;
;  laplace-adjust.scm - Get edges using the laplace filter, adjustable
;  to get fine edges (lots of detail) to coarse edges (broader strokes)
;
;
;;; --------------------------------------------------------------------
;;; version 0.1  by Jeff Trefftzs <trefftzs@tcsn.net>
;;;     - Initial relase
;;; version 0.2 Raymond Ostertag <r.ostertag@caramail.com>
;;;     - ported to Gimp 2.0, changed menu entry
;;;
;;; --------------------------------------------------------------------
;
; This program 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 2 of the License, or
; (at your option) any later version.
; 
; This program 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 this program; if not, write to the Free Software
; Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;
;  Helper function to create a new layer
;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(define (copylayer layer layername)
  (set! new (car(gimp-layer-copy layer 1))) ; Add an alpha channel
  (gimp-drawable-set-name new layername)
  new
  )

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;;;
;;;  This script combines the idiom of a saturation layer and a color
;;;  layer, used also in the illustration.scm script and several others,
;;;  with the idea of variable edge detection using the laplace edge
;;;  detection filter.  Laplacian edges are more or less detailed in
;;;  inverse proportion to the degree of blurring that takes place before
;;;  the filter is invoked.  
;;;
;;;  The appearance of the final image depends greatly on the background
;;;  color that is chosen.  Darker colors lead to darker images - which 
;;;  can serve nicely to highlight the lighter regions of the original.
;;;
;;;  It's also worthwhile trying various levels of blur on the saturation
;;;  layer, particularly if the original image had regions of great
;;;  darkness.  
;;;
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;


(define (script-fu-laplace-adjust inImage inLayer inRadius inColor)
  (let*
      (
       (oldfg (car (gimp-palette-get-foreground)))
       (whitelayer (copylayer inLayer "Solid Background"))
       (edgelayer1 (copylayer inLayer "Edge Layer 1"))
       (satlayer (copylayer inLayer "Saturation Layer"))
       (colorlayer (copylayer inLayer "Color Layer"))
       )
    (gimp-image-undo-group-start inImage)

    ;; Real work goes in here
    
    (gimp-image-add-layer inImage whitelayer -1)
    (gimp-palette-set-foreground inColor)
    (gimp-drawable-fill whitelayer FOREGROUND-FILL)

    (gimp-image-add-layer inImage edgelayer1 -1)

    (gimp-drawable-set-visible edgelayer1 TRUE)

    (if (> inRadius 0)
	(plug-in-gauss-iir 1 inImage edgelayer1 inRadius TRUE TRUE) 
	)
    (plug-in-laplace 1 inImage edgelayer1)

    (if (< GRAY-IMAGE (car (gimp-image-base-type inImage))) ; RGB* image?
	(gimp-desaturate linelayer)		; then desaturate it
	())
    
    (gimp-image-add-layer inImage satlayer -1) ; the saturation layer
    (gimp-layer-set-mode satlayer SATURATION-MODE)	; saturation

    (gimp-image-add-layer inImage colorlayer -1)
    (gimp-layer-set-mode colorlayer COLOR-MODE)	; color

    (gimp-palette-set-foreground oldfg)
    (gimp-image-set-active-layer inImage inLayer)
    )
  (gimp-image-undo-group-end inImage)
  (gimp-displays-flush)
  )

(script-fu-register
 "script-fu-laplace-adjust"
 _"<Image>/Script-Fu/Line-Art/Adjustable Laplacian Edges..."
 "Gets Laplacian edges by blurring a copy of the original and then invoking the laplacian edge plug-in.  Larger blur values lead to coarser edges."
 "Jeff Trefftzs"
 "Copyright 2001, Jeff Trefftzs"
 "June 21, 2001"
 "RGB* GRAY* INDEXED*"
 SF-IMAGE "The Image" 0
 SF-DRAWABLE "The Layer" 0
 SF-ADJUSTMENT "Fine (0 <----> 64) Coarse" '(5 0 64 1 5 0 1)
 SF-COLOR "Background Color" '(128 128 128)
 )