Export module for a website gallery with selected images

This export module should replace the PhotoSwipe copy in darktable.

See darktable-org/darktable#16205 for more
details.

Author: Tino Mettler

contrib/website_gallery_export.lua

@@ -0,0 +1,262 @@
+--[[Export module to create a web gallery from selected images
+
+  copyright (c) 2025 Tino Mettler
+
+  darktable 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.
+
+  darktable 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 software.  If not, see <http://www.gnu.org/licenses/>.
+]]
+
+--[[
+   TODO:
+   - before PR: Zoom, export code from wpferguson, use share_dir
+   - Lua: remove images dir if already existent
+   - Lua: implement "supported" callback to limit export to suited file formats
+   - Lua: translations
+]]
+
+local dt = require "darktable"
+local df = require "lib/dtutils.file"
+
+local temp = dt.preferences.read('web_gallery', 'title', 'string')
+if temp == nil then temp = 'Darktable gallery' end
+
+local title_widget = dt.new_widget("entry")
+{
+   text = temp
+}
+
+local temp = dt.preferences.read('web_gallery', 'destination_dir', 'string')
+if temp == nil then temp = '' end
+
+local dest_dir_widget = dt.new_widget("file_chooser_button")
+{
+   title = "select output folder",
+   tooltip = "select output folder",
+   value = temp,
+   is_directory = true,
+   changed_callback = function(this) dt.preferences.write('web_gallery', 'destination_dir', 'string', this.value) end
+}
+
+local gallery_widget = dt.new_widget("box")
+{
+    orientation=vertical,
+    dt.new_widget("label"){label = "gallery title"},
+    title_widget,
+    dt.new_widget("label"){label = "destination directory"},
+    dest_dir_widget
+}
+
+local function get_file_name(file)
+    return file:match("[^/]*.$")
+end
+
+function escape_js_string(str)
+  local replacements = {
+    ['\\'] = '\\\\',
+    ['"']  = '\\"',
+    ["'"]  = "\\'",
+    ['\n'] = '\\n',
+    ['\r'] = '\\r',
+    ['\t'] = '\\t',
+    ['\b'] = '\\b',
+    ['\f'] = '\\f',
+    ['\v'] = '\\v'
+  }
+  return (str:gsub('[\\\"\n\r\t\b\f\v\']', replacements))
+end
+
+local function export_thumbnail(image, filename)
+    dt.print("export thumbnail image "..filename)
+    exporter = dt.new_format("jpeg")
+    exporter.quality = 90
+    exporter.max_height = 512
+    exporter.max_width = 512
+    exporter:write_image(image, filename, true)
+end
+
+local function write_image(image, dest_dir, filename)
+    df.file_move(filename, dest_dir.."/"..get_file_name(filename))
+    export_thumbnail(image, dest_dir.."/thumb_"..get_file_name(filename))
+end
+
+function exiftool_get_image_dimensions(filename)
+    local handle = io.popen("exiftool " .. filename)
+    local result = handle:read("*a")
+    handle:close()
+    for line in result:gmatch("[^\r\n]+") do
+        local w = line:match("^Image Width%s*:%s*(%d+)")
+        if w then
+            width = tonumber(w)
+        end
+        local h = line:match("^Image Height%s*:%s*(%d+)")
+        if h then
+            height = tonumber(h)
+        end
+    end
+    if width and height then
+        return width, height
+    else
+        return nil, nil
+    end
+end
+
+local function fill_gallery_table(images_ordered, images_table, title, dest_dir, sizes, exiftool)
+    dest_dir = dest_dir.."/images"
+    local gallery_data = { name = escape_js_string(title) }
+
+    local images = {}
+    local index = 1
+    for i, image in pairs(images_ordered) do
+        local filename = images_table[image]
+        write_image(image, dest_dir, filename)
+
+        if exiftool then
+            width, height = exiftool_get_image_dimensions(dest_dir.."/"..get_file_name(filename))
+        else
+            width = sizes[index].width
+            height = sizes[index].height
+        end
+
+        local entry = { filename = "images/"..get_file_name(escape_js_string(filename)),
+                        width = width, height = height }
+
+        images[index] = entry
+        index = index + 1
+    end
+
+    gallery_data.images = images
+    return gallery_data
+end
+
+local function generate_javascript_gallery_object(gallery)
+    local js = 'const gallery_data = {\n'
+    js = js .. '  name: "' .. gallery.name .. '",\n'
+    js = js .. '  images: [\n'
+
+    for i, img in ipairs(gallery.images) do
+        js = js .. string.format('    { filename: "%s",\n      height: %d,\n      width: %d }', img.filename, img.height, img.width)
+        if i < #gallery.images then
+            js = js .. ',\n'
+        else
+            js = js .. '\n'
+        end
+    end
+
+    js = js .. '  ]\n};\n'
+
+    return(js)
+end
+
+local function write_javascript_file(gallery_table, dest_dir)
+    dt.print("write JavaScript file")
+    javascript_object = generate_javascript_gallery_object(gallery_table)
+
+    local fileOut, errr = io.open(dest_dir.."/images.js", 'w+')
+    if fileOut then
+        fileOut:write(javascript_object)
+    else
+        log.msg(log.error, errr)
+    end
+    fileOut:close()
+end
+
+local function copy_static_files(dest_dir)
+    dt.print("copy static gallery files")
+    gfsrc = dt.configuration.config_dir.."/lua/data/website_gallery"
+    gfiles = {
+        "index.html",
+        "gallery.css",
+        "modal.css",
+	"modal.js",
+        "gallery.js",
+        "fullscreen.js"
+    }
+
+    for _, file in ipairs(gfiles) do
+        df.file_copy(gfsrc.."/"..file, dest_dir.."/"..file)
+    end
+end
+
+local function build_gallery(storage, images_table, extra_data)
+    local dest_dir = dest_dir_widget.value
+    df.mkdir(dest_dir)
+    df.mkdir(dest_dir.."/images")
+
+    local images_ordered = extra_data["images"] -- process images in the correct order
+    local sizes = extra_data["sizes"]
+    local title = "Darktable export"
+    if title_widget.text ~= "" then
+        title = title_widget.text
+    end
+    local exiftool = df.check_if_bin_exists("exiftool");
+    gallerydata = fill_gallery_table(images_ordered, images_table, title, dest_dir, sizes, exiftool)
+    write_javascript_file(gallerydata, dest_dir)
+    copy_static_files(dest_dir)
+end
+
+local script_data = {}
+
+script_data.metadata = {
+    name = "website gallery (new)",
+    purpose = "create a web gallery from exported images",
+    author = "Tino Mettler <tino+darktable@tikei.de>",
+    help = "https://docs.darktable.org/lua/stable/lua.scripts.manual/scripts/contrib/TODO"
+}
+
+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 destroy()
+    dt.preferences.write('web_gallery', 'title', 'string', title_widget.text)
+    dt.destroy_storage("module_webgallery")
+end
+script_data.destroy = destroy
+
+local function show_status(storage, image, format, filename,
+  number, total, high_quality, extra_data)
+    dt.print(string.format("export image %i/%i", number, total))
+    aspect = image.aspect_ratio
+    -- calculate the size of the exported image and store it in extra_data
+    -- to make it available in the finalize function
+    if image.final_height == 0 then
+        if aspect < 1 then
+            dimensions = { width = image.height, height = image.width }
+        else
+            dimensions = { width = image.width, height = image.height }
+        end
+    else
+        dimensions = { width = image.final_width, height = image.final_height }
+    end
+    if format.max_height > 0 and dimensions.height > format.max_height then
+        scale = format.max_height / dimensions.height
+        dimensions.height = math.floor(dimensions.height * scale + 0.5)
+        dimensions.width = math.floor(dimensions.width * scale + 0.5)
+    end
+    if format.max_width > 0 and dimensions.width > format.max_width then
+        scale = format.max_width / dimensions.width
+        dimensions.height = math.floor(dimensions.height * scale + 0.5)
+        dimensions.width = math.floor(dimensions.width * scale + 0.5)
+    end
+    extra_data["sizes"][number] = dimensions
+end
+
+local function initialize(storage, img_format, images, high_quality, extra_data)
+    dt.preferences.write('web_gallery', 'title', 'string', title_widget.text)
+    extra_data["images"] = images -- needed, to preserve images order
+    extra_data["sizes"] = {};
+end
+
+dt.register_storage("module_webgallery", "website gallery (new)", show_status, build_gallery, nil, initialize, gallery_widget)
+
+return script_data

data/website_gallery/fullscreen.js

@@ -0,0 +1,40 @@
+var isFullscreen = false;
+
+var toggleFullscreen = function (ele) {
+    return isFullscreen ? exitFullscreen(ele) : requestFullscreen(ele);
+};
+
+var requestFullscreen = function (ele) {
+    if(isFullscreen == true) return 0 ;
+    
+    isFullscreen = true;
+    if (ele.requestFullscreen) {
+	ele.requestFullscreen();
+    } else if (ele.webkitRequestFullscreen) {
+	ele.webkitRequestFullscreen();
+    } else if (ele.mozRequestFullScreen) {
+	ele.mozRequestFullScreen();
+    } else if (ele.msRequestFullscreen) {
+	ele.msRequestFullscreen();
+    } else {
+	console.log('Fullscreen API is not supported.');
+    }
+};
+
+var exitFullscreen = function () {
+    if(isFullscreen == false) return 0;
+    
+    isFullscreen = false;
+    if (document.exitFullscreen) {
+	document.exitFullscreen();
+    } else if (document.webkitExitFullscreen) {
+	document.webkitExitFullscreen();
+    } else if (document.mozCancelFullScreen) {
+	document.mozCancelFullScreen();
+    } else if (document.msExitFullscreen) {
+	document.msExitFullscreen();
+    } else {
+	console.log('Fullscreen API is not supported.');
+    }
+};
+