The Handling of Input, Output, and Constraints in the CY1 Drawing Toolkit

• Main Authors: Wang ,Hsiao Peng, 王效鵬
• Other Authors: Hsia, Yen-Teh
• Format: Others
• Language: zh-TW
• Published: 1995
• Online Access: http://ndltd.ncl.edu.tw/handle/70209242707850780666

碩士 === 中原大學 === 資訊工程研究所 === 83 === This thesis introduces Dt, a drawing toolkit in the CY1 programming environment. Dt is a class library written in C++ programming language, and runs on top of X Window System. Besides its powerful capability of graphical output, Dt supports a novel method, called behavior, to handle user inputs that occur "on" graphical objects. Using the notion of behavior, we can separate the look of an graphical object from its feel. Because of the build-in object-oriented approach, a graphical object is also an input handler, and servers as the fundamental unit of user input handling. A graphical object may have a close relation with other graphical objects. There may also be some relationships among graphical objects and application data structure that must be maintained. Maintaining that relations keeps the consistency between the application and presentation. It is a burden for a programmer to write a program to maintain these relations. Constraints are one of several techniques devised to handle it. Dt supports constraints. In this thesis, I will describe how to use constraint to maintain consistency among objects and how the constraint mechanism works in detail.