fix handling undo event

ff52da00 · Durman · 5b198c89 · ff52da00 · ff52da00
--- a/core/handlers.py
+++ b/core/handlers.py
@@ -84,14 +84,6 @@ def sv_handler_undo_post(scene):

    undo_handler_node_count['sv_groups'] = 0

-    # ideally we would like to recalculate all from scratch
-    # but with heavy trees user can be scared of pressing undo button
-    # I consider changes in tree topology as most common case
-    # but if properties or work of some viewer node (removing generated objects) was effected by undo
-    # only recalculating of all can restore the adequate state of a tree
-    for tree in BlTrees().sv_main_trees:
-        tree.update()  # the tree could changed by undo event
-

 @persistent
 def sv_update_handler(scene):

--- a/core/update_system.py
+++ b/core/update_system.py
@@ -58,6 +58,9 @@ def control_center(event):
        ts.tasks.add(ts.Task(event.tree, UpdateTree.main_update(event.tree)))

    # mark that the tree topology has changed
+    # also this can be called (by Blender) during undo event in this case all
+    # nodes will have another hash id and the comparison method will decide that
+    # all nodes are new, and won't be able to detect changes, and will update all
    elif type(event) is ev.TreeEvent:
        UpdateTree.get(event.tree).is_updated = False
        if event.tree.sv_process:
@@ -279,7 +282,7 @@ class UpdateTree(SearchTree):
                # update topology
                if not _tree.is_updated:
                    old = _tree
-                    _tree = old.copy()
+                    _tree = old.copy(tree)

                # update outdated nodes list
                if _tree._outdated_nodes is not None:
@@ -343,10 +346,12 @@ class UpdateTree(SearchTree):
        else:
            cls._tree_catch.clear()

-    def copy(self) -> 'UpdateTree':
+    def copy(self, new_tree: NodeTree) -> 'UpdateTree':
        """They copy will be with new topology if original tree was changed
-        since instancing of the first tree. Other attributes copied as is."""
-        copy_ = type(self)(self._tree)
+        since instancing of the first tree. Other attributes copied as is.
+        :new_tree: it's import to pass fresh tree object because during undo
+        events all previous tree objects invalidates"""
+        copy_ = type(self)(new_tree)
        for attr in self._copy_attrs:
            setattr(copy_, attr, copy(getattr(self, attr)))
        return copy_