Base class for graphic elements: Q.Element, simply called element, which provides basic support to graphic element, and basic functions such as event monitoring, property support and set membership etc. Two basic elements are provided on this basis: Q.Node and Q.Edge, separately for describing node and edge. In one graphic-theory, the Node represents a point, and Edge represents a side. The nodes are connected via edges. More edges exist among two nodes. In addition, there are some extension types: Q.Group, Q.Text, Q.ShapeNode etc.
Basic features of elements are introduced hereinafter