Only load .webp & .avif images if the PixBuf module is installed

Previously it would try to load the image only for the size check to fail, printing a not-so-helpful error message:
WARNING: 2025-10-13 16:02:08,387: image_ok() 'Error in image_ok for file /tmp/wallpaper-test/test.webp'

Author: jlu5

variety/Util.py

@@ -47,6 +47,7 @@
 from gi.repository import Gdk, GdkPixbuf, GExiv2, Gio, GLib, Pango  # isort:skip
 # fmt: on
 
+_PIXBUF_SUPPORTED_FORMATS = {loader.get_name() for loader in GdkPixbuf.Pixbuf.get_formats()}
 
 USER_AGENT = "Variety Wallpaper Changer " + get_version()
 
@@ -369,13 +370,21 @@ def makedirs(path):
 
     @staticmethod
     def is_image(filename, check_contents=False):
+        ext = os.path.splitext(filename)[1].lower()
+
+        if ext == '.webp' and 'webp' not in _PIXBUF_SUPPORTED_FORMATS:
+            logger.warning(lambda: "Skipping %s - install webp-pixbuf-loader for WebP support" % filename)
+            return False
+
+        if ext == '.avif' and 'avif' not in _PIXBUF_SUPPORTED_FORMATS:
+            logger.warning(lambda: "Skipping %s - install libavif-pixbuf-loader for AVIF support" % filename)
+            return False
+
         if Util.is_animated_gif(filename):
             return False
 
         if not check_contents:
-            return filename.lower().endswith(
-                (".jpg", ".jpeg", ".gif", ".png", ".tiff", ".svg", ".bmp", ".avif", ".webp")
-            )
+            return ext in (".jpg", ".jpeg", ".gif", ".png", ".tiff", ".svg", ".bmp", ".avif", ".webp")
         else:
             format, image_width, image_height = GdkPixbuf.Pixbuf.get_file_info(filename)
             return bool(format)

variety/VarietyWindow.py

@@ -1910,6 +1910,7 @@ def image_ok(self, img, fuzziness):
 
         except Exception:
             logger.warning(lambda: "Error in image_ok for file %s" % img)
+            logger.info(lambda: "Debug details:", exc_info=True)
             return False
 
     def size_ok(self, width, height, fuzziness=0):