Image Manager/CVBpy/CompositeStreamHandler

This example program is located in your CVB installation under %CVB%Tutorial/Image Manager/CVBpy/CompositeStreamHandler.

composite_stream_handler.py:

# @brief CVBpy Example Script for 3rd generation acquisition stack
# to demonstrate a basic usage of CompositeStreamHandler.
#
# 1. Discover all devices.
# 2. Open the first device found.
# 3. Create a stream handler.
# 4. Start acquiring composites.
# 5. Wait for the handler acquires 10 composites.
# 6. Stop acquiring composites.
#
# Requires: CVMockTL.
 
from typing import List, Tuple
from threading import Thread, Lock
import time
 
import cvb
 
 
TIMEOUT = 3  # sec
NUM_ELEMENTS_TO_ACQUIRE = 10  # composites
 
 
class Observer:
    """
    A demonstration helper that is used to check if a particular event happened.
    """
    def __init__(self):
        self._is_notified = False
 
    def notify(self) -> None:
        """
        Notifies the observer that the expected event has just happened.
        """
        self._is_notified = True
 
    @property
    def is_notified(self) -> bool:
        """
        Returns true if the observer has been notified. false otherwise.
        """
        return self._is_notified
 
 
class Monitor(Thread):
    """
    Waits until a given observer finishes its job.
    """
    def __init__(self, observer: Observer, lock: Lock):
        super().__init__()
        self._observer = observer
        self._is_completed = False
        self._lock = lock
 
    def run(self) -> None:
        while not self._is_completed:
            with self._lock:
                if self._observer.is_notified:
                    self._is_completed = True
            time.sleep(0.1)
 
 
class CustomStreamHandler(cvb.CompositeStreamHandler):
    """
    Derives the CompositeStreamHandler class so that we can implement our own
    customized tasks for the demonstration.
    """
    def __init__(self, streams: List[cvb.CompositeStream], observer: Observer,
                 lock: Lock):
        super().__init__(streams)
        self._num_deliverables = 0
        self._observer = observer
        self._lock = lock
 
    def handle_async_stream(self, streams: List[cvb.CompositeStream]) -> None:
        """
        Asynchronously called for all registered streams.
        """
 
        # the following code is the same as the default implementation;
        # this is just to demonstrate that you can freely override depending
        # on your demand.
        wait_result_list = []
        for stream in streams:
            wait_result_list.append(stream.wait_for(TIMEOUT * 1000))
 
        # let it take care of the acquired deliverables.
        self.handle_async_wait_result(wait_result_list)
 
    def handle_async_wait_result(
            self,
            result_tuples: List[
                Tuple[cvb.Composite, int, cvb.NodeMapEnumerator]]) -> None:
        """
        Asynchronously called for all acquired deliverables.
        """
 
        # the default implementation does nothing; you may add tasks by
        # yourself.
 
        with self._lock:
            if self._observer.is_notified:
                return
 
            # iterate over streams.
            print(f"round: #{self._num_deliverables}")
            for m, wait_result in enumerate(result_tuples):
                # check the wait status.
                print(f"stream: #{m}")
 
                status = wait_result[1]
                if status == cvb.WaitStatus.Ok:
                    status_string = "ok"
                else:
                    status_string = "not ok; "
                    if status == cvb.WaitStatus.Timeout:
                        status_string += "timeout"
                    elif status == cvb.WaitStatus.Abort:
                        status_string += "abort"
                    else:
                        status_string = "unknown"
                print(f"wait status: {status_string}")
 
                # pick up the delivered composite.
                composite = wait_result[0]
                for n in range(composite.item_count):
                    item = composite[n]
                    item_type = "unknown"
                    if isinstance(item, cvb.Image):
                        item_type = "image"
                    elif isinstance(item, cvb.Plane):
                        item_type = "plane"
                    elif isinstance(item, cvb.PlaneEnumerator):
                        item_type = "plane enumerator"
                    elif isinstance(item, cvb.PFNCBuffer):
                        item_type = "pfnc buffer"
                    print(f"composite item #{n}: {item_type}")
 
            print("")  # delimiter
            self._num_deliverables += 1
            if self._num_deliverables == NUM_ELEMENTS_TO_ACQUIRE:
                self._observer.notify()
 
 
if __name__ == "__main__":
    # enumerate devices.
    device_info_list = cvb.DeviceFactory.discover_from_root(
        cvb.DiscoverFlags.IgnoreVins)
 
    # cannot continue the demonstration if CVMockTL is not present
    access_token = None
    for device_info in device_info_list:
        if "MockTL" in device_info.access_token:
            access_token = device_info.access_token
    assert access_token
 
    # instantiate CVMockTL on the list; however, it is worth knowing
    # that you can bind streams of other devices to a stream handle if needed.
    with cvb.DeviceFactory.open(
            access_token,
            cvb.AcquisitionStack.GenTL) as device:  # type: cvb.GenICamDevice
 
        # create a stream handler.
        # IMPORTANT: this tutorial assumes that each stream is synchronized,
        # i.e., it is running at the same acquisition frame rate; if any of
        # them is out of sync the application will lose images. if any of the
        # streams are not synchronized, please consider preparing a dedicated
        # stream handler object for every single stream.
        streams = []
        for n in range(device.stream_count):
            streams.append(device.stream(cvb.CompositeStream, n))
 
        lock = Lock()
        observer = Observer()
        handler = CustomStreamHandler(streams, observer, lock)
 
        # start the data acquisition.
        handler.run()
 
        # wait for the job is done.
        monitor = Monitor(observer, lock)
        monitor.start()
        monitor.join(TIMEOUT)
 
        # stop the data acquisition, ignore errors.
        handler.try_finish()