The X Toolkit and Athena widget set do not provide classical two-dimensional vector graphics capabilities, which are a firm CAD requirement. To support platform-independent vector graphics output a minimum-functionality vector graphics widget has been implemented (Figure 3.6) directly using the generic Xlib and X Toolkit.
Figure 3.6: The Simple Vector Graphics (SVG) widget
The widget operates on the SVG data structure created by the SVG library (see Section 5.8). It keeps the SVG plot in memory to offer zoom and pan functions for the user, which the programmer does hence not need to care for. Callbacks can be added for example to digitize data points. This widget is used as basis for the interactive back-end (xpif2d, see Section 5.9) of VISTA's visualization library.