Deduplicate extra network preview-search code

modules/ui_extra_networks.py

@@ -2,6 +2,7 @@ import glob
 import os.path
 import urllib.parse
 from pathlib import Path
+from typing import Optional
 
 from modules import shared
 import gradio as gr
@@ -137,6 +138,15 @@ class ExtraNetworksPage:
 
         return self.card_page.format(**args)
 
+    def _find_preview(self, path: str) -> Optional[str]:
+        """
+        Find a preview PNG for a given path (without extension) and call link_preview on it.
+        """
+        for file in [path + ".png", path + ".preview.png"]:
+            if os.path.isfile(file):
+                return self.link_preview(file)
+        return None
+
 
 def intialize():
     extra_pages.clear()