| Summary: | 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.
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