;; layers-view.scm -*-scheme-*-

;; Alan Horkan, April 2004.  Copyright: Public Domain.  
;; You may do whatever you like with this script but please do share 
;; and try to let me know if you make any interesting changes.  

;; Ideas from Jasc Paint Shop Pro 8 (same menu locations used, mostly)
;; Layers, View: Current Only; All; None; Invert; Show Link Set; Hide Link Set.  
;; Undoable view changes seem odd but i like 'em (and Paint Shop Pro does it too)

; failed to get it working using a straight list
; looked at copy-visible.scm for inspiration: answer use an array.  
; TODO learn more Scheme, read 'the Wizard book' again ;)

; ideally moving through the layer stack should be abstracted 
; and the specific function passed in a parameter as needed
; again must read 'the wizard book'

(define (layers-show image boolean)
  (let* (
      (layers (gimp-image-get-layers image))  
	(number-layers (car layers))
	(layer-array (cadr layers))
    )
  (gimp-image-undo-group-start image)
  ; hide all the layers, set visibilty FALSE
  (set! layer-count 0)
  (while (< layer-count number-layers)
      (set! layer (aref layer-array layer-count))
      (gimp-drawable-set-visible layer boolean) 
      (set! layer-count (+ layer-count 1)))
  ) 
  (gimp-image-undo-group-end image)
)


(define (script-fu-layers-view-all image drawable) 
  (layers-show image TRUE) ; show all the layers
  (gimp-displays-flush) ; update the display
)


(define (script-fu-layers-view-none image drawable) 
  (layers-show image FALSE) ; hide all the layers
  (gimp-displays-flush) ; update the display
)

; hide all layers, then (re)show current layer
(define (script-fu-layers-view-current-only image drawable) 
    (gimp-image-undo-group-start image) 
    (script-fu-layers-view-none image drawable) 
    ; drawable could be a channel, must check it.   
    (if (not (= 0 (car (gimp-drawable-is-layer drawable))))
        (gimp-drawable-set-visible drawable TRUE) 
    )
    (gimp-displays-flush) 
    (gimp-image-undo-group-end image)
) 

; not the most elegant implementation but it'll do
(define (script-fu-layers-view-invert image drawable) 
  (let* (
      (layers (gimp-image-get-layers image))  
	(number-layers (car layers))
	(layer-array (cadr layers))
    )
  (gimp-image-undo-group-start image)
  ; hide all the layers, set visibilty FALSE
  (set! layer-count 0)
  (while (< layer-count number-layers)
      (set! layer (aref layer-array layer-count))
      (if (= (car (gimp-drawable-get-visible layer)) TRUE) 
          (set! boolean FALSE)
          (set! boolean TRUE)        
      ) 
      (gimp-drawable-set-visible layer boolean) 
      (set! layer-count (+ layer-count 1)))
  ) 
  (gimp-image-undo-group-end image) 
  (gimp-displays-flush) 
)


(define (layers-view-linked image drawable boolean)
  (let* (
      (layers (gimp-image-get-layers image))  
	(number-layers (car layers))
	(layer-array (cadr layers))
    )
  (gimp-image-undo-group-start image)
  ; hide all the layers, set visibilty FALSE
  (set! layer-count 0)
  (while (< layer-count number-layers)
      (set! layer (aref layer-array layer-count))
      ; show/hide linked layer and hide/show the others
      (if (= FALSE (car (gimp-drawable-get-linked layer))) 
          ; must use #t or #f booleans, TRUE or FALSE unrecognised by (not)
          ;(set! boolean (not boolean)) ; this isn't working quite right 
          ; dirty inelegant hack because (not) wont work as expected
          (set! boolean (if (= boolean TRUE) FALSE TRUE) ) 
      ) 
      (gimp-drawable-set-visible layer boolean) 
      (set! layer-count (+ layer-count 1)))
  ) 
  (gimp-image-undo-group-end image) 
)

(define (script-fu-layers-view-linked-show image drawable)
    (layers-view-linked image drawable TRUE) ; #t == TRUE
    (gimp-displays-flush) 
)

(define (script-fu-layers-view-linked-hide image drawable)
    (layers-view-linked image drawable FALSE) ; #f == FALSE
    (gimp-displays-flush) 
)
; this doesn't make as much sense as it does in Paint Shop Pro
; it has many seperate numbered link sets, gimp allows only 1

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;

(set! menu _"<Image>/Layer/View/") 
;(set! menu _"<Image>/Layer/Show ")
;; uncomment above line to move (Show) All/None up to the Layer menu.  
 
;; append/prepend description(s) to about string.  
(set! description "
With sincere thanks to Jasc Paint Shop Pro 8 for the inspiration.  "
) 
(set! authors "Alan Horkan.  ")
(set! copyrights "Alan Horkan, 2004.  Public Domain.  ") 
(set! date "2004 04 02 UTC")  


(script-fu-register "script-fu-layers-view-current-only"
    _"<Image>/Layer/View/_Current Only"
    (string-append "Show only the current Layer, hide all other layers.  " description)
    authors copyrights date "" ; strings set using variables, see above
    SF-IMAGE "Image" 0
    SF-DRAWABLE "Drawable" 0
)

(script-fu-register "script-fu-layers-view-all"
    (string-append menu _"_All") 
    (string-append "Show All Layers.  Sets every layer to visible.  " description)
    authors copyrights date ""
    SF-IMAGE "Image" 0
    SF-DRAWABLE "Drawable" 0
)

(script-fu-register "script-fu-layers-view-none"
    (string-append menu _"_None")
    (string-append "Show None of the Layers.  Hides every layer.  " description) 
    authors copyrights date ""
    SF-IMAGE "Image" 0
    SF-DRAWABLE "Drawable" 0
)

(script-fu-register "script-fu-layers-view-invert"
    _"<Image>/Layer/View/_Invert"
    "Invert the visibility of all Layers.  
If a layer is showing, it gets hidden and if a layer is hidden it will be shown.  "
    authors copyrights date "" ; strings set using variables, see above
    SF-IMAGE "Image" 0
    SF-DRAWABLE "Drawable" 0
)


;; the names "Link Set Show" and "Link Set Hide" are only a workaround 
;; so the two menu items will be beside each other sorted alphabetically sorted  

(script-fu-register "script-fu-layers-view-linked-show"
    _"<Image>/Layer/View/Link Set _Show" 
    (string-append "Show Link Set.  Show only the linked layers and hide all other layers.  " description) 
     
    authors copyrights date ""
    SF-IMAGE "Image" 0
    SF-DRAWABLE "Drawable" 0
)

(script-fu-register "script-fu-layers-view-linked-hide"
    _"<Image>/Layer/View/Link Set _Hide" ; sorted, beside link set show
    (string-append "Hide Link Set.  Hide only the linked layers and show all other layers.  " description)     
    authors copyrights date ""
    SF-IMAGE "Image" 0
    SF-DRAWABLE "Drawable" 0
)