; polaroid.scm  A Script-Fu script to turn a GIMP-image into a 'Polaroid' snap.
;               The script can also recreate the yellow/red colour 
;               characteristics of a traditional polaroid snapshot.
;
; Copyright (C) 2003, Avi Bercovich <avi@sillypages.org>
;
; version 0.4

; TODO:
; - work on selections
; - stacking
; - bump-mapping the polaroid 'paper'

; 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.
;

(define (script-fu-polaroid image drawable size colouring)

	(let* 
 		(
		(imgWidth (car (gimp-image-width image)))
		(imgHeight (car (gimp-image-height image)))

		(sideoffset (abs (* 0.04 size)))
		(bottomoffset (* 4 sideoffset))

		(pImgWidth size)
		(pImgHeight (+ pImgWidth bottomoffset))
		(pImgSize (abs (- pImgWidth (* 2 sideoffset))))

		(pTmp (car (gimp-image-new imgWidth imgHeight RGB)))
		(pTmpBackground (car (gimp-layer-new pTmp imgWidth imgHeight RGB "Background" 100 NORMAL )))

		(pImg (car (gimp-image-new pImgWidth pImgHeight RGB)))
		(pImgBackground (car (gimp-layer-new pImg pImgWidth pImgHeight RGB "Background" 100 NORMAL )))
		(pImgContent (car (gimp-layer-new pImg pImgSize pImgSize RGBA-IMAGE "Content" 100 NORMAL )))
 	)

; disable undo on new image
(gimp-image-undo-disable pImg)

; setup pTmp layer
(gimp-image-add-layer pTmp pTmpBackground 0)

; setup pImg layers
(gimp-image-add-layer pImg pImgBackground 0)
(gimp-image-add-layer pImg pImgContent -1)
(gimp-layer-set-offsets pImgContent sideoffset sideoffset)

; clear pImg background to white
(gimp-palette-set-background '(255 255 255) )
(gimp-palette-set-foreground '(0 0 0) )
(gimp-selection-all pImg)
(gimp-edit-clear pImgBackground)
(gimp-selection-none pImg)

; copy content into pTmp, scale to pImgSize and then composite into pImg
(gimp-edit-copy drawable)
(gimp-floating-sel-anchor (car (gimp-edit-paste pTmpBackground TRUE)))
(gimp-scale pTmpBackground TRUE 0 0 pImgSize pImgSize)
(gimp-image-resize pTmp pImgSize pImgSize 0 0)
(gimp-edit-copy pTmpBackground)
(gimp-image-delete pTmp)
(gimp-floating-sel-anchor (car (gimp-edit-paste pImgContent TRUE)))

; if requested colourify to traditional polaroid
(if (= colouring TRUE)
	(begin
		(gimp-color-balance pImgContent SHADOWS TRUE 20 0 -20)
		(gimp-brightness-contrast pImgContent 0 20)
	)
)

; enable undo on new image.
(gimp-image-undo-enable pImg)

; dump new image to the user
(gimp-display-new pImg)
(gimp-displays-flush)

)
)

(script-fu-register "script-fu-polaroid"
		    _"<Image>/Script-Fu/Decor/Polaroid..."
		    "Turn an image into a 'Polaroid' snap.\n\nImage widths larger than 170 pixels seem to yield the best results.\n\nEnjoy!"
		    "Avi Bercovich <avi@sillypages.org>"
		    "Avi Bercovich"
		    "April 2003" 
		    "RGB* GRAY* INDEXED*"
		    SF-IMAGE "Image" 0
		    SF-DRAWABLE "Drawable" 0
				SF-ADJUSTMENT "Image Width" '(256 32 16384 1 10 0 1)
				SF-TOGGLE "Polaroid Colouring?" TRUE
)