anchor.diff:  ;; OUTPUT-PIXEL-FORMAT                                          [class]
   ;; IO-PIXEL-FORMAT                                              [class]
   
  -(defclass pixel-format ()
  +(define-protocol-class pixel-format ()
  +  ((composer :initform nil)))
  +
  +(define-protocol-class input-pixel-format (pixel-format) 
     ())
   
  -(defclass input-pixel-format (pixel-format) ())
  -
  -(defclass output-pixel-format (pixel-format)
  +(define-protocol-class output-pixel-format (pixel-format)
     ())
   
  -(defclass io-pixel-format (input-pixel-format output-pixel-format) ())
  -
  -(defclass uniform-pixel-format () ()
  +(define-protocol-class io-pixel-format (input-pixel-format output-pixel-format) ())
  +
  +(define-protocol-class uniform-pixel-format () ()
     ;; Mixin class for uniform pixel formats
     )
   
  -(defclass non-uniform-pixel-format () ()
  +(define-protocol-class non-uniform-pixel-format () ()
     ;; Mixin class for non-uniform pixel formats
     )
   
   ;; and their predicates
  -
  -(defmethod pixel-format-p ((object pixel-format)) t)
  -(defmethod input-pixel-format-p ((object input-pixel-format)) t)
  -(defmethod output-pixel-format-p ((object output-pixel-format)) t)
  -(defmethod io-pixel-format-p ((object io-pixel-format)) t)
  -(defmethod uniform-pixel-format ((object uniform-pixel-format)) t)
  -(defmethod non-uniform-pixel-format ((object non-uniform-pixel-format)) t)
   
   ;; The protocol
   
  
positive.code:                             nil nil sample x y)) ))))
  
  (defmethod pixels-translator (input-pixel-format output-pixel-format)
    (or ;; (gethash (list input-pixel-format output-pixel-format) *pixels-translator-cache*)
        (setf (gethash (list input-pixel-format output-pixel-format) *pixels-translator-cache*)
              (compile
               nil
  
negative.code: ;;;   Created: 2001-07-14
  ;;;    Author: Gilbert Baumann <unk6@rz.uni-karlsruhe.de>
  ;;;   License: LGPL (See file COPYING for details).
  ;;;       $Id: pixel-format.lisp,v 1.2 2002-02-21 03:38:24 gilbert Exp $
  ;;; --------------------------------------------------------------------------------------
  ;;;  (c) copyright 2001 by Gilbert Baumann
  
  