findLinkablePort method
Return the GraphObject at the mouse-down point, if it is part of a node and if it is valid to link with it.
This starts looking for a port at the #startObject if it is non-null, otherwise it looks for an object at the Diagram#firstInput's InputEvent#documentPoint. If it finds no object, or if the object it finds is not in a node, this method returns null. If it does find a port, it should set #isForwards to declare which direction the new link is being drawn.
This method may be overridden, but we recommend that you call this base method. Please read the Introduction page on Extensions for how to override methods and how to call this base method. @expose @return {GraphObject} If the #direction is LinkingTool.Either or LinkingTool.ForwardsOnly, this checks the element and its parent Node by calling LinkingBaseTool#isValidFrom. If the #direction is LinkingTool.Either or LinkingTool.BackwardsOnly, this checks the element and its parent Node by calling LinkingBaseTool#isValidTo. In either case finding a matching port will return that port and set LinkingBaseTool#isForwards appropriately. Otherwise this will return null.
Implementation
_i3.GraphObject? findLinkablePort() => _i4.callMethod(
this,
'findLinkablePort',
[],
);