diff --git a/app/src/main/kotlin/com/simplemobiletools/gallery/helpers/Constants.kt b/app/src/main/kotlin/com/simplemobiletools/gallery/helpers/Constants.kt
index 1a8dbb70e..f278a6398 100644
--- a/app/src/main/kotlin/com/simplemobiletools/gallery/helpers/Constants.kt
+++ b/app/src/main/kotlin/com/simplemobiletools/gallery/helpers/Constants.kt
@@ -1,110 +1,106 @@
 package com.simplemobiletools.gallery.helpers
 
 // shared preferences
-val SORT_ORDER = "sort_order"
-val DIRECTORY_SORT_ORDER = "directory_sort_order"
-val SORT_FOLDER_PREFIX = "sort_folder_"
-val SHOW_HIDDEN_MEDIA = "show_hidden_media"
-val TEMPORARILY_SHOW_HIDDEN = "temporarily_show_hidden"
-val IS_THIRD_PARTY_INTENT = "is_third_party_intent"
-val AUTOPLAY_VIDEOS = "autoplay_videos"
-val LOOP_VIDEOS = "loop_videos"
-val ANIMATE_GIFS = "animate_gifs"
-val MAX_BRIGHTNESS = "max_brightness"
-val CROP_THUMBNAILS = "crop_thumbnails"
-val SCREEN_ROTATION = "screen_rotation"
-val DISPLAY_FILE_NAMES = "display_file_names"
-val DARK_BACKGROUND = "dark_background"
-val PINNED_FOLDERS = "pinned_folders"
-val FILTER_MEDIA = "filter_media"
-val DIR_COLUMN_CNT = "dir_column_cnt"
-val DIR_LANDSCAPE_COLUMN_CNT = "dir_landscape_column_cnt"
-val DIR_HORIZONTAL_COLUMN_CNT = "dir_horizontal_column_cnt"
-val DIR_LANDSCAPE_HORIZONTAL_COLUMN_CNT = "dir_landscape_horizontal_column_cnt"
-val MEDIA_COLUMN_CNT = "media_column_cnt"
-val MEDIA_LANDSCAPE_COLUMN_CNT = "media_landscape_column_cnt"
-val MEDIA_HORIZONTAL_COLUMN_CNT = "media_horizontal_column_cnt"
-val MEDIA_LANDSCAPE_HORIZONTAL_COLUMN_CNT = "media_landscape_horizontal_column_cnt"
-val SHOW_ALL = "show_all"                           // display images and videos from all folders together
-val SAVE_FOLDER_PREFIX = "folder2_"
-val HIDE_FOLDER_TOOLTIP_SHOWN = "hide_folder_tooltip_shown"
-val EXCLUDED_FOLDERS = "excluded_folders"
-val INCLUDED_FOLDERS = "included_folders"
-val ALBUM_COVERS = "album_covers"
-val SCROLL_HORIZONTALLY = "scroll_horizontally"
-val HIDE_SYSTEM_UI = "hide_system_ui"
-val REPLACE_SHARE_WITH_ROTATE = "replace_share_with_rotate"
-val DELETE_EMPTY_FOLDERS = "delete_empty_folders"
-val ALLOW_VIDEO_GESTURES = "allow_video_gestures"
-val SHOW_MEDIA_COUNT = "show_media_count"
-val TEMP_FOLDER_PATH = "temp_folder_path"
-val VIEW_TYPE_FOLDERS = "view_type_folders"
-val VIEW_TYPE_FILES = "view_type_files"
-val SHOW_EXTENDED_DETAILS = "show_extended_details"
-val EXTENDED_DETAILS = "extended_details"
-val LAST_FILE_CLEANUP = "last_file_cleanup"
-val ONE_FINGER_ZOOM = "one_finger_zoom"
-val ALLOW_INSTANT_CHANGE = "allow_instant_change"
-val REPLACE_ZOOMABLE_IMAGES = "replace_zoomable_images"
+const val SORT_ORDER = "sort_order"
+const val DIRECTORY_SORT_ORDER = "directory_sort_order"
+const val SORT_FOLDER_PREFIX = "sort_folder_"
+const val SHOW_HIDDEN_MEDIA = "show_hidden_media"
+const val TEMPORARILY_SHOW_HIDDEN = "temporarily_show_hidden"
+const val IS_THIRD_PARTY_INTENT = "is_third_party_intent"
+const val AUTOPLAY_VIDEOS = "autoplay_videos"
+const val LOOP_VIDEOS = "loop_videos"
+const val ANIMATE_GIFS = "animate_gifs"
+const val MAX_BRIGHTNESS = "max_brightness"
+const val CROP_THUMBNAILS = "crop_thumbnails"
+const val SCREEN_ROTATION = "screen_rotation"
+const val DISPLAY_FILE_NAMES = "display_file_names"
+const val DARK_BACKGROUND = "dark_background"
+const val PINNED_FOLDERS = "pinned_folders"
+const val FILTER_MEDIA = "filter_media"
+const val DIR_COLUMN_CNT = "dir_column_cnt"
+const val DIR_LANDSCAPE_COLUMN_CNT = "dir_landscape_column_cnt"
+const val DIR_HORIZONTAL_COLUMN_CNT = "dir_horizontal_column_cnt"
+const val DIR_LANDSCAPE_HORIZONTAL_COLUMN_CNT = "dir_landscape_horizontal_column_cnt"
+const val MEDIA_COLUMN_CNT = "media_column_cnt"
+const val MEDIA_LANDSCAPE_COLUMN_CNT = "media_landscape_column_cnt"
+const val MEDIA_HORIZONTAL_COLUMN_CNT = "media_horizontal_column_cnt"
+const val MEDIA_LANDSCAPE_HORIZONTAL_COLUMN_CNT = "media_landscape_horizontal_column_cnt"
+const val SHOW_ALL = "show_all"                           // display images and videos from all folders together
+const val SAVE_FOLDER_PREFIX = "folder2_"
+const val HIDE_FOLDER_TOOLTIP_SHOWN = "hide_folder_tooltip_shown"
+const val EXCLUDED_FOLDERS = "excluded_folders"
+const val INCLUDED_FOLDERS = "included_folders"
+const val ALBUM_COVERS = "album_covers"
+const val SCROLL_HORIZONTALLY = "scroll_horizontally"
+const val HIDE_SYSTEM_UI = "hide_system_ui"
+const val REPLACE_SHARE_WITH_ROTATE = "replace_share_with_rotate"
+const val DELETE_EMPTY_FOLDERS = "delete_empty_folders"
+const val ALLOW_VIDEO_GESTURES = "allow_video_gestures"
+const val SHOW_MEDIA_COUNT = "show_media_count"
+const val TEMP_FOLDER_PATH = "temp_folder_path"
+const val VIEW_TYPE_FOLDERS = "view_type_folders"
+const val VIEW_TYPE_FILES = "view_type_files"
+const val SHOW_EXTENDED_DETAILS = "show_extended_details"
+const val EXTENDED_DETAILS = "extended_details"
+const val LAST_FILE_CLEANUP = "last_file_cleanup"
+const val ONE_FINGER_ZOOM = "one_finger_zoom"
+const val ALLOW_INSTANT_CHANGE = "allow_instant_change"
+const val REPLACE_ZOOMABLE_IMAGES = "replace_zoomable_images"
 
 // slideshow
-val SLIDESHOW_INTERVAL = "slideshow_interval"
-val SLIDESHOW_INCLUDE_PHOTOS = "slideshow_include_photos"
-val SLIDESHOW_INCLUDE_VIDEOS = "slideshow_include_videos"
-val SLIDESHOW_INCLUDE_GIFS = "slideshow_include_gifs"
-val SLIDESHOW_RANDOM_ORDER = "slideshow_random_order"
-val SLIDESHOW_USE_FADE = "slideshow_use_fade"
-val SLIDESHOW_MOVE_BACKWARDS = "slideshow_move_backwards"
-val SLIDESHOW_LOOP = "loop_slideshow"
-val SLIDESHOW_DEFAULT_INTERVAL = 5
-val SLIDESHOW_SCROLL_DURATION = 500L
+const val SLIDESHOW_INTERVAL = "slideshow_interval"
+const val SLIDESHOW_INCLUDE_PHOTOS = "slideshow_include_photos"
+const val SLIDESHOW_INCLUDE_VIDEOS = "slideshow_include_videos"
+const val SLIDESHOW_INCLUDE_GIFS = "slideshow_include_gifs"
+const val SLIDESHOW_RANDOM_ORDER = "slideshow_random_order"
+const val SLIDESHOW_USE_FADE = "slideshow_use_fade"
+const val SLIDESHOW_MOVE_BACKWARDS = "slideshow_move_backwards"
+const val SLIDESHOW_LOOP = "loop_slideshow"
+const val SLIDESHOW_DEFAULT_INTERVAL = 5
+const val SLIDESHOW_SCROLL_DURATION = 500L
 
-val NOMEDIA = ".nomedia"
-val MAX_COLUMN_COUNT = 20
+const val NOMEDIA = ".nomedia"
+const val MAX_COLUMN_COUNT = 20
 
-val DIRECTORY = "directory"
-val MEDIUM = "medium"
-val PATH = "path"
-val GET_IMAGE_INTENT = "get_image_intent"
-val GET_VIDEO_INTENT = "get_video_intent"
-val GET_ANY_INTENT = "get_any_intent"
-val SET_WALLPAPER_INTENT = "set_wallpaper_intent"
-val DIRECTORIES = "directories2"
-val IS_VIEW_INTENT = "is_view_intent"
-val PICKED_PATHS = "picked_paths"
+const val DIRECTORY = "directory"
+const val MEDIUM = "medium"
+const val PATH = "path"
+const val GET_IMAGE_INTENT = "get_image_intent"
+const val GET_VIDEO_INTENT = "get_video_intent"
+const val GET_ANY_INTENT = "get_any_intent"
+const val SET_WALLPAPER_INTENT = "set_wallpaper_intent"
+const val DIRECTORIES = "directories2"
+const val IS_VIEW_INTENT = "is_view_intent"
+const val PICKED_PATHS = "picked_paths"
 
 // rotations
-val ROTATE_BY_SYSTEM_SETTING = 0
-val ROTATE_BY_DEVICE_ROTATION = 1
-val ROTATE_BY_ASPECT_RATIO = 2
-
-val ORIENT_PORTRAIT = 0
-val ORIENT_LANDSCAPE_LEFT = 1
-val ORIENT_LANDSCAPE_RIGHT = 2
+const val ROTATE_BY_SYSTEM_SETTING = 0
+const val ROTATE_BY_DEVICE_ROTATION = 1
+const val ROTATE_BY_ASPECT_RATIO = 2
 
 // filter media
-val IMAGES = 1
-val VIDEOS = 2
-val GIFS = 4
+const val IMAGES = 1
+const val VIDEOS = 2
+const val GIFS = 4
 
 // view types
-val VIEW_TYPE_GRID = 1
-val VIEW_TYPE_LIST = 2
+const val VIEW_TYPE_GRID = 1
+const val VIEW_TYPE_LIST = 2
 
 // extended details values
-val EXT_NAME = 1
-val EXT_PATH = 2
-val EXT_SIZE = 4
-val EXT_RESOLUTION = 8
-val EXT_LAST_MODIFIED = 16
-val EXT_DATE_TAKEN = 32
-val EXT_CAMERA_MODEL = 64
-val EXT_EXIF_PROPERTIES = 128
-val EXT_DURATION = 256
-val EXT_ARTIST = 512
-val EXT_ALBUM = 1024
+const val EXT_NAME = 1
+const val EXT_PATH = 2
+const val EXT_SIZE = 4
+const val EXT_RESOLUTION = 8
+const val EXT_LAST_MODIFIED = 16
+const val EXT_DATE_TAKEN = 32
+const val EXT_CAMERA_MODEL = 64
+const val EXT_EXIF_PROPERTIES = 128
+const val EXT_DURATION = 256
+const val EXT_ARTIST = 512
+const val EXT_ALBUM = 1024
 
 // media types
-val TYPE_IMAGE = 1
-val TYPE_VIDEO = 2
-val TYPE_GIF = 3
+const val TYPE_IMAGE = 1
+const val TYPE_VIDEO = 2
+const val TYPE_GIF = 3