add member NO & staticmethod auto to Preview enum

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

Author: pantheraleo-7

examples/capture_old_request.py

@@ -5,11 +5,11 @@
 
 import time
 
-from picamera2 import Picamera2
+from picamera2 import Picamera2, Preview
 
 picam2 = Picamera2()
 capture_config = picam2.create_still_configuration()
-picam2.start(show_preview=True)
+picam2.start(show_preview=Preview.auto())
 
 time.sleep(1)
 

examples/imx500/imx500_classification_demo.py

@@ -6,7 +6,7 @@
 import cv2
 import numpy as np
 
-from picamera2 import CompletedRequest, MappedArray, Picamera2
+from picamera2 import CompletedRequest, MappedArray, Picamera2, Preview
 from picamera2.devices import IMX500
 from picamera2.devices.imx500 import NetworkIntrinsics
 from picamera2.devices.imx500.postprocess import softmax
@@ -146,7 +146,7 @@ def get_args():
     config = picam2.create_preview_configuration(controls={"FrameRate": intrinsics.inference_rate}, buffer_count=12)
 
     imx500.show_network_fw_progress_bar()
-    picam2.start(config, show_preview=True)
+    picam2.start(config, show_preview=Preview.auto())
     if intrinsics.preserve_aspect_ratio:
         imx500.set_auto_aspect_ratio()
     # Register the callback to parse and draw classification results

examples/imx500/imx500_object_detection_demo.py

@@ -5,7 +5,7 @@
 import cv2
 import numpy as np
 
-from picamera2 import MappedArray, Picamera2
+from picamera2 import MappedArray, Picamera2, Preview
 from picamera2.devices import IMX500
 from picamera2.devices.imx500 import (NetworkIntrinsics,
                                       postprocess_nanodet_detection)
@@ -168,7 +168,7 @@ def get_args():
     config = picam2.create_preview_configuration(controls={"FrameRate": intrinsics.inference_rate}, buffer_count=12)
 
     imx500.show_network_fw_progress_bar()
-    picam2.start(config, show_preview=True)
+    picam2.start(config, show_preview=Preview.auto())
 
     if intrinsics.preserve_aspect_ratio:
         imx500.set_auto_aspect_ratio()

examples/imx500/imx500_pose_estimation_higherhrnet_demo.py

@@ -4,7 +4,7 @@
 
 import numpy as np
 
-from picamera2 import CompletedRequest, MappedArray, Picamera2
+from picamera2 import CompletedRequest, MappedArray, Picamera2, Preview
 from picamera2.devices.imx500 import IMX500, NetworkIntrinsics
 from picamera2.devices.imx500.postprocess import COCODrawer
 from picamera2.devices.imx500.postprocess_highernet import \
@@ -109,7 +109,7 @@ def get_drawer():
     config = picam2.create_preview_configuration(controls={'FrameRate': intrinsics.inference_rate}, buffer_count=12)
 
     imx500.show_network_fw_progress_bar()
-    picam2.start(config, show_preview=True)
+    picam2.start(config, show_preview=Preview.auto())
     imx500.set_auto_aspect_ratio()
     picam2.pre_callback = picamera2_pre_callback
 

examples/imx500/imx500_segmentation_demo.py

@@ -5,7 +5,7 @@
 
 import numpy as np
 
-from picamera2 import CompletedRequest, Picamera2
+from picamera2 import CompletedRequest, Picamera2, Preview
 from picamera2.devices import IMX500
 from picamera2.devices.imx500 import NetworkIntrinsics
 
@@ -94,7 +94,7 @@ def get_args():
     picam2 = Picamera2(imx500.camera_num)
     config = picam2.create_preview_configuration(controls={'FrameRate': intrinsics.inference_rate}, buffer_count=12)
     imx500.show_network_fw_progress_bar()
-    picam2.start(config, show_preview=True)
+    picam2.start(config, show_preview=Preview.auto())
     picam2.pre_callback = create_and_draw_masks
 
     while True:

examples/stereo_preview.py

@@ -3,7 +3,7 @@
 import time
 from threading import Lock
 
-from picamera2 import MappedArray, Picamera2, libcamera
+from picamera2 import MappedArray, Picamera2, Preview, libcamera
 
 cam2_request = None
 lock = Lock()
@@ -57,7 +57,7 @@ def save_request(request):
     controls={"ScalerCrop": (0, 0, picam2a.sensor_resolution[0], picam2a.sensor_resolution[1])}
 )
 picam2a.configure(main_config)
-picam2a.start_preview(True)
+picam2a.start_preview(Preview.auto())
 
 # Configure as half frame normally
 picam2b = Picamera2(1)

examples/still_capture_with_config.py

@@ -4,7 +4,7 @@
 
 import time
 
-from picamera2 import Picamera2
+from picamera2 import Picamera2, Preview
 
 picam2 = Picamera2()
 
@@ -15,7 +15,7 @@
 picam2.still_configuration.enable_raw()
 picam2.still_configuration.raw.size = picam2.sensor_resolution
 
-picam2.start("preview", show_preview=True)
+picam2.start("preview", show_preview=Preview.auto())
 time.sleep(2)
 
 picam2.switch_mode_and_capture_file("still", "test_full.jpg")

examples/title_bar.py

@@ -2,10 +2,10 @@
 
 import time
 
-from picamera2 import Picamera2
+from picamera2 import Picamera2, Preview
 
 picam2 = Picamera2()
-picam2.start(show_preview=True)
+picam2.start(show_preview=Preview.auto())
 time.sleep(0.5)
 
 # Or you could do this before starting the camera.

picamera2/picamera2.py

@@ -53,6 +53,19 @@ class Preview(Enum):
     DRM = DrmPreview
     QT = QtPreview
     QTGL = QtGlPreview
+    NO = None
+
+    @staticmethod
+    def auto():
+        # Crude attempt at "autodetection" but which will mostly (?) work. We will
+        # probably find situations that need fixing, VNC perhaps.
+        display = os.getenv('DISPLAY')
+        if display is None:
+            return Preview.DRM
+        elif display.startswith(':'):
+            return Preview.QTGL
+        else:
+            return Preview.QT
 
 
 class GlobalCameraInfo(TypedDict):
@@ -578,34 +591,23 @@ def start_preview(self, preview=None, **kwargs) -> None:
         """
         Start the given preview which drives the camera processing.
 
-        The preview may be either:
-          None or False - in which case a NullPreview is made,
-          True - which we hope in future to use to autodetect
-          a Preview enum value - in which case a preview of that type is made,
-          or an actual preview object.
+        preview - a Preview enum or an actual preview object.
+        Pass Preview.auto() to autodetect. Defaults to NullPreview.
 
-        When using the enum form, extra keyword arguments can be supplied that
-        will be forwarded to the preview class constructor.
+        **kwargs - keyword arguments to be forwarded to the preview
+        class constructor, when using the enum form
         """
-        if self._event_loop_running:
-            raise RuntimeError("An event loop is already running")
-
-        if preview is True:
-            # Crude attempt at "autodetection" but which will mostly (?) work. We will
-            # probably find situations that need fixing, VNC perhaps.
-            display = os.getenv('DISPLAY')
-            if display is None:
-                preview = Preview.DRM.value(**kwargs)
-            elif display.startswith(':'):
-                preview = Preview.QTGL.value(**kwargs)
-            else:
-                preview = Preview.QT.value(**kwargs)
-        elif preview is False or preview is None:
-            preview = Preview.NULL.value(**kwargs)
+        if preview is None:
+            preview = NullPreview(**kwargs)
         elif isinstance(preview, Preview):
+            if preview is Preview.NO:
+                return
             preview = preview.value(**kwargs)
         # Assume it's already a preview object.
 
+        if self._event_loop_running:
+            raise RuntimeError("An event loop is already running")
+
         # The preview windows call the attach_preview method.
         self._preview_stopped.clear()
         preview.start(self)
@@ -1189,20 +1191,16 @@ def start(self, config=None, show_preview=None) -> None:
 
         Camera controls may be sent to the camera before it starts running.
 
-        config - if given it is used to configure the camera.
-        Defaults to 'preview' configuration if the camera is unconfigured.
+        config - Camera configuration to be set. Defaults to 'preview' configuration.
+        Note: if the camera is already configured, this has no effect.
 
-        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.
+        show_preview - a Preview enum or an actual preview object.
+        Pass Preview.auto() to autodetect. Defaults to NullPreview.
         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:
+        if not self.camera_config:
             self.configure(config)
-        # By default we will create an event loop if there isn't one running already.
-        if show_preview is not False and not self._event_loop_running:
+        if not self._event_loop_running:
             self.start_preview(show_preview)
         self.start_()
 

tests/crop_test.py

@@ -4,7 +4,7 @@
 
 import cv2
 
-from picamera2 import Picamera2, Platform
+from picamera2 import Picamera2, Platform, Preview
 
 # VC4 platforms do not support different crops for the two outputs.
 if Picamera2.platform == Platform.VC4:
@@ -18,7 +18,7 @@
                                             lores={"size": (320, 320), "format": 'XRGB8888', "preserve_ar": l},
                                             display="main")
     picam2.configure(cfg)
-    picam2.start(show_preview=True)
+    picam2.start(show_preview=Preview.auto())
 
     for _ in range(50):
         im = picam2.capture_array("lores")