Motif and VUIT

~ ~ Motif is a popular set of graphic interface tools for use with the X window system. The basic construct in Motif is a widget. A widget is the name given to any graphical object in Motif. Each different type of widget has its own specific properties. Widgets are arranged in a type hierarchy, and many attributes are inherited through this hierarchy. A widget can be as simple as a single button or as complex as a dialog box, containing a message and several buttons. For more information on Motif and Motif programming see [Berlage 1991].

VUIT, Visual User Interface Tool, a product of Digital Equipment Corporation, is used for building Motif based graphical user interfaces. One of the advantages of this product is that actual Motif widgets are used to build the screen. This means that the interface designer can see what the interface will look like when it is finished, as it is being built. More about VUIT can be found in [Digital 1990].

The interface is built by dragging Motif widgets from a menu palette and placing them on the screen building area. The menu is arranged hierarchically: all buttons are grouped together; all windows, dialogs, etc. The physical attributes of these widgets are set by directly manipulating the widgets. Attributes such as height, width, and physical positioning are set in this way. Other attributes can be added by choosing from a list of valid attributes and values. The system offers a great amount of guidance and keeps the user from making invalid choices.

Callbacks are the means of interacting in a Motif built environment. A callback is executed when the user performs an action on a widget. The callbacks needed in a particular application can be added to the widgets as they are built in VUIT.

VUIT can output the code for implementing the interface that has been developed using it. It can output this code in several languages. However, C was the only one used for developing SNEAKERS. VUIT outputs a makefile, a file used to build the entire program from a set of individual modules. It also outputs the C program necessary to invoke the X and Motif environments. Finally, it outputs a uil file, which contains all the information about the widgets, their attributes, and the callbacks associated with them. The user still has to assign the functionality to the callbacks that are assigned to each widget, but the code generated by VUIT is sufficient to run a skeleton simulation of the interface, lacking full functionality.

These tools are useful for quickly developing the interface after it has been designed. Functionality can be added after the basic interface structure has been established.