Bitmap/Write a PPM file: Difference between revisions

=={{header|Scheme}}==

{{Works with|Scheme|R<math>^5</math>RS}}

<lang scheme>(define (write-ppm image file)

(define (write-image image)

(define (write-row row)

(define (write-colour colour)

(if (not (null? colour))

(begin (write-char (integer->char (car colour)))

(write-colour (cdr colour)))))

(if (not (null? row))

(begin (write-colour (car row)) (write-row (cdr row)))))

(if (not (null? image))

(begin (write-row (car image)) (write-image (cdr image)))))

(with-output-to-file file

(lambda ()

(begin (display "P6")

(newline)

(display (length (car image)))

(display " ")

(display (length image))

(newline)

(display 255)

(newline)

(write-image image)))))</lang>

Example using definitions in [[Basic bitmap storage#Scheme]]:

<lang scheme>(define image (make-image 800 600))

(image-fill! image *black*)

(image-set! image 400 300 *blue*)

(write-ppm image "out.ppm")</lang>