneitem_set_bounds(obs_sceneitem_t *item, const struct vec2 *bounds)
 {
 	if (item) {
 		item->bounds = *bounds;
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -1976,7 +1984,7 @@ void obs_sceneitem_set_info(obs_sceneitem_t *item,
 		item->bounds_type  = info->bounds_type;
 		item->bounds_align = info->bounds_alignment;
 		item->bounds       = info->bounds;
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 	}
 }
 
@@ -2217,7 +2225,7 @@ void obs_sceneitem_defer_update_end(obs_sceneitem_t *item)
 		return;
 
 	if (os_atomic_dec_long(&item->defer_update) == 0)
-		os_atomic_set_bool(&item->update_transform, true);
+		do_update_transform(item);
 }
 
 void obs_sceneitem_defer_group_resize_begin(obs_sceneitem_t *item)