Unlike xpaint, xfig is a drawing rather than a painting package. The difference is subtle. In a paint package if you have for instance drawn a line, the application no longer remembers that it is a line, it is simply a bunch of individual (unrelated) pixels that are now a different colour than they were previously. In a drawing package the application considers the line as an ``object'' that can be moved, modified or deleted without disturbing anything else. xfig allows you to construct figures using objects such as circles, boxes, lines and spline curves. It is also possible to import images in formats such as GIF, JPEG or PostScript, imported images are treated as ``objects''. A simple example of what can be easily done with the package is shown in Figure .
Figure: Creating a figure showing line of sight effects on a magnetically accreting white dwarf using the xfig package.
xfig saves figures in its native format, Fig format, but they may be converted into various formats such as PostScript, GIF or JPEG. There are other applications that are capable of producing output in Fig format that can subsequently be read into xfig. For example, xfig doesn't have a facility to create graphs, but tools such as GNUPLOT can create graphs and output them in Fig format.
The Graphics Cookbook