; Auto colorize image into random number of colors of random hues
; author: Tin Tran
; date: 2015
(define (script-fu-auto-colorize image layer 
              hatches
         )
	
		(let* 
		   (
		   (color-map 0)
		   (colors 0)
		   (image-width)
		   (image-height)
		   ;(R 0.2126)   ;constants for calculating luminance
		   ;(G 0.7152)
		   ;(B 0.0722)
		   ;(0.299*R + 0.587*G + 0.114*B)
		   ;(R 0.299)
		   ;(G 0.587)
		   ;(B 0.114)
		   ;sqrt( 0.299*R^2 + 0.587*G^2 + 0.114*B^2 )
		   (B (/ 18.0 255))
		   (R (/ 54.0 255))
		   (G (/ 182.0 255))
		   (r)          ;randomly generated r g b values
		   (g)
		   (b)
		   (l-original) ;luminance original
		   (l-new)
		   (red 0)
		   (green 0)
		   (blue 0)
		   (y 0)
		   (hue)
		   (floating)
		   (difference)
		   (try)
		   (tries 1000)
		   (counter)
		    )
			;(gimp-image-undo-disable image); DN = NO UNDO
		  (gimp-image-undo-group-start image)                   ;undo-group in one step
		  ;convert to indexed
		  (set! image-width (car (gimp-image-width image)))
	      (set! image-height (car (gimp-image-height image)))
		  (gimp-image-convert-indexed image NO-DITHER MAKE-PALETTE hatches FALSE FALSE "unused palette name")
		  ;grabs color map
		  (set! colors (vector->list (cadr (gimp-image-get-colormap image))))
		  
		  (gimp-image-convert-rgb image) ;converts it to rgb before we call hatch loop
		  
		  (set! y hatches) ;loop hatches number of times
		  (srand (car (gettimeofday)))
		  (gimp-context-set-sample-threshold 0)
		  (while (> y 0)
              ;do work here
			  (set! red (car colors))
			  (set! green (cadr colors))
			  (set! blue (caddr colors))
			  ;select each color
			  (gimp-image-set-active-layer image layer)
			  (gimp-image-select-color image CHANNEL-OP-REPLACE layer (list red green blue))
			  ;(set! hue (rand 360))
			  ;(gimp-colorize layer hue 100 0)
			  
			  
			  ;(gimp-edit-copy layer)
			  ;(set! floating (car(gimp-edit-paste layer TRUE)))
			  ;(gimp-floating-sel-to-layer floating)
			  ;(gimp-image-set-active-layer image floating)
			  (set! floating (car (gimp-layer-new image image-width image-height
	                           RGBA-IMAGE "Colorize" 100 NORMAL-MODE)))  ;creates layer
				;insert above current layer
				;(gimp-image-insert-layer image new-layer 0 (car (gimp-image-get-item-position image layer)))	
				(gimp-image-insert-layer image floating 0 0)	 	  
				;set that layer to be active layer
				(gimp-image-set-active-layer image floating)
			  
			  ;(set! hue (rand 360))
			  ;(gimp-colorize floating hue 100 0)
			  ;sqrt( 0.299*R^2 + 0.587*G^2 + 0.114*B^2 )
			  ;(set! l-original (sqrt(+ (pow(* red R) 2) (pow (* green G) 2)  (pow (* blue B) 2))))
			  (set! l-original (+ (* red R) (* green G)  (* blue B)))
			  (set! difference 10)
			  
			  ;just randomly pick a color until we find a color of similar luminance
			  ;absolutely not the ideal way of getting a color
			  (set! try 255)
			  (set! counter tries)
			  (while (> difference 1)
			    (if (= counter 0)
					(begin
					   (set! try (- try 1))
					   (if (< try 0)
							(begin
								(set! try 255) ;retry from 255
							)
							(begin)
					   )
					   (set! counter tries)
					)
					(begin
					   
					)
			    )
				(if (< l-original 85)
					(begin
						(set! r (rand 255))
						(set! g (rand 255))
						(set! b try)        ;try blueish
					)
					(begin
						(if (> l-original (* 85 2))
							(begin
								(set! r (rand 255))
								(set! g try)       ;try greenish
								(set! b (rand 255))
							)
							(begin
								(set! r try)       ;try red
								(set! g (rand 255))      
								(set! b (rand 255))
							)
						)
					)
				)
				;(set! l-new (sqrt(+ (pow(* r R) 2) (pow (* g G) 2)  (pow (* b B) 2))))
				(set! l-new (+ (* r R) (* g G)  (* b B)))
				(set! difference (abs (- l-new l-original)))
				
				(set! counter (- counter 1))
			  )
			  
			  ;(script-fu-colorize image floating (list r g b) 100)
			  (gimp-context-set-foreground (list r g b))
			  (gimp-edit-fill floating FOREGROUND-FILL)
			  
			  
			  (if (> y 1) ;if y is still valid we set colors to the next colors
			     (begin
				 (set! colors (cdddr colors))
				 )
				 (begin ;else
				 )
			  )
			  
              ;loop control
			  (set! y (- y 1))
		  );end of while 
          (gimp-selection-none image)	
		   ;(gimp-image-undo-enable image) ;DN = NO UNDO
		   (gimp-image-undo-group-end image)                     ;undo group in one step
	       (gimp-displays-flush)
	    )
	
	
    
) ;end of define

(script-fu-register
  "script-fu-auto-colorize"         ;function name
  "<Image>/Script-Fu/Auto Colorize"    ;menu register
  "Randomly colorize image with specified number of colors."       ;description
  "Tin Tran"                          ;author name
  "copyright info and description"         ;copyright info or description
  "2015"                          ;date
  "RGB*, GRAY*"                        ;mode
  SF-IMAGE      "Image" 0                   
  SF-DRAWABLE   "Layer" 0
  SF-ADJUSTMENT "Number of colors" '(5 2 255 1 10 0 0)
  
)