;
; invert-adjustment-layer
;
; Creates a invert "adjustment layer".
;
; Alexander Melcher (a.melchers@planet.nl)
; At xMedia, The Netherlands

; 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.

; Define the function

(define (script-fu-invert-adjustment-layer inImage
	                                   inLayer
	                                   inReplaceLayer
	)
(let* (
    (adjustment 0)
    (theLayer)
    (currentSelection 0)
    (currentFgColor '(0 0 0))
    (currentColor '(0 0 0))
    (theOpacity 0)
    (adjustmentMask 0)
    )
	; Make sure to work on the layer, not the layer mask
	(if (= (car (gimp-drawable-is-layer-mask inLayer)) TRUE)
		(set! theLayer (car (gimp-image-get-active-layer inImage)))
		(set! theLayer inLayer)
	)

	; Group undo information
	(gimp-undo-push-group-start inImage)

	; Create the adjustment layer
	(set! adjustment (car (gimp-layer-new inImage
	                 (car (gimp-image-width inImage))
	                 (car (gimp-image-height inImage))
	                 (car (gimp-drawable-type-with-alpha inLayer))
	                 "Invert"
	                 100 6)))
    (gimp-image-insert-layer inImage adjustment 0 0)
	(if (= inReplaceLayer TRUE)
		(begin
			(gimp-layer-set-linked adjustment
			         (car (gimp-layer-get-linked theLayer)))
			(gimp-layer-set-opacity adjustment
			         (car (gimp-layer-get-opacity theLayer)))
		)
		()
	)

	; Create the effect
	(set! currentSelection (car (gimp-selection-save inImage)))
	;(gimp-image-remove-channel inImage currentSelection)
	(gimp-selection-all inImage)
	(gimp-edit-clear adjustment)
	(set! currentFgColor (car (gimp-palette-get-foreground)))
	(gimp-palette-set-foreground '(255 255 255))
	(gimp-bucket-fill adjustment 0 0 100 255 FALSE 0 0)
	(gimp-palette-set-foreground currentFgColor)
	;(gimp-image-add-layer inImage adjustment -1)
	(if (= inReplaceLayer TRUE)
		(begin
			(gimp-image-remove-layer inImage theLayer)
			(if (= (car (gimp-drawable-is-layer-mask inLayer)) TRUE)
				;(gimp-selection-load inLayer)
                (gimp-image-select-item inImage CHANNEL-OP-REPLACE inLayer)
			(if (= (car (gimp-layer-mask theLayer)) -1)
				;(gimp-selection-none inImage)
				;(gimp-selection-load (car (gimp-layer-mask theLayer)))
                (gimp-image-select-item inImage CHANNEL-OP-REPLACE (car (gimp-layer-get-mask theLayer)))
			)
			)
		)
		;(gimp-selection-load currentSelection)
        (gimp-image-select-item inImage CHANNEL-OP-REPLACE currentSelection)
	)

	; Add a layer mask
	(if (= (car (gimp-selection-is-empty inImage)) FALSE)
		(begin
			(set! adjustmentMask (car (gimp-layer-create-mask adjustment 1)))
            (gimp-layer-add-mask adjustment adjustmentMask)
			(set! currentFgColor (car (gimp-palette-get-foreground)))
			(gimp-palette-set-foreground '(255 255 255))
			(gimp-bucket-fill adjustmentMask 0 0 100 255 FALSE 0 0)
			(gimp-palette-set-foreground currentFgColor)
		)
		(set! adjustmentMask (car (gimp-layer-create-mask adjustment 0)))
        (gimp-layer-add-mask adjustment adjustmentMask)
	)
	;(gimp-image-add-layer-mask inImage adjustment adjustmentMask)

	(if (= inReplaceLayer TRUE)
		(gimp-selection-load currentSelection)
		()
	)

	; Group undo information
	(gimp-undo-push-group-end inImage)

	; Force update
	(gimp-displays-flush)

	; Return
	(list 1)
)
)
; Register script-fu-invert-adjustment-layer

(script-fu-register
    "script-fu-invert-adjustment-layer"
    "<Image>/Adjustment Layers/Invert"
    "Creates a invert \"adjustment layer\"."
    "Alexander Melchers"
    "2002, Alexander Melchers, xMedia"
    "7th November 2002"
    "RGB* GRAY*"
    SF-IMAGE      "The Image"           0
    SF-DRAWABLE   "The Layer"           0
    SF-TOGGLE     "Replace Layer"       FALSE
)