;; GIMP "save area" function, (c) Silas S. Brown 2005, 2007, 2019, 2021-22.  Version 1.22
;; License: Apache 2 (see below)

;; INSTALLATION INSTRUCTIONS
;; -------------------------

;; 1.  If you haven't already run the Gimp, run it.

;; - If you are running Gimp on a shared system on which
;; you have limited quota, you might like to set it up
;; in /tmp using a command like:
;;
;; mkdir -p /tmp/$USER ; XAUTHORITY=$HOME/.Xauthority HOME=/tmp/$USER gimp
;; then in the step below, note your .gimp or .config/GIMP directory
;; will be in /tmp/$USER
;;
;; (or you could set swap-path and temp-path in .gimprc, but you may
;; then need to alter areas2pdf.sh, unless you symlink from .gimp*/tmp,
;; and you may still need to create a private tmp subdirectory each time)

;; 2.  Find your .gimp directory.  On Unix this will be in
;; your home directory, called .config/GIMP/2.10 or similar
;; (for 2.10+), or .gimp or .gimp-1.2 or .gimp-2.8 or
;; similar.  If there's more than one then pick the one that
;; corresponds to the version of The GIMP that you're
;; using.  On Windows it'll probably be in
;; C:\Documents and Settings\your user ID\.gimp-2.2 or
;; similar (in other words it will be in the CygWin home
;; directory) or you can find it by searching all files and
;; folders for .gimp.
;; On a Mac, try Library/Application Support/Gimp

;; 3. If your GIMP is 2.10+, replace the word NORMAL with 0
;; in this file (Gimp 2.10+ no longer defines NORMAL).
;; If your GIMP is 2.8 or below, BEWARE that if it's ever
;; upgraded to 2.10+ you will have to make this replacement
;; and must do so under .config/GIMP not the old .gimp-2.8
;; (which is NOT automatically deleted by the upgrade).

;; 4.  Save this file (savearea.scm) into the "scripts"
;; subdirectory of the gimp directory, and restart Gimp.
;; (If the "scripts" directory does not exist, create it.)

;; 5.  Open a new image, right-click on it, go to "File",
;; and there should be an option called "Save area".  It's
;; a good idea to assign a shortcut key to it.  Personally I
;; use the slash key (/).
;;
;; - In Gimp 2.8, from an image window go to Edit / Preferences,
;; Interface / Configure keyboard shortcuts, search for
;; Save Area, and press the key (/) then Close / OK.
;;
;; - In older Gimp 1.x you may need to find the main window
;; (not the image window), and navigate through
;; File / Preferences / Interface / Configure keyboard
;; shortcuts / Plug-ins, find "Save area" somewhere in the
;; long list that appears, and then type the shortcut key.
;;
;; - In some even older Gimp versions, all you have to
;; do is point at this option on the menu itself and then
;; press the shortcut key that you want to assign to it
;; (and it will then appear next to the menu item).

;; 6. While configuring The GIMP, I also recommend choosing
;; the Selection tool (the box) if it's not already chosen,
;; and going to Preferences (via Edit or File as above),
;; Input Devices, "Save Input Device Settings Now".
;; This will cause The GIMP to load with the selection
;; tool by default, which is useful if you do more work
;; with selections than with actual drawing.
;; (Older versions of The GIMP had the selection tool as
;; the default anyway.)

;; 7.  You should now be able to make a selection and then
;; use that shortcut key to save it quickly, then make
;; another selection and so on.  If this doesn't work in
;; your version of The GIMP then try converting the input
;; images into a different format first (you can use netpbm
;; or imagemagick to batch-convert if necessary).

;; END OF INSTALLATION INSTRUCTIONS

;; Licensed under the Apache License, Version 2.0 (the "License");
;; you may not use this file except in compliance with the License.
;; You may obtain a copy of the License at

;;     http://www.apache.org/licenses/LICENSE-2.0

;; Unless required by applicable law or agreed to in writing, software
;; distributed under the License is distributed on an "AS IS" BASIS,
;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;; See the License for the specific language governing permissions and
;; limitations under the License.

;; Where to find history:
;; on GitHub at https://github.com/ssb22/scan-reflow
;; and on GitLab at https://gitlab.com/ssb22/scan-reflow
;; and on BitBucket https://bitbucket.org/ssb22/scan-reflow
;; and at https://gitlab.developers.cam.ac.uk/ssb22/scan-reflow
;; and in China: https://gitee.com/ssb22/scan-reflow

;; ------------------------------------------------------


(define (saveArea img layer)
  (let* ((selection (gimp-selection-bounds img))
    (x1 (cadr selection))
    (y1 (caddr selection))
    (x2 (car (cdr (cdr (cdr selection)))))
    (y2 (car (cdr (cdr (cdr (cdr selection))))))
    (width (- x2 x1))
    (height (- y2 y1))
    (newType (car (gimp-image-base-type img)))
    (myNewType (if (equal? newType 1) 1 0))  ;; "indexed" type (2) is awkward so convert it to RGB (0).  May get a completely-black area anyway, but at least will be able to save as PNG to get the dimensions for derotate.sh.  For other uses I suggest batch-converting first as mentioned in instructions above.
    (newImg (car (gimp-image-new width height myNewType)))
    (newLayer (car (gimp-layer-new newImg width height (* myNewType 2) "layer 1" 100 NORMAL)))
    (_ (gimp-image-add-layer newImg newLayer 0))
    (disp (car (gimp-display-new newImg))) ;; MUST do this otherwise gimp may corrupt when save
    (_ (gimp-edit-copy layer))
    (floatingLayer (car (gimp-edit-paste newLayer 0)))
    (_ (gimp-floating-sel-anchor floatingLayer))
    (_ (plug-in-autocrop 1 newImg newLayer))
    (file (car (gimp-temp-name "-area.png")))
    (_ (file-png-save 1 newImg newLayer file file 0 9 0 0 0 0 0))
    (_ (gimp-display-delete disp))
    ) ()))

   (script-fu-register "saveArea"
      "<Image>/File/Save area"
      "Saves the selected area to a PNG file"
      "Silas S. Brown"
      "Silas S. Brown"
      "2005"
      "" ; any image type
      SF-IMAGE "Image" 0
      SF-DRAWABLE "Layer" 0
      )