An Object-oriented drawing package in smalltalk/v

Graphics creation applications tend to fall into two categories: bit-mapped paint packages, and object-oriented drawing packages. Although each interface has its own unique advantages, few vendors have attempted to integrate the two into a single package. Those who have tried have, in fact, poor integration both from the user\u27s perspective and in the underlying mathematical model. In this thesis, I have addressed the issue of integrating bit-mapped and object-oriented interfaces by creating an object-oriented graphics package which provides the user with a consistent interface for creating and manipulating both graphical objects and bit-mapped graphics. The consistency of the interface was facilitated by the consistency of the design, the underlying geometric model, and the implementation, all of which are themselves object-oriented. The thesis is written in Smalltalk/V for the Macintosh* . While the solution for this integration was not derived overnight, the use of object-oriented design principles sped the development of a complex graphical user interface, while providing fresh insight into the problem of representing bit-mapped objects. Because Smalltalk enforces the notion that every element in the system is an object, the Smalltalk developer is forced to begin designing his solution purely in terms of objects. This mind-set allowed me to view the point as no other graphics package has presented it: as a unique graphical entity (just as ll IS 1R formal geometry) available to the user as a graphical tool. As a result, users of my package are able to enjoy the benefits of both bit-mapped and object-oriented editors without ever abandoning an environment in which every graphical element is an object, in terms of both the interface and the underlying mathematical model

EBG: a lazy functional programming language implemented on the Java virtual machine.

The Java programming language offers a number of features including: portability; graphics; networking. Java implements the object-oriented execution model in terms of classes, objects with state, message passing and inclusion polymorphism. This work aims to provide a mixed paradigm environment which offers the advantages of both object-oriented and functional programming. The functional paradigm is supported by a new language called EBG which compiles to the Java VM. The resulting environment can support applications which use both object-oriented and functional programming as appropriate

Animator: an object-oriented approach

Object-oriented programming is presented as a paradigm for developing interactive systems for computer animation. Object types, evolved conceptually from graphics turtles, are implemented to provide the animator with familiar metaphors for the specification of motion in three-dimensional space. The intention is to create objects that can represent actors, cameras, and decor that the user can direct and animate in a relatively intuitive manner. Vector and turtle objects support the actors, which respond to messages to orient, accelerate and draw themselves on the screen. The MacApp object libraries are used to implement the standard Macintosh user interface and a unit is developed which implements vectors, actors and three-dimensional graphics turtles as obects. The object-oriented approach encourages a conceptual consistency in the external and internal interfaces and is intended to facilitate the development of extensible characters and tools through the cooperative efforts of animators and programmers

EBG : a lazy functional programming language implemented on the Java virtual machine.

The Java programming language offers a number of features including: portability; graphics; networking. Java implements the object-oriented execution model in terms of classes, objects with state, message passing and inclusion polymorphism. This work aims to provide a mixed paradigm environment which offers the advantages of both object-oriented and functional programming. The functional paradigm is supported by a new language called EBG which compiles to the Java VM. The resulting environment can support applications which use both object-oriented and functional programming as appropriate

Semantic Analysis of the Postscript Page Description Language

The Postscript page description language is a functional programming language. Central to the effective use of the language are the functional properties of delayed evaluation and referential transparency. Postscript performs all of its operations via distinct, multiple stacks which stores function binding lists, function parameters, and function code. By way of these stacks, Postscript creates dynamic computational states which leads identical expressions to evaluate to different results. This hints towards the polymorphic quality of an object-oriented language, even though it contradicts the functional precept of manifest interfaces thereby introducing a nonorthogonality. One other streak of object-orientation that shows up in Postscript is pointer semantics. Postscript\u27s graphics intentions are at the center of its slippery semantics and typeface and letter form rendering underpin Postscript\u27s data and execution model. Properties from both functional and object-oriented programming languages create Postscript\u27s robust font, graphics, and publishing abilities