PHIGURE provides a set of functions, each of which creates an image of a more or less complex graphic object. Unlike many other graphic functions libraries, an object generated by PHIGURE is not plotted when the function which generated it is called. In fact, when a PHIGURE function generates an object, it simply stores a geometrical description of that object.
The object is stored in a memory unit called a structure, in compliance with the PHIGS standard. The term PHIGS structure is used to refer to the memorized image of a graphic object.
Each PHIGS structure is associated with an identifier, known as a structure identifier. This identifier is a whole number of the programer's choice. In this manual, the variable corresponding to the structure identifier is always called STRID. The set of completed structures at a given moment in the execution of a program is called the CSS (Centralized Structure Store).
GPHIGS provides a set of functions for building a structure "by hand". These include a structure open function, a close function and a set of functions for creating basic structure element. These basic elements may be points, lines, fill areas, etc. GPHIGS also provides a set of functions for modifying an existing structure.
PHIGURE provides a set of functions which are complementary to GPHIGS. Each of these functions automatically builds a complete structure representing a graphic object. As PHIGURE is entirely based on GPHIGS, these PHIGURE functions use basic GPHIGS functions to build the structure. Of course, all these PHIGURE functions include the identifier STRID of the structure to be produced as a parameter.
For example PHIGURE includes the TAXYLN function which creates a structure representing an axis parallel to the horizontal axis with linear graduations.
As shown in the following diagram, PHIGURE is complementary to GPHIGS. An application may create structures with PHIGURE functions, but also with basic PHIGS functions.
