-;; Procedures to read a file in raw pgm format into a picture
+#| -*-Scheme-*-
-(declare (usual-integrations))
+$Header: /Users/cph/tmp/foo/mit-scheme/mit-scheme/v7/src/6001/pic-read.scm,v 1.3 1992/07/10 21:56:55 cph Exp $
+
+Copyright (c) 1991-92 Massachusetts Institute of Technology
+
+This material was developed by the Scheme project at the Massachusetts
+Institute of Technology, Department of Electrical Engineering and
+Computer Science. Permission to copy this software, to redistribute
+it, and to use it for any purpose is granted, subject to the following
+restrictions and understandings.
+
+1. Any copy made of this software must include this copyright notice
+in full.
+
+2. Users of this software agree to make their best efforts (a) to
+return to the MIT Scheme project any improvements or extensions that
+they make, so that these may be included in future releases; and (b)
+to inform MIT of noteworthy uses of this software.
+
+3. All materials developed as a consequence of the use of this
+software shall duly acknowledge such use, in accordance with the usual
+standards of acknowledging credit in academic research.
+
+4. MIT has made no warrantee or representation that the operation of
+this software will be error-free, and MIT is under no obligation to
+provide any services, by way of maintenance, update, or otherwise.
+
+5. In conjunction with products arising from the use of this material,
+there shall be no use of the name of the Massachusetts Institute of
+Technology nor of any adaptation thereof in any advertising,
+promotional, or sales literature without prior written consent from
+MIT in each case. |#
+
+;;;; Procedures to read a file in raw pgm format into a picture
+(declare (usual-integrations))
+\f
(define (pgm-file->picture filename)
- (let* ((path-name (->pathname filename))
- (file-name (if (pathname-type path-name)
- path-name
- (if (file-exists? path-name)
- path-name
- (pathname-new-type path-name "pgm")))))
-
- (call-with-input-file file-name (lambda (port)
- (get-body port (get-header port))))))
+ (call-with-input-file (standard-pathname filename "pgm")
+ (lambda (port)
+ (get-body port (get-header port)))))
-(define (get-line port result) ; read a line of data
- (let ((c (read-char port)))
- (cond ((eof-object? c) (reverse result))
- ((eq? c #\Linefeed)
- (let ((res (reverse result)))
- (if (eq? (car res) #\#) ; ignore comments
- (get-line port '())
- res)))
- (else (get-line port (cons c result))))))
+(define (standard-pathname filename type)
+ (let ((pathname (->pathname filename)))
+ (if (or (pathname-type pathname)
+ (file-exists? pathname))
+ pathname
+ (pathname-new-type pathname type))))
(define (get-header port)
- (let* ((type (list->string (get-line port '())))
- (dims (list->string (get-line port '())))
- (no-of-greys (string->number
- (list->string (get-line port '()))))
- (spc-index (string-find-next-char dims #\space))
- (length (string->number
- (string-head dims spc-index)))
- (width (string->number
- (string-tail dims (1+ spc-index)))))
+ (let* ((type (get-line port))
+ (dims (get-line port))
+ (no-of-greys (string->number (get-line port)))
+ (spc-index (string-find-next-char dims #\space)))
(if (not (equal? type "P5")) ; P5 is the magic number for raw PGM format
- (error "Unrecognized format. (Convert to raw PGM) -- PICTURE-READ")
- (vector type length width no-of-greys))))
+ (error "Unrecognized format (Convert to raw PGM)."))
+ (vector type
+ (string->number (string-head dims spc-index))
+ (string->number (string-tail dims (+ spc-index 1)))
+ no-of-greys)))
+
+(define get-line
+ (let ((delimiters (char-set #\newline)))
+ (lambda (port)
+ (let loop ()
+ (let ((line (read-string delimiters port)))
+ (if (eof-object? line)
+ (error "EOF encountered when parsing line."))
+ ;; ignore comments
+ (if (and (not (string-null? line))
+ (char=? #\# (string-ref line 0)))
+ (loop)
+ line))))))
(define (get-body port attributes)
(let* ((length (vector-ref attributes 1))
(width (vector-ref attributes 2))
- (max-grey (vector-ref attributes 3))
(pic (make-picture length width))
- (data (make-initialized-vector
- width
- (lambda (index)
- index ; ignored
- (make-floating-vector length 0.))))) ;initialize to blank
-
+ (data
+ (make-initialized-vector
+ width
+ (lambda (index)
+ index ; ignored
+ (make-floating-vector length 0.))))) ;initialize to blank
(side-effecting-iter
width
(lambda (n)
(side-effecting-iter
length
(lambda (m)
- (floating-vector-set! nth-row m
- (exact->inexact (char->ascii (read-char port)))))))))
+ (floating-vector-set!
+ nth-row
+ m
+ (exact->inexact (char->ascii (read-char port)))))))))
(picture-set-data! pic data)
-;; (%picture-set-min! pic 0.) ; set min, max of picture according to
-;; (%picture-set-max! pic (exact->inexact max-grey)) ; information in file
pic))
-
-;;; Procedure to read in a picture that was previously saved using
+\f
+;;; Procedure to read in a picture that was previously saved using
;;; picture-write.
(define (picture-read filename)
- (let* ((path-name (->pathname filename))
- (pic-mimic (fasload (if (pathname-type path-name)
- path-name
- (if (file-exists? path-name)
- path-name
- (pathname-new-type path-name "pic"))))))
+ (let ((pic-mimic (fasload (standard-pathname filename "pic"))))
(if (not (record? pic-mimic))
- (error "Object loaded is not a picture -- PICTURE-READ"))
-
- (define mimic-type (record-type-descriptor pic-mimic))
-
- (if (not (equal? (record-type-field-names mimic-type)
- (record-type-field-names picture-type)))
- (error "Object loaded is not a picture -- PICTURE-READ"))
-
- (define mimic-width (record-accessor mimic-type 'width))
- (define mimic-height (record-accessor mimic-type 'height))
- (define mimic-data (record-accessor mimic-type 'data))
- (define mimic-min (record-accessor mimic-type 'min))
- (define mimic-max (record-accessor mimic-type 'max))
-
- (define new-pic (make-picture (mimic-width pic-mimic)
- (mimic-height pic-mimic)))
- (picture-set-data! new-pic (mimic-data pic-mimic))
- (%picture-set-min! new-pic (mimic-min pic-mimic))
- (%picture-set-max! new-pic (mimic-max pic-mimic))
- new-pic))
-
+ (error "Object loaded is not a record:" pic-mimic))
+ (let ((mimic-type (record-type-descriptor pic-mimic)))
+ (if (not (equal? (record-type-field-names mimic-type)
+ (record-type-field-names picture-type)))
+ (error "Object loaded is not a picture:" pic-mimic))
+ (let ((new-pic
+ (make-picture ((record-accessor mimic-type 'width) pic-mimic)
+ ((record-accessor mimic-type 'height) pic-mimic))))
+ (picture-set-data! new-pic
+ ((record-accessor mimic-type 'data) pic-mimic))
+ (%picture-set-min! new-pic
+ ((record-accessor mimic-type 'min) pic-mimic))
+ (%picture-set-max! new-pic
+ ((record-accessor mimic-type 'max) pic-mimic))
+ new-pic))))
\ No newline at end of file
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