class QrReaderCameraDialog(Logger, MessageBoxMixin, QDialog):
"""
Dialog for reading QR codes from a camera
"""
# Try to crop so we have minimum 512 dimensions
SCAN_SIZE: int = 512
qr_finished = pyqtSignal(bool, str, object)
def __init__(self, parent, *, config: SimpleConfig):
''' Note: make sure parent is a "top_level_window()" as per
MessageBoxMixin API else bad things can happen on macOS. '''
QDialog.__init__(self, parent=parent)
Logger.__init__(self)
self.validator: AbstractQrReaderValidator = None
self.frame_id: int = 0
self.qr_crop: QRect = None
self.qrreader_res: List[QrCodeResult] = []
self.validator_res: QrReaderValidatorResult = None
self.last_stats_time: float = 0.0
self.frame_counter: int = 0
self.qr_frame_counter: int = 0
self.last_qr_scan_ts: float = 0.0
self.camera: QCamera = None
self._error_message: str = None
self._ok_done: bool = False
self.camera_sc_conn = None
self.resolution: QSize = None
self.config = config
# Try to get the QR reader for this system
self.qrreader = get_qr_reader()
if not self.qrreader:
raise MissingQrDetectionLib(
_("The platform QR detection library is not available."))
# Set up the window, add the maximize button
flags = self.windowFlags()
flags = flags | Qt.WindowMaximizeButtonHint
self.setWindowFlags(flags)
self.setWindowTitle(_("Scan QR Code"))
self.setWindowModality(
Qt.WindowModal if parent else Qt.ApplicationModal)
# Create video widget and fixed aspect ratio layout to contain it
self.video_widget = QrReaderVideoWidget()
self.video_overlay = QrReaderVideoOverlay()
self.video_layout = FixedAspectRatioLayout()
self.video_layout.addWidget(self.video_widget)
self.video_layout.addWidget(self.video_overlay)
# Create root layout and add the video widget layout to it
vbox = QVBoxLayout()
self.setLayout(vbox)
vbox.setContentsMargins(0, 0, 0, 0)
vbox.addLayout(self.video_layout)
self.lowres_label = QLabel(
_("Note: This camera generates frames of relatively low resolution; QR scanning accuracy may be affected"
))
self.lowres_label.setWordWrap(True)
self.lowres_label.setAlignment(Qt.AlignVCenter | Qt.AlignHCenter)
vbox.addWidget(self.lowres_label)
self.lowres_label.setHidden(True)
# Create a layout for the controls
controls_layout = QHBoxLayout()
controls_layout.addStretch(2)
controls_layout.setContentsMargins(10, 10, 10, 10)
controls_layout.setSpacing(10)
vbox.addLayout(controls_layout)
# Flip horizontally checkbox with default coming from global config
self.flip_x = QCheckBox()
self.flip_x.setText(_("&Flip horizontally"))
self.flip_x.setChecked(bool(self.config.get('qrreader_flip_x', True)))
self.flip_x.stateChanged.connect(self._on_flip_x_changed)
controls_layout.addWidget(self.flip_x)
close_but = QPushButton(_("&Close"))
close_but.clicked.connect(self.reject)
controls_layout.addWidget(close_but)
# Create the video surface and receive events when new frames arrive
self.video_surface = QrReaderVideoSurface(self)
self.video_surface.frame_available.connect(self._on_frame_available)
# Create the crop blur effect
self.crop_blur_effect = QrReaderCropBlurEffect(self)
self.image_effect = ImageGraphicsEffect(self, self.crop_blur_effect)
# Note these should stay as queued connections becasue we use the idiom
# self.reject() and self.accept() in this class to kill the scan --
# and we do it from within callback functions. If you don't use
# queued connections here, bad things can happen.
self.finished.connect(self._boilerplate_cleanup, Qt.QueuedConnection)
self.finished.connect(self._on_finished, Qt.QueuedConnection)
def _on_flip_x_changed(self, _state: int):
self.config.set_key('qrreader_flip_x', self.flip_x.isChecked())
def _get_resolution(self, resolutions: List[QSize],
min_size: int) -> QSize:
"""
Given a list of resolutions that the camera supports this function picks the
lowest resolution that is at least min_size in both width and height.
If no resolution is found, NoCameraResolutionsFound is raised.
"""
def res_list_to_str(res_list: List[QSize]) -> str:
return ', '.join(
['{}x{}'.format(r.width(), r.height()) for r in res_list])
def check_res(res: QSize):
return res.width() >= min_size and res.height() >= min_size
self.logger.info('searching for at least {0}x{0}'.format(min_size))
# Query and display all resolutions the camera supports
format_str = 'camera resolutions: {}'
self.logger.info(format_str.format(res_list_to_str(resolutions)))
# Filter to those that are at least min_size in both width and height
candidate_resolutions = []
ideal_resolutions = [r for r in resolutions if check_res(r)]
less_than_ideal_resolutions = [
r for r in resolutions if r not in ideal_resolutions
]
format_str = 'ideal resolutions: {}, less-than-ideal resolutions: {}'
self.logger.info(
format_str.format(res_list_to_str(ideal_resolutions),
res_list_to_str(less_than_ideal_resolutions)))
# Raise an error if we have no usable resolutions
if not ideal_resolutions and not less_than_ideal_resolutions:
raise NoCameraResolutionsFound(
_("Cannot start QR scanner, no usable camera resolution found."
) + self._linux_pyqt5bug_msg())
if not ideal_resolutions:
self.logger.warning(
'No ideal resolutions found, falling back to less-than-ideal resolutions -- QR recognition may fail!'
)
candidate_resolutions = less_than_ideal_resolutions
is_ideal = False
else:
candidate_resolutions = ideal_resolutions
is_ideal = True
# Sort the usable resolutions, least number of pixels first, get the first element
resolution = sorted(candidate_resolutions,
key=lambda r: r.width() * r.height(),
reverse=not is_ideal)[0]
format_str = 'chosen resolution is {}x{}'
self.logger.info(
format_str.format(resolution.width(), resolution.height()))
return resolution, is_ideal
@staticmethod
def _get_crop(resolution: QSize, scan_size: int) -> QRect:
"""
Returns a QRect that is scan_size x scan_size in the middle of the resolution
"""
scan_pos_x = (resolution.width() - scan_size) // 2
scan_pos_y = (resolution.height() - scan_size) // 2
return QRect(scan_pos_x, scan_pos_y, scan_size, scan_size)
@staticmethod
def _linux_pyqt5bug_msg():
''' Returns a string that may be appended to an exception error message
only if on Linux and PyQt5 < 5.12.2, otherwise returns an empty string. '''
if (sys.platform == 'linux'
and PYQT_VERSION < 0x050c02 # Check if PyQt5 < 5.12.2 on linux
# Also: this warning is not relevant to APPIMAGE; so make sure
# we are not running from APPIMAGE.
and not os.environ.get('APPIMAGE')):
# In this case it's possible we couldn't detect a camera because
# of that missing libQt5MultimediaGstTools.so problem.
return ("\n\n" + _(
'If you indeed do have a usable camera connected, then this error may be caused by bugs in previous PyQt5 versions on Linux. Try installing the latest PyQt5:'
) + "\n\n" + "python3 -m pip install --user -I pyqt5")
return ''
def start_scan(self, device: str = ''):
"""
Scans a QR code from the given camera device.
If no QR code is found the returned string will be empty.
If the camera is not found or can't be opened NoCamerasFound will be raised.
"""
self.validator = QrReaderValidatorCounted()
self.validator.strong_count = 5 # FIXME: make this time based rather than framect based
device_info = None
for camera in QCameraInfo.availableCameras():
if camera.deviceName() == device:
device_info = camera
break
if not device_info:
self.logger.info(
'Failed to open selected camera, trying to use default camera')
device_info = QCameraInfo.defaultCamera()
if not device_info or device_info.isNull():
raise NoCamerasFound(
_("Cannot start QR scanner, no usable camera found.") +
self._linux_pyqt5bug_msg())
self._init_stats()
self.qrreader_res = []
self.validator_res = None
self._ok_done = False
self._error_message = None
if self.camera:
self.logger.info(
"Warning: start_scan already called for this instance.")
self.camera = QCamera(device_info)
self.camera.setViewfinder(self.video_surface)
self.camera.setCaptureMode(QCamera.CaptureViewfinder)
# this operates on camera from within the signal handler, so should be a queued connection
self.camera_sc_conn = self.camera.statusChanged.connect(
self._on_camera_status_changed, Qt.QueuedConnection)
self.camera.error.connect(
self._on_camera_error
) # log the errors we get, if any, for debugging
# Camera needs to be loaded to query resolutions, this tries to open the camera
self.camera.load()
_camera_status_names = {
QCamera.UnavailableStatus: _('unavailable'),
QCamera.UnloadedStatus: _('unloaded'),
QCamera.UnloadingStatus: _('unloading'),
QCamera.LoadingStatus: _('loading'),
QCamera.LoadedStatus: _('loaded'),
QCamera.StandbyStatus: _('standby'),
QCamera.StartingStatus: _('starting'),
QCamera.StoppingStatus: _('stopping'),
QCamera.ActiveStatus: _('active')
}
def _get_camera_status_name(self, status: QCamera.Status):
return self._camera_status_names.get(status, _('unknown'))
def _set_resolution(self, resolution: QSize):
self.resolution = resolution
self.qr_crop = self._get_crop(resolution, self.SCAN_SIZE)
# Initialize the video widget
#self.video_widget.setMinimumSize(resolution) # <-- on macOS this makes it fixed size for some reason.
self.resize(720, 540)
self.video_overlay.set_crop(self.qr_crop)
self.video_overlay.set_resolution(resolution)
self.video_layout.set_aspect_ratio(resolution.width() /
resolution.height())
# Set up the crop blur effect
self.crop_blur_effect.setCrop(self.qr_crop)
def _on_camera_status_changed(self, status: QCamera.Status):
if self._ok_done:
# camera/scan is quitting, abort.
return
self.logger.info('camera status changed to {}'.format(
self._get_camera_status_name(status)))
if status == QCamera.LoadedStatus:
# Determine the optimal resolution and compute the crop rect
camera_resolutions = self.camera.supportedViewfinderResolutions()
try:
resolution, was_ideal = self._get_resolution(
camera_resolutions, self.SCAN_SIZE)
except RuntimeError as e:
self._error_message = str(e)
self.reject()
return
self._set_resolution(resolution)
# Set the camera resolution
viewfinder_settings = QCameraViewfinderSettings()
viewfinder_settings.setResolution(resolution)
self.camera.setViewfinderSettings(viewfinder_settings)
# Counter for the QR scanner frame number
self.frame_id = 0
self.camera.start()
self.lowres_label.setVisible(
not was_ideal
) # if they have a low res camera, show the warning label.
elif status == QCamera.UnloadedStatus or status == QCamera.UnavailableStatus:
self._error_message = _(
"Cannot start QR scanner, camera is unavailable.")
self.reject()
elif status == QCamera.ActiveStatus:
self.open()
CameraErrorStrings = {
QCamera.NoError: "No Error",
QCamera.CameraError: "Camera Error",
QCamera.InvalidRequestError: "Invalid Request Error",
QCamera.ServiceMissingError: "Service Missing Error",
QCamera.NotSupportedFeatureError: "Unsupported Feature Error"
}
def _on_camera_error(self, errorCode):
errStr = self.CameraErrorStrings.get(errorCode, "Unknown Error")
self.logger.info(f"QCamera error: {errStr}")
def accept(self):
self._ok_done = True # immediately blocks further processing
super().accept()
def reject(self):
self._ok_done = True # immediately blocks further processing
super().reject()
def _boilerplate_cleanup(self):
self._close_camera()
if self.isVisible():
self.close()
def _close_camera(self):
if self.camera:
self.camera.setViewfinder(None)
if self.camera_sc_conn:
self.camera.statusChanged.disconnect(self.camera_sc_conn)
self.camera_sc_conn = None
self.camera.unload()
self.camera = None
def _on_finished(self, code):
res = ((code == QDialog.Accepted and self.validator_res
and self.validator_res.accepted
and self.validator_res.simple_result) or '')
self.validator = None
self.logger.info(f'closed {res}')
self.qr_finished.emit(code == QDialog.Accepted, self._error_message,
res)
def _on_frame_available(self, frame: QImage):
if self._ok_done:
return
self.frame_id += 1
if frame.size() != self.resolution:
self.logger.info(
'Getting video data at {}x{} instead of the requested {}x{}, switching resolution.'
.format(frame.size().width(),
frame.size().height(), self.resolution.width(),
self.resolution.height()))
self._set_resolution(frame.size())
flip_x = self.flip_x.isChecked()
# Only QR scan every QR_SCAN_PERIOD secs
qr_scanned = time.time(
) - self.last_qr_scan_ts >= self.qrreader.interval()
if qr_scanned:
self.last_qr_scan_ts = time.time()
# Crop the frame so we only scan a SCAN_SIZE rect
frame_cropped = frame.copy(self.qr_crop)
# Convert to Y800 / GREY FourCC (single 8-bit channel)
# This creates a copy, so we don't need to keep the frame around anymore
frame_y800 = frame_cropped.convertToFormat(
QImage.Format_Grayscale8)
# Read the QR codes from the frame
self.qrreader_res = self.qrreader.read_qr_code(
frame_y800.constBits().__int__(), frame_y800.byteCount(),
frame_y800.bytesPerLine(), frame_y800.width(),
frame_y800.height(), self.frame_id)
# Call the validator to see if the scanned results are acceptable
self.validator_res = self.validator.validate_results(
self.qrreader_res)
# Update the video overlay with the results
self.video_overlay.set_results(self.qrreader_res, flip_x,
self.validator_res)
# Close the dialog if the validator accepted the result
if self.validator_res.accepted:
self.accept()
return
# Apply the crop blur effect
if self.image_effect:
frame = self.image_effect.apply(frame)
# If horizontal flipping is enabled, only flip the display
if flip_x:
frame = frame.mirrored(True, False)
# Display the frame in the widget
self.video_widget.setPixmap(QPixmap.fromImage(frame))
self._update_stats(qr_scanned)
def _init_stats(self):
self.last_stats_time = time.perf_counter()
self.frame_counter = 0
self.qr_frame_counter = 0
def _update_stats(self, qr_scanned):
self.frame_counter += 1
if qr_scanned:
self.qr_frame_counter += 1
now = time.perf_counter()
last_stats_delta = now - self.last_stats_time
if last_stats_delta > 1.0: # stats every 1.0 seconds
fps = self.frame_counter / last_stats_delta
qr_fps = self.qr_frame_counter / last_stats_delta
if self.validator is not None:
self.validator.strong_count = math.ceil(
qr_fps / 3
) # 1/3 of a second's worth of qr frames determines strong_count
stats_format = 'running at {} FPS, scanner at {} FPS'
self.logger.info(stats_format.format(fps, qr_fps))
self.frame_counter = 0
self.qr_frame_counter = 0
self.last_stats_time = now
class CQCameraPreviewWindow(QtWidgets.QMainWindow):
closeSignal = QtCore.pyqtSignal()
ioctlRequest = QtCore.pyqtSignal(dict)
def __init__(self, *args, **kwargs):
super(CQCameraPreviewWindow, self).__init__(*args, **kwargs)
self._MIN_WIN_WIDTH = 640
self.oc_camera_info = None
self.oc_camera = None
self.b_guard = False
self.toolbar = QtWidgets.QToolBar("Preview")
self.cbox_resolution = CLabeledComboBox("Resolution:")
self.cbox_resolution.cbox.currentIndexChanged.connect(self.__cb_on_resolution_cbox_index_changed)
self.toolbar.addWidget(self.cbox_resolution)
self.toolbar.addSeparator()
self.cbox_frame_rate = CLabeledComboBox("Frame Rate:")
self.cbox_frame_rate.cbox.currentIndexChanged.connect(self.__cb_on_frame_rate_cbox_index_changed)
self.toolbar.addWidget(self.cbox_frame_rate)
self.addToolBar(self.toolbar)
self.toolbar.addSeparator()
self.oc_view_finder = QCameraViewfinder()
self.setCentralWidget(self.oc_view_finder)
def __cb_on_resolution_cbox_index_changed(self, i_idx):
if self.oc_camera is None:
self.fatal_error("Unallocated camera object detected")
if self.b_guard: return
l_res = self.cbox_resolution.cbox.itemText(i_idx).split(" x ")
oc_vf_settings = self.oc_camera.viewfinderSettings()
if oc_vf_settings.isNull():
self.fatal_error("Unable to retrieve camera settings")
i_w, i_h = int(l_res[0]), int(l_res[1])
oc_vf_settings.setResolution(i_w, i_h)
self.oc_camera.setViewfinderSettings(oc_vf_settings)
self.oc_view_finder.setFixedSize(i_w, i_h)
if i_w >= self._MIN_WIN_WIDTH:
self.adjustSize()
self.setFixedSize(self.sizeHint())
def __cb_on_frame_rate_cbox_index_changed(self, i_idx):
if self.oc_camera is None:
self.fatal_error("Unallocated camera object detected")
if self.b_guard: return
f_res = float(self.cbox_frame_rate.cbox.itemText(i_idx))
oc_vf_settings = self.oc_camera.viewfinderSettings()
if oc_vf_settings.isNull():
self.fatal_error("Unable to retrieve camera settings")
oc_vf_settings.setMinimumFrameRate(f_res)
oc_vf_settings.setMaximumFrameRate(f_res)
self.oc_camera.setViewfinderSettings(oc_vf_settings)
def __camera_sync_start(self):
i_sec_cnt = 0
self.oc_camera.start()
while True:
cam_status = self.oc_camera.status()
if cam_status == QCamera.ActiveStatus: break
else:
time.sleep(1)
i_sec_cnt += 1
if i_sec_cnt >= 10: self.fatal_error("Unable to start the camera")
def __update_UI(self):
# retrieve all supported resolutions and populate the resolution combo box
l_resolutions = self.oc_camera.supportedViewfinderResolutions()
if len(l_resolutions) > 0:
l_res = []
for oc_res in l_resolutions:
l_res.append("%i x %i" % (oc_res.width(), oc_res.height()))
self.cbox_resolution.cbox.clear()
self.cbox_resolution.cbox.addItems(l_res)
oc_vf_settings = self.oc_camera.viewfinderSettings()
if oc_vf_settings.isNull():
self.fatal_error("Unable to retrieve camera settings")
# set current item index in the resolution combo box
# according to the current resolution of our camera
oc_curr_res = oc_vf_settings.resolution()
s_res_hash = "%i x %i" % (oc_curr_res.width(), oc_curr_res.height())
for i_idx in range(self.cbox_resolution.cbox.count()):
if self.cbox_resolution.cbox.itemText(i_idx) == s_res_hash:
self.cbox_resolution.cbox.setCurrentIndex(i_idx)
# retrieve all supported frame rates and populate the frame rate combo box
l_frates = self.oc_camera.supportedViewfinderFrameRateRanges()
if len(l_frates) > 0:
l_res = []
for oc_frate in l_frates:
l_res.append("%f" % oc_frate.minimumFrameRate)
self.cbox_frame_rate.cbox.clear()
self.cbox_frame_rate.cbox.addItems(l_res)
# set current item index in the frame rate combo box
# according to the current frame rate of our camera
i_curr_frate = int(oc_vf_settings.minimumFrameRate())
for i_idx in range(self.cbox_frame_rate.cbox.count()):
if int(float(self.cbox_frame_rate.cbox.itemText(i_idx))) == i_curr_frate:
self.cbox_frame_rate.cbox.setCurrentIndex(i_idx)
def fatal_error(self, s_msg):
if self.oc_camera is not None: self.oc_camera.stop()
QtWidgets.QMessageBox.critical(None, "Fatal Error", "%s\nThe application will exit now." % s_msg)
sys.exit(-1)
def start_preview(self, oc_camera_info, oc_frame_cap_thread):
if self.oc_camera is not None:
self.fatal_error("Preallocated camera object detected")
self.oc_camera_info = oc_camera_info
self.oc_camera = QCamera(self.oc_camera_info)
self.oc_camera.setViewfinder(self.oc_view_finder)
self.oc_camera.setCaptureMode(QCamera.CaptureVideo)
self.oc_camera.error.connect(lambda: self.show_error_message(self.oc_camera.errorString()))
self.b_guard = True
self.__camera_sync_start()
self.__update_UI()
self.b_guard = False
self.setWindowTitle(self.oc_camera_info.description())
self.adjustSize()
self.setFixedSize(self.sizeHint())
def stop_preview(self):
if self.oc_camera is None:
return # this is correct logic, no error here
self.oc_camera.stop()
self.oc_camera.unload()
self.oc_camera = None
self.oc_camera_info = None
def is_save_state_needed(self):
return False
def save_state(self):
pass
def show_error_message(self, s_msg):
err = QtWidgets.QErrorMessage(self)
err.showMessage(s_msg)
def closeEvent(self, event):
if self.is_save_state_needed():
self.save_state()
self.stop_preview()
self.closeSignal.emit()
def __init__(self, d_param, oc_cam_info, *args, **kwargs):
super(CSmartCameraPreviewWindow, self).__init__(d_param, *args, **kwargs)
self.i_initial_cbox_resolution_idx = -1
self.f_initial_frame_rate = d_param['initial_frame_rate'] # in Hz
self.i_initial_frame_width = d_param['initial_frame_width']
self.i_initial_frame_height = d_param['initial_frame_height']
self.s_initial_frame_wh = "%i x %i" % (self.i_initial_frame_width, self.i_initial_frame_height)
s_cam_descr = oc_cam_info.description()
print("DEBUG: CSmartCameraPreviewWindow(): [%s @ %.1f Hz] %s" % \
(self.s_initial_frame_wh, self.f_initial_frame_rate, s_cam_descr) \
)
oc_cam = QCamera(oc_cam_info)
oc_cam.load()
l_resolutions = oc_cam.supportedViewfinderResolutions()
l_frate_ranges = oc_cam.supportedViewfinderFrameRateRanges()
oc_cam.unload()
del oc_cam
if len(l_frate_ranges) == 0 or len(l_resolutions) == 0:
raise RuntimeError("The camera (%s) does not support frame rate/resolution information retrieval" % s_cam_descr)
b_requested_fsize_found = False
for oc_res in l_resolutions:
if self.s_initial_frame_wh == "%i x %i" % (oc_res.width(), oc_res.height()):
b_requested_fsize_found = True
break
if not b_requested_fsize_found:
raise RuntimeError( \
"The camera [%s] does not support frame size value [%s] requested in the ini file" % \
(s_cam_descr, self.s_initial_frame_wh) \
)
b_requested_frate_found = False
for oc_frate in l_frate_ranges:
if abs(oc_frate.minimumFrameRate - self.f_initial_frame_rate) <= 0.5:
b_requested_frate_found = True
if not b_requested_frate_found:
raise RuntimeError( \
"The camera [%s] does not support frame rate value [%i Hz] requested in the ini file" % \
(s_cam_descr, self.f_initial_frame_rate) \
)
self.b_startup_guard = False
self.toolbar = QtWidgets.QToolBar("Preview")
l_items = []
for oc_res in l_resolutions:
l_items.append("%i x %i" % (oc_res.width(), oc_res.height()))
self.cbox_resolution = CLabeledComboBox("Resolution:")
self.cbox_resolution.cbox.addItems(l_items)
self.cbox_resolution.cbox.currentIndexChanged.connect(self.__cb_on_resolution_cbox_index_changed)
self.toolbar.addWidget(self.cbox_resolution)
self.toolbar.addSeparator()
l_items = []
for oc_frate in l_frate_ranges:
l_items.append("%f" % oc_frate.minimumFrameRate)
self.cbox_frame_rate = CLabeledComboBox("Frame Rate:")
self.cbox_frame_rate.cbox.addItems(l_items)
self.cbox_frame_rate.cbox.currentIndexChanged.connect(self.__cb_on_frame_rate_cbox_index_changed)
self.toolbar.addWidget(self.cbox_frame_rate)
self.toolbar.addSeparator()
self.addToolBar(self.toolbar)
class CMainWindow(QtWidgets.QMainWindow):
def __init__(self, *args, **kwargs):
super(CMainWindow, self).__init__(*args, **kwargs)
self.oc_camera = None
self.l_cameras = QCameraInfo.availableCameras()
if len(self.l_cameras) == 0:
self.fatal_error("No cameras found!")
# Top tool-bar
self.oc_toolbar = QtWidgets.QToolBar("Video source selector")
self.oc_toolbar.setMovable(False)
lbl = QtWidgets.QLabel("Select video source:")
self.oc_toolbar.addWidget(lbl)
camera_selector = QtWidgets.QComboBox()
camera_selector.addItems([ "[ %i ] %s" % (i_idx, oc_cam.description()) for i_idx, oc_cam in enumerate(self.l_cameras)])
camera_selector.currentIndexChanged.connect( self.start_preview )
self.oc_toolbar.addWidget(camera_selector)
self.oc_toolbar.layout().setSpacing(5)
self.oc_toolbar.layout().setContentsMargins(5, 5, 5, 5)
self.addToolBar(self.oc_toolbar)
# Central part (video frame)
self.oc_viewfinder = QCameraViewfinder()
self.setCentralWidget(self.oc_viewfinder)
# Bottom status bar
self.status = QtWidgets.QStatusBar()
self.setStatusBar(self.status)
self.setWindowTitle("CamView")
self.start_preview(0)
def fatal_error(self, s_msg):
QtWidgets.QMessageBox.critical(None, "Fatal Error", "%s\nThe application will exit now." % s_msg)
sys.exit(-1)
def start_preview(self, i_cam_idx):
if self.oc_camera is not None:
self.oc_camera.stop()
del self.oc_camera
self.oc_camera = QCamera(self.l_cameras[i_cam_idx])
self.oc_camera.setViewfinder(self.oc_viewfinder)
self.oc_camera.setCaptureMode(QCamera.CaptureVideo)
self.oc_camera.error.connect(lambda: self.show_error(self.oc_camera.errorString()))
self.oc_camera.start()
def stop_preview(self):
if self.oc_camera is None:
return # this is correct logic, no error here
self.oc_camera.stop()
self.oc_camera.unload()
self.oc_camera = None
def show_error(self, s):
err = QtWidgets.QErrorMessage(self)
err.showMessage(s)
def closeEvent(self, event):
self.stop_preview()
