dtlua/ext_proc.lua

--[[

    ext_proc.lua - export and process with an arbitrary binary

    Copyright (C) 2025 Florian Tham <fgtham@gmail.com>.

    Heavily based on gimp.lua and thus is

    Copyright (c) 2016  Bill Ferguson


    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 3 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, see <http://www.gnu.org/licenses/>.
]]
--[[
    ext_proc - export images and process with an arbitrary binary

    This script provides another storage (export target) for darktable.  Selected
    images are exporte in the specified format to temporary storage. The script
    given in executable_path is launched, possibly with the parameters from executable_args,
    followed by the list of exported files. After script execution the temporary
    files are removed.

    USAGE
    * require this script from your main lua file
    * select an image or images
    * in the export dialog select "external process" and select the format and bit depth for the
      exported image(s).  Specify the full path to your script.
    * Specify the script parameters, if any.
    * Press "export"

    BUGS, COMMENTS, SUGGESTIONS
    * Send to Florian Tham, fgtham@gmail.com

]]

local dt = require "darktable"
local du = require "lib/dtutils"
local df = require "lib/dtutils.file"
local dtsys = require "lib/dtutils.system"
local ext_proc_widget = nil

local wg = {}

local MODULE = "ext_proc"

du.check_min_api_version("7.0.0", MODULE) 

-- from https://github.com/ChristianBirzer/darktable_extra_scripts/blob/main/HeliconFocus.lua
-- find locale directory:
local os_path_seperator = "/"
local scriptfile = debug.getinfo( 1, "S" )
local localedir = dt.configuration.config_dir..'/lua/locale/'
if scriptfile ~= nil and scriptfile.source ~= nil then
  local path = scriptfile.source:match( "[^@].*[/\\]" )
  localedir = path..os_path_seperator..'locale'
end
dt.print_log( "localedir: "..localedir )

local gettext = dt.gettext
gettext.bindtextdomain(MODULE, localedir)

local function _(msgid)
    return gettext.dgettext(MODULE, msgid)
end

-- return data structure for script_manager

local script_data = {}

script_data.metadata = {
  name = _("external processing"),
  purpose = _("export and process with an arbitrary executable"),
  author = "Florian Tham <fgtham@gmail.com>",
  help = "https://docs.darktable.org/lua/stable/lua.scripts.manual/scripts/contrib/ext_proc"
}

script_data.destroy = nil -- function to destory the script
script_data.destroy_method = nil -- set to hide for libs since we can't destroy them commpletely yet, otherwise leave as nil
script_data.restart = nil -- how to restart the (lib) script after it's been hidden - i.e. make it visible again
script_data.show = nil -- only required for libs since the destroy_method only hides them

local function run_executable(storage, image_table, extra_data) --finalize

  local executable_path = wg.text_executable_path.text
  local executable_args = wg.text_executable_args.text

  local executable_exists = df.check_if_file_exists(executable_path)
  local has_exec_bit = df.test_file(executable_path, "x")

  if not executable_exists then
    dt.print(executable_path .. ": file not found")
    dt.print_error("file not found")
    return
  end

  if not has_exec_bit then
    dt.print(executable_path .. ": not executable")
    dt.print_error("file is not executable")
    return
  end

  dt.preferences.write(MODULE, "executable_path", "string", executable_path)
  dt.preferences.write(MODULE, "executable_args", "string", executable_args)

  -- list of exported images
  local img_list

   -- reset and create image list
  img_list = ""

  for _,exp_img in pairs(image_table) do
    exp_img = df.sanitize_filename(exp_img)
    img_list = img_list ..exp_img.. " "
  end

  dt.print(_("launching script..."))

  local cmdline = executable_path .. " " .. executable_args .. " " .. img_list

  dt.print_log(cmdline)

  dtsys.external_command(cmdline)
  dt.print(_("done"))

  for _,exp_img in pairs(image_table) do
    os.remove(exp_img)
  end
end

local function destroy()
  dt.destroy_storage(MODULE)
end

-- Register

wg.text_executable_path = dt.new_widget("entry"){
  text = dt.preferences.read(MODULE, "executable_path", "string"),
  placeholder = _("/path/to/executable"),
  tooltip = _("absolute path to the binary or script that should be called"),
  editable = true,
}

wg.text_executable_args = dt.new_widget("entry"){
  text = dt.preferences.read(MODULE, "executable_args", "string"),
  tooltip = _("optional parameters to be passed to the executable"),
  editable = true,
}

local ext_proc_widget = dt.new_widget("box"){
  orientation = "vertical",
  dt.new_widget("label"){label = _("absolute file path")},
  wg.text_executable_path,
  dt.new_widget("label"){label = _("optional parameters")},
  wg.text_executable_args,
}

dt.register_storage(
    MODULE,
    _("external processing"),
    nil,
    run_executable,
    nil,
    nil,
    ext_proc_widget
)

--
script_data.destroy = destroy

return script_data