Description

UIObject is the base class for each object in VMD which provides some form of user interface. There is a UIObject subclass for dealing with the text console, for the 2D pointer interface (the Mouse), and for the 3D user interface (currently in development). Also, each of the different GUI forms which appear on the screen are a separate UIObject.

VMD contains many different UIObject, each for the most part independent of the others. A UIObject has the ability to get input from the user on what that would like to do, and convert these into particular commands to do that action. These commands (embodied by different subclasses of the Command object) are put in a queue for execution. Each UIObject must also present some form of visual representation of the state of VMD to the user, which changes as different actions are performed. As commands are executed, each UIObject must be informed of what the action was, in order to update its display. No user interface component is capable of executing ALL the commands available in VMD, however, and conversely no user interface component is interested in hearing about all the different possible actions in VMD.

Each UIObject has the following characteristics:

• A list of the particular Command objects which are interesting to the UIObject. When it is initialized, each UIObject must call particular functions which store the list of commands which will require some change to the user interface when they are executed. This is usually done in the specialized constructor for the class derived from UIObject.
• A UIList which will store the UIObject.
• A unique ID code, which is provided by the particular UIList object with which the UIObject registers when it is created.
• A CommandQueue variable which is used by the UIObject to have Commands queued and executed.

The main UIObjects in VMD are all created in the routine VMDinitUI, in the file Global.C.