add checkpoints tab for extra networks UI

modules/ui_extra_networks_checkpoints.py

@@ -0,0 +1,38 @@
+import html
+import json
+import os
+import urllib.parse
+
+from modules import shared, ui_extra_networks, sd_models
+
+
+class ExtraNetworksPageCheckpoints(ui_extra_networks.ExtraNetworksPage):
+    def __init__(self):
+        super().__init__('Checkpoints')
+
+    def refresh(self):
+        shared.refresh_checkpoints()
+
+    def list_items(self):
+        for name, checkpoint1 in sd_models.checkpoints_list.items():
+            checkpoint: sd_models.CheckpointInfo = checkpoint1
+            path, ext = os.path.splitext(checkpoint.filename)
+            previews = [path + ".png", path + ".preview.png"]
+
+            preview = None
+            for file in previews:
+                if os.path.isfile(file):
+                    preview = self.link_preview(file)
+                    break
+
+            yield {
+                "name": checkpoint.model_name,
+                "filename": path,
+                "preview": preview,
+                "onclick": '"' + html.escape(f"""return selectCheckpoint({json.dumps(name)})""") + '"',
+                "local_preview": path + ".png",
+            }
+
+    def allowed_directories_for_previews(self):
+        return [shared.cmd_opts.ckpt_dir, sd_models.model_path]
+