Edge labels (code-set, user-read-only)¶

Edges support a short text label drawn centered on top of the edge path.

Not user-editable. The label is a QGraphicsSimpleTextItem child of QDMGraphicsEdge with ItemIsSelectable / ItemIsMovable / ItemIsFocusable unset and acceptedMouseButtons() == Qt.NoButton. QGraphicsSimpleTextItem has no editing API at all, so users cannot change it from the view.
Code can set it at creation time and at runtime.

Two edges carrying a label

Usage¶

from nodeeditor.node_edge import Edge

# creation time
edge = Edge(scene, out_socket, in_socket, label="yes")

# runtime (equivalent)
edge.label = "no"
edge.setLabel("no")
assert edge.label == edge.getLabel() == edge.grEdge.label()

# styling (optional)
edge.grEdge.setLabelColor("#ffffff")
edge.grEdge.setLabelFont(my_qfont)
edge.grEdge.setLabelOffset(0, -18)  # px offset from path midpoint

# hiding
edge.setLabel("")

How it works¶

Edge(label=...) forwards to QDMGraphicsEdge.setLabel() after the graphics item is created (nodeeditor/node_edge.py).
QDMGraphicsEdge.labelItem is recentered in updateLabelPosition() using path().pointAtPercent(0.5) (fallback: source/destination midpoint) plus the label offset. It is called from paint() after setPath(), so the label follows node drags, reroutes, and collapsed-group stub positions with no extra signals (nodeeditor/node_graphics_edge.py).
boundingRect() unions the path rect with the label rect so the label is not clipped. shape() stays path-only, so cut-line / intersect / hover behavior is unchanged.

Persistence¶

Edge.serialize() stores 'label'; Edge.deserialize() restores it with data.get('label', ""), so old files without the key load as "".
Clipboard (Edge(self.scene) + deserialize) and file save/load round-trip the label automatically.