;;;; This file is part of LilyPond, the GNU music typesetter.
;;;;
;;;; Copyright (C) 2006--2012 Han-Wen Nienhuys <hanwen@lilypond.org>
;;;;
;;;; LilyPond is free software: you can redistribute it and/or modify
;;;; it under the terms of the GNU General Public License as published by
;;;; the Free Software Foundation, either version 3 of the License, or
;;;; (at your option) any later version.
;;;;
;;;; LilyPond is distributed in the hope that it will be useful,
;;;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;;;; GNU General Public License for more details.
;;;;
;;;; You should have received a copy of the GNU General Public License
;;;; along with LilyPond.  If not, see <http://www.gnu.org/licenses/>.

(define-module (scm clip-region))

(use-modules (lily))

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;
;; The procedures shown in this list have been moved to
;; scm/output-lib.scm
;;
;;
;; 	(define-public (make-rhythmic-location bar-num num den)
;: 	(define-public (rhythmic-location? a)
;; 	(define-public (make-graceless-rhythmic-location loc)
;; 	(define-public rhythmic-location-measure-position cdr)
;; 	(define-public rhythmic-location-bar-number car)
;; 	(define-public (rhythmic-location<? a b)
;:	(define-public (rhythmic-location<=? a b)
;:	(define-public (rhythmic-location>=? a b)
;;	(define-public (rhythmic-location>? a b)
;:	(define-public (rhythmic-location=? a b)
;;	(define-public (rhythmic-location->file-string a)
;;	(define-public (rhythmic-location->string a)


;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;  Actual clipping logic.

;;
;; the total of this will be
;; O(#systems * #regions)
;; 
;; we can actually do better by sorting the regions as well,
;; but let's leave that for future extensions.
;;
(define-public (system-clipped-x-extent system-grob clip-region)
  "Return the X-extent of @var{system-grob} when clipped with
@var{clip-region}.  Return @code{#f} if not appropriate."
  
  (let*
      ((region-start (car clip-region))
       (columns (ly:grob-object system-grob 'columns))
       (region-end (cdr clip-region))
       (found-grace-end  #f)
       (candidate-columns 
	(filter
	 (lambda (j)
	   (let*
	       ((column (ly:grob-array-ref columns j))
		(loc (ly:grob-property column 'rhythmic-location))
		(grace-less (make-graceless-rhythmic-location loc))
		)
		
	     (and (rhythmic-location? loc)
		  (rhythmic-location<=? region-start loc)
		  (or (rhythmic-location<? grace-less region-end)
		      (and (rhythmic-location=? grace-less region-end)
			   (eq? #t (ly:grob-property column 'non-musical))

			   )))

	     ))
	 
	 (iota (ly:grob-array-length columns))))
       
       (column-range
	(if (>= 1 (length candidate-columns))
	    #f
	    (cons (car candidate-columns)
		  (car (last-pair candidate-columns)))))

       (clipped-x-interval
	(if column-range
	    (cons

	     (interval-start
	      (ly:grob-robust-relative-extent
	       (if (= 0 (car column-range))
		   system-grob
		   (ly:grob-array-ref columns (car column-range)))
	       system-grob X))
	     
	     (interval-end
	      (ly:grob-robust-relative-extent
	      (if (= (1- (ly:grob-array-length columns)) (cdr column-range))
		  system-grob
		  (ly:grob-array-ref columns (cdr column-range)))
	      system-grob X)))
	    
	    
	    #f
	    )))
    
    clipped-x-interval))