;
; $Id: dlblend.scm,v 1.2 1998/01/04 10:23:49 dl Exp $
;
; (C) 1998 - Laurent Demailly - L@Demailly.com
;
; What this script does :
; ----------------------- 
; Makes a copy of your image and creates an animation of the active layer
; + The image is assumed to have only 1 layer (with transparency)
; + A custom gradient must be selected using the gradient editor
;   it is assumed to be suitable for bi-linear application
;   (like Flare_Radial_102)
; + The desired background color must be set (to get proper
;   anti aliasing)
;
; 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 (script-fu-dlblendanim img 
			    drawable
			    num-frames
			    gradient
			    span
			    rel-y1
			    rel-y2
			    anti-aliasing
			    bg-remove
			    threshold
			    )
  (let* ((num-frames (max 1 num-frames))
	 (remaining-frames (+ num-frames (* 2 span)))
         (image (car (gimp-channel-ops-duplicate img)))
	 (height (car (gimp-image-height image)))
	 (width (car (gimp-image-width image)))
	 (y1 (* height rel-y1))
	 (y2 (* height rel-y2))
	 (offset (/ width num-frames))
	 (x (- (* offset span)))
	 (bg-layer FALSE)
	 (color (car (gimp-palette-get-background)))
	 )
 
  (gimp-image-disable-undo image)
  
  (set! source-layer (car (gimp-image-get-active-layer image)))
  (gimp-layer-set-visible source-layer 0)

  (while (> remaining-frames 0)
         (set! anim-layer (car (gimp-layer-copy source-layer TRUE)))
         (gimp-layer-set-preserve-trans anim-layer TRUE)
	 (set! bg-layer (car (gimp-layer-new image 
					     width 
					     height
					     RGB_IMAGE
					     "bg"
					     100
					     NORMAL)))
	 (gimp-drawable-fill bg-layer BG-IMAGE-FILL)
	 (gimp-image-add-layer image bg-layer -1)
	 (gimp-image-add-layer image anim-layer -1)
	 (gimp-layer-set-visible bg-layer 1)
	 (gimp-layer-set-visible anim-layer 1)
	 (set! layer-name (string-append "Frame " 
					 (number->string
					  (- (+ num-frames span 1) 
					     remaining-frames) 
					  10)))
	 (gimp-layer-set-name anim-layer layer-name)
	 (gimp-layer-set-name bg-layer layer-name)
	 
	 (gimp-blend image
		     anim-layer
		     CUSTOM
		     NORMAL
		     gradient
		     100 ; opacity
		     0. ; offset ?
		     REPEAT-NONE
		     anti-aliasing ; anti aliasing
		     3
		     0.2
		     x y1 
		     (+ x (* span offset)) y2
		     )
	 (gimp-image-merge-visible-layers image 0)
	 (set! anim-layer (aref (cadr (gimp-image-get-layers image)) 0))
	 (if (= bg-remove TRUE) (begin
			 (gimp-by-color-select image anim-layer
					       color
					       threshold
					       REPLACE
					       FALSE ; anti aliasing
					       FALSE ; feather
					       0 ; feather radius
					       FALSE ; composite/merged
					       )
			 (gimp-edit-clear image anim-layer)
			 (gimp-selection-none image)
			 )
	     )
	 (gimp-layer-set-visible anim-layer 0)
	 (set! remaining-frames (- remaining-frames 1))
	 (set! x (+ x offset))
	 )
					

  (gimp-image-remove-layer image source-layer)
  (gimp-layer-set-visible anim-layer 1)

  (gimp-image-enable-undo image)
  (gimp-display-new image)))

(script-fu-register "script-fu-dlblendanim" 
		    "<Image>/Script-Fu/Animators/DlBlend"
		    "Animates an image by moving gradient over it"
		    "Laurent Demailly (L@demailly.com)"
		    "Laurent Demailly"
		    "1/3/98"
		    "RGBA"
		    SF-IMAGE "Image" 0
		    SF-DRAWABLE "Drawable" 0
		    SF-VALUE "Number of Frames" "12"
		    SF-VALUE "Gradient type" "BILINEAR"
		    SF-VALUE "Span" "3"
		    SF-VALUE "Relative Y1" ".4"
		    SF-VALUE "Relative Y2" ".6"
		    SF-TOGGLE "AntiAliasing" 0
		    SF-TOGGLE "Remove Background" 1
		    SF-VALUE "Threshold" "10"
		    )