serve images from where they are saved instead of a temporary directory

add an option to choose a different temporary directory in the UI
add an option to cleanup the selected temporary directory at startup

modules/ui_tempdir.py

@@ -0,0 +1,62 @@
+import os
+import tempfile
+from collections import namedtuple
+
+import gradio as gr
+
+from PIL import PngImagePlugin
+
+from modules import shared
+
+
+Savedfile = namedtuple("Savedfile", ["name"])
+
+
+def save_pil_to_file(pil_image, dir=None):
+    already_saved_as = getattr(pil_image, 'already_saved_as', None)
+    if already_saved_as:
+        shared.demo.temp_dirs = shared.demo.temp_dirs | {os.path.abspath(os.path.dirname(already_saved_as))}
+        file_obj = Savedfile(already_saved_as)
+        return file_obj
+
+    if shared.opts.temp_dir != "":
+        dir = shared.opts.temp_dir
+
+    use_metadata = False
+    metadata = PngImagePlugin.PngInfo()
+    for key, value in pil_image.info.items():
+        if isinstance(key, str) and isinstance(value, str):
+            metadata.add_text(key, value)
+            use_metadata = True
+
+    file_obj = tempfile.NamedTemporaryFile(delete=False, suffix=".png", dir=dir)
+    pil_image.save(file_obj, pnginfo=(metadata if use_metadata else None))
+    return file_obj
+
+
+# override save to file function so that it also writes PNG info
+gr.processing_utils.save_pil_to_file = save_pil_to_file
+
+
+def on_tmpdir_changed():
+    if shared.opts.temp_dir == "" or shared.demo is None:
+        return
+
+    os.makedirs(shared.opts.temp_dir, exist_ok=True)
+
+    shared.demo.temp_dirs = shared.demo.temp_dirs | {os.path.abspath(shared.opts.temp_dir)}
+
+
+def cleanup_tmpdr():
+    temp_dir = shared.opts.temp_dir
+    if temp_dir == "" or not os.path.isdir(temp_dir):
+        return
+
+    for root, dirs, files in os.walk(temp_dir, topdown=False):
+        for name in files:
+            _, extension = os.path.splitext(name)
+            if extension != ".png":
+                continue
+
+            filename = os.path.join(root, name)
+            os.remove(filename)