;;; thirds.scm v0.1
;;; Copyright (c) 2005 John Hall (jhall@alum.wpi.edu)
;;;
;;; A Script-Fu script for The GIMP to draw the lines for the "Rule Of
;;; Thirds."
;;;
;;;
;;; 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
;;;
;;;
;;; Revision history:
;;;
;;;   v0.1: - First public release

;; Draws the lines for the "Rule Of Thirds."  The lines are drawn on a
;; new layer.
(define (script-fu-rule-of-thirds image drawable)
  (let* ((old-brush (gimp-context-get-brush))
	 (old-foreground (gimp-context-get-foreground))
	 (*points* (cons-array 4 'double))
	 (width (car (gimp-image-width image)))
	 (height (car (gimp-image-height image)))
	 (new-layer (car (gimp-layer-new image
                                         width
                                         height
                                         RGBA-IMAGE
                                         "Rule Of Thirds"
                                         100.0
                                         NORMAL-MODE))))

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

    (gimp-image-add-layer image new-layer -1)
    (gimp-edit-clear new-layer)

    (gimp-context-set-brush "Circle (03)")
    (gimp-context-set-foreground '(255 0 0))

    (aset *points* 0 (/ width 3))
    (aset *points* 1 0)
    (aset *points* 2 (/ width 3))
    (aset *points* 3 height)
    (gimp-pencil new-layer 4 *points*)

    (aset *points* 0 (* 2 (/ width 3)))
    (aset *points* 2 (* 2 (/ width 3)))
    (gimp-pencil new-layer 4 *points*)

    (aset *points* 0 0)
    (aset *points* 1 (/ height 3))
    (aset *points* 2 width)
    (aset *points* 3 (/ height 3))
    (gimp-pencil new-layer 4 *points*)

    (aset *points* 1 (* 2 (/ height 3)))
    (aset *points* 3 (* 2 (/ height 3)))
    (gimp-pencil new-layer 4 *points*)

    (gimp-context-set-brush (car old-brush))
    (gimp-context-set-foreground (car old-foreground))
    (gimp-image-undo-group-end image)
    (gimp-displays-flush)

    (list image)))

(script-fu-register "script-fu-rule-of-thirds"
                    "<Image>/Script-Fu/Utils/Rule Of Thirds"
                    "Draws the lines for the Rule Of Thirds."
                    "John Hall"
                    "John Hall"
                    "2004"
                    ""
                    SF-IMAGE "The image" 0
                    SF-DRAWABLE "The layer (not used)" 0)