For the actual drawing, I'm wondering if the cairo library and drawing model would help. It effectively gives you the move-to line-to curve-to drawing, with some additional capabilities. A simple script around cairo seems like it would cover many more cases, and then this ASCIImage mechanism will help generate those scripts.
Specific features that would make sense to have available rather than drawing art in an image editor:
Line width, to draw the chevron without having to draw two adjacent lines.