Prolog Terms

Prolog terms represent a few of the documented C structures. Most of the documented C structures are not needed in ProXL, for example the XWindowChanges structure. The documented structures that are represented in ProXL by Prolog terms are XPoint, XSegment, XRectangle, XArc, and XColor. The functor of these terms is the structure name translated by the naming conventions above. The first four kinds of terms have the same arguments as the corresponding C struct members, except that the angles in an arc specification are given in degrees, rather than 64ths of a degree, as in Xlib. Color terms have only the red, green, and blue components, and these are given as numbers between 0 and 1. For example, a 30 by 40 pixel rectangle at location (10, 20) would be represented by the term rectangle(10,20,30,40), and the color magenta would be represented by color(1,0,1). See the section of the ProXL manual on colors for information.