Included with the program are a few simple examples of this. By combining the graphics primitives it is possible to add complex forms such as recursive figures or other graphic types without modifying the program itself. Macros are added to the macro menu by adding an appropriate line in the drawtoolrc file. To activate it, the user selects it from the menu, then draws it's bounding box in the drawing window. In both cases r,g,b is the current colour chosen by the user.
Macros send vector data to drawtool by outputting it to standard output.
This is piped into drawtool where it is interpreted. Ok, I concede. That may be a slightly grandiose name.