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from UM.Scene.SceneNodeDecorator import SceneNodeDecorator
from UM.Scene.Selection import Selection
from typing import TYPE_CHECKING, Optional
if TYPE_CHECKING:
from UM.Scene.SceneNode import SceneNode
class GroupDecorator(SceneNodeDecorator):
def __init__(self, remove_when_empty: bool = True) -> None:
super().__init__()
# Used to keep track of previous parent when an empty group removes itself from the scene.
# We keep this option so that it's possible to undo it.
self._old_parent = None # type: Optional[SceneNode]
self._remove_when_empty = remove_when_empty
def setNode(self, node: "SceneNode") -> None:
super().setNode(node)
if self._node is not None:
self._node.childrenChanged.connect(self._onChildrenChanged)
def isGroup(self) -> bool:
return True
def getOldParent(self) -> Optional["SceneNode"]:
return self._old_parent
def _onChildrenChanged(self, node: "SceneNode") -> None:
if self._node is None:
return
if not self._remove_when_empty:
return
if not self._node.hasChildren():
# A group that no longer has children may remove itself from the scene
self._old_parent = self._node.getParent()
self._node.setParent(None)
Selection.remove(self._node)
else:
# A group that has removed itself from the scene because it had no children may add itself back to the scene
# when a child is added to it.
if not self._node.getParent() and self._old_parent:
self._node.setParent(self._old_parent)
self._old_parent = None
def __deepcopy__(self, memo):
return GroupDecorator()
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