python_streamer.py source

An example showing how to make a FAST streamer in python.

An example showing how to make a FAST streamer in python. A FAST streamer is a special process object which inherits from Streamer, and generates data asynchronously. This can for instance be streaming data from an ultrasound scanner in real-time or from disk.

import fast
import os
import numpy as np
from time import sleep

fast.Reporter.setGlobalReportMethod(fast.Reporter.COUT)
fast.downloadTestDataIfNotExists()


class MyStreamer(fast.PythonStreamer):
    """
    A simple FAST streamer which runs in its own thread.
    This streamer reads a series of MHD images on disk.
    This can be done easily with the ImageFileStreamer, but this is just an example.
    """

    def __init__(self):
        """
        Constructor, remember to create the output port here
        """
        super().__init__()
        self.createOutputPort(0)

    def generateStream(self):
        """
        This method runs in its own thread.
        Run you streaming loop here.
        Remember to call self.addOutputData and self.frameAdded for each frame.
        If these calls return and exception, it means the streaming should stop, thus you need to exit
        your streaming loop
        """
        path = fast.Config.getTestDataPath() + '/US/Heart/ApicalFourChamber/US-2D_#.mhd'
        frame = 0
        stop = False
        while not self.isStopped() and not stop: # Run until stopped
            print('Streaming', frame)

            try:
                # Read frame from disk
                importer = fast.ImageFileImporter.create(path.replace('#', str(frame)))
                image = importer.runAndGetOutputData()
                # Check if this was the last frame
                if not os.path.exists(path.replace('#', str(frame+1))):
                    # If last frame, we need to mark it as 'last frame'
                    image.setLastFrame('MyStreamer')

                self.addOutputData(0, image)
                self.frameAdded() # Important to notify any listeners
                sleep(0.02) # Sleep a little bit to mimick a framerate of 50
            except:
                # Streaming has been requested to stop OR there are no more frames OR some other error occured.
                # Thus we break the while loop
                break
            frame += 1


# Setup processing chain and run
streamer = MyStreamer.create()

renderer = fast.ImageRenderer.create().connect(streamer)

fast.SimpleWindow2D.create().connect(renderer).run()