The Amulet Environment: New Models for Effective User Interface Software Development

The Amulet user interface development environment makes it easier for programmers to create highly-interactive, graphical user interface software for Unix, Windows or Macintosh. Amulet uses new models for objects, constraints, animation, input, output, commands, and undo. The object system is a prototype-instance model in which there is no distinction between classes and instances or between methods and data. The constraint system allows any value of any object to be computed by arbitrary code and supports multiple constraint solvers. Animations can be attached to existing objects with a single line of code. Input from the user is handled by "Interactor" objects which support reuse of behavior objects. The output model provides a declarative definition of the graphics, and supports automatic refresh. Command objects encapsulate all of the information needed about operations, including support for various ways to undo them. An key feature of the Amulet design is that all graphical objec..

Overview of the Amulet User Interface Toolkit

Amulet is a new user interface software environment for C++ on X/11, Microsoft Windows NT or 95, and the Macintosh, which facilitates user interface research by being very open and flexible. In particular, new constraint and undo algorithms can be added, the widgets can modified and replaced, and support is provided for building high-level tools. Keywords : UI Toolkit Attending Workshop: Brad A. Myers Presented at the Human-Computer Interaction Consortium, Winter Park, CO. February 14-18, 1996 This research was sponsored by NCCOSC under Contract No. N66001-94-C-6037, Arpa Order No. B326. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of NCCOSC or the U.S. Government. The Design for the Amulet User Interface Toolkit - 1 1. Introduction The Amulet user interface development environment includes a number of design and implementation innovations including new..

The Amulet Environment: New Models for Effective User Interface Software Development

The Amulet user interface development environment makes it easier for programmers to create highly-interactive, graphical user interface software for Unix, Windows or Macintosh. Amulet uses new models for objects, constraints, animation, input, output, commands, and undo. The object system is a prototype-instance model in which there is no distinction between classes and instances or between methods and data. The constraint system allows any value of any object to be computed by arbitrary code and supports multiple constraint solvers. Animations can be attached to existing objects with a single line of code. Input from the user is handled by "Interactor" objects which support reuse of behavior objects. The output model provides a declarative definition of the graphics, and supports automatic refresh. Command objects encapsulate all of the information needed about operations, including support for various ways to undo them. An key feature of the Amulet design is that all graphical objects and behaviors of those objects are explicitly represented at run-time, so the system can provide a number of high-level built-in functions, including automatic display and editing of objects, and external analysis and control of interfaces. Amulet integrates these capabilities in a flexible and effective manner.</p

Reusable Hierarchical Command Objects

The Amulet user interface development environment uses hierarchical command objects to support the creation of highly-interactive graphical user interfaces. When input arrives or a widget is operated by the user, instead of invoking a call-back procedure as in most other toolkits, Amulet allocates a command object and calls its DOmethod. Unlike previous uses of command objects, Amulet organizes the commands into a hierarchy, so that low-level operations like dragging or selection invoke low-level commands, which in turn might invoke widget-level commands, which invoke high-level, application-specific commands, and so on. The top-level commands correspond to semantic actions of the program. The result is better modularization because different levels of the user interface are independent, and better code reuse because the lower-level commands, and even many high-level commands such as cut, copy, paste, text edit, and change-color, can be reused from the library. Furthermore, the commands in Amulet support a new form of Undo, where the user can select any previous operation and selectively undo it, repeat it on the same objects, or repeat it on new objects. In addition, operations like scrolling and selections can be undone or repeated, which can be very useful. Thus, the command objects in Amulet make it easier for developers by providing more reusable components, while at the same time providing new capabilities for users.</p