よしビューア作った

(eval-when (:compile-toplevel :load-toplevel :execute)
  (require :cl-opengl)
  (require :cl-glu)
  (require :cl-glut)
  (require :cl-jpeg)
  (require :drakma))

(defclass jpeg-viewer (glut:window)
  ((image :initarg :image :initform nil :accessor image))
  (:default-initargs :mode '(:rgb :single)))

(defmethod glut:display-window :before ((w jpeg-viewer))
  (gl:clear-color 0 0 0 0)
  (%gl:shade-model :flat)
  (gl:pixel-store :unpack-alignment 1))

(defmethod glut:display ((window jpeg-viewer))
  (with-accessors ((image image)
                   (width glut:width)
                   (height glut:height)) window
    (gl:clear :color-buffer-bit)
    (gl:raster-pos 0 0)
    (gl:draw-pixels width height :rgb :unsigned-byte image)
    (%gl:flush)))

(defmethod glut:reshape ((window jpeg-viewer) w h)
  (%gl:viewport 0 0 w h)
  (%gl:matrix-mode :projection)
  (%gl:load-identity)
  (glu:ortho-2d 0 w 0 h)
  (%gl:matrix-mode :modelview)
  (%gl:load-identity))

(defmethod glut:keyboard ((window jpeg-viewer) key x y)
  (declare (ignore x y))
  (case key
    ((#\Esc #\q) (glut:destroy-current-window))))

(defun view (url)
  (multiple-value-bind (image height width)
      (jpeg:decode-stream (drakma:http-request url :want-stream t))
    (loop for h from 0 below (/ height 2)
          do (rotatef (subseq image (* h width 3) (* (1+ h) width 3))
                      (subseq image (- (* height width 3)
                                       (* (1+ h) width 3))
                                    (- (* height width 3)
                                       (* h width 3)))))
    (loop for i from 0 below (* height width 3) by 3
          do (rotatef (aref image i) (aref image (+ i 2))))
    (glut:display-window
     (make-instance 'jpeg-viewer
                    :image image
                    :width width
                    :height height))))

;;(view "http://anime.nifty.com/luckystar/images/ls_wp_tpa.jpg")