VisComp: 2.1 VisCompClass Instance Data: VCI_comp

GEOS SDK TechDocs

2 VisCompClass Instance Data

2.2 VCI_gadgetExcl

Normal visible objects have just one instance field for tree construction: the VI_link field that points to the object's next sibling. For an object to have children, it must also have an instance field declared with the keyword @composite ; this field, in VisCompClass , is VCI_comp . The composite field contains the optr of the object's first child; the link field contains a pointer to either the object's next sibling or its parent.

Applications should never access the VI_link or VCI_comp fields directly at run-time; instead, these fields can be altered or queried with the following messages (all defined in VisClass ):

MSG_VIS_ADD_CHILD

This message adds a new child object to the composite.

MSG_VIS_REMOVE_CHILD

This message removes a child from the composite.

MSG_VIS_MOVE_CHILD

This message moves a child within the composite's list of children.

MSG_VIS_GET_PARENT

This message returns a pointer to the object's parent.

Several other messages may also be used to change or query any visible object's VI_link and VCI_comp fields. These are discussed in the VisClass chapter.

GEOS SDK TechDocs

2 VisCompClass Instance Data

2.2 VCI_gadgetExcl