This is an extension and not part of the main GoJS library. Note that the API for this class may change at any time. If you intend to use an extension in production, you should copy the code to your own source directory. See the Extensions intro page for more information.
Constructs a LinkLabelDraggingTool and sets the name for the tool.
Optional init: Partial<LinkLabelDraggingTool>OverridecanThis tool can only start if the mouse has moved enough so that it is not a click, and if the mouse down point is on a GraphObject "label" in a Link Panel, as determined by findLabel.
OverridedoStart a transaction, call findLabel and remember it as the "label" property, and remember the original value for the label's go.GraphObject.segmentOffset property.
OverridedoRestore the label's original value for go.GraphObject.segmentOffset.
OverridedoOverridedoDuring the drag, call updateSegmentOffset in order to set the go.GraphObject.segmentOffset of the label.
OverridedoOverridedoFrom the GraphObject at the mouse point, search up the visual tree until we get to an object that is a label of a Link.
This returns null if no such label is at the mouse down point.
Save the label's go.GraphObject.segmentOffset as a rotated offset from the midpoint of the Link that the label is in.
The label being dragged.
The LinkLabelDraggingTool class lets the user move a label on a go.Link.
This tool only works when the Link has a label that is positioned at the go.Link.midPoint plus some offset. It does not work for labels that have a particular go.GraphObject.segmentIndex.
If you want to experiment with this extension, try the Link Label Dragging sample.