VisComp: 1 VisCompClass Features

GEOS SDK TechDocs

VisComp

2 VisCompClass Instance Data

Composite visible objects provide several features and functions that normal visible objects can not. VisCompClass has several instance data fields above and beyond those found in VisClass (since VisCompClass is a subclass of VisClass , it inherits all its instance data and methods). Although it only handles a few messages not defined in VisClass , it provides much more functionality. Some of the main features of composite objects are listed below:

• They can have children.
  Normal visible objects can exist only as leaves of a visible object tree. VisCompClass can have children, allowing the tree to be built to any number of levels. See the VisClass chapterfor full information on visible trees.
• They can manage their children's geometry.
  A composite's children can be managed arbitrarily by the composite, or the composite can use the geometry manager to automatically position and size its children. Since a composite can have other composites as its children, this sizing can descend recursively throughout the visible tree, making the entire tree's geometry completely self-managed. See Managing Geometry for information on geometry management.
• They can create and manage their own windows.
  Composite objects can create their own graphics windows. Though this is not typically done (except in Specific UI libraries), it is possible. See Managing Graphic Windows for more information on windows.
• They support other VisClass functions.
  VisCompClass inherits all the instance data fields and messages of VisClass . As such, it can do everything normal VisClass objects can do. See the VisClass chapterfor full information on VisClass .

GEOS SDK TechDocs

VisComp

2 VisCompClass Instance Data