change the behaviour of the following values to show_preview parameter for all the methods using it:

`None` -> `NullPreview` (default)
`False` -> no preview

Signed-off-by: Asadullah Shaikh <asadshaikh20022002@gmail.com>

Author: pantheraleo-7

examples/imx500/imx500_object_detection_demo_mp.py

@@ -173,7 +173,7 @@ def get_args():
     config = picam2.create_preview_configuration(main, controls={"FrameRate": intrinsics.inference_rate}, buffer_count=12)
 
     imx500.show_network_fw_progress_bar()
-    picam2.start(config, show_preview=False)
+    picam2.start(config)
     if intrinsics.preserve_aspect_ratio:
         imx500.set_auto_aspect_ratio()
 

picamera2/picamera2.py

@@ -1183,31 +1183,26 @@ def start_(self):
         _log.info("Camera started")
         self.started = True
 
-    def start(self, config=None, show_preview=False) -> None:
+    def start(self, config=None, show_preview=None) -> None:
         """
         Start the camera system running.
 
         Camera controls may be sent to the camera before it starts running.
 
-        The following parameters may be supplied:
+        config - if given it is used to configure the camera.
+        Defaults to 'preview' configuration if the camera is unconfigured.
 
-        config - if not None this is used to configure the camera. This is just a
-            convenience so that you don't have to call configure explicitly.
-
-        show_preview - whether to show a preview window. You can pass in the preview
-            type or True to attempt to autodetect. If left as False you'll get no
-            visible preview window but the "NULL preview" will still be run. The
-            value None would mean no event loop runs at all and you would have to
-            implement your own.
+        show_preview - whether to show a preview window. By default no visible preview window
+        will be shown but the NullPreview would still run. True will attempt to autodetect.
+        False would skip starting an event loop altogether. A Preview enum could also given.
+        Note: if an event loop is already running, this has no effect.
         """
         if not self.camera_config and config is None:
             config = "preview"
         if config is not None:
             self.configure(config)
-        if not self.camera_config:
-            raise RuntimeError("Camera has not been configured")
         # By default we will create an event loop if there isn't one running already.
-        if show_preview is not None and not self._event_loop_running:
+        if show_preview is not False and not self._event_loop_running:
             self.start_preview(show_preview)
         self.start_()
 
@@ -2394,7 +2389,7 @@ def set_overlay(self, overlay) -> None:
     def start_and_capture_files(self, name="image{:03d}.jpg",
                                 initial_delay=1, preview_mode="preview",
                                 capture_mode="still", num_files=1, delay=1,
-                                show_preview=True, exif_data=None) -> None:
+                                show_preview=None, exif_data=None) -> None:
         """This function makes capturing multiple images more convenient.
 
         Should only be used in command line line applications (not from a Qt application, for example).
@@ -2417,7 +2412,7 @@ def start_and_capture_files(self, name="image{:03d}.jpg",
 
         delay - the time delay for every capture after the first (default 1s).
 
-        show_preview - whether to show a preview window (default: yes). The preview window only
+        show_preview - whether to show a preview window (default: no). The preview window only
             displays an image by default during the preview phase, so if captures are back-to-back
             with delay zero, then there may be no images shown. This parameter only has any
             effect if a preview is not already running. If it is, it would have to be stopped first
@@ -2453,7 +2448,7 @@ def start_and_capture_files(self, name="image{:03d}.jpg",
         self.stop()
 
     def start_and_capture_file(self, name="image.jpg", delay=1, preview_mode="preview",
-                               capture_mode="still", show_preview=True, exif_data=None) -> None:
+                               capture_mode="still", show_preview=None, exif_data=None) -> None:
         """This function makes capturing a single image more convenient.
 
         Should only be used in command line line applications (not from a Qt application, for example).
@@ -2471,7 +2466,7 @@ def start_and_capture_file(self, name="image.jpg", delay=1, preview_mode="previe
         capture_mode - the camera mode to use to capture the still images (defaulting to the
             Picamera2 object's still_configuration field).
 
-        show_preview - whether to show a preview window (default: yes). The preview window only
+        show_preview - whether to show a preview window (default: no). The preview window only
             displays an image by default during the preview phase. This parameter only has any
             effect if a preview is not already running. If it is, it would have to be stopped first
             (with the stop_preview method).
@@ -2485,7 +2480,7 @@ def start_and_capture_file(self, name="image.jpg", delay=1, preview_mode="previe
                                      exif_data=exif_data)
 
     def start_and_record_video(self, output, encoder=None, config=None, quality=Quality.MEDIUM,
-                               show_preview=False, duration=0, audio=False) -> None:
+                               show_preview=None, duration=0, audio=False) -> None:
         """This function makes video recording more convenient.
 
         Should only be used in command line applications (not from a Qt application, for example).

tests/preview_cycle_test.py

@@ -14,7 +14,7 @@ def main():
     preview = picam2.create_preview_configuration()
     picam2.configure(preview)
 
-    picam2.start(show_preview=None)
+    picam2.start(show_preview=False)
 
     qtgl1 = time.monotonic()
     print("QT GL Preview")