Implementing none backend

This is to use waypaper as a filepicker, as explained in #33

waypaper/app.py

@@ -222,7 +222,7 @@ class App(Gtk.Window):
 
     def check_backends(self):
         """Before running the app, check which backends are installed or show the error"""
-        if not self.cf.installed_backends:
+        if len(self.cf.installed_backends) == 1:
             self.show_message(self.txt.err_backend)
             exit()
 

waypaper/changer.py

@@ -84,6 +84,9 @@ def change_wallpaper(image_path, cf, monitor, txt):
             subprocess.Popen(["setwallpaper", "--mode", fill, image_path])
             print(f"{txt.msg_setwith} {cf.backend}")
 
+        elif cf.backend == "none":
+            pass
+
         else:
             print(f"{txt.err_notsup} {cf.backend}")
 

waypaper/common.py

@@ -55,8 +55,10 @@ def get_random_file(backend, folder, include_subfolders, include_hidden=False):
 
 def check_installed_backends():
     """Check which backends are installed in the system"""
-    installed_backends = []
+    installed_backends = ["none"]
     for backend in BACKEND_OPTIONS:
+        if backend == "none":
+            continue
         if backend == "wallutils":
             binary_name = "setwallpaper"
         else:

waypaper/options.py

@@ -1,4 +1,4 @@
-BACKEND_OPTIONS = ["swaybg", "swww", "feh", "wallutils"]
+BACKEND_OPTIONS = ["none", "swaybg", "swww", "feh", "wallutils"]
 FILL_OPTIONS = ["fill", "stretch", "fit", "center", "tile"]
 SORT_OPTIONS = ["name", "namerev", "date", "daterev"]
 SORT_DISPLAYS = {