; Updated for Gimp 2.1

(define (script-fu-fore-to-gray image
                                drawable)
  (let* ((fg-color (car (gimp-context-get-foreground)))
	 (red (car fg-color))
	 (green (cadr fg-color))
         (blue (caddr fg-color))
	 (gray (+ (* red 0.30) (* green 0.59) (* blue 0.11)))
	 (red-array (cons-array 6 'byte))
	 (green-array (cons-array 6 'byte))
	 (blue-array (cons-array 6 'byte)))

  (gimp-image-undo-group-start image)

  (aset red-array 0 0)
  (aset red-array 1 0)
  (aset red-array 2 red)
  (aset red-array 3 gray)
  (aset red-array 4 255)
  (aset red-array 5 255)

  (aset green-array 0 0)
  (aset green-array 1 0)
  (aset green-array 2 green)
  (aset green-array 3 gray)
  (aset green-array 4 255)
  (aset green-array 5 255)

  (aset blue-array 0 0)
  (aset blue-array 1 0)
  (aset blue-array 2 blue)
  (aset blue-array 3 gray)
  (aset blue-array 4 255)
  (aset blue-array 5 255)

  (gimp-curves-spline drawable HISTOGRAM-RED   6 red-array)
  (gimp-curves-spline drawable HISTOGRAM-GREEN 6 green-array)
  (gimp-curves-spline drawable HISTOGRAM-BLUE  6 blue-array)

  ; Aufräumarbeiten
  (gimp-image-undo-group-end image)
  (gimp-displays-flush)))

(script-fu-register "script-fu-fore-to-gray"
		    _"<Image>/Layer/Colors/FG->Gray"
		    "Maps the current foreground color to gray"
		    "Simon Budig <simon@gimp.org>"
		    "Simon Budig"
		    "2002/1/1"
		    "RGB*"
		    SF-IMAGE "Image" 0
		    SF-DRAWABLE "Drawable" 0)