Very rudimentary library for generating simple SVG files from Common Lisp. Handles points, lines, and polygons.

svg.lisp

(defstruct svg
  (points nil :type list)
  (polys nil :type list)
  (lines nil :type list))

(defstruct point
  (x 0.0 :type (or float integer))
  (y 0.0 :type (or float integer)))

(defstruct line
  (pt1 0.0 :type point)
  (pt2 0.0 :type point))

(defstruct polygon
  (points nil :type list))

(defun add-point (img x y)
  (setf (svg-points img) (cons (make-point :x x :y y) (svg-points img))))

(defun add-line (img x1 y1 x2 y2)
  (setf (svg-lines img) (cons (make-line :pt1 (make-point :x x1 :y y1) :pt2 (make-point :x x2 :y y2)) (svg-lines img))))

(defun add-polygon (img &rest pts)
  (setf (svg-polys img) (cons (make-polygon :points (mapcar #'(lambda (pt) (make-point :x (car pt) :y (cadr pt))) pts)) (svg-polys img))))

(defun to_file (img &key (stream t))
  (format stream "<?xml version=\"1.0\" standalone=\"no\"?> <!DOCTYPE svg PUBLIC \"-//W3C//DTD SVG 1.1//EN\" \"http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd\"> <svg width=\"100%\" height=\"100%\" version=\"1.1\" xmlns=\"http://www.w3.org/2000/svg\">")

  (dolist (poly (svg-polys img))
	(format stream "<polygon points=\"")
	(dolist (pt (polygon-points poly))
	  (let ((ptstr (mapcar #'(lambda (x) (format nil "~a,~a" (point-x x) (point-y x))) pt)))
		(format stream "~{~a ~}" ptstr)))
	(format stream "\" style=\"fill:#cccccc; stroke:#000000;stroke-width:1\"/>"))

  (dolist (line (svg-lines img))
	(let* ((p1 (line-pt1 line))
		   (p2 (line-pt2 line)))
			   
	(format stream "<line x1=\"~a\" y1=\"~a\" x2=\"~a\" y2=\"~a\" style=\"stroke:rgb(99,99,99);stroke-width:2\"/>" (point-x p1) (point-y p1) (point-x p2) (point-y p2))))
			
  (dolist (pt (svg-points img))
	(format stream "<circle cx=\"~a\" cy=\"~a\" r=\"3\" stroke=\"blue\" stroke-width=\"2\" fill=\"green\"/>" (point-x pt) (point-y pt)))
  (format stream "</svg>"))

testsvg.lisp

;; (load "svg.lisp")

(defun test-it ()
  (let ((img (make-svg)))
	(add-line img 0 0 500 500)
	(add-line img 0 500 500 0)

	(add-point img 250 250)
	(add-point img 125 125)
	(add-point img 375 125)
	(add-point img 375 375)
	(add-point img 125 375)

	(add-polygon img '(250 250) '(125 125) '(125 375))

	(add-polygon img '(250 250) '(375 375) '(375 125))

	(add-polygon img '(125 125) '(375 125) '(310 190) '(190 190))

	(with-open-file (stream "/tmp/test3.svg" :direction :output :if-exists :supersede)
					(to_file img :stream stream))))