Update app.py

app.py

@@ -787,35 +787,98 @@ def create_demo():
                 preview_cache[url] = (preview, False)
             return preview
 
-        # when preview_path_state changes, update preview components appropriately
-        # Update preview logic in apply_preview function
+        preview_path_state   = gr.State("")          # current preview file
+        prev_preview_state   = gr.State("")          # remembers the last file we showed
+        
         def apply_preview(path: str, last_path: str):
+            """
+            Returns:
+                (image_update, video_update, status_msg)
+        
+            * If the path is the same as the previous one we do nothing – this stops
+              the UI from flickering on every job completion.
+            * Otherwise we decide whether the file is an image or a video and show the
+              appropriate component.
+            """
+            # ------------------------------------------------------------------
+            # 1️⃣  No‑op when the preview hasn’t changed
+            # ------------------------------------------------------------------
             if path == last_path:
-            if not path:
+                # keep the current UI state unchanged
                 return gr.update(), gr.update(), ""
-            
+        
+            # ------------------------------------------------------------------
+            # 2️⃣  Nothing to show
+            # ------------------------------------------------------------------
+            if not path:
+                return (
+                    gr.update(value=None, visible=False),
+                    gr.update(value=None, visible=False),
+                    "",
+                )
+        
             try:
-                # Check for valid image previews
+                # ------------------------------------------------------------------
+                # 3️⃣  Image preview
+                # ------------------------------------------------------------------
                 if any(path.lower().endswith(ext) for ext in IMAGE_EXTS):
-                    return gr.update(value=path, visible=True), gr.update(value=None, visible=False), "Preview updated."
+                    return (
+                        gr.update(value=path, visible=True),
+                        gr.update(value=None, visible=False),
+                        "Preview updated.",
+                    )
         
-                # Video previews
+                # ------------------------------------------------------------------
+                # 4️⃣  Video preview
+                # ------------------------------------------------------------------
                 if any(path.lower().endswith(ext) for ext in VIDEO_EXTS):
-                    return gr.update(value=None, visible=False), gr.update(value=path, visible=True), "Preview updated."
-                
-                # Attempt to open as image for fallback
+                    return (
+                        gr.update(value=None, visible=False),
+                        gr.update(value=path, visible=True),
+                        "Preview updated.",
+                    )
+        
+                # ------------------------------------------------------------------
+                # 5️⃣  Fallback – try to open as an image (covers odd extensions)
+                # ------------------------------------------------------------------
                 img = Image.open(path)
-                img.verify()  # Ensures it's a valid image
-                return gr.update(value=path, visible=True), gr.update(value=None, visible=False), "Preview updated."
-                
+                img.verify()                     # raises if not a valid image
+                return (
+                    gr.update(value=path, visible=True),
+                    gr.update(value=None, visible=False),
+                    "Preview updated.",
+                )
             except Exception as e:
-                print(f"Failed to update preview: {e}")  # Log the error
-                return gr.update(value=None, visible=False), gr.update(value=None, visible=False), ""
-
-        preview_path_state.change(fn=apply_preview, inputs=[preview_path_state], outputs=[preview_image, preview_video, preview_status])
-
+                # Log the problem – the UI will simply hide both previews
+                print(f"Failed to update preview for {path!r}: {e}")
+                return (
+                    gr.update(value=None, visible=False),
+                    gr.update(value=None, visible=False),
+                    "",
+                )
+        
+        # ----------------------------------------------------------------------
+        #  Bind the function – we feed both the current preview path and the
+        #  previously‑shown path, then store the new path back into both states.
+        # ----------------------------------------------------------------------
+        preview_path_state.change(
+            fn=apply_preview,
+            inputs=[preview_path_state, prev_preview_state],
+            outputs=[preview_image, preview_video, preview_status],
+        )
+        
+        # After the preview is updated we also need to remember the new path.
+        # This tiny helper copies the new path into the “previous” state.
+        def _store_new_path(new_path: str):
+            return new_path, new_path   # (prev_state, preview_state)
+        
+        preview_path_state.change(
+            fn=_store_new_path,
+            inputs=[preview_path_state],
+            outputs=[prev_preview_state, preview_path_state],
+            queue=False,
+        )
+        
+        # ----------------------------------------------------------------------
         demo.queue()
-    return demo
-
-if __name__ == "__main__":
-    create_demo().launch(share=False, server_name="0.0.0.0", server_port=7860, max_threads=8)
+        return demo